Thèses : « Land Surface Water Index »

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Gortan, Emmanuelle. « Misura dello stato idrico di fraxinus ornus L. quale biomonitor dell'aridità ambientale in siti diversi del carso triestino ». Doctoral thesis, Università degli studi di Trieste, 2008. http://hdl.handle.net/10077/2658.

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2006/2007
L'aridità è una condizione ambientale che comporta una ridotta disponibilità d'acqua per le piante all'interno del suolo. La disponibilità d'acqua rappresenta, unitamente alla temperatura, il fattore ambientale che più di ogni altro condiziona la distribuzione e la produttività primaria della vegetazione. Poiché una prolungata aridità ambientale ha serie conseguenze sulla produttività degli ecosistemi forestali e sulla sopravvivenza di alcune specie vegetali meno competitive di altre in tali condizioni, è di fondamentale importanza quantificare il livello di aridità ambientale per poterne prevedere l'impatto attuale e le tendenze in atto. Il progetto di ricerca si poneva quindi l’obiettivo di individuare e definire un indice di aridità ambientale, che consentisse di rappresentare le relazioni che la pianta contrae con l’acqua presente nell’ambiente in funzione della risposta fisiologica della pianta al variare del contenuto idrico del suolo, attraverso un valore unico a significato ecofisiologico. L'individuazione di un parametro ecofisiologico in grado di stimare in modo affidabile l'impatto dello stress idrico poneva le basi per valutare possibili correlazioni con parametri ottenibili con il telerilevamento. Un'altra finalità del lavoro era, infatti, l'individuazione di un parametro di riferimento mediante l'utilizzo di tecniche di telerilevamento da satellite da applicare nello “scaling up” ecologico, che a partire dallo studio dell'impatto dello stress idrico su singole specie potesse indagare sistemi di vegetazione sempre più grandi nell'ottica di sviluppare una visione olistica di grandi aree in relazione all'aridità ambientale. La specie vegetale che è stata scelta come potenziale biomonitor è Fraxinus ornus L. ossia l'orniello, che è stato selezionato in quanto trattasi di una specie vegetale che si distingue per la notevole capacità di resistenza a condizioni di stress idrico e proprio per questa sua capacità, è una specie diffusa in una grande varietà di ambienti. L'area di studio scelta è stata la provincia di Trieste ed in particolare l'area carsica. Questa zona, infatti, offre l'opportunità di eseguire significativi biomonitoraggi per valutazioni quantitative e qualitative sull'ambiente, in quanto presenta una elevata variabilità di substrati litologici, costituiti da rocce soggette a fenomeni di dissoluzione da parte delle acque meteoriche chimicamente aggressive (rocce carsificabili), a cui sono associati diversi tipi di circolazione idrica. La presenza di una fitta rete di fessure e fratture nei substrati geologici a tratti determina un forte drenaggio dell'acqua all'interno del suolo dovuto a percolamento della stessa verso gli strati più profondi. Nella zona del Carso triestino, sono state selezionate 21 stazioni in base ad un criterio geomorfologico noto come carsificabilità, che misura in modo indiretto e qualitativo la capacità di campo di un suolo, e in modo tale da ricoprire tutto il territorio dell'area carsica all'interno della provincia di Trieste. Al fine di identificare quale fosse il parametro fisiologico o morfologico che meglio si addicesse allo scopo della ricerca, sono stati misurati nel periodo da Maggio a Settembre i parametri relativi alle relazioni pianta-acqua generalmente correlati allo stress idrico e cioè la conduttanza fogliare al vapore d'acqua (gL), il potenziale dell'acqua della foglia (Ψfoglia) e la conduttanza idraulica della foglia (Kfoglia). Contestualmente, sono stati misurati anche i diametri dei vasi xilematici. Grazie all'analisi di questi parametri è stato possibile eseguire uno studio biofisico accurato del comportamento idraulico dell'orniello in condizioni di limitazione della disponibilità d'acqua. Da questi dati emerge che la conduttanza fogliare al vapore d'acqua (gL) è il parametro più affidabile a rappresentare l'indice di aridità ambientale, in quanto è risultato essere il più sensibile alle variazioni nella disponibilità d'acqua. Il tentativo di integrare i dati di campo relativi a gL con quelli ottenuti mediante elaborazione di immagini satellitari non ha portato ai risultati sperati. L'indice ottenuto da dati telerilevati è risultato poco promettente come indice di riferimento per la realizzazione di uno “scaling-up”, in quanto non è risultato essere in grado di rilevare condizioni di stress idrico in aree caratterizzate da forte drenaggio dell'acqua (aree ad alta carsificabilità). L'applicabilità delle tecniche di telerilevamento da satellite nel monitoraggio dell'aridità ambientale risulta quindi fortemente limitata dalla struttura geomorfologica del territorio oggetto di studio.
XX Ciclo
1973

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Muche, Muluken Eyayu. « Surface water hydrologic modeling using remote sensing data for natural and disturbed lands ». Diss., Kansas State University, 2016. http://hdl.handle.net/2097/32609.

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Doctor of Philosophy
Department of Biological & Agricultural Engineering
Stacy L. Hutchinson
The Soil Conservation Service-Curve Number (SCS-CN) method is widely used to estimate direct runoff from rainfall events; however, the method does not account for the dynamic rainfall-runoff relationship. This study used back-calculated curve numbers (CNs) and Normalized Difference Vegetation Index (NDVI) to develop NDVI-based CNs (CN[subscript]NDV) using four small northeastern Kansas grassland watersheds with average areas of 1 km² and twelve years (2001–2012) of daily precipitation and runoff data. Analysis indicated that the CN[subscript]NDVI model improved runoff predictions compared to the SCS-CN method. The CN[subscript]NDVI also showed greater variability in CNs, especially during growing season, thereby increasing the model’s ability to estimate relatively accurate runoff from rainfall events since most rainfall occurs during the growing season. The CN[subscript]NDVI model was applied to small, disturbed grassland watersheds to assess the model’s ability to detect land cover change impact for military maneuver damage and large, diverse land use/cover watersheds to assess the impact of scaling up the model. CN[subscript]NDVI application was assessed using a paired watershed study at Fort Riley, Kansas. Paired watersheds were identified through k-means and hierarchical-agglomerative clustering techniques. At the large watershed scale, Daymet precipitation was used to estimate runoff, which was compared to direct runoff extracted from stream flow at gauging points for Chapman (grassland dominated) and Upper Delaware (agriculture dominated) watersheds. In large, diverse watersheds, CN[subscript]NDVI performed better in moderate and overall flow years. Overall, CN[subscript]NDVI more accurately simulated runoff compared to SCS-CN results: The calibrated model increased by 0.91 for every unit increase in observed flow (r = 0.83), while standard CN-based flow increased by 0.506 for every unit increase in observed flow (r = 0.404). Therefore, CN[subscript]NDVI could help identify land use/cover changes and disturbances and spatiotemporal changes in runoff at various scales. CN[subscript]NDVI could also be used to accurately estimate runoff from precipitation events in order to instigate more timely land management decisions.

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Amazirh, Abdelhakim. « Monitoring crops water needs at high spatio-temporal resolution by synergy of optical/thermal and radar observations ». Thesis, Toulouse 3, 2019. http://www.theses.fr/2019TOU30101.

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L'optimisation de la gestion de l'eau en agriculture est essentielle dans les zones semi-arides afin de préserver les ressources en eau qui sont déjà faibles et erratiques dues à des actions humaines et au changement climatique. Cette thèse vise à utiliser la synergie des observations de télédétection multispectrales (données radar, optiques et thermiques) pour un suivi à haute résolution spatio-temporelle des besoins en eau des cultures. Dans ce contexte, différentes approches utilisant divers capteurs (Landsat-7/8, Sentinel-1 et MODIS) ont été developpées pour apporter une information sur l'humidité du sol (SM) et le stress hydrique des cultures à une échelle spatio-temporelle pertinente pour la gestion de l'irrigation. Ce travail va parfaitement dans le sens des objectifs du projet REC "Root zone soil moisture Estimates at the daily and agricultural parcel scales for Crop irrigation management and water use impact: a multi-sensor remote sensing approach" (http://rec.isardsat.com/) qui visent à estimer l'humidité du sol dans la zone racinaire (RZSM) afin d'optimiser la gestion de l'eau d'irrigation. Des approches innovantes et prometteuses sont mises en place pour estimer l'évapotranspiration (ET), RZSM, la température de surface du sol (LST) et le stress hydrique de la végétation à travers des indices de SM dérivés des observations multispectrales à haute résolution spatio-temporelle. Les méthodologies proposées reposent sur des méthodes basées sur l'imagerie, la modélisation du transfert radiatif et la modélisation du bilan hydrique et d'énergie et sont appliquées dans une région à climat semi-aride (centre du Maroc). Dans le cadre de ma thèse, trois axes ont été explorés. Dans le premier axe, un indice de RZSM dérivé de LST-Landsat est utilisé pour estimer l'ET sur des parcelles de blé et des sols nus. L'estimation par modélisation de ET a été explorée en utilisant l'équation de Penman-monteith modifiée obtenue en introduisant une relation empirique simple entre la résistance de surface (rc) et l'indice de RZSM. Ce dernier est estimé à partir de la température de surface (LST) dérivée de Landsat, combinée avec les températures extrêmes (en conditions humides et sèches) simulée par un modèle de bilan d'énergie de surface piloté par le forçage météorologique et la fraction de couverture végétale dérivée de Landsat. La méthode utilisée est calibrée et validée sur deux parcelles de blé situées dans la même zone près de Marrakech au Maroc. Dans l'axe suivant, une méthode permettant de récupérer la SM de la surface (0-5 cm) à une résolution spatiale et temporelle élevée est développée à partir d'une synergie entre données radar (Sentinel-1) et thermique (Landsat) et en utilisant un modèle de bilan d'énergie du sol. L'approche développée a été validée sur des parcelles agricoles en sol nu et elle donne une estimation précise de la SM avec une différence quadratique moyenne en comparant à la SM in situ, égale à 0,03 m3 m-3. Dans le dernier axe, une nouvelle méthode est développée pour désagréger la MODIS LST de 1 km à 100 m de résolution en intégrant le SM proche de la surface dérivée des données radar Sentinel-1 et l'indice de végétation optique dérivé des observations Landsat. Le nouvel algorithme, qui inclut la rétrodiffusion S-1 en tant qu'entrée dans la désagrégation, produit des résultats plus stables et robustes au cours de l'année sélectionnée. Dont, 3,35 °C était le RMSE le plus bas et 0,75 le coefficient de corrélation le plus élevé évalués en utilisant le nouvel algorithme
Optimizing water management in agriculture is essential over semi-arid areas in order to preserve water resources which are already low and erratic due to human actions and climate change. This thesis aims to use the synergy of multispectral remote sensing observations (radar, optical and thermal data) for high spatio-temporal resolution monitoring of crops water needs. In this context, different approaches using various sensors (Landsat-7/8, Sentinel-1 and MODIS) have been developed to provide information on the crop Soil Moisture (SM) and water stress at a spatio-temporal scale relevant to irrigation management. This work fits well the REC "Root zone soil moisture Estimates at the daily and agricultural parcel scales for Crop irrigation management and water use impact: a multi-sensor remote sensing approach" (http://rec.isardsat.com/) project objectives, which aim to estimate the Root Zone Soil Moisture (RZSM) for optimizing the management of irrigation water. Innovative and promising approaches are set up to estimate evapotranspiration (ET), RZSM, land surface temperature (LST) and vegetation water stress through SM indices derived from multispectral observations with high spatio-temporal resolution. The proposed methodologies rely on image-based methods, radiative transfer modelling and water and energy balance modelling and are applied in a semi-arid climate region (central Morocco). In the frame of my PhD thesis, three axes have been investigated. In the first axis, a Landsat LST-derived RZSM index is used to estimate the ET over wheat parcels and bare soil. The ET modelling estimation is explored using a modified Penman-Monteith equation obtained by introducing a simple empirical relationship between surface resistance (rc) and a RZSM index. The later is estimated from Landsat-derived land surface temperature (LST) combined with the LST endmembers (in wet and dry conditions) simulated by a surface energy balance model driven by meteorological forcing and Landsat-derived fractional vegetation cover. The investigated method is calibrated and validated over two wheat parcels located in the same area near Marrakech City in Morocco. In the next axis, a method to retrieve near surface (0-5 cm) SM at high spatial and temporal resolution is developed from a synergy between radar (Sentinel-1) and thermal (Landsat) data and by using a soil energy balance model. The developed approach is validated over bare soil agricultural fields and gives an accurate estimates of near surface SM with a root mean square difference compared to in situ SM equal to 0.03 m3 m-3. In the final axis a new method is developed to disaggregate the 1 km resolution MODIS LST at 100 m resolution by integrating the near surface SM derived from Sentinel-1 radar data and the optical-vegetation index derived from Landsat observations. The new algorithm including the S-1 backscatter as input to the disaggregation, produces more stable and robust results during the selected year. Where, 3.35 °C and 0.75 were the lowest RMSE and the highest correlation coefficient assessed using the new algorithm

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Elbag, Mark A. « Impact of surrounding land uses on surface water quality ». Link to electronic thesis, 2006. http://www.wpi.edu/Pubs/ETD/Available/etd-050306-155834/.

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Thesis (M.S.)--Worcester Polytechnic Institute.
Keywords: Conductivity, pH, Dissolved Oxygen, UV absorbance, Source Water, Surface Water, Dissolved Organic Carbon, Total Organic Carbon, Particle Counts, Turbidity, E. coli, Fecal Coliforms, West Boylston Brook, Wachusett Reservoir, source water protection, surface water protection Includes bibliographical references (p.73-77).

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Elbag, Jr Mark A. « Impact of Surrounding Land Uses on Surface Water Quality ». Digital WPI, 2006. https://digitalcommons.wpi.edu/etd-theses/665.

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Source water protection is important to maintain public health by keeping harmful pathogens out of drinking water. Non-point source pollution is often times a major contributor of pollution to surface waters, and this form of pollution can be difficult to quantify. This study examined physical, chemical, and microbiological water quality parameters that may indicate pollution and may help to identify sources of pollution. These included measures of organic matter, particles, and indicator organisms (fecal coliforms and E. coli). The parameters were quantified in the West Boylston Brook, which serves as a tributary to the Wachusett Reservoir and is part of the drinking water supply for the Metropolitan Boston area. Water quality was determined over four seasons at seven locations in the brook that were selected to isolate specific land uses. The water quality parameters were first analyzed for trends by site and by season. Then, a correlation analysis was performed to determine relationships among the water quality parameters. Lastly, ANOVA analyses were used to determine statistically significant variations in water quality along the tributary.

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Cheng, Chi Han. « Land use effects on energy and water balance-developing a land use adapted drought index ». Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5160.

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Climate change is expected to increase the frequency, intensity and duration of droughts in all parts of the United States (US). Snow packs are disappearing earlier in the spring and summer, with reduced stream-flow. Lower reservoir levels, higher temperatures, and greater precipitation variability have been observed. Drought events in the US have threatened drinking water supplies for communities in Maryland and Chesapeake Bay as observed in 2001 through September 2002; Lake Mead in Las Vegas in 2000 through 2004; Peace River and Lake Okeechobee in South Florida in 2006; and Lake Lanier in Atlanta, Georgia in 2007. ENSO influences the climate of Florida; where El Nino years tend to be cooler and wetter, while La Nina years tend to be warmer and drier than normal in the fall through the spring, with the strongest effect in the winter. Both prolonged heavy rainfall and drought potentially have impacts on land uses and many aspects of Florida's economy and quality of life. Drought indices could integrate various hydrological and meteorological parameters and quantify climate anomalies in terms of intensity, duration, and spatial extent, thus making it easier to communicate information to diverse users. Hence, understanding local ENSO patterns on regional scales and developing a new land use drought index in Florida are critical in agriculture and water resources planning and managements. Current drought indices have limitations and drawbacks such as calculation using climate data from meteorological stations, which are point measurements. In addition, weather stations are scarce in remote areas and are not uniformly distributed. Currently used drought indices like the PDSI and the Standardized Precipitation Index (SPI) could not fully demonstrate the land use effects. Other limitations include no single index that addresses universal drought impact. Hence, there is a renewed interest to develop a new "Regional Land Use Drought Index (RLDI) that could be applied for various land use areas and serve for short term water resources planning. In this study, the first and second research topics investigated water and energy budgets on the specific and important land use areas (urban, forest, agriculture and lake) in the State of Florida by using the North American Regional Reanalysis (NARR) reanalysis data. NARR data were used to understand how drought events, EI Nino, La Nina, and seasonal and inter-annual variations in climatic variables affect the hydrologic and energy cycle over different land use areas. The results showed that the NARR data could provide valuable, independent analysis of the water and energy budgets for various land uses in Florida. Finally, the high resolution land use (32km x 32km) adapted drought indices were developed based on the NARR data from 1979 to 2002. The new regional land use drought indices were developed from normalized Bowen ratio and the results showed that they could reflect not only the level of severity in drought events resulting from land use effects, but also La Nina driven drought impacts.
ID: 031001561; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Title from PDF title page (viewed August 26, 2013).; Thesis (Ph.D.)--University of Central Florida, 2012.; Includes bibliographical references.
Ph.D.
Doctorate
Civil, Environmental, and Construction Engineering
Engineering and Computer Science
Civil Engineering

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Decker, Mark Ryan. « IMPROVING THE HYDROLOGICAL CYCLE IN LAND SURFACE CLIMATE MODELS ». Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/195627.

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The hydrological components of land surface climate models have increased greatly in complexity over the past decade, from simple bucket models to multilayer models including separate and distinct soil water and ground water components. While the parameterizations included in these models have also increased in complexity, the fundamental ability of the numerical solution for the vertical movement of soil water in the Community Land Model (or other land surface models) to simply maintain the hydrostatic solution of the original partial differential equation has yet to be determined.Also, the ability of current generation reanalysis products to simulate near surface quantities as gauged by flux tower measurements has yet to be determined.This study demonstrates that the numerical solution as used in CLM3.5 cannot maintain the hydrostatic state. An alternate form of the equation, titled the Modified Richards equation is presented so that the numerical solution maintains steady statesolutions. Also, an improved and simple bottom boundary condition is derived that itself doesn't destroy hydrostatic initial conditions. The new solution is demonstrated to be as accurate as proven numerical solutions while being one to three orders more computationally efficient. The Modified Richards equation together with the new bottom boundary condition is shown to improve the ability of CLM to simulate soil water, water table depth, and near surface turbulent fluxes.Comparison with flux tower observations shows that ERA-Interim better simulates near surface temperature and wind speed than other current generation reanalysis products. Reanalysis products are able to reproduce the flux tower observations on monthly timescales, and the errors between the products and the measurements are primarily due to biases. However, at six hourly timescales the errors are not only larger but also caused primarily by a lack of correlation with the observations.

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Chingombe, Wisemen. « Effects of land-cover - land-use on water quality within the Kuils - Eerste River catchment ». Thesis, University of Western Cape, 2012. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_5893_1373463134.

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The most significant human impacts on the hydrological system are due to land-use change. The conversion of land to agricultural, mining, industrial, or residential uses significantly alters the hydrological characteristics of the land surface and modifies pathways and rates of water flow. If this occurs over large or critical areas of a catchment, it can have significant short and long-term impacts, on the quality of water. While there are methods available to quantify the pollutants in surface water, methods of linking non-point source pollution to water quality at catchment scale are lacking. Therefore, the research presented in this thesis investigated modelling techniques to estimate the effect of land-cover type on water quality. The main goal of the study was to contribute towards improving the understanding of how different land-covers in an urbanizing catchment affect surface water quality. The aim of the research presented in this thesis was to explain how the quality of surface runoff varies on different land-cover types and to provide guidelines for minimizing water pollution that may be occurring in the Kuils-Eerste River catchment. The research objectives were
(1) to establish types and spatial distribution of land-cover types within the Kuils-Eerste River catchment, (2) to establish water quality characteristics of surface runoff from specific land-cover types at the experimental plot level, (3) to establish the contribution of each land-cover type to pollutant loads at the catchment scale. Land-cover characteristics and water quality were investigated using GIS and Remote Sensing tools. The application of these tools resulted in the development of a land-cover map with 36 land classifications covering the whole catchment. Land-cover in the catchment is predominantly agricultural with vineyards and grassland covering the northern section of the catchment. Vineyards occupy over 35% of the total area followed by fynbos (indigenous vegetation) (12.5 %), open hard rock area (5.8 %), riparian forest (5.2 %), mountain forest

(5 %), dense scrub (4.4 %), and improved grassland (3.6 %). The residential area covers about 14 %. Roads cover 3.4 % of the total area. Surface runoff is responsible for the transportation of large quantities of pollutants that affect the quality of water in the Kuils-Eerste River catchment. The different land-cover types and the distribution and concentration levels of the pollutants are not uniform. Experimental work was conducted at plot scale to understand whether land-cover types differed in their contributions to the concentration of water quality attributes emerging from them. Four plots each with a length of 10 m to 12 m and 5 m width were set up. Plot I was set up on open grassland, Plot II represented the vineyards, Plot III covered the mountain forests, and Plot IV represented the fynbos land-cover. Soil samples analyzed from the experimental plots fell in the category of sandy soil (Sa) with the top layer of Plot IV (fynbos) having loamy sand (LmSa). The soil particle sizes range between fine sand (59.1 % and 78.9 %) to coarse sand (between 7 % and 22 %). The content of clay and silt was between 0.2 % and 2.4 %. Medium sand was between 10.7 % and 17.6 %. In terms of vertical distribution of the particle sizes, a general decrease with respect to the size of particles was noted from the top layer (15 cm) to the bottom layer (30 cm) for all categories of the particle sizes. There was variation in particle size with depth and location within the experimental plots.Two primary methods of collecting water samples were used
grab sampling and composite sampling. The quality of water as represented by the samples collected during storm events during the rainfall season of 2006 and 2007 was
used to establish
water quality characteristics for the different land-cover types. The concentration of total average suspended solids was highest in the following land-cover types, cemeteries (5.06 mg L^-1), arterial roads/main roads (3.94 mg L^-1), low density residential informal squatter camps (3.21 mg L^-1) and medium density residential informal townships (3.21 mg L^-1). Chloride concentrations were high on the following land-cover types, recreation grass/ golf course (2.61 mg L^-1), open area/barren land (1.59 mg L^-1), and improved grassland/vegetation crop (1.57 mg L^-1). The event mean concentration (EMC) values for NO₃-N were high on commercial mercantile (6 mg L^-1) and water channel (5 mg L^-1). The total phosphorus concentration mean values recorded high values on improved grassland/vegetation crop (3.78 mg L^-1), medium density residential informal townships (3mgL^-1) and low density residential informal squatter camps (3 mg L^-1). Surface runoff may also contribute soil particles into rivers during rainfall events, particularly from areas of disturbed soil, for example areas where market gardening is taking place. The study found that different land cover types contributed differently to nonpoint source pollution. A GIS model was used to estimate the diffuse pollution of five pollutants (chloride, phosphorus, TSS, nitrogen and NO₃-N) in response to land cover variation using water quality data. The GIS model linked land cover information to diffuse nutrient signatures in response to surface runoff using the Curve Number method and EMC data were developed. Two models (RINSPE and N-SPECT) were used to estimate nonpoint source pollution using various GIS databases. The outputs from the GIS-based model were compared with recommended water quality standards. It was found that the RINSPE model gave accurate results in cases where NPS pollution dominate the total pollutant inputs over a given land cover type. However, the N-SPECT model simulations were too uncertain in cases where there were large numbers of land cover types with diverse NPS pollution load. All land-cover types with concentration values above the recommended national water quality standard were considered as areas that needed measures to mitigate the adverse effects of nonpoint pollution. The expansion of urban areas and agricultural land has a direct effect on land cover types within the catchment. The land cover changes have adverse effect which has a potential to contribute to pollution.

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De, Chiara Giovanna. « Satellite remote sensing for surface soil water content estimation ». Doctoral thesis, Universita degli studi di Salerno, 2010. http://hdl.handle.net/10556/125.

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2008 - 2009
Satellite remote sensing is a useful source of observations of land surface hydrologic variables and processes and could be a practical substitution of conventional in-situ monitoring. Most of hydrological dynamic processes change not only throughout the years but also within weeks or months and their monitoring requires frequent observations. The most prominent advantage of the remote sensing technologies is that they offer a synoptic view of the dynamics and spatial distribution of phenomena and parameters, often difficult to monitor with traditional ground survey, with a frequent temporal coverage. Many of the variables in the land surface water balance can now be observed with satellite techniques thanks to an extensive development over the last decades. Often the problem connected to the use of remotely sensed data is their accuracy that, according to the sensor used and to the application considered, can ranges from moderate to excellent. The objective of this thesis has been to evaluate the use of satellite remote sensing techniques for the monitoring of two variables useful for hydrology applications: water body extension and soil moisture monitoring. The capability to map water surface is important in many hydrological applications, in particular accurate information on the extent of water boundary is essential for flood monitoring and water reservoir management. Often, this information is difficult to retrieve using traditional survey techniques because water boundaries can be fast moving as in floods or may be inaccessible. In this PhD thesis, an artificial basin for which in-situ information about the water extension are available is used as case study. The area extension recorded daily by the dam owner is compared to the one retrieved by using satellite images acquired from SAR and TM/ETM+ sensors. The outcomes of the analysis show that satellite images are able to map water body surfaces with a good accuracy. The analysis also highlighted the factor to be taken into account while using types of sensors. Soil moisture is recognized as a key variable in different hydrological and ecological processes as it controls the exchange of water and heat energy between land surface and the atmosphere. Despite the high spatial variability of this parameter it has been demonstrated that many satellite sensors are able to retrieve soil moisture information of the surface layer at catchment scale. Among other sensors, the Scatterometer is very useful for climatic studies and modelling analysis thanks, respectively, to the temporal frequency, global coverage and to the long time series availability. Even though the ERS Scatterometer has been designed to measure the wind over the ocean surface, in recent years it has been pointed out that backscattering measurements have high potentiality for soil moisture retrieval. The second task of this PhD thesis, concerning the use of satellite data for soil moisture monitoring, has been developed at Serco S.p.A. in the framework of the Advanced Scatterometer Processing System (ASPS) project developed by ESA (European Space Agency) to reprocess the entire ERS Scatterometer mission. Since the beginning of the ERS-1 Scatterometer mission in 1991 a long dataset of C-band backscattering signal from the Earth surface is available for studies and researches. This is a very consistent dataset, but in particular for climatology studies it is important to have high quality and homogeneous long term observation as also stated in the key guidelines included in the Global Climate Observing System (GCOS) from the World Meteorological Organization (WMO). The main goal of this task has been the generation of the new Scatterometer ASPS products with improved data quality and spatial resolution. This achievement required a long preparation activity but represents an important contribution to the C-band Scatterometer dataset available to the scientific community. In order to evaluate the usage of the re-processed Scatterometer data for soil moisture estimation, the backscattering measurements derived in the new ASPS products have been then compared to in-situ volumetric soil moisture data and the relationship between radar backscattering and soil moisture measurements has been investigated under different conditions: angle of incidence, angle of azimuth, data measurements resolution, season of the year. Analysis results show that a relationship between the C-band backscattering coefficient and the in-situ volumetric soil moisture exists and takes into account the incidence and azimuth angles and the vegetation cover. [edited by author]
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Wang, Shusen. « Modelling water, carbon, and nitrogen dynamics in CLASS, Canadian Land Surface Scheme ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0008/NQ59692.pdf.

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Tediosi, A. « HERBICIDE TRANSPORT FROM LAND TO SURFACE WATER IN AN ARTIFICIALLY DRAINED CATCHMENT ». Doctoral thesis, Università degli Studi di Milano, 2010. http://hdl.handle.net/2434/150206.

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Pesticide use is often associated with a number of negative impacts on the environment and on water quality. In this thesis the processes contributing to herbicide transport from land to surface water were examined, using a combination of existing data analysis, modelling, and monitoring. Field investigations of herbicide transport were conducted on an artificially drained field dominated by heavy clay soil (Denchworth soil association), in the Upper Cherwell catchment (UK). The main drain was monitored over five months during November 2009 to March 2010, when the field was in oilseed rape (OSR) and was treated with propyzamide and carbetamide. In the UK recent attention has focused on these two herbicides, which are used to control black grass in OSR. Both chemicals were detected at very high concentrations (up to 55.7 μg l-1 and 694 μg l-1 for propyzamide and carbetamide, respectively). The concentration pattern clearly followed drain discharge, with rapid increase on the rising hydrograph limb and a quasi-exponential decline on the recession limb. The MACRO pesticide fate model, which was applied to represent field observations, supported the hypothesis that herbicide transport to drains is a very quick process and suggested that preferential flow is a major transport mechanism. This analysis has contributed to the development of a preliminary model of catchment-scale pesticide transfers, which integrates hillslope responses through the river network to simulate flow and herbicide losses at the catchment outlet. The application of this model tends to corroborate the hypothesis that rapid transport to drains play a major role in herbicide contamination of surface water at the catchment outlet. Herbicides seem to peak about one day after rainfall events. The results also suggest that the first few rain events following herbicide application are very critical in terms of chemical losses.

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James, Tosin. « Changes in Land Use Land Cover (LULC), Surface Water Quality and Modelling Surface Discharge in Beaver Creek Watershed, Northeast Tennessee and Southwest Virginia ». Digital Commons @ East Tennessee State University, 2020. https://dc.etsu.edu/etd/3747.

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Beaver Creek is an impaired streams that is not supporting its designated use for recreation due to Escherichia coli (E.coli), and sediment. To address this problem, this thesis was divided into two studies. The first study explored changes in Land Use Land Cover (LULC), and its impact on surface water quality. Changes in E.coli load between 1997-2001 and 2014-2018 were analyzed. Also, Landsat data of 2001, and 2018 were examined in Terrset 18.31. Mann-Whitney test only showed a significant reduction in E.coli for one site. Negative correlation was established between E.coli load, and Developed LULC, Forest LULC, and Cultivated LULC. The second study modelled discharge for Beaver Creek watershed using HEC-HMS. This study simulated discharge in an upstream sub-watershed of Beaver Creek, and the full Beaver Creek with a Nash-Sutcliffe of 0.007, and R2 0.20. Sub-basins with high discharge were identified for further examination for possible high sediment load.

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Bourgeois-Calvin, Andrea. « Relationship between Land Use and Surface Water Quality in a Rapidly Developing Watershed in Southeast Louisiana ». ScholarWorks@UNO, 2008. http://scholarworks.uno.edu/td/714.

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The Tangipahoa River and Natalbany River watersheds (Tangipahoa Parish/County) in the Lake Pontchartrain Basin (southeastern Louisiana) are experiencing rapid urbanization, particularly in the wake of the 2005 hurricane season. To document the impact of land use on water quality, thirty sites were monitored for surface water physiochemical, geochemical, and bacteriological parameters. Water quality data was compared to land use within four sub-watersheds of the Tangipahoa Watershed and three sub-watersheds of the Natalbany Watershed. Urbanization had the most profound impact on water quality of all land uses. In watersheds with little urban land cover (< 7% with the sub-watershed) waterbodies had low dissolved salt, nutrient, and fecal coliform concentrations and high dissolved oxygen levels. Waterbodies within the urban region (> 28% urban land cover within the sub-watershed) of the parish had significantly greater dissolved salt, nutrient, and fecal coliform concentrations and decreased dissolved oxygen concentrations. Specifically, nutrient and fecal coliform concentrations increased as streams flowed through urban areas. The specific conductance, fecal coliform counts, concentrations of sulfate, HCO3-C, sodium, and nutrients (NO3-N, NO2-N, NH4-N, and PO4-P), and the ratios of Na:Cl, Cl:Br, and SO4:Cl were shown to be the parameters most indicative of urban impacts. Many of the geochemical parameters correlated significantly with each other, particularly within the urban streams (the streams with the greatest concentrations). While fecal coliform counts were high within the urban streams, programs to address malfunctioning wastewater treatment plants (WWTP) appear to be working, with fecal coliform counts declining and dissolved oxygen levels rising during the course of the data collection. In contrast, sites undergoing rapid development showed an increase in turbidity levels and a decrease on dissolved oxygen levels (both going from healthy to unhealthy levels) during the 18-month course of the data collection. By understanding the impacts of urbanization on streams of the Gulf Coast, local and regional municipalities may be able to reduce the impacts in already urbanized areas or mitigate the impacts at the outset of development.

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Gustafsson, David. « Boreal land surface water and heat balance : Modelling soil-snow-vegetation-atmosphere behaviour ». Doctoral thesis, KTH, Mark- och vattenteknik, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3406.

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The water and heat exchange in thesoil-snow-vegetation-atmosphere system was studied in order toimprove the quantitative knowledge of land surface processes.In this study, numerical simulation models and availabledatasets representing arable land, sub-alpine snowpack, andboreal forest were evaluated at both diurnal and seasonaltimescales. Surface heat fluxes, snow depth, soil temperatures andmeteorological conditions were measured at an agriculturalfield in central Sweden during three winters and two summersfrom 1997 to 2000 within the WINTEX project. A one-dimensionalsimulation model (COUP) was used to simulate the water and heatbalance of the field. Comparison of simulated and measured heatfluxes in winter showed that parameter values governing theupper boundary condition were more important for explainingmeasured fluxes than the formulation of the internal mass andheat balance of the snow cover. The assumption of steady stateheat exchange between the surface and the reference height wasinadequate during stable atmospheric conditions. Independentestimates of the soil heat and water balance together with thecomparison of simulated and measured surface heat fluxes showedthat the eddy-correlation estimates of latent heat fluxes fromthe arable field were on average 40 % too low. The ability of a multi-layered snowpack model (SNTHERM) tosimulate the layered nature of a sub-alpine snowpack wasevaluated based on a dataset from Switzerland. The modelsimulated the seasonal development of snow depth and densitywith high accuracy. However, the models ability to reproducethe strong observed snowpack layering was limited by theneglection of the effect of snow microstructure on snowsettling, and a poor representation of water redistributionwithin the snowpack. The representation of boreal forest in the land surfacescheme used within a weather forecast (ECMWF) model was testedwith a three-year dataset from the NOPEX forest site in centralSweden. The new formulation with separate energy balances forvegetation and the soil/snow beneath the tree cover improvedthe simulation of seasonal and diurnal variations in latent andsensible heat flux. Further improvements of simulated latentheat fluxes were obtained when seasonal variation in vegetationproperties was introduced. Application of the COUP model withthe same dataset showed that simulation of evaporation fromintercepted snow contributed to a better agreement with themeasured sensible heat flux above forests, but also indicatedthat the measurements might have underestimated latent heatflux. The winter sensible heat flux above the forest wasfurther improved if an upper limit of the aerodynamicresistance of 500 s m-1 was applied for stable conditions. A comparison of the water and heat balance of arable landand forest confirmed the general knowledge of the differencesbetween these two surface types. The forest contributed withconsiderably more sensible heat flux to the atmosphere than thearable land in spring and summer due to the lower albedo andrelatively less latent heat flux. Latent heat flux from theforest was higher in winter due to the evaporation ofintercepted snow and rain. The net radiation absorbed by theforest was 60 % higher than that absorbed by the arable land,due to the lower surface albedo in winter. Key words:soil; snow; land surface heat exchange;forest; arable land; eddy-correlation.
QC 20100614

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Yeh, Pat Jen-Feng 1969. « Representation of water table dynamics in a land surface scheme : observations, models, and analyses ». Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/29617.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2003.
Includes bibliographical references (leaves 198-207).
A recent regional-scale water balance analysis has indicated that the groundwater storage and groundwater runoff are significant terms in the monthly and annual water balance for areas with a shallow water table. However, most of the current land surface parameterization schemes lack any representation of regional groundwater aquifers. Such a simplified representation of subsurface hydrological processes would result in significant errors in the predicted land-surface states and fluxes especially for the shallow water table areas in humid regions. This study attempts to address this deficiency. To incorporate the water table dynamics into a land surface scheme LSX, a lumped aquifer model is developed to represent the regional unconfined aquifer as a nonlinear reservoir, in which the aquifer simultaneously receives the recharge from the overlying soils, and discharges runoff into streams. The dependence of groundwater runoff on the water table depth (WTD), i.e., groundwater rating-curve, is parameterized empirically based on the observations in Illinois. The unconfined aquifer model is linked to the soil model in a land surface scheme LSX through the groundwater recharge flux (i.e., soil drainage flux). The total thickness of the unsaturated zone varies in response to the water table fluctuations, thereby interactively couples the aquifer model with the soil model. The second issue to be addressed in this thesis is the representation of the sub-grid variability of water table depths (WTD) in the coupled model LSXGW. A statistical-dynamical (SD) approach is used to account for the effects of the unresolved sub-grid variability of WTD in the grid-scale groundwater runoff. The probability distribution function (PDF) of WTD is specified as a two-parameter Gamma distribution based on observations.
(cont.) The scale of this PDF is dynamic according to the varying grid-mean WTD at each time step. The shape parameter of the PDF describing the WTD is kept constant. The grid-scale groundwater rating-curve (i.e., aquifer storage-discharge relationship) is derived statistically by integrating a point groundwater runoff model with respect to the PDF of WTD. Next, a mosaic approach is utilized to account for the effects of sub-grid variability of WTD in the grid-scale groundwater recharge. According to the time-varying PDF, a grid-cell is categorized into different sub-grids based on WTD. The fraction describing each sub-grid can be determined from the WTD PDF; hence it varies with time. The grid-scale hydrologic fluxes are computed by averaging all the sub-grid fluxes weighted by their fractions. This new methodology combines the strengths of the SD approach and the mosaic approach. The developed model has been successfully tested in Illinois for an 11-year period (1984-1994). The results indicate that the simulated hydrologic variables (soil saturation and WTD) and fluxes (evaporation, runoff, and groundwater recharge) agree well with the observations in Illinois. Nevertheless, it is recognized that the excellent performance of LSXGW in the Illinois simulation is significantly attributed to the reliable estimation of the macro-scale groundwater rating-curve ...
by Pat Jen-Feng Yeh.
Ph.D.

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El, Vilaly Mohamed Abd salam Mohamdy. « Drought Monitoring with Remote Sensing Based Land Surface Phenology Applications and Validation ». Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/301553.

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Droughts are a recurrent part of our climate, and are still considered to be one of the most complex and least understood of all natural hazards in terms of their impact on the environment. In recent years drought has become more common and more severe across the world. For more than a decade, the US southwest has faced extensive and persistent drought conditions that have impacted vegetation communities and local water resources. The focus of this work is achieving a better understanding of the impact of drought on the lands of the Hopi Tribe and Navajo Nation, situated in the Northeastern corner of Arizona. This research explores the application of remote sensing data and geospatial tools in two studies to monitor drought impacts on vegetation productivity. In both studies we used land surface phenometrics as the data tool. In a third related study, I have compared satellite-derived land surface phenology (LSP) to field observations of crop stages at the Maricopa Agricultural Center to achieve a better understanding of the temporal sensitivity of satellite derived phenology of vegetation and understand their accuracy as a tool for monitoring change. The first study explores long-term vegetation productivity responses to drought. The paper develops a framework for drought monitoring and assessment by integrating land cover, climate, and topographical data with LSP. The objective of the framework is to detect long-term vegetation changes and trends in the Normalized Difference Vegetation Index (NDVI) related productivity. The second study examines the major driving forces of vegetation dynamics in order to provide valuable spatial information related to inter-annual variability in vegetation productivity for mitigating drought impacts. The third study tests the accuracy of remote sensing-derived LSP by comparing them to the actual seasonal phases of crop growth. This provides a way to compare and validate the various LSP algorithms, and more crucially, helps to characterize the remote sensing-based metrics that contrast with the actual biological phenophases of the crops. These studies demonstrate how remote sensing data and simple statistical tools can be used to assess drought effects on vegetation productivity and to inform about land conditions, as well as to better understand the accuracy of satellite derived LSP.

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K, C. Pratima, et C. Pratima K. « Effect of Climate Conditions on Land Surface Productivity Across the Mojave, Sonoran, and Chihuahua Deserts and Apache Highlands ». Thesis, The University of Arizona, 2017. http://hdl.handle.net/10150/626150.

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Understanding the patterns and relationships between land surface productivity and the climatic condition is essential to predict the impact of climate change. This study aims to understand spatial temporal variability and relationships of land surface productivity using Normalized Difference Vegetation Index (NDVI) and drought indices, mainly Standard Precipitation Index (SPI) and Standard Precipitation Evaporation Index (SPEI) across four ecoregions: Mojave, Sonoran, Apache Highlands and Chihuahua of the Southwest United States. Moderate Resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) and land cover data, and Parameter Regression on Independent Slopes Model (PRISM) precipitation and temperature data were used for analysis. Using Mann-Kendall, I calculated the trends in annual and seasonal NDVI, SPI and SPEI datasets. I used the Pearson Correlation Coefficients to examine the response of integrated and monthly NDVI values to SPI and SPEI values. The positive and negative trends were found during the annual and monsoon seasons whereas only negative trends were found during the spring season for NDVI, SPI and SPEI values. The relationship between NDVI and coincident and antecedent SPEI values changed significantly by area and season for each of the ecoregions across the east-west seasonal precipitation gradient.

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Mitchell, Bruce Coffyn. « Urbanization and Land Surface Temperature in Pinellas County, Florida ». Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3250.

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Since the early 1800's, many studies have recognized increased heat in urban areas, known as the urban heat island (UHI) effect, as one of the results of human modification to the natural landscape. UHI is related to differences in land surface temperature (LST) between rural areas and urban areas where factors of the built environment such as the thermodynamic capacities of materials, structural geometry, and heat generating activities cause increased storage and re-radiation of heat to the atmosphere. This thesis examines the correlation between factors of urbanization and differences in land surface temperature (LST) in the subtropical climate of Pinellas County, Florida using remote sensing techniques. It describes the spatial pattern of LST, analyzes its relationship to factors of urbanization relative to NDVI, percentage of impervious surface, and land use land cover in the study area. It also assesses the effectiveness of remote sensing as an efficient method of identifying LST patterns at the local and neighborhood level for mitigation strategies. Landsat TM thermal band imagery for three dates; April 1986, 2001 and 2009 was processed using Qin's mono-window algorithm (MWA) technique to derive LST levels. This data was compared to in-situ readings, then normalized and statistically analyzed for correlation with vegetation ratio (NDVI) and imperviousness percentages derived using linear spectral mixing/unmixing, and also with land use/land cover classification. The resulting LST spatial pattern is a gradient across the peninsular landscape, from cooler water and wetland areas to a generally warmer interior, interspersed with micro-urban heat islands (MUHIs), corresponding to urban structures and "cool-islands" of parkland and lakes. Correspondence between LST pattern and urban structures and land use demonstrates the suitability of medium resolution remote sensing data and techniques for identifying micro-urban heat islands (MUHIs) for possible mitigation. Mitigation could include relatively low-cost measures like replacement of inefficient asphalt roofs with more reflective and emissive "cool roofs," placement of "street trees" to enhance shade, and replacement of impervious pavements by permeable surfaces. The thesis concludes that Landsat TM imagery processed with the MWA provides an efficient, relatively low-cost method for locating MUHIs. Satellite remote sensing, combined with aerial photography can facilitate neighborhood level analysis for the implementation of low-cost mitigation techniques. Previous studies have demonstrated that these are successful ways to mitigate the UHI effect at the micro-scale level; lowering urban heat and saving energy, and also facilitating the reintegration of natural elements into the urban environment.

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Naugler, Trudy Lynn. « Groundwater - surface water interactions in the Salmon River Watershed, BC : integrating spectroscopy, isotopes, water quality, and land use analyses ». Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/31782.

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Understanding the sources and pathways of water pollutants is critical for protecting freshwater resources. Relationships between water quality and land use can be obscured by variable land use, seasonal variability, and interactions between surface water and groundwater. This research combines the tools of fluorescence spectroscopy, nitrate stable isotopes and water chemistry to better understand land use impacts on water quality. The Hopington aquifer, one of the most vulnerable aquifers in the Lower Fraser Valley, is a source of drinking water for the Township of Langley. This aquifer is also responsible for maintaining the summer stream flow in the Salmon River, a productive Coho salmon stream. Elevated nitrates in both ground and stream water are a concern. Twelve stream sites and eleven groundwater wells were sampled during 2006 to try and "fingerprint" different water sources. Samples were analyzed for: uv-visible absorbance, fluorescence, DOC, nutrients (ammonium, nitrate, ortho-phosphate), chloride, trace elements, and nitrate-isotopes (δ¹⁸0 and δ¹⁵N). The combination of these tools provided a more detailed look at the groundwater - surface water interactions and helped track pollutants within the system. Nitrate concentrations in the Salmon River increase where it cuts through the Hopington aquifer; concentrations peak in August when groundwater makes up the greatest proportion of the stream flow. Humic-like fluorescence was able to measure this groundwater influence because groundwater has much lower fluorescence. Nitrate isotopes showed that inorganic fertilizers were not a dominant source, but that soil N, septic tank leakage, and manure were possible sources. Stream sites influenced by groundwater had an isotopic fingerprint similar to nearby wells, showing that the nitrate source(s) were the same. A GIS-based land use analysis suggested that agricultural land use was having the greatest impact on local water quality, especially on surface waters in the wet season. Protein-like fluorescence showed potential as a tool for pollution monitoring and should be explored further.
Science, Faculty of
Resources, Environment and Sustainability (IRES), Institute for
Graduate

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Lanfranco, R. « OPTICAL DETECTION OF MOLECULAR INTERACTIONS ON THE SURFACE OF MATERIALS INDEX-MATCHED TO WATER ». Doctoral thesis, Università degli Studi di Milano, 2015. http://hdl.handle.net/2434/378031.

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The idea to have highly effective autonomous sensors able to measure and share information about the quality of our environment, and particularly water, in our lakes and rivers, our water supply system and the outputs of municipal and industrial wastewater treatment systems is revolutionary and fascinating. These sensors could be densely deployed at multiple locations, and the information may be available to citizens through the Internet. This idyllic vision, nowadays, is far away from being reality, despite the huge effort made to develop innovative molecular sensors. The main challenges related to the realization of these autonomous sensors network are the biofouling, power supply and compactness. In fact, despite thousands of papers in literature about development of novel nanostractured materials for sensing, for instance, there is still not a single example of any of these device being used in direct contact with water for long-term environmental monitoring. The work presented in this thesis proposes a new kind of optical sensor that combines a fast and low cost method to detect water pollutant with good performance and robustness. In particular, this work is focused on the detection of small molecular pollutants, as oils compounds and surfactants. An innovative aspect of the proposed approach relies on the use of a novel class of materials as sensing substrate which have peculiar and fascinating optical properties: these are amorphous perfluorinated polymers with refractive index similar to that of water. When immersed in aqueous solutions, they provide extremely low reflection or scattering of light, hence they become barely visible. For this reason, this class of materials is called phantom. In this limit, when a thin molecular layer spontaneously adsorbs on the surfaces of these materials, the reflected or scattered light increases, providing the basis for optical detection of molecules. In this work, three different phantom materials made of perfluorinated polymers are exploited in the framework of the detection of water contaminants: a prism, microporous membranes and micro-beads, that represent the building blocks for the assembly of an invisible chromatography column. The membrane and the micro-beads were produced for the first time during this work. The use of fluoropolymer prism substrate for molecular detection was already proposed in recent works to realize label-free biosensors based on the functionalization of the surface with antibodies. Here I extend the exploitation of this system to the detection of molecular pollutant through their adsorption on the bare surface of the fluoropolymer materials, without the need of any surface treatment. Despite the lack of surface functionalization, a selectivity in the adsorption of various classes of molecules is demonstrated.

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Valayamkunnath, Prasanth. « Understanding the Role of Vegetation Dynamics and Anthropogenic induced Changes on the Terrestrial Water Cycle ». Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/105061.

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The land surface and atmosphere interact through complex feedback loops that link energy and water cycles. Effectively characterizing these linkages is critical to modeling weather and climate extremes accurately. Seasonal variability in vegetation growth and human-driven land cover changes (LCC) can alter the biophysical properties of the land surface, which can in turn influence the water cycle. We quantified the impacts of seasonal variability in vegetation growth on land surface energy and water balances using ecosystem-scale eddy covariance and large aperture scintillometer observations. Our results indicated that the monthly precipitation and seasonal vegetation characteristics such as leaf area index, root length, and stomatal resistance are the main factors influencing ecosystem land surface energy and water balances when soil moisture and available energy are not limited. Using a regional-scale climate model, we examined the effect of LCC and irrigation on summer water cycle characteristics. Changes in biophysical properties due to LCC reducing the evapotranspiration, atmospheric moisture, and summer precipitation over the contiguous United States (CONUS). The combined effects of LCC and irrigation indicated a significant drying over the CONUS, with increased duration and decreased intensity of dry spells, and reduced duration, frequency, and intensity of wet spells. Irrigated cropland areas will become drier due to the added effect of low-precipitation wet spells and long periods (3-4% increase) of dry days, whereas rainfed croplands are characterized by intense (1-5% increase), short-duration wet spells and long periods of dry days. An analysis based on future climate change projections indicated that 3–4 °C of warming and an intensified water cycle will occur over the CONUS by the end of the 21st century. The results of this study highlighted the importance of the accurate representation of seasonal vegetation changes and LCC while forecasting present and future climate.
Doctor of Philosophy

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Widén-Nilsson, Elin. « Global-Scale Modelling of the Land-Surface Water Balance : Development and Analysis of WASMOD-M ». Doctoral thesis, Uppsala University, Department of Earth Sciences, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8352.

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Water is essential for all life on earth. Global population increase and climate change are projected to increase the water stress, which already today is very high in many areas of the world. The differences between the largest and smallest global runoff estimates exceed the highest continental runoff estimates. These differences, which are caused by different modelling and measurement techniques together with large natural variabilities need to be further addressed. This thesis focuses on global water balance models that calculate global runoff, evaporation and water storage from precipitation and other climate data.

A new global water balance model, WASMOD-M was developed. Already when tuned against the volume error it reasonable produced within-year runoff patterns, but the volume error was not enough to confine the model parameter space. The parameter space and the simulated hydrograph could be better confined with, e.g., the Nash criterion. Calibration against snow-cover data confined the snow parameters better, although some equifinality still persisted. Thus, even the simple WASMOD-M showed signs of being overparameterised.

A simple regionalisation procedure that only utilised proximity contributed to calculate a global runoff estimate in line with earlier estimations. The need for better specifications of global runoff estimates was highlighted.

Global modellers depend on global data-sets that can have low quality in many areas. Major sources of uncertainty are precipitation and river regulation. A new routing method that utilises high-resolution flow network information in low-resolution calculations was developed and shown to perform well over all spatial scales, while the standard linear reservoir routing decreased in performance with decreasing resolution. This algorithm, called aggregated time-delay-histogram routing, is intended for inclusion in WASMOD-M.

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Browning, Drew. « Modeling non-point source pollution in surface water under non-stationary climates and land uses ». The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1408983669.

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Urteaga, Crovetto Patricia. « Biofuels and water. Spatial transformation in Piura, Perú ». Pontificia Universidad Católica del Perú, 2017. http://repositorio.pucp.edu.pe/index/handle/123456789/79027.

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A mediados de los años 2000, la llegada de empresas de biocombustibles al valle del Chira en Piura, Perú, para producir etanol usando como base el cultivo de la caña de azúcar intensificó el uso agrícola de la tierra y los recursos hídricos. En este artículo analizo las transformaciones ecológicas, políticas y sociales que la producción de biocombustibles generó en este valle. Para ello, describo el rol que tuvo el Estado en la promoción de biocombustibles y los procesos concomitantes de acumulación de tierra y agua en el valle, y exploro las consecuencias que ello tuvo para algunas comunidades y pequeños y medianos agricultores locales. La producción de etanol en el valle del Chira significó una profunda transformación en el espacio, debido a que los procesos de acumulación de tierra y agua para los biocombustibles reforzaron las desigualdades sociales. La información para este artículo ha sido recopilada de fuentes primarias y secundarias. Se trata de una investigación cualitativa a partir de dieciocho entrevistas en Piura y Lima.
The arrival of biofuels companies in the Chira Valley, Piura, Peru, in order to produce ethanol on sugarcane cultivation, intensified the agricultural use of land and water in the mid-2000s. This article analyzes the ecological, political and social transformations that biofuels production brought about in the valley. For that purpose the paper describes the role of the state in promoting biofuels and the concomitant land and water-grabbing processes in the valley. It also explores the consequences it had for local communities and medium-sized and small farmers. Ethanol production in the Chira valley produced a profound space transformation because land and water-grabbing processes for biofuels reinforced social inequalities. Information for this article was gathered from primary and secondarysources. This is a qualitative research. Eighteen interviews were conducted in Piura and Lima.

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LIU, ZHONGWEI. « WATER QUALITY SIMULATION AND ECONOMIC VALUATION OF RIPARIAN LAND-USE CHANGES ». University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1153507620.

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Mölders, Nicole, et Armin Raabe. « On the influence of grid resolution and land surface heterogeneity on hydrologically relevant quantities ». Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-212321.

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Numerische Experimente wurden durchgeführt, um den Einfluß von Gittermaschenweite und subskaliger Heterogenität auf die Vorhersage der am Wasserkreislauf beteiligten Größen zu untersuchen. Die Modellergebnisse zeigen, daß die Evapotranspiration, Bewölkung und der Niederschlag von der Gittermaschenweite und der Heterogenität beeinflußt werden. Es zeigte sich, daß bei Verwendung gröberer Maschenweiten unter Einbezug der verschiedenen Landnutzungstypen innerhalb der Gittermasche die Obertlächenprozesse und Phänomene (z.B. Wärmeinseleffekt) realistischer beschrieben werden, als wenn nur ein Landnutzungstyp für das gesamte Gitterelement angenommen wird
Numerical experiments were performed to investigate the influence of grid resolution and subgrid heterogeneity on the prediction of the quantities of the water cycle. The results were compared with each other and with those provided by a simulation using the same surface parameterization scheme but taking subgrid scale surface heterogeneity into account. The model results substantiate that the evapotranspiration, cloudiness and precipitation are affected by the grid resolution and the heterogeneity. lt was found that increasing the grid size but including the heterogeneity describes more realistically the surface processes and phenomena (e.g„ heat island effect) than assuming one land use type for the whole grid element

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Hendriks, Jan, et Rutgerd Boelens. « Accumulation of water rights in Peru ». Pontificia Universidad Católica del Perú, 2016. http://repositorio.pucp.edu.pe/index/handle/123456789/80114.

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En Latinoamérica, la gobernanza del agua se enfrenta con el problema del aumento de la demanda de recursos hídricos, la creciente variabilidad hidrológica en un contexto de cambio climático, y la contaminación que sigue proliferándose. Por lo tanto, se observa una creciente escasez de agua, en cantidad y calidad, generando competencia y conflictos entre los actores involucrados. El problema coincide con el urgente temario internacional de la concentración de tierra, que está muy entrelazado con la concentración del agua en pocas manos. La globalización y un clima político neoliberal facilitan que actores poderosos acumulen derechos y volúmenes de agua a expensas de usuarios de menor poder. Este documento tiene por objetivo examinar el contexto nacional poniendo atención especial en la acumulación en casos ejemplares de la costa peruana. Se basa en revisión de literatura, informes y archivos pertinentes. Concluye que la distribución injusta de tierra y agua, a expensas de familias rurales y de territorios comunales e indígenas, constituye una grave amenaza para la sostenibilidad ambiental, la seguridad hídrica y la seguridad alimentaria.
In Latin America, water governance is facing the problem of rising demand for water resources, increased hydrological variability in a context of climate change, proliferating contamination and thus —in general— increasing scarcity of water in terms of quantity, quality, and opportunity. This creates competition and conflicts among stakeholders. The issue coincides with the urgent international problem of concentration of land, which is heavily intertwined with the concentration of water in the hands of the few. Globalization and a neoliberal political climate facilitate that powerful actors accumulate water rights and volumes at the expense of less powerful water users. This paper examines some exemplary situations in Peru. It is based on literature review, reports and archival research. The paper concludes that the unfair distribution of land and water, at the expense of rural families, communities and indigenous territories, constitutes a serious threat to environmental sustainability, water security and food security.

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Farhadi, Leila. « Estimation of land surface water and energy balance flux components and closure relation using conditional sampling ». Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/70757.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 348-364).
Models of terrestrial water and energy balance include numerical treatment of heat and moisture diffusion in the soil-vegetation-atmosphere continuum. These two diffusion and exchange processes are linked only at a few critical points. The performance and sensitivity of models are highly dependent on the nature of these linkages that are expressed as the closure function between heat and moisture dynamics. Land response to radiative forcing and partitioning of available energy into sensible and latent heat fluxes are dependant on the functional form. Since the function affects the surface fluxes, the influence reaches through the boundary layer and affects the lower atmosphere weather. As important as these closure functions are, they remain essentially empirical and untested across diverse conditions. It is critically important to develop observation-driven estimation procedures for the terrestrial water and energy closure problem, especially at the scale of modeling and with global coverage. In this dissertation a new approach to the estimation of key unknown parameters of water and energy balance equation and their closure relationship is introduced. This approach is based on averaging of heat and moisture diffusion equations conditioned on land surface temperature and moisture states respectively. The method is derived only from statistical stationarity and conservation statements of water and energy and thus it is scale free. The aim of this dissertation is to establish the theoretical basis for the approach and perform a global test using multi-platform remote sensing measurements. The feasibility of this approach is demonstrated at point-scale using synthetic data and flux-tower field site data. The method is applied to the mesoscale region of Gourma (West Africa) using multi-platform remote sensing data. The retrievals were verified against tower-flux field site data and physiographic characteristics of the region. The approach is used to find the functional form of the Evaporative Fraction (ratio of latent heat flux to sum of latent and sensible heat fluxes) dependence on soil moisture. Evaporative Fraction is a key closure function for surface and subsurface heat and moisture dynamics. With remote sensing data the dependence of this function on governing soil and vegetation characteristics is established.
by Leila Farhadi.
Ph.D.

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Mölders, Nicole, et Armin Raabe. « On the influence of grid resolution and land surface heterogeneity on hydrologically relevant quantities ». Universität Leipzig, 1995. https://ul.qucosa.de/id/qucosa%3A15016.

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Numerische Experimente wurden durchgeführt, um den Einfluß von Gittermaschenweite und subskaliger Heterogenität auf die Vorhersage der am Wasserkreislauf beteiligten Größen zu untersuchen. Die Modellergebnisse zeigen, daß die Evapotranspiration, Bewölkung und der Niederschlag von der Gittermaschenweite und der Heterogenität beeinflußt werden. Es zeigte sich, daß bei Verwendung gröberer Maschenweiten unter Einbezug der verschiedenen Landnutzungstypen innerhalb der Gittermasche die Obertlächenprozesse und Phänomene (z.B. Wärmeinseleffekt) realistischer beschrieben werden, als wenn nur ein Landnutzungstyp für das gesamte Gitterelement angenommen wird.
Numerical experiments were performed to investigate the influence of grid resolution and subgrid heterogeneity on the prediction of the quantities of the water cycle. The results were compared with each other and with those provided by a simulation using the same surface parameterization scheme but taking subgrid scale surface heterogeneity into account. The model results substantiate that the evapotranspiration, cloudiness and precipitation are affected by the grid resolution and the heterogeneity. lt was found that increasing the grid size but including the heterogeneity describes more realistically the surface processes and phenomena (e.g„ heat island effect) than assuming one land use type for the whole grid element.

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Evans, Jason Peter, et jason evans@yale edu. « Modelling Climate - Surface Hydrology Interactions in Data Sparse Areas ». The Australian National University. Centre for Resource and Environmental Studies, 2000. http://thesis.anu.edu.au./public/adt-ANU20020313.032142.

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The interaction between climate and land-surface hydrology is extremely important in relation to long term water resource planning. This is especially so in the presence of global warming and massive land use change, issues which seem likely to have a disproportionate impact on developing countries. This thesis develops tools aimed at the study and prediction of climate effects on land-surface hydrology (in particular streamflow), which require a minimum amount of site specific data. This minimum data requirement allows studies to be performed in areas that are data sparse, such as the developing world. ¶ A simple lumped dynamics-encapsulating conceptual rainfall-runoff model, which explicitly calculates the evaporative feedback to the atmosphere, was developed. It uses the linear streamflow routing module of the rainfall-runoff model IHACRES, with a new non-linear loss module based on the Catchment Moisture Deficit accounting scheme, and is referred to as CMD-IHACRES. In this model, evaporation can be calculated using a number of techniques depending on the data available, as a minimum, one to two years of precipitation, temperature and streamflow data are required. The model was tested on catchments covering a large range of hydroclimatologies and shown to estimate streamflow well. When tested against evaporation data the simplest technique was found to capture the medium to long term average well but had difficulty reproducing the short-term variations. ¶ A comparison of the performance of three limited area climate models (MM5/BATS, MM5/SHEELS and RegCM2) was conducted in order to quantify their ability to reproduce near surface variables. Components of the energy and water balance over the land surface display considerable variation among the models, with no model performing consistently better than the other two. However, several conclusions can be made. The MM5 longwave radiation scheme performed worse than the scheme implemented in RegCM2. Estimates of runoff displayed the largest variations and differed from observations by as much as 100%. The climate models exhibited greater variance than the observations for almost all the energy and water related fluxes investigated. ¶ An investigation into improving these streamflow predictions by utilizing CMD-IHACRES was conducted. Using CMD-IHACRES in an 'offline' mode greatly improved the streamflow estimates while the simplest evaporation technique reproduced the evaporative time series to an accuracy comparable to that obtained from the limited area models alone. The ability to conduct a climate change impact study using CMD-IHACRES and a stochastic weather generator is also demonstrated. These results warrant further investigation into incorporating the rainfall-runoff model CMD-IHACRES in a fully coupled 'online' approach.

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Martinez, Agudelo John Alejandro. « On the Hydroclimate of Southern South America : Water Vapor Transport and the Role of Shallow Groundwater on Land-Atmosphere Interactions ». Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/595679.

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The present work focuses on the sources and transport of water vapor to the La Plata Basin (LPB), and the role of groundwater dynamics on the simulation of hydrometeorological conditions over the basin. In the first part of the study an extension to the Dynamic Recycling Model (DRM) is developed to estimate the water vapor transported to the LPB from different regions in South America and the nearby oceans, and the corresponding contribution to precipitation over the LPB. It is found that more than 23% of the precipitation over the LPB is from local origin, while nearly 20% originates from evapotranspiration from the southern Amazon. Most of the moisture comes from terrestrial sources, with the South American continent contributing more than 62% of the moisture for precipitation over the LPB. The Amazonian contribution increases during the positive phase of El Niño and the negative phase of the Antarctic Oscillation. In the second part of the study the effect of a groundwater scheme on the simulation of terrestrial water storage, soil moisture and evapotranspiration (ET) over the LPB is investigated. It is found that the groundwater scheme improves the simulation of fluctuations in the terrestrial water storage over parts of the southern Amazon. There is also an increase in the soil moisture in the root zone over those regions where the water table is closer to the surface, including parts of the western and southern Amazon, and of the central and southern LPB. ET increases in the central and southern LPB, where it is water limited. Over parts of the southeastern Amazon the effects of the groundwater scheme are only observed at higher resolution, when the convergence of lateral groundwater flow in local topographical depressions is resolved by the model. Finally, the effects of the groundwater scheme on near surface conditions and precipitation are explored. It is found that the increase in ET induced by the groundwater scheme over parts of the LPB induces an increase in near surface specific humidity, accompanied by a decrease in near surface temperature. During the dry season, downstream of the regions where ET increases, there is also a slight increase in precipitation, over a region where the model has a dry bias compared with observations. During the early rainy season, there is also an increase in the local convective available potential energy. Over the southern LPB, groundwater induces an increase in ET and precipitation of 13 and 10%, respectively. Over the LPB, the groundwater scheme tends to improve the warm and dry biases of the model. It is suggested that a more realistic simulation of the water table depth could further increase the simulated precipitation during the early rainy season.

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Tanaka, Kenji. « Development of the new land surface scheme SiBUC commonly applicable to basin water management and numerical weather prediction model ». 京都大学 (Kyoto University), 2005. http://hdl.handle.net/2433/145376.

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Kyoto University (京都大学)
0048
新制・論文博士
博士(工学)
乙第11576号
論工博第3817号
新制||工||1329(附属図書館)
22875
UT51-2004-U473
京都大学大学院工学研究科環境地球工学専攻
(主査)教授池淵周一, 教授椎葉充晴, 教授中北英一
学位規則第4条第2項該当

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Cairampoma, Arroyo Alberto, et Vega Paul Villegas. « Legal regime ground water in Peru ». THĒMIS-Revista de Derecho, 2017. http://repositorio.pucp.edu.pe/index/handle/123456789/108913.

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This article studies the legal regime of groundwater by analyzing the context of integrated water resources management and recognizing its definition and characteristics.Furthermore, it analyses the ownership of ground water, the planning regime applicable, the exploration and exploitation activities, their authorization certificates, the activity of supervision over them, and finally the article describes the special schemes for management and limitation recognized in Peruvian law.
En el presente artículo se estudia el régimen jurídico de las aguas subterráneas, analizando el marco de la gestión integrada de recursos hídricos y reconociendo su definición y particularidades.Asimismo, se analiza la titularidad de las aguas subterráneas, el régimen de planificación aplicable, las actividades de exploración y explotación, sus títulos habilitantes, la actividad de supervisión que sobre ellas recae, para finalmente, dejar anotados los regímenes especiales de gestión y limitación reconocidos en el ordenamiento jurídico peruano.

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Jesus, Bruna Luiza Pereira de. « A relação entre a temperatura radiométrica de superfície (Land Surface Temperature-LST), índice de vegetação (Normalizes Diference Vegetation Index-NDVI) e os diferentes padrões de uso da terra do município de São Paulo ». Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/8/8135/tde-11012016-143102/.

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Esse trabalho tem como objetivo compreender as relações entre a Land Surface Temperature (LST), Normalized Difference Vegetation Índex (NDVI) e os padrões do uso da terra do município de São Paulo no período de 1985 a 2010. Analisou-se 15 bairros, nos quais foram extraídas 45 amostras aleatórias de diferentes padrões de uso da terra; subdivididas em baixo padrão, médio padrão e médio alto padrão. Com o aporte de geotecnologia, foi feita a extração dos dados das imagens de satélite Landsat 5 (TM) e das Ortofotos do ano de 2010. O comportamento das amostras variou de acordo como os diferentes perfis dos grupos analisados. O grupo de baixo padrão foi o que apresentou as maiores amplitudes térmicas, ausência de arborização urbana atreladas a um baixo padrão construtivo. O grupo de médio padrão é caracterizado pela predominância de área verticalizada e apresenta uma arborização urbana escassa em meio a uma malha urbana consolidada. O grupo de médio alto padrão foi o que mais apresentou arborização urbana, distribuída de forma homogênea na maioria das amostras, portanto foi o grupo que teve baixas amplitudes térmicas e o índice de Normalized Difference Vegetation Index (NDVI) com pouca variação. Os testes mostraram fortes correlações negativas entre as amostras de Land Surface Temperature (LST) e o índice de Normalized Difference Vegetation Index (NDVI), sendo -0,58 em 1985, -0,43 em 2004 e -0,82 em 2010. Os diferentes padrões de uso da terra, relacionados à temperatura de superfície, e o índice de vegetação, aliado à preocupação com o planejamento ambiental, deve resultar na melhoria da qualidade de vida da população. Esta pesquisa faz parte do Projeto Temático processo FAPESP 08/58161 -1, \"Assessment of Impacts and Vulnerability to Climate Change in Brazil and strategies for Adaptation options\", Component 5: Vulnerability of the metropolitan region of São Paulo to climate Change.
This study aims to understand the relationship between Land Surface Temperature (LST), Normalized Difference Vegetation Index (NDVI) and the patterns of land use in the municipality of São Paulo, from 1985 to 2010. A totoal of 45 random samples were extracted from the 15 districts used in this study, with different patterns of land use which were subdivided into three different clases: low-end, middle and middle-high. Geospatial approaches allowed the extraction of satellite image data from Landsat 5 data (TM) and from Orthophotos from 2010. The behavior of the samples varied accordingly to the different group profiles. The low-end group presented the highest thermal amplitudes and more significant absence of urban vegetation linked, both to low urbanization and construction standards. The average standard group is characterized by the predominance of vertical buildings and lacks urban trees amidst a consolidated urban landscape. The average-high standard group displayed the highest concentration of green urban areas, distributed homogeneously in most samples, so this group presented low variations both in temperature amplitude and in the Normalized Difference Vegetation Index (NDVI). The correlation tests showed strong negative correlations between samples of Land Surface Temperature (LST) and the NDVI samples, of -0.58 in 1985, -0.43 in 2004 and -0.82 in 2010. Understanding the relations between the different patterns of land use, surface temperature and the NDVI (with due concern for environmental planning) is an important step in the identification and rehabilitation of enviromentally. This research is part of the Thematic Project FAPESP 08/58161 -1 process, \"Assessment of Impacts and Vulnerability to Climate Change in Brazil and strategies for Adaptation options\", Component 5: Vulnerability of the metropolitan region of São Paulo to climate Change.

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Hu, Tian. « Thermal Directionality Study and Application of Thermal Radiation to Drought Monitoring ». Thesis, Griffith University, 2020. http://hdl.handle.net/10072/392051.

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Remote sensing (RS), with its large spatial coverage and easily accessible observations, has attracted a lot of attention in recent years. Thermal infrared (TIR) RS, collecting radiation between 3.75 and 12.5 μm in the electromagnetic spectrum, is one of the major parts of RS. TIR RS is widely used in various fields, including evapotranspiration (ET), global climate change, hydrological cycle, vegetation monitoring and urban climate given the important role TIR radiation plays in surface energy and water balance. TIR radiation is closely related to land surface temperature (LST) and land surface emissivity (LSE). Angular variation is an important characteristic of LSE, which could influence the subsequent estimation of surface upwelling longwave radiation (SULR) and LST. In this study, a look-up table (LUT) of directional emissivities was built from the MYD21A product. The compiled LUT was then applied to SULR and LST estimation by considering the angular variation of LSE. The results showed that the influence of LSE angular variation on SULR estimation was not pronounced. Whereas, the influence on LST retrievals was > 0.5 K and the accuracy of the split-window (SW) was improved by > 1 K over barren surfaces after considering LSE directionality. LST is connected to ET through the surface energy balance equation, thereby reflecting vegetation water availability. In this study, applying TIR radiation in agricultural drought early warning was of interest. Based on the underlying principle that the rate of LST rise between 1.5 and 3.5 h after the sunrise is approximately linear and over vegetated surfaces occurs more rapidly under dry conditions as a consequence of stomatal control, the temperature rise index (TRI) was developed using the LST retrievals from the geostationary Multifunction Transport Satellite-2 (MTSAT-2) instrument and using the Himawairi-8 brightness temperatures (BT), respectively. The proposed TRI was evaluated by comparing with more commonly-used indices, including precipitation condition index (PCI), soil moisture condition index (SMCI) and vegetation condition index (VCI). In addition, the indices were also compared to annual wheat yield over large areas in the Australian Wheatbelt. The results showed that the TRI produced spatiotemporal dryness patterns that were very similar to those in soil moisture and precipitation, but with more detail due to its finer resolution. A time lag was found between TRI and observed vegetation condition, supporting the use of TRI in early warning. Among the compared drought indices, the TRI had the strongest and earliest correlation with wheat yield. The TRI calculated from LST and BT had close performances. It is concluded that this study provides insights into the basic theory study as well as practical applications of TIR RS, and adds value to the state-of-the-art studies in the field of TIR RS.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
Full Text

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Nagai, Haruyasu. « Development of a New Atmosphere-Soil-Vegetation Model to Study Heat, Water, and CO2 Exchanges between the Atmosphere and Land-surface ». 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/147889.

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Moutahir, Hassane. « Likely effects of climate change on water resources and vegetation growth period in the province of Alicante, southeastern Spain ». Doctoral thesis, Universidad de Alicante, 2016. http://hdl.handle.net/10045/70649.

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Dawson, Emily Kathleen. « A river health assessment of selected South-Western Cape Rivers : index of habitat integrity, water quality and the influence of surrounding land use ». Thesis, Stellenbosch : University of Stellenbosch, 2003. http://hdl.handle.net/10019.1/16297.

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Thesis (MSc)--University of Stellenbosch, 2003.
ENGLISH ABSTRACT: The River Health Programme (RHP) is an assessment tool for monitoring the ecological state of rivers to ensure that they remain fit for use by present and future generations. This study, forming part of a RHP assessment conducted on the south-western Cape Hout Bay, Lourens and Palmiet Rivers, has the aim to (1) zone the rivers for representative site selection, (2) assess their habitat integrity (HI), (3) determine the influence of land use on riverine HI and (4) assess the river water quality at the time of the RHP assessments. (1) The desktop geomorphological zonation method used in RHP assessments has not been sufficiently previously tested on short rivers draining the Western Cape Mountains. The Lowland River Zone of the rivers studied, as well as the Hout Bay River’s Upper Foothill Zone, were found to have steeper gradients than expected, probably due to these rivers being shorter and consequently steeper than any on which the method was previously tested. The notion of one gradient river classification system being applicable throughout South Africa, with its diverse geology and climate, is unlikely. Rather a classification system modified for various physiographic features regions or by a factor based on river length is more realistic. (2) Although there is a general longitudinal decrease in HI downstream along the Hout Bay and Lourens Rivers, coinciding with increased anthropogenic activities, HI improves in the Palmiet River’s lower reaches through the Kogelberg Nature Reserve. Surrounding land use thus seems to be a major determinant of HI. Although the Index of Habitat Integrity (IHI) used appears to achieve its aim, it was found to be subjective. Categorisation of the IHI scoring is suggested. (3) The amount of natural versus disturbed land use occurring upstream of a site at a regional and local scale, is a good predictor of riverine HI. Regional alien forestry and local urbanisation have significantly strong negative effects on instream (r2 = -0.80, r2 = 0.80, p<0.05) and riparian (r2 = -0.81, r2 = -0.83, p<0.05) HI. Different land use types therefore appear to affect riverine HI at differing scales and thus managers must not only think on a local but also a catchment scale. (4) In the Hout Bay River, a filtering system (e.g. wetland) appears to improve the water quality between the middle and lower reaches. Along the Lourens River, high total dissolved salts, conductivity and inorganic nitrogen concentrations in the middle reaches are cause for concern. Along the Palmiet River there appeared to be insufficient oxygen to support most aquatic life forms at Grabouw. Impoundments in the middle reaches act as sinks for nutrients and salts, but the Huis and Krom tributaries downstream then appear to degrade the water quality of the Palmiet River’s lower reaches within the Kogelberg Nature Reserve. Together with the results of simultaneous biotic assessments, these results should be used to develop management actions to improve the ecological health of these rivers. The results have been used in a State-of-Rivers Report for the south-western Cape.
AFRIKAANSE OPSOMMING: Die Riviergesondheidsprogram (RGP) is 'n asseseringsinstrument wat die ekologiese stand van riviere monitor om te verseker dat hulle steeds bruikbaar bly vir huidige en toekomstige geslagte. Hierdie studie maak deel uit van 'n RGP-assessering van die Lourens-, Houtbaai- en Palmietrivier in die Suidwes-Kaap en het ten doel om (1) die riviere te soneer vir verteenwoordigende terreinseleksie, (2) die habitat-integriteit (HI) te assesseer, (3) die invloed van grondgebruik op rivier-HI te bepaal en (4) die kwaliteit van rivierwater tydens die RGP-assesserings te bepaal. (1) Die geomorfologiese-soneringsmetode wat in RGP-assesserings gebruik word, is nog nie voorheen genoegsaam vir die kort riviere wat die Wes-Kaapse berge dreineer, getoets nie. Daar is bevind dat die studiegebied riviere in die laagland-sones skerper gradiënte het as verwag, gehad het. Dit kan moontlik toegeskryf word aan die riviere wat korter en dus steiler is as enige van dié wat voorheen met die metode getoets is. Die moontlikheid dat een gradiëntklassifikasiestelsel vir riviere regdeur Suid-Afrika met sy diverse geologie en klimaat toegepas kan word, is onwaarskynlik. 'n Klassifikasiestelsel aangepas vir verskillende fisiografiese streke of met 'n faktor gebaseer op rivierlengte, is meer realisties. (2) Alhoewel HI stroomaf langs die Lourens- en Houtbaairivier in die algemeen longitudinaal saam met die toename in antropogeniese aktiwiteite afneem, verbeter die Palmietrivier se HI waar dit laer af deur die Kogelbergnatuurreservaat vloei. Die gebruike van aanliggende grond blyk dus 'n belangrike bepaler van HI te wees. Die Indeks van Habitatintegriteit (IHI) bereik klaarblyklik die vereiste doel, maar is te subjektief. Kategorisering van die IHI-waardes word voorgestel. (3) 'n Goeie voorspeller van rivier-HI is die hoeveelheid natuurlike teenoor versteurde grondgebruik stroomop van 'n terrein op 'n streeks- en lokale skaal. Die sterk negatiewe effek van uitheemse plantegroei in die omgewing en lokale verstedeliking op stroom- (r² = -0.80, r² = 0.80, p<0.05 ) en oewer-HI (r² = -0.81, r² = -0.83, p<0.05) is beduidend. Verskille in tipe grondgebruik beïnvloed rivier-HI op verskillende vlakke; bestuurders moet dus plaaslik en aan die opvanggebied dink. (4) In die Houtbaairivier lyk dit asof 'n filtreringstelsel (bv. vleigrond) die waterkwaliteit tussen die middel- en lae gedeeltes verbeter. In die loop van die Lourensrivier is hoë totale opgeloste soute, geleidingsvermoë en anorganiese stikstofkonsentrasies in die middelgedeelte 'n rede tot kommer. In die Palmietrivier by Grabouw was die suurstof te min om die meeste akwatiese lewensvorme te onderhou. Opgedamde water in die middel gedeeltes dien as 'n sink vir voedingstowwe en soute, maar dit lyk asof die Huis- en Kromrivier die waterkwaliteit van die Palmietrivier stroomaf in die Kogelbergnatuurreservaat degradeer. Saam met die resultate van gelyktydige biotiese assesserings, kan hierdie resultate gebruik word vir die ontwikkeling van bestuursaksies om die ekologiese toestand van hierdie riviere te verbeter. Die resultate is gebruik in 'n toestand-van-riviere-verslag vir die Suidwes-Kaap.

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Mölders, Nicole, Thomas Beckmann et Armin Raabe. « A module to couple an atmospheric and a hydrologic model ». Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-212867.

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A land-surface module to couple a meteorological and a hydrologic model is described. lt was implemented and tested in the Leipzig\'s version of GESIMA. Preliminary results of a coupling with NASMO are presented, although this article mainly focuses on the description of the module and its effect on the atmospheric water cycle. One positive impact of the module is that it allows to produce subgrid-scale evapotranspiration in more details and to heterogenize precipitation. This strongly affects soil wetness, cloudiness and the thermal regime of the atmospheric boundary layer
Ein Bodenmodul zur Kopplung eines meteorologischen mit einem hydrologischen Modell wird vorgestellt. Er wurde implementiert und getestet in der Leipziger Version von GESIMA. Obgleich der Schwerpunkt des Artikels auf der Beschreibung des Moduls und seiner Auswirkung auf den atmosphärischen Wasserkreislauf liegt, werden auch vorläufige Ergebnisse einer Kopplung mit NASMO präsentiert. Ein positiver Effekt des Moduls ist, daß er ermöglicht, detaillierter die subskalige Evapotranspiration zu beschreiben und den Niederschlag zu heterogenisieren. Dies wirkt sich stark auf die Bodenfeuchte, die Bewölkung und das thermische Regime der atmosphärischen Grenzschicht aus

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Ma, Ning, Guo-Yue Niu, Youlong Xia, Xitian Cai, Yinsheng Zhang, Yaoming Ma et Yuanhao Fang. « A Systematic Evaluation of Noah-MP in Simulating Land-Atmosphere Energy, Water, and Carbon Exchanges Over the Continental United States ». AMER GEOPHYSICAL UNION, 2017. http://hdl.handle.net/10150/626444.

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Accurate simulation of energy, water, and carbon fluxes exchanging between the land surface and the atmosphere is beneficial for improving terrestrial ecohydrological and climate predictions. We systematically assessed the Noah land surface model (LSM) with mutiparameterization options (Noah-MP) in simulating these fluxes and associated variations in terrestrial water storage (TWS) and snow cover fraction (SCF) against various reference products over 18 United States Geological Survey two-digital hydrological unit code regions of the continental United States (CONUS). In general, Noah-MP captures better the observed seasonal and interregional variability of net radiation, SCF, and runoff than other variables. With a dynamic vegetation model, it overestimates gross primary productivity by 40% and evapotranspiration (ET) by 22% over the whole CONUS domain; however, with a prescribed climatology of leaf area index, it greatly improves ET simulation with relative bias dropping to 4%. It accurately simulates regional TWS dynamics in most regions except those with large lakes or severely affected by irrigation and/or impoundments. Incorporating the lake water storage variations into the modeled TWS variations largely reduces the TWS simulation bias more obviously over the Great Lakes with model efficiency increasing from 0.18 to 0.76. Noah-MP simulates runoff well in most regions except an obvious overestimation (underestimation) in the Rio Grande and Lower Colorado (New England). Compared with North American Land Data Assimilation System Phase 2 (NLDAS-2) LSMs, Noah-MP shows a better ability to simulate runoff and a comparable skill in simulating R-n but a worse skill in simulating ET over most regions. This study suggests that future model developments should focus on improving the representations of vegetation dynamics, lake water storage dynamics, and human activities including irrigation and impoundments.

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Redfearn, Howard Daniel. « Rainfall-runoff changes due to urbanization : a comparison of different spatial resolutions for lumped surface water hydrology models using HEC-HMS ». Thesis, University of North Texas, 2005. https://digital.library.unt.edu/ark:/67531/metadc4939/.

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Hydrologic models were used to examine the effects of land cover change on the flow regime of a watershed located in North-Central Texas. Additionally, the effect of spatial resolution was examined by conducting the simulations using sub-watersheds of different sizes to account for the watershed. Using the Army Corps of Engineers, Hydrologic Engineering Center Hydrologic Modeling System (HEC-HMS), two different modeling methods were evaluated at the different sub-watershed resolutions for four rainfall events. Calibration results indicate using the smaller spatial resolutions improves the model results. Different scenarios for land cover change were evaluated for all resolutions using both models. As land cover change increased, the amount of flow from the watershed increased.

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Ohta, Takeshi, Tetsuya Hiyama, Hiroki Tanaka, Takeshi Kuwada, Trofim C. Maximov, Tetsuo Ohata et Yoshihiro Fukushima. « Seasonal variation in the energy and water exchanges above and below a larch forest in eastern Siberia ». Wiley, 2001. http://hdl.handle.net/2237/7756.

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Brunke, Michael A., Patrick Broxton, Jon Pelletier, David Gochis, Pieter Hazenberg, David M. Lawrence, L. Ruby Leung, Guo-Yue Niu, Peter A. Troch et Xubin Zeng. « Implementing and Evaluating Variable Soil Thickness in the Community Land Model, Version 4.5 (CLM4.5) ». AMER METEOROLOGICAL SOC, 2016. http://hdl.handle.net/10150/612995.

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One of the recognized weaknesses of land surface models as used in weather and climate models is the assumption of constant soil thickness because of the lack of global estimates of bedrock depth. Using a 30-arc-s global dataset for the thickness of relatively porous, unconsolidated sediments over bedrock, spatial variation in soil thickness is included here in version 4.5 of the Community Land Model (CLM4.5). The number of soil layers for each grid cell is determined from the average soil depth for each 0.9 degrees latitude x 1.25 degrees longitude grid cell. The greatest changes in the simulation with variable soil thickness are to baseflow, with the annual minimum generally occurring earlier. Smaller changes are seen in latent heat flux and surface runoff primarily as a result of an increase in the annual cycle amplitude. These changes are related to soil moisture changes that are most substantial in locations with shallow bedrock. Total water storage (TWS) anomalies are not strongly affected over most river basins since most basins contain mostly deep soils, but TWS anomalies are substantially different for a river basin with more mountainous terrain. Additionally, the annual cycle in soil temperature is partially affected by including realistic soil thicknesses resulting from changes in the vertical profile of heat capacity and thermal conductivity. However, the largest changes to soil temperature are introduced by the soil moisture changes in the variable soil thickness simulation. This implementation of variable soil thickness represents a step forward in land surface model development.

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Lemon, Michelle M. « The effects of land use and regional hydrology on surface water quality in the upper San Pedro River, Arizona, United States of America ». Thesis, The University of Arizona, 2004. http://hdl.handle.net/10150/292075.

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The purpose of this study is to examine the effects of land use and hydrology on surface water quality in a semi-arid watershed. Six synoptic sampling events were performed along the upper San Pedro River, AZ, USA before, during, and after the 2002 monsoon season. Water samples were analyzed for conservative solutes, nutrients, and organic matter. During non-monsoon baseflow periods, conservative solutes indicated limited hydrologic connection between regions. Protected reaches had significantly higher DOC concentrations and agricultural reaches had significantly higher DON and NO₃-N levels. In contrast, solute concentrations during the monsoon season indicated all regions were hydrologically linked. DOM and NO₃-N concentrations increased as terrestrially derived solutes were flushed into the stream. Nutrient loads were variable suggesting that changes in nutrient concentrations were related to individual reaches. This research demonstrates that hydrologic flowpaths and land cover are important controls on surface water quality at the reach and river scales.

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Törnqvist, Rebecka. « Basin-scale change in water availability and water quality under intensified irrigated agriculture ». Doctoral thesis, Stockholms universitet, Institutionen för naturgeografi och kvartärgeologi (INK), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-93214.

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Changes in land use and water use can greatly impact the cycling of water and water-borne substances. Increased redistribution of river water to irrigated fields can cause enhanced evapotranspiration and decreased river discharge. Additionally, the water quality can be affected by the external input of fertilisers and pesticides, and by changed pollutant transport pathways in expansive irrigation canal systems. This thesis examines basin-scale changes in water use, river discharge, water quality and nitrogen (N) loading under conditions of intensified irrigated agriculture, using the Aral Sea drainage basin (ASDB) with its two large rivers Syr Darya and Amu Darya in Central Asia as study area. Results show that more efficient irrigation techniques could reduce outtake of river water to the cotton fields in the ASDB by about 10 km3/year, while the corresponding river water saving at the outlet would be 60% lower. The result illustrates the importance of accounting for return flows of irrigation water in basin-scale water saving assessments. Moreover, a decrease in riverine N concentrations at the outlet of the Amu Darya River Basin (ADRB) was observed during a 40-year period of increasing N fertiliser input. The decrease was identified to be primarily caused by increased recirculation of river water in the irrigation system, leading to increased flow-path lengths and enhanced N attenuation. Decreasing N loads were shown to be primarily related to reduced discharge. N export from the basin may further decrease due to projected discharge reductions related to climate change. Furthermore, nutrients and metals were occasionally found at concentrations above drinking water guideline values in surface waters in the ADRB. However, metal concentrations in groundwater in the lower ADRB were subject to orders of magnitude higher health hazards. Projected decrease in downstream surface water availability would thus imply decreased access to water suitable for drinking.

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Submitted. Paper 5: Manuscript.

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Barreto-Munoz, Armando. « Multi-Sensor Vegetation Index and Land Surface Phenology Earth Science Data Records in Support of Global Change Studies : Data Quality Challenges and Data Explorer System ». Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/301661.

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Synoptic global remote sensing provides a multitude of land surface state variables. The continuous collection, for more than 30 years, of global observations has contributed to the creation of a unique and long term satellite imagery archive from different sensors. These records have become an invaluable source of data for many environmental and global change related studies. The problem, however, is that they are not readily available for use in research and application environment and require multiple preprocessing. Here, we looked at the daily global data records from the Advanced Very High Resolution Radiometer (AVHRR) and the Moderate Resolution Imaging Spectroradiometer (MODIS), two of the most widely available and used datasets, with the objective of assessing their quality and suitability to support studies dealing with global trends and changes at the land surface. Findings show that clouds are the major data quality inhibitors, and that the MODIS cloud masking algorithm performs better than the AVHRR. Results show that areas of high ecological importance, like the Amazon, are most prone to lack of data due to cloud cover and aerosols leading to extended periods of time with no useful data, sometimes months. While the standard approach to these challenges has been compositing of daily images to generate a representative map over a preset time periods, our results indicate that preset compositing is not the optimal solution and a hybrid location dependent method that preserves the high frequency of these observations over the areas where clouds are not as prevalent works better. Using this data quality information the Vegetation Index and Phenology (VIP) Laboratory at The University of Arizona produced over 30 years of seamless sensor independent record of vegetation indices and land surface phenology metrics. These data records consist of 0.05-degree resolution global images for daily, 7-days, 15-days and monthly temporal frequency. These sort of remote sensing based products are normally made available through the internet by large data centers, like the Land Processes Distributed Active Archive Center (LP DAAC), however, in this project an online tool, the VIP Data Explorer, was developed to support the visualization, exploration, and distribution of these Earth Science Data Records (ESDRs) keeping it closer to the data generation center which provides a more active data support and distribution model. This web application has made it possible for users to explore and evaluate the products suite before download and use.

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Van, Heerden Karien. « Geological and anthropogenic impacts on inorganic water quality at rural clinics in the Limpopo Province, South Africa / van Heerden, K ». Thesis, North-West University, 2011. http://hdl.handle.net/10394/6978.

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This study gives insight to the origin of pollution in the water resources of the Limpopo province of South Africa. The Limpopo province is the largest rural province in South Africa. Up to 40% of the total population does not have access to sufficient water supply, resulting in adverse health effects. The purpose of this study is to determine (1) the degree of inorganic pollution of borehole water; (2) to identify the pollution sources, and (3) to determine whether the pollution is inherited from the surface water that recharges the groundwater or is caused on site near the bore holes. In order to achieve these objectives, surface water quality data (14 675 samples) and borehole water data (340 samples) at health facilities were analysed. A pollution index, defined by the following ratio: Pollution index (%) = 100 x ([Cl–] + 2[SO4^-2] + [NO3-] + 3[PO4^-3]) ÷ ([Cl-] + 2SO4^-2 + [NO3-] + [PO4^-3] + [HCO3-]) was used to determine the percentage of contribution of each chemical species towards pollution. This ratio is based on the fact that bicarbonate is released during chemical weathering of rocks whereas sulphate, nitrate, chloride, and phosphate are anthropogenic in origin. The pollution index shows that 6% of the surface waters and 21% of the borehole water is severely polluted. The pollution of the surface water is characterized by high concentrations of sulphate whereas the pollution of the borehole water is characterized by high concentrations of chloride. This indicates that the pollution of the borehole water is not so much the result of the infiltration of polluted surface water, but rather the result of on–site pollution on the surface near the bore holes.
Thesis (M.Sc. (Geography and Environmental Studies))--North-West University, Potchefstroom Campus, 2011.

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Christoffersen, Bradley. « The Ecohydrological Mechanisms of Resilience and Vulnerability of Amazonian Tropical Forests to Water Stress ». Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/293566.

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Predicting the interactions between climate change and ecosystems remains a core problem in global change research; tropical forest ecosystems are of particular importance because of their disproportionate role in global carbon and water cycling. Amazonia is unique among tropical forest ecosystems, exhibiting a high degree of coupling with its regional hydrometeorology, such that the stability of the entire forest-climate system is dependent on the functioning of its component parts. Belowground ecohydrological interactions between soil moisture environments and the roots which permeate them initiate the water transport pathway to leaf stomata, yet despite the disproportionate role they play in vegetation-atmosphere coupling in Amazonian forest ecosystems, the impacts of climate variability on the belowground environment remain understudied. The research which follows is designed to address critical knowledge gaps in our understanding of root functioning in Amazonian tropical forests as it relates to seasonality and extremes in belowground moisture regime as well as discerning which ecohydrological mechanisms govern ecosystem-level processes of carbon and water flux. A secondary research theme is the evaluation and use of models of ecosystem function as applied to Amazonia - these models are the "knowledge boxes" which build in the ecohydrological hypotheses (some testable than others) deemed to be most important for the forest ecosystems of Amazonia. In what follows, I investigate (i) which mechanisms of water supply (from the soil environment) and water demand (by vegetation) regulate the magnitude and seasonality of evapotranspiration across broad environmental gradients of Amazonia, (ii) how specific hypotheses of root function are or are not corroborated by soil moisture measurements conducted under normal seasonal and experimentally-induced extreme drought conditions, and (iii) the linkage between an extreme drought event with associated impacts on root zone soil moisture, the inferred response of root water uptake, and the observed impacts on ecosystem carbon and water flux in an east central Amazonian forest.

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GHIRARDINI, Andrea. « Main sources and emission pathways of micropollutants released in surface water at a catchment scale : from a theoretical approach to a practical application on a case-study ». Doctoral thesis, Università degli studi di Ferrara, 2021. http://hdl.handle.net/11392/2488226.

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Due to the rising global population and the steady growth of the health care sector, the consumption of pharmaceuticals increased consistently in the last decades. Although modern medicine significantly developed, this brought to the possibility that residues of these compounds reach surface water, soil, and plants through several routes during their manufacture, use, and disposal. Considering a rural or peri-urban areas, pharmaceutical compounds may enter in the water environment via wastewater treatment plant efflluent, combined sewer overflow, and soil water flows originated from arable lands in which sewage sludge or animal manure have been amended as fertilizers. This thesis takes place in this background, aiming to, firstly, characterize the content of PPCPs in sewage sludge and zootechnical wastes originated from different animals and with various characteristics. Afterwards, the remobilization of these micropollutants was studied in order to have an overall view of their potential occurrence in the soil water flows and of the main factors influencing it (such as soil characteristics, physico-chemical properties of the compounds, sludge application rate and method, and so forth). These two first steps were carried out through a comprehensive and exhaustive literature review and were essential to prepare a general overview of the state-of-the-art on the topic. Then, all the elements were on the table to try to estimate the contribution of different sources (among them WWTP effluent, CSO, and surface runoff from manure or sewage sludge-amended soils) to the occurrence of selected pharmaceuticals in surface water, on a catchment scale. This last task was conducted in collaboration with the Institute for Water Quality, Resources and Waste Management of the TU Wien, and focused on a specific case-study regarding an Austrian peri-urban watershed. The result was the development of a modelling approach in order to identify the most relevant sources and emission pathways of pharmaceuticals, with particular attention to the significance of agricultural land runoff. The strength and weaknesses related to this model are discussed in this thesis, in order to lay the groundwork for moving from a case-study to an overall discussion of the topic. Finally, as a consequence of the work done, one last task was performed investigating the potential toxic effects on edible crops due to their irrigation with surface water contaminated by residues of PPCPs. The subject was explored in collaboration with the Department of Environment and Geography of the University of York, through a laboratory experiment in which garden cress plants – an edible crop commonly cultivated in northern Europe – were treated with mixtures of PPCPs simulating the irrigation with surface water similar to those that can be sampled worldwide. The results of this work showed that residues of micropollutants might cause visible effects on plant biomass even when occurring at very low concentrations (ng L-1 level), due to the synergistic and additive effects between the compounds. In conclusion, the findings of this thesis highlighted that the effects of the occurrence of PPCPs in the agricultural agroecosystem (soil, water, and plants), and mutatis mutandis in the receiving water environment, are measurable. This thesis pinpoints some issue related to this complex phenomenon, and the necessity to further investigate in this field to exhaustively deepen the problem.

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Sheler, Rebecca Joy. « The impact of agricultural drainage systems on hydrologic responses ». Thesis, University of Iowa, 2013. https://ir.uiowa.edu/etd/2630.

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Over the past century of settlement, the landscapes of the Midwestern United States have experienced extensive anthropogenic modifications in order to convert prior wetlands-lowlands to subsequent fruitful croplands. The hydrologic responses of these landscapes have been significantly altered by the installation of artificial drainage (surface ditches and subsurface tile drains) and the change in natural preferential flow paths (increased cracks or root holes due to land use practices). Changes to peak stream flow behaviors is a result of many different inter-related variables; however, intensified agricultural drainage remains one of the largest suspects. Though the effects of subsurface drainage (primarily in the form of tile drains) on landscape, hydrology, ecology, and economy have been questioned, theories of hydrologic controls continue to be vague at best. Soil-Water-Atmosphere-Plant, known as SWAP, was developed to simulate the interaction of vegetation development with the transport of water, solutes, and heat in the unsaturated zone. It is a one-dimensional, vertically directed model with a domain reaching from a plane just above the canopy to a plane in the shallow saturated zone. In the horizontal direction, the model's main focus is the field scale since most transport processes can be described in a deterministic way. The SWAP model was calibrated and validated for simulating flow regimes of drained and undrained landscapes in Iowa. A new term `flashiness' is used to characterize flow data. The Richards-Baker Flashiness Index quantifies the frequency and intensity of short term changes in streamflow. From the simulated results, the effect of anthropomorphic modifications to a landscape is determined to be strongly influenced by soil structural properties and hydraulic properties, along with rainfall regimes. Adding subsurface drains to soils with lower hydraulic conductivities, such as clay, tends to reduce peak flows during precipitation events. Conversely, adding drainage to soils with higher hydraulic conductivities, such as sand, increases peak flows. During years with heavy precipitation, soils with lower permeability show a `saddle shape' relationship between the flashiness index and the distance between tile drains produces. The lowest point of the `saddle' determines the ideal drain spacing for mitigating flashiness. When the shrinking and cracking of clay soils is considered, macropores dominate water flow pathways into the soil matrix and tile drains have a minimal effect on the flow regime. The volume of macropores at the surface of the soil profile is indirectly proportional to flashiness index. Independent of rainfall regimes, cropping season, and soil type, subsurface flows of drained landscapes always exceed that of undrained landscapes. Continuance of comprehensive studies of artificial subsurface drainage can produce positive impacts on engineering, economic, and ecological environments.

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Thèses sur le sujet « Land Surface Water Index »

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