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1
Zanardo, Stefano. "Catchment-scale transport phenomena: rainfall intermittency, age of runoff, anthropic catchment management." Doctoral thesis, Università degli studi di Padova, 2011. http://hdl.handle.net/11577/3427400.
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Complexity of transport phenomena at the catchment scale arises from the interconnection of several processes over a range of spatial and temporal scales. The hydrologic and biogeochemical response of catchments is produced by the highly non-linear interaction between meteorological forcing, landscape heterogeneity, and human activity. As a result, a simple experimental analysis does not give significant insight into the processes involved and exploring such phenomena is a challenging task. Nevertheless, investigating these processes is important in order to evaluate the dominant controls on catchment-scale mechanisms as well as predict the response of the systems to human activities and climate-related perturbations. This is particularly relevant in changing environments, where a deep understanding of the systems is critical for a proper management of landscape and water resources. This thesis aims at exploring catchment-scale transport phenomena by applying novel modeling tools to relevant case studies. Both deterministic and probabilistic approaches are followed, as the latter are required by the random nature physical processes whereas the former allow for the analysis of the systems under certain, well defined conditions. Model evaluations are supported by robust analyses of extensive datasets, whose purpose is not simply to validate the approaches but rather to provide further insight into the processes. Long term effects of hydrologic fluctuations are captured by stochastic models in terms of steady state statistical distributions of relevant physical quantities. This modeling approach provides a causal relationship between daily rainfall random fluctuations and daily stream flow variability, this, in turn, relates to the variability of stream stage, and in-stream nutrients removal. The stochastic approach is further extended to evaluate the effect of the daily variability of precipitation on the inter-annual variability of water balance. The application of the model to a large amount of experimental catchment across the United States shows how there exist regions where the daily variability of water partitioning is the major control on inter-annual variability of water balance, and regions where the inter-annual variability arises from controls other than the simple scaling-up of short term processes. A deterministic approach, namely Mass Response Function (MRF), is used to evaluate the effect of soil heterogeneities, as well as the effect of water-mixing mechanisms on the hydrologic and biogeochemical response of catchments. The main idea underlying this framework is that the evolution of solute and water pulses moving within the soil largely depends on their residence time. The application of the MRF model to a tracer study on nitrates and lithium suggests that runoff is composed by a collection of water particles with a mixture of ages and that, in this case, the effect of unmixed preferential flow can be ruled out. The MRF is then coupled with a `source zone' model suitable to describe pesticides release from the top soil layer in intensively managed catchments. This additional module proves necessary to properly simulate the pesticides transport mechanisms. The application of the model to a decade-long water-quality monitoring dataset suggests that the prediction of the agro-chemical response requires an accurate knowledge of the management practices. In particular, the interval between the occurrence of large rainfall events and the pesticide application dates seems to constitute the main control on the pesticide release dynamics. These considerations are of particular interest when modeling pesticides as they are exclusively of anthropic origin. Whereas, when considering other types contaminant such as nutrients, the anthropic component may be clouded by the effect of chemical soil production.La complessità dei fenomeni di trasporto alla scala di bacino deriva dall'interconnessione di diversi processi su diverse scale temporali e spaziali. La risposta idrologica e biogeochimica dei bacini è il prodotto di interazioni altamente non lineari tra le forzanti meteorologiche, le eterogeneità del territorio e le attività umane. Di conseguenza, semplici analisi sperimentali non permettono un'adeguata comprensione dei processi coinvolti, e l'analisi di questi fenomeni rappresenta un obiettivo ambizioso. Tuttavia, l'esplorazione di questi processi è importante per valutare i controlli dominanti su meccanismi di trasporto alla scala di bacino e predirne la risposta idrologica e biogeochimica a perturbazioni climatiche ed alla gestione del territorio. Questo è particolarmente importante nel caso di ecosistemi in cambiamento, dove una profonda comprensione dei processi è fondamentale per una corretta gestione del territorio e delle risorse idriche. Lo scopo di questa tesi è l'analisi di fenomeni di trasporto alla scala di bacino attraverso l'applicazione di nuovi approcci modellistici a casi studio di interesse. A questo scopo si è utilizzato sia un approccio probabilistico sia un approccio deterministico: il primo richiesto dalla natura casuale di numerosi processi fisici coinvolti, il secondo necessario per analizzare le dinamiche sotto condizioni ben definite. Lo studio è supportato da una robusta analisi dei dati disponibili, il cui scopo non è semplicemente quello di validare i modelli ma piuttosto di fornire una comprensione più approfondita delle dinamiche in gioco. Gli effetti di fluttuazioni idrologiche nel lungo termine sono simulati attraverso distribuzioni di probabilità stazionarie relative a grandezze fisiche rilevanti. Questo approccio modellistico fornisce una relazione causale tra la fluttuazione giornaliera della pioggia e la fluttuazione giornaliera dei deflussi, la quale, a sua volta, è messa in relazione con l'atezza di moto nei corsi d'acqua ed infine con i processi rimozione di nutrienti nelle reti idrografiche. Tale approccio stocastico è successivamente utilizzato per valutare l'effetto delle fluttuazioni giornaliere delle precipitazioni sulla variabilità inter-annuale del bilancio idrico alla scala di bacino. L'applicazione del modello ad un esteso numero di bacini sperimentali, distribuiti sul territorio degli Stati Uniti, mostra come esistano alcune regioni dove le fluttuazioni della pioggia giornaliera rappresentano il controllo principale sulla la variabilità inter-annuale del bilancio idrico, ed altre regioni dove questa variabilità è determinata da altri processi che non necessariamente avvengono alla scala giornaliera. Un modello deterministico, detto Mass Response Function (MRF), è utilizzato per valutare l'effetto delle eterogeneità del suolo e dei meccanismi di mescolamento sulla risposta idrologica e biogeochimica dei bacini. Il concetto principale che caratterizza questo approccio si basa sull'assunzione che l'evoluzione degli impulsi di acqua e soluti che si muovono nel suolo sia prevalentemente governata dal relativo tempo di residenza. L'applicazione del modello MRF ad uno studio di traccianti effettuato utilizzando nitrati e litio suggerisce che i deflussi sono composti da un insieme di impulsi aventi differenti età e che, almeno nel caso in esame, l'effetto di flussi preferenziali non mescolati può essere trascurato. Il modello MRF è stato successivamente accoppiato con un modello detto `source zone' atto a simulare il rilascio di pesticidi dallo strato superficiale del suolo in bacini intensamente antropizzati. L'aggiunta di questo secondo modello si è dimostrata necessaria per rappresentare accuratamente le dinamiche di trasporto dei pesticidi. L'applicazione ad un caso di studio sperimentale suggerisce come la previsione della risposta agro-chimica richieda un'accurata conoscenza della pratiche agricole utilizzate. In particolare, l'intervallo tra la data di applicazione dei pesticidi e i primi eventi di pioggia successivi sembra costituire il fattore principale nelle dinamiche di rilascio di contaminanti. Queste considerazioni sono di particolare interesse nella modellazione dei pesticidi in quanto di origine esclusivamente antropica. Nel caso invece della modellazione contaminanti quali i nutrienti, la componente antropica può venire oscurata dalla produzione chimica del suolo.
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Newham, Lachlan Thomas Hopkins, and lachlan newham@anu edu au. "Catchment Scale Modelling of Water Quality and Quantity." The Australian National University. Centre for Resource and Environmental Studies, 2002. http://thesis.anu.edu.au./public/adt-ANU20050919.144548.
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Appropriately constructed pollutant export models can help set management priorities for catchments, identify critical pollutant source areas, and are important tools for developing and evaluating economically viable ways of minimising surface water pollution.¶
This thesis presents a comparison, an evaluation and an integration of models for predicting the export of environmental pollutants, in particular sediment, through river systems. A review of the capabilities and limitations of current water quality modelling approaches is made. Several water quality and quantity modelling approaches are applied and evaluated in the catchment of the upper Murrumbidgee River.¶
The IHACRES rainfall-runoff model and a simple hydrologic routing model are applied with the aim of developing a capacity to predict streamflow at various catchment scales and to enable integration with other pollutant load estimation techniques. Methods for calculating pollutant loads from observed pollutant concentration and modelled streamflow data are also investigated. Sediment export is estimated using these methods over a 10-year period for two case study subcatchments. Approaches for water quality sampling are discussed and a novel monitoring program using rising stage siphon samplers is presented.
Results from a refinement of the Sediment River Network model in the upper Murrumbidgee catchment (SedNet-UM) are presented. The model provides a capacity to quantify sediment source, transport and to simulate the effects of management change in the catchment. The investigation of the model includes rigorous examination of the behaviour of the model through sensitivity assessment and comparison with other sediment modelling studies. The major conclusion reached through sensitivity assessment was that the outputs of the model are most sensitive to perturbation of the hydrologic parameters of the model.¶
The SedNet-UM application demonstrates that it is possible to construct stream pollutant models that assist in prioritising management across catchment scales. It can be concluded that SedNet and similar variants have much potential to address common resource management issues requiring the identification of the source, propagation and fate of environmental pollutants. In addition, incorporating the strengths of a conceptual rainfall-runoff model and the semi-distributed SedNet model has been identified as very useful for the future prediction of environmental pollutant export.
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Diamantini, Elena. "Catchment scale modelling of micro and emerging pollutants." Doctoral thesis, Università degli studi di Trento, 2018. https://hdl.handle.net/11572/368591.
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The fate and transport of solutes introduced into a watershed and sampled at the catchment outlet depends on many environmental, chemical and hydro-climatological forces.Moreover, if the solutes are micro and emerging pollutants (i.e. pharmaceuticals), which are non-regulated contaminants not routinely monitored but often-detected in fresh waters, the description of the transport sources and routes becomes an interesting and challenging topic to investigate and describe, especially in conjunction with the well-known travel time transport approach at the catchment-scale. In fact, with the travel time approach to pharmaceuticals represents a framework that allows dealing in a unitary and simple way the main two mitigation mechanisms controlling them, which are dilution and biological decay. Moreover, possible consequences on the health of humans and of aquatic organisms have become issue of increasing concern by the scientific community worldwide. The topics have been extensively studied in the last decades, with some recent benchmark contributions. Nevertheless, there is still room for further development for emerging contaminant models and there is still the necessity of complementing the applications with measured data. This doctoral thesis aimed at contributing with new insights into the multi-faceted aspects of solute transport at catchment-scale, proposing novel solutions, with applications to real-world case studies and including a detailed description of the major aspects that influence the water quality dynamics in rivers. The thesis is divided into three interconnected and chronological subsequent parts. In the first part, a detailed description of three large European river basins are presented (i.e. Adige, Ebro and Sava), believing that an accurate analysis of existing information is therefore useful and necessary to identify stressors that may act in synergy and to design new field campaigns. In addition, a detailed data analysis of the main water quality variables is presented: advanced statistical analyses (i.e. Spearman rank correlation, Principal Component Analysis, andMann-Kendall trend tests) were applied to long-term time series of water quality data both in the Adige River Basin and in the Ebro and Sava catchments, aiming at providing an integrated and comparative analysis of recent trends, in order to investigate the relationships between water quality parameters and the main factors controlling them (i.e. climate change, streamflow, land use, population) in the Mediterranean region. These catchments are included into the EU project “Globaqua †, dealing with the analysis of the combined effect of several stressors on the freshwater ecosystems inMediterranean rivers. In fact, little attention has been paid to linkages between long-term trends in climate, streamflow and water quality in European basins; nevertheless, such analysis can represent, complementary to a deep knowledge of the investigated systems, a reliable tool for decision makers in river basin planning by providing a reliable estimate of the impacts on the aquatic ecosystem of the studied basins. In the second part, sampling campaigns performed in our study basin, the Adige catchment, are presented in detail. Special attention is also given to emerging pollutants, whose study on the occurrence patterns and spatiotemporal variability in the Adige River Basin has been conducted in conjunction with population patterns and touristic fluxes. In the third and last part, novel theoretical solutions of the well-known advection-dispersion-reaction (ADR) equation are presented. The theory was developed for both general water quality variables and pharmaceuticals, evidencing differences and analysing the main factors that influence water quality dynamics. An application is also proposed to the Adige catchment.
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Diamantini, Elena. "Catchment scale modelling of micro and emerging pollutants." Doctoral thesis, University of Trento, 2018. http://eprints-phd.biblio.unitn.it/2870/1/Tesi_PhD_Diamantini_definitiva.pdf.
Full textAbstract:
The fate and transport of solutes introduced into a watershed and sampled at the catchment outlet depends on many environmental, chemical and hydro-climatological forces.Moreover, if the solutes are micro and emerging pollutants (i.e. pharmaceuticals), which are non-regulated contaminants not routinely monitored but often-detected in fresh waters, the description of the transport sources and routes becomes an interesting and challenging topic to investigate and describe, especially in conjunction with the well-known travel time transport approach at the catchment-scale. In fact, with the travel time approach to pharmaceuticals represents a framework that allows dealing in a unitary and simple way the main two mitigation mechanisms controlling them, which are dilution and biological decay. Moreover, possible consequences on the health of humans and of aquatic organisms have become issue of increasing concern by the scientific community worldwide. The topics have been extensively studied in the last decades, with some recent benchmark contributions. Nevertheless, there is still room for further development for emerging contaminant models and there is still the necessity of complementing the applications with measured data. This doctoral thesis aimed at contributing with new insights into the multi-faceted aspects of solute transport at catchment-scale, proposing novel solutions, with applications to real-world case studies and including a detailed description of the major aspects that influence the water quality dynamics in rivers. The thesis is divided into three interconnected and chronological subsequent parts. In the first part, a detailed description of three large European river basins are presented (i.e. Adige, Ebro and Sava), believing that an accurate analysis of existing information is therefore useful and necessary to identify stressors that may act in synergy and to design new field campaigns. In addition, a detailed data analysis of the main water quality variables is presented: advanced statistical analyses (i.e. Spearman rank correlation, Principal Component Analysis, andMann-Kendall trend tests) were applied to long-term time series of water quality data both in the Adige River Basin and in the Ebro and Sava catchments, aiming at providing an integrated and comparative analysis of recent trends, in order to investigate the relationships between water quality parameters and the main factors controlling them (i.e. climate change, streamflow, land use, population) in the Mediterranean region. These catchments are included into the EU project “Globaqua ”, dealing with the analysis of the combined effect of several stressors on the freshwater ecosystems inMediterranean rivers. In fact, little attention has been paid to linkages between long-term trends in climate, streamflow and water quality in European basins; nevertheless, such analysis can represent, complementary to a deep knowledge of the investigated systems, a reliable tool for decision makers in river basin planning by providing a reliable estimate of the impacts on the aquatic ecosystem of the studied basins. In the second part, sampling campaigns performed in our study basin, the Adige catchment, are presented in detail. Special attention is also given to emerging pollutants, whose study on the occurrence patterns and spatiotemporal variability in the Adige River Basin has been conducted in conjunction with population patterns and touristic fluxes. In the third and last part, novel theoretical solutions of the well-known advection-dispersion-reaction (ADR) equation are presented. The theory was developed for both general water quality variables and pharmaceuticals, evidencing differences and analysing the main factors that influence water quality dynamics. An application is also proposed to the Adige catchment.
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Higgins, David Ian. "Catchment scale influences on brown trout fry populations in the Upper Ure catchment, North Yorkshire." Thesis, Durham University, 2011. http://etheses.dur.ac.uk/3571/.
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A multi-scale approach for restoration site selection is presented and applied to an upland catchment, the River Ure, North Yorkshire. Traditional survey methods, advances in remote sensing, Geographical Information Systems (GIS) and risk-based fine sediment modelling using the SCIMAP module are combined to gather data at the catchment-scale through to the in-stream habitat-scale. The data gathered have been assessed against spatially distributed brown trout fry populations using Pearson’s correlation and multiple stepwise regressions. Fine sediment was shown to have a positive correlation with fry populations when upland drainage channels (grips) were added to the SCIMAP model. This suggests risk from peatland drainage is realised further down the catchment where eroded sediments are deposited. Farm-scale SCIMAP modelling was tested against farmers’ knowledge with variable results. It appears there is a cultural response to risk developed over generations. Management of meadows and pasture land through sub-surface drainage and stock rotation resulted in the risk being negated or re-routed across the holding. At other locations apparently low-risk zones become risky through less sensitive farming methods. This multi-scale approach reveals that the largest impacts on brown trout recruitment operate at the habitat-adjacent scale in tributaries with small upstream areas. The results show a hierarchy of impact, and risk-filters, arising from different intensity land management. This offers potential for targeted restoration site selection. In low-order streams it seems that restoration measures which exclude livestock, and provide bankside shading, can be effective. At such sites the catchment-scale shows a reduced signal on in-stream biota. Thus, brown trout stocks could be significantly enhanced by targeting restoration at riffle-habitat zones and adjacent land in order to disconnect the stream from farm-derived impacts and through adding structure to the stream channel.
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Parker, Chris. "Quantifying catchment-scale coarse sediment dynamics in British rivers." Thesis, University of Nottingham, 2010. http://eprints.nottingham.ac.uk/11980/.
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It has become increasingly clear that river channel sediment dynamics must be taken into account within British flood risk management because changes in channel morphology resulting from sediment transfer can have an impact on channel flood capacity. It is also recognised that an understanding of catchment-scale sediment dynamics is desirable with respect to many other aspects of river management. However, despite this recognition, application of existing approaches that account for coarse sediment dynamics has been limited within British river management. Based on these considerations, this study aims to develop and substantiate a new approach that quantitatively accounts for catchment-scale coarse sediment dynamics in British rivers. These research efforts contribute to the activity of the Flood Risk Management Research Consortium (http://www.floodrisk.org.uk/) A review of the availability and accuracy of data sources useful to considerations of coarse sediment dynamics reveals that only discharge, channel slope, and channel width can be represented widely at the catchment-scale. As a result, none of the approaches currently available to account for coarse sediment dynamics were found to be both scientifically robust and practically applicable at the catchment-scale. This leads to the conclusion that the most suitable approach to account for coarse sediment dynamics at the catchment-scale in British rivers is a reach-based sediment balance model, using no more than slope, width and discharge data. A new reach-based sediment balance model, ST:REAM (Sediment Transport: Reach Equilibrium Assessment Method), is developed. It has several unique features including: representation of the entire catchment network; automatic delineation of the catchment network into functional reaches using a zonation algorithm; application of a new general formula for the prediction of bed surface material transport rate; and adoption of an assumption that makes it unnecessary to collect bed material size data. The outputs from ST:REAM are in the form of predicted Capacity Supply Ratios which compare the annual mass of sediment predicted to enter a reach with the annual mass of sediment predicted to leave it. Initial assessment of ST:REAM using two test catchments shows that it can produce a reasonable representation of observed, broad-scale sediment dynamics. The accuracy of its predictions decreases when attempting to incorporate downstream variability in bed material size into the model, and scale issues are encountered when attempting to increase the resolution at which reaches are identified by the zonation algorithm. ST:REAM has many potential applications within river management, but it is of most value when providing a broad-scale picture of predicted reach sediment balances throughout the drainage network. As well as the practical applications of ST:REAM, the research contained within this thesis has important theoretical implications, relating both to the insights it provides on catchment-scale sediment dynamics in particular and methodological and foundational developments in the field of sediment studies more generally. Online version lacks Appendices, which were submitted on CD-ROM accompanying printed version.
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Pattison, Ian. "Rural land management impacts on catchment scale flood risk." Thesis, Durham University, 2010. http://etheses.dur.ac.uk/531/.
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This thesis examines the relationship between rural land management and downstream flood risk. The recent increase in flood frequency and magnitude has been hypothesised to have been caused by either climate change or land management. The theoretical basis for why these factors might increase flood risk is well known, but showing their impact on downstream flood risk remains a challenge. Field scale studies have found that changing land management practices does affect local runoff and streamflow. Upscaling these effects to the catchment scale continues to be problematic,both conceptually and, more importantly, methodologically. Conceptually, upscaling is critical. As land management may impact upon the relative timing as well as the magnitude of runoff, any changes in land management practice may lead to changes in the synchronisation of tributaries flows, either reducing or increasing downstream flood risk. Methodologically, understanding this effect requires capturing the spatial resolution associated with field-scale hydrological processes simultaneously with the upscaling of these processes to the downstream locations where flood risk is of concern. Most approaches to this problem aim to upscale from individual grid cells to whole catchments, something that restricts the complexity of possible process representation,produces models that may not be parsimonious with the data needed to calibrate them and, faced with data uncertainties, provides computational limitations on the extent to which model uncertainty can be fully explored. Rather than upscaling to problems of concern, this thesis seeks to downscale from locations of known flood risk, as a means of identifying where land use management changes might be beneficial and then uses numerical modelling to identify the kinds of management changes required in those downscaled locations. Thus, the aim of this thesis is to test an approach to understanding the impacts of rural land management upon flood risk based upon catchment-to-source downscaling. This thesis uses the case study of the River Eden catchment (2400 km2) as a test case. Firstly the downstream flood risk problem was assessed using both gauged data and documentary evidence to investigate the historical flood record. This found the last decade does not differ significantly from previous flood rich periods, which were defined as 1) 1873-1904; 2) 1923-1933; and 3) 1994-present. Second, the potential causes of floods within the catchment were investigated; firstly climate variability was assessed using Lamb weather types, which found that five weather types were responsible for causing 90% of the floods in the last 30 years. Third, spatial downscaling of catchment-scale flood risk was undertaken using two methods; databased statistical analysis; and hydraulic modelling. Both approaches consider the magnitudes and the timing of the flows from each major sub-catchment. The statistical approach involved a principal components analysis to simplify the complex subcatchment interactions and a stepwise regression to predict downstream flood risk. The hydraulic modelling approach used iSIS-Flow to undertake a series of numerical experiments, where the input hydrographs from each tributary were shifted individually and the effect on downstream peak stage assessed. Both these approaches found that the Upper Eden and Eamont sub-catchments were the most important in explaining downstream flood risk. The Eamont sub-catchment was chosen for future analysis as:(1) it was shown to have a significant impact on downstream flood risk; and (2) it had range of data and information needed for modelling land use changes. The second part of this thesis explored the land management scenarios that could be used to reduce flood risk at the catchment scale. The scenarios to be tested were determined through a stakeholder participation approach, whereby workshops were held to brainstorm and prioritise land management options, and then to identify specific locations within the Eamont sub-catchment where they could tested. There were two main types of land management scenarios chosen: (1) landscape-scale changes,including afforestation and compaction; and (2) channel modification and floodplain storage scenarios, including flood bank removal and wet woodland creation. The hydrological model CRUM3 was used to test the catchment scale land use changes,while the hydraulic model iSIS-Flow was used to test the channel and floodplain scenarios. It was found that through changing the whole of a small sub-catchment(Dacre Beck), the scenarios of reducing compaction and arabilisation could reduce catchment scale (2400 km2) flood risk by up to 3.5% for a 1 in 175 year flood event(January 2005). Changing localised floodplain roughness reduced sub-catchment (Lowther) peak stage by up to 0.134 m. This impact diminished to hardly any effect on peak flow magnitudes at the sub-catchment scale (Eamont). However, these scenarios caused a delay of the flood peak by up to 5 hours at the sub-catchment scale, which has been found to reduce peak stage at Carlisle by between 0.167 m to 0.232 m, corresponding to a 5.8% decrease in peak discharge. A key conclusion is that land management practices have been shown to have an effect on catchment scale flooding, even for extreme flood events. However, the effect of land management scenarios are both spatially and temporally dependent i.e. the same land management practice has different effects depending on where it is implemented, and when implemented in the same location has different effects on different flood events.
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Kernan, Martin Richard. "Predicting surface water critical loads at the catchment scale." Thesis, University College London (University of London), 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298825.
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Current applications of the critical loads concept are geared primarily towards targeting emission control strategies at a national and international level. In the UK maps of critical loads for freshwaters are available at 10km2 resolution based on a single representative site in each grid square. These maps do not take variations of water chemistry within mapping units into account and are therefore of limited use for application to non-mapped sites. This thesis describes the development of an empirical statistical model, which uses nationally available secondary data, to predict freshwater critical loads for catchments lacking the appropriate water chemistry information. A calibration exercise using data from 78 catchments throughout Scotland is described. Water chemistry for each catchment has been determined and each catchment is characterised according to a number of attributes. Multivariate statistical analysis of these data shows clear relationships between catchment attributes and water chemistry and between water chemistry and diatom critical load. The key variables which explain most of the variation in critical load relate to soil, geology and land use within the catchment. Using these variables (as predictors) in a regression analysis diatom critical load could be predicted across a broad gradient of sensitivity (R2adj = c. 0.8). The predictive power of the model was maintained when different combinations of explanatory variables were used. This accords the model a degree of flexibility in that model paramaterisation can be geared towards availability of secondary data. There are limitations with the model. These relate to the nature of the predictor variables and the ability of the model to predict critical loads for more sensitive sites. Nevertheless the ability of the model to differentiate between sensitive and non-sensitive sites offers considerable scope for environmental managers to undertake national inventories of catchment sensitivity and specific assessments of individual catchments.
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Arnott, Sean. "An assessment of methods for catchment-scale identification of goundwater-suface water interractions in lowland permeable catchments." Thesis, University of Exeter, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.532017.
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A better understanding f groundwater-surface water interactions is urgently required o underpin the implementation of the Water Framework Directive and to increase our knowledge of environmental processes in relation to base flow, chemical and nutrient fluxes, contaminated groundwater-surface water transfers, the selection of spawning sites by Atlantic salmon( Salmos alar) and the abstraction of groundwater. This project assessed a range of methods, other than the time-consuming technique of flow gauging, as fast and effective indicators of groundwater-surface water interactions over a catchment-wide scale.The study was aided by the results of two high resolution catchment-wide flow-accretion surveys. Physical and chemical tracers were shown to be ineffective when compared against the results of the flow-accretion surveys. A number of factors, such as long reach lengths, anthropogenic discharges, other in-stream processes and similar groundwater and surface water composition, appeared to diminish the signals produced by groundwater inputs to below detectable levels. A detailed reach-scale investigation assessed a range of methods over different temporal and spatial scales. The direct measurement of groundwater and surface water levels were 100% accurate in the identification of groundwater-surface water interactions, but this method would be impractical for catchment-scale assessment. Three methods for predicting groundwater-surface water interaction sites were assessed based on hydrogeological theory, such as groundwater flow systems, dry valley inputs and localised aspects of the solid geology. The effectiveness of the predictions were compared against the results of the Frome and Piddle flow-accretion surveys. The method using the localised aspects of the solid geology showed relatively high accuracy (60-70%)and was quite fast for catchment-scale assessment. The final investigation showed a statistically insignificant correlation between groundwater inputs and the location of Atlantic salmon( Salmos alar) redds. However, lower densities of Atlantic salmon redds were observed a long certain survey reaches that were subjected to surface water losses.
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Abancó, i. Martínez de Arenzana Clàudia. "Monitoring and geomorphologic characterization of debris flows at catchment scale." Doctoral thesis, Universitat Politècnica de Catalunya, 2013. http://hdl.handle.net/10803/128677.
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Debris flows are very fast mass movements and are considered as one of the most hazardous phenomenain mountainous regions. Research on this field has strongly improved during the last decades. However,many open questions remain concerning the details of the triggering mechanisms of this type of phenomena and their dynamic behaviour; both of them key points in the hazard assessment.
The global purpose of this work is to improve some aspects of the debris-flow hazard assessment atcatchment scale; particularly the estimation of the events¿ magnitude, the determination of their intensity and the characterization of the triggering factors. Most of the objectives have been carried out by means of the auscultation of a catchment in wich the debris flows are frequent. Furthermore, data of geomorphological characterization of other catchments have been analysed. This work aims at increasing the knowledge on debris flows in the Pyrenees.
In the context of this thesis, a debris-flow monitoring system has been set up in the Pyrenees, in the Rebaixader torrent (Alta Ribagorça, Central Pyrenees). Since July 2009, six debris flows involving volumes ranging from 1000 to 21000 m3, eleven debris floods (volumes from 350 to 2800 m3) and four rockfalls have been registered. The distinction between processes and the identification of the different phases of the flow events have mainly been based on ground vibration data. The detailed analysis of the ground vibration generated by torrential processes has revealed that there are several on-site factors strongly influencing the signal registered by the geophones. In particular, a significant decrease of the signal has been recognized at the geophones that were not placed close to the active channel. The ground vibration signal generated by some debris-flow events has not only been registered using the conventional digital sampling of the ground velocity signal, but also by means of transforming the ground velocity into impulses. Both techniques are suitable for the detection and characterization of the debris-flow events. However, the transformation into impulses shows interesting advantages, such as the low power consumption and the simplicity of the analysis of this type of signal in comparison to the conventional one.
Both aspects are crucial in early warning and alarm systems (EWAS). Besides, the characterization of the rainfalls in the catchment has revealed that the most common debris-flow triggering rainfalls in the Rebaixader torrent last around 2 hours and the critical hourly intensity value is around 15 mm/h. However, it has been detected that also spring episodes of moderate intensity, accompanied by the potential infiltration from snowmelt can trigger torrential flows and rockfalls. In particular, a detailed analysis of three rockfalls that occurred in spring is presented.
Moreover, a methodology to estimate the entrainment of bed material in a debris-flow event is presented within this study. The methodology was based on the creation of a decision tree (applying data mining techniques) over a database of geomorphologic parameters, collected in the field and from a digital elevation model, which incorporates 110 reaches from 17 torrents. Finally, a general decision tree was proposed that should be calibrated and adapted, in order to widen its application to other catchments and climatic regions.
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Fedak, Ryan Michael. "Effect of Spatial Scale on Hydrologic Modeling in a Headwater Catchment." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/31115.
Full textAbstract:
In this study, two hydrologic models were applied to the mountainous Back Creek catchment, located in the headwaters of the Roanoke River in Southwest Virginia. The two models employed were HEC-1, an event based lumped model, and TOPMODEL, a continuous semi-distributed model. These models were used to investigate (a) the issue of spatial scale in hydrologic modeling, and (b) two approaches to modeling, continuous versus event based. Two HEC-1 models were developed with a different number of subareas in each. The hydrographs generated by each HEC-1 model for a number of large rainfall events were analyzed visually and statistically. No observable improvement resulted from increasing the number of subareas in the HEC-1 models from 20 to 81.
TOPMODEL was applied to the same watershed using a series of different size grid cells. The first step in applying TOPMODEL to a watershed involves GIS analysis which results in a raster grid of elevations used for the calculation of the topographic index, ln(a/tan b). The hydrographs generated by TOPMODEL with each grid cell size were compared in order to assess the sensitivity of TOPMODEL hydrographs to grid cell size. An increase in grid cell size from 15 to 120 meters resulted in increased values of the watershed mean of the topographic index. However, hydrographs generated by TOPMODEL were completely unaffected by this increase in the topographic index. Analyses were also performed to determine the sensitivity of TOPMODEL hydrographs to several model parameters. It was determined that the parameters that had the greatest effect on hydrographs generated by TOPMODEL were the m and ln(To) parameters.
The modeling performances of the event based HEC-1 and the continuous TOPMODEL were analyzed and compared visually and statistically for a number of large storms. The limited number of storms used to compare HEC-1 and TOPMODEL makes it difficult to determine definitively which model simulates large storms better. It does appear that perhaps HEC-1 is slightly superior in that regard. TOPMODEL was also executed as an event based model for two single events and the resulting hydrographs were compared to the HEC-1 and continuous TOPMODEL results. Both HEC-1 and TOPMODEL (when used as a continuous model) simulate large storms better than TOPMODEL (when used as an event based model).Master of Science
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Jencso, Kelsey Graham. "Hydrologic connectivity between landscapes and streams: transferring reach and plot scale understanding to the catchment scale." Diss., Montana State University, 2010. http://etd.lib.montana.edu/etd/2010/jencso/JencsoK1210.pdf.
Full textAbstract:
Transferring plot and reach scale hydrologic understanding to the catchment scale and elucidating the link between catchment structure and runoff and solute response remains a challenge. To address this challenge, I pursued the following questions as part of this dissertation: How do spatiotemporal distributions of hillslope-riparian-stream (HRS) hydrologic connectivity influence whole catchment hydrologic dynamics and what are the implications of this for stream biogeochemistry? What are the implications of catchment structure for riparian buffering and streamflow source water composition? What are the hierarchical controls on hydrologic connectivity and catchment runoff dynamics across 11 diverse headwater catchments and across flow states? I addressed these questions through detailed hydrometric monitoring and analysis (160 recording wells across 24 HRS transects and stream discharge across 11 catchments), tracer sampling and analysis (groundwater, soil water, and stream water sampling of major ions, specific conductance and dissolved organic carbon (DOC)), and newly developed digital landscape and terrain analyses. I installed this unprecedented network of instrumentation to address these questions across 11 adjacent and nested catchments within the Tenderfoot Creek Experimental Forest (TCEF), Rocky Mountains, MT. I determined that 1) hillslope topography, specifically upslope accumulated area (UAA), was the first order control on the duration of transient water table connectivity observed across HRS landscape positions; 2) the intersection of HRS connectivity with riparian area extents determined the degree of riparian groundwater turnover, riparian buffering of upslope water, and the magnitude of DOC transport to streams; 3) 11 catchments' stream network hydrologic connectivity duration curves were highly correlated to streamflow duration curves and the variable slopes of these relationships were explained by vegetation, geology, and within catchment distributions flowpath length and gradient ratios. This dissertation consists of five key chapters / manuscripts that address how landscape structure/organization within and across catchments can control the timing and magnitude of water and solutes observed at catchment outlets.
'Co-authored by Brian L. McGlynn, Michael N. Gooseff, Steven M. Wondzell, Kenneth E. Bencala, Lucy A. Marshall, Vincent J. Pacific, Thomas J. Grabs and Jan Seibert.'
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Egodawatta, Prasanna Kumarasiri. "Translation of small-plot scale pollutant build-up and wash-off measurements to urban catchment scale." Thesis, Queensland University of Technology, 2007. https://eprints.qut.edu.au/16502/1/Prasanna_Egodawatta_Thesis.pdf.
Full textAbstract:
Accurate and reliable estimations are the most important factors for the development of efficient stormwater pollutant mitigation strategies. Modelling is the primary tool used for such estimations. The general architecture of typical modelling approaches is to replicate pollutant processes along with hydrologic processes on catchment surfaces. However, due to the lack of understanding of these pollutant processes and the underlying physical parameters, the estimations are subjected to gross errors. Furthermore, the essential requirement of model calibration leads to significant data and resource requirements. This underlines the necessity for simplified and robust stormwater pollutant estimation procedures.
The research described in this thesis primarily details the extensive knowledge developed on pollutant build-up and wash-off processes. Knowledge on both build-up and wash-off were generated by in-depth field investigations conducted on residential road and roof surfaces. Additionally, the research describes the use of a rainfall simulator as a tool in urban water quality research. The rainfall simulator was used to collect runoff samples from small-plot surfaces. The use of a rainfall simulator reduced the number of variables which are common to pollutant wash-off.
Pollutant build-up on road and roof surfaces was found to be rapid during the initial time period and the rate reduced when the antecedent dry days increase becoming asymptote to a constant value. However, build-up on roofs was gradual when compared to road surfaces where the build-up on the first two days was 66% of the total build-up. Though the variations were different, it was possible to develop a common replication equation in the form of a power function for build-up for the two surface types with a as a multiplication coefficient and b as a power coefficient. However, the values for the two build-up equation coefficients, a, and b were different in each case. It was understood that the power coefficient b varies only with the surface type. The multiplication coefficient varies with a range of parameters including land-use and traffic volume. Additionally, the build-up observed on road surfaces was highly dynamic. It was found that pollutant re-distribution occurs with finer particles being removed from the surface thus allowing coarser particles to build up. This process results in changes to the particle size composition of build-up.
However, little evidence was noted of re-distribution of pollutants on roof surfaces.
Furthermore, the particulate pollutants in both road and roof surfaces were high in adsorption capacity. More than 50% of the road and more than 60% of the roof surface particulates were finer than 100 μm which increases the capacity to adsorb other pollutants such as heavy metals and hydrocarbons. In addition, the samples contained a significant amount of DOC which would enhance the solubility of other pollutants.
The wash-off investigations on road and roof surfaces showed a high concentration of solid pollutants during the initial part of events. This confirmed the occurrence of the 'first flush' phenomenon. The observed wash-off patterns for road and roof surfaces were able to be mathematically replicated using an exponential equation. The exponential equation proposed is a modified version of an equation proposed in past research. The modification was primarily in terms of an additional parameter referred to as the 'capacity factor' (CF). CF defines the rainfall's ability to mobilise solid pollutants from a given surface. It was noted that CF varies with rainfall intensity, particle size distribution and surface characteristics. Additional to the mathematical replication of wash-off, analysis further focused on understanding the physical processes governing wash-off. For this, both particle size distribution and physicochemical parameters of wash-off pollutants were analysed. It was noted that there is little variation in the particle size distribution of particulates in wash-off with rainfall intensity and duration. This suggested that particle size is not an influential parameter in wash-off. It is hypothesised that the particulate density and adhesion to road surfaces are the primary criteria that govern wash-off. Additionally, significantly high pollutant contribution from roof surfaces was noted. This justifies the significance of roof surfaces as an urban pollutant source particularly in the case of first flush.
This dissertation further describes a procedure to translate the knowledge created on pollutant build-up and wash-off processes using small-plots to urban catchment scale.
This leads to a simple and robust urban water quality estimation tool. Due to its basic architecture, the estimation tool is referred to as a 'translation procedure'. It is designed to operate without a calibration process which would require a large amount of data. This is done by using the pollutant nature of the catchment in terms of buildup and wash-off processes as the basis of measurements. Therefore, the translation procedure is an extension of the current estimation techniques which are typically complex and resource consuming. The use of a translation procedure is simple and based on the graphical estimation of parameters and tabular form of calculations. The translation procedure developed is particularly accurate in estimating water quality in the initial part of runoff events.
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Egodawatta, Prasanna Kumarasiri. "Translation of small-plot scale pollutant build-up and wash-off measurements to urban catchment scale." Queensland University of Technology, 2007. http://eprints.qut.edu.au/16502/.
Full textAbstract:
Accurate and reliable estimations are the most important factors for the development of efficient stormwater pollutant mitigation strategies. Modelling is the primary tool used for such estimations. The general architecture of typical modelling approaches is to replicate pollutant processes along with hydrologic processes on catchment surfaces. However, due to the lack of understanding of these pollutant processes and the underlying physical parameters, the estimations are subjected to gross errors. Furthermore, the essential requirement of model calibration leads to significant data and resource requirements. This underlines the necessity for simplified and robust stormwater pollutant estimation procedures. The research described in this thesis primarily details the extensive knowledge developed on pollutant build-up and wash-off processes. Knowledge on both build-up and wash-off were generated by in-depth field investigations conducted on residential road and roof surfaces. Additionally, the research describes the use of a rainfall simulator as a tool in urban water quality research. The rainfall simulator was used to collect runoff samples from small-plot surfaces. The use of a rainfall simulator reduced the number of variables which are common to pollutant wash-off. Pollutant build-up on road and roof surfaces was found to be rapid during the initial time period and the rate reduced when the antecedent dry days increase becoming asymptote to a constant value. However, build-up on roofs was gradual when compared to road surfaces where the build-up on the first two days was 66% of the total build-up. Though the variations were different, it was possible to develop a common replication equation in the form of a power function for build-up for the two surface types with a as a multiplication coefficient and b as a power coefficient. However, the values for the two build-up equation coefficients, a, and b were different in each case. It was understood that the power coefficient b varies only with the surface type. The multiplication coefficient varies with a range of parameters including land-use and traffic volume. Additionally, the build-up observed on road surfaces was highly dynamic. It was found that pollutant re-distribution occurs with finer particles being removed from the surface thus allowing coarser particles to build up. This process results in changes to the particle size composition of build-up. However, little evidence was noted of re-distribution of pollutants on roof surfaces. Furthermore, the particulate pollutants in both road and roof surfaces were high in adsorption capacity. More than 50% of the road and more than 60% of the roof surface particulates were finer than 100 μm which increases the capacity to adsorb other pollutants such as heavy metals and hydrocarbons. In addition, the samples contained a significant amount of DOC which would enhance the solubility of other pollutants. The wash-off investigations on road and roof surfaces showed a high concentration of solid pollutants during the initial part of events. This confirmed the occurrence of the 'first flush' phenomenon. The observed wash-off patterns for road and roof surfaces were able to be mathematically replicated using an exponential equation. The exponential equation proposed is a modified version of an equation proposed in past research. The modification was primarily in terms of an additional parameter referred to as the 'capacity factor' (CF). CF defines the rainfall's ability to mobilise solid pollutants from a given surface. It was noted that CF varies with rainfall intensity, particle size distribution and surface characteristics. Additional to the mathematical replication of wash-off, analysis further focused on understanding the physical processes governing wash-off. For this, both particle size distribution and physicochemical parameters of wash-off pollutants were analysed. It was noted that there is little variation in the particle size distribution of particulates in wash-off with rainfall intensity and duration. This suggested that particle size is not an influential parameter in wash-off. It is hypothesised that the particulate density and adhesion to road surfaces are the primary criteria that govern wash-off. Additionally, significantly high pollutant contribution from roof surfaces was noted. This justifies the significance of roof surfaces as an urban pollutant source particularly in the case of first flush. This dissertation further describes a procedure to translate the knowledge created on pollutant build-up and wash-off processes using small-plots to urban catchment scale. This leads to a simple and robust urban water quality estimation tool. Due to its basic architecture, the estimation tool is referred to as a 'translation procedure'. It is designed to operate without a calibration process which would require a large amount of data. This is done by using the pollutant nature of the catchment in terms of buildup and wash-off processes as the basis of measurements. Therefore, the translation procedure is an extension of the current estimation techniques which are typically complex and resource consuming. The use of a translation procedure is simple and based on the graphical estimation of parameters and tabular form of calculations. The translation procedure developed is particularly accurate in estimating water quality in the initial part of runoff events.
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Lancaster, James William. "Multi-scale estimation of effective permeability within the Greenholes Beck catchment." Thesis, Lancaster University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369589.
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Sabetraftar, Karim, and Karim Sabetraftar@anu edu au. "The hydrological flux of organic carbon at the catchment scale: a case study in the Cotter River catchment, Australia." The Australian National University. Centre for Resource and Environmental Studies, 2005. http://thesis.anu.edu.au./public/adt-ANU20070502.141450.
Full textAbstract:
Existing terrestrial carbon accounting models have mainly investigated atmosphere-vegetationsoil
stocks and fluxes but have largely ignored the hydrological flux of organic carbon. It is
generally assumed that biomass and soil carbon are the only relevant pools in a landscape
ecosystem. However, recent findings have suggested that significant amounts of organic carbon
can dissolve (dissolved organic carbon or DOC) or particulate (particulate organic carbon or
POC) in water and enter the hydrological flux at the catchment scale. A significant quantity of
total organic carbon (TOC) sequestered through photosynthesis may be exported from the
landscape through the hydrological flux and stored in downstream stocks.¶
This thesis presents a catchment-scale case study investigation into the export of organic carbon
through a river system in comparison with carbon that is produced by vegetation through
photosynthesis. The Cotter River Catchment was selected as the case study. It is a forested
catchment that experienced a major wildfire event in January 2003. The approach is based on an
integration of a number of models. The main input data were time series of in-stream carbon
measurements and remotely sensed vegetation greenness. The application of models to
investigate diffuse chemical substances has dramatically increased in the past few years because
of the significant role of hydrology in controlling ecosystem exchange. The research firstly
discusses the use of a hydrological simulation model (IHACRES) to analyse organic carbon
samples from stream and tributaries in the Cotter River Catchment case study. The IHACRES
rainfall-runoff model and a regionalization method are used to estimate stream-flow for the 75
sub-catchments. The simulated streamflow data were used to calculate organic carbon loads
from concentrations sampled at five locations in the catchment.¶
The gross primary productivity (GPP) of the vegetation cover in the catchment was estimated
using a radiation use efficiency (RUE) model driven by MODIS TERRA data on vegetation
greenness and modeled surface irradiance (RS). The relationship between total organic carbon
discharged in-stream and total carbon uptake by plants was assessed using a cross-correlation
analysis.¶
The IHACRES rainfall-runoff model was successfully calibrated at three gauged sites and
performed well. The results of the calibration procedure were used in the regionalization method
that enabled streamflow to be estimated at ungauged locations including the seven sampling
sites and the 75 sub-catchment areas. The IHACRES modelling approach was found appropriate
for investigating a wide range of issues related to the hydrological export of organic carbon at
the catchment scale. A weekly sampling program was implemented to provide estimates of
TOC, DOC and POC concentrations in the Cotter River Catchment between July 2003 and June
2004. The organic carbon load was estimated using an averaging method.¶
The rate of photosynthesis by vegetation (GPP) was successfully estimated using the radiation
use efficiency model to discern general patterns of vegetation productivity at sub-catchment
scales. This analysis required detailed spatial resolution of the GPP across the entire catchment
area (comprising 75 sub-catchment areas) in addition to the sampling locations. Important
factors that varied at the catchment scale during the sampling period July 2003 June 2004,
particularly the wildfire impacts, were also considered in this assessment.
¶
The results of the hydrologic modelling approach and terrestrial GPP outcome were compared
using cross correlation and regression analysis. This comparison revealed the likely proportion
of catchment GPP that contributes to in-stream hydrological flux of organic carbon. TOC Load
was 0.45% of GPP and 22.5 - 25% of litter layer. As a result of this investigation and giving due
consideration to the uncertainties in the approach, it can be concluded that the hydrological flux
of organic carbon in a forested catchment is a function of gross primary productivity.
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Sabetraftar, Karim. "The hydrological flux of organic carbon at the catchment scale : a case study in the Cotter River Catchment, Australia /." View thesis entry in Australian Digital Theses Program, 2005. http://thesis.anu.edu.au/public/adt-ANU20070502.141450/index.html.
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Welsh, Katharine Elizabeth. "Modelling basin-scale sediment dynamics in the Petit lac d'Annecy catchment, France." Thesis, University of Liverpool, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.533908.
Full textAbstract:
This research describes the testing, development and application of an established hydro-geomorphic numerical model (CAESAR) over different time scales (170-2000 years) to simulate at hourly time resolution, the changes in the hydrological and sediment regime of the Petit lac d’Annecy catchment in response to changes in system drivers. Two thousand year long model runs in five different morphological settings were simulated, the results suggest that intrinsic system behaviour such as storage-release, hillslope-channel coupling and supply-capacity relationships may well exert larger controls on sediment discharge patterns over this timescale than climate or land use drivers. Hypothetical scenarios to investigate the geomorphic implications of a snow-free pre-alpine region over the last 2000 years show that there would be around 1.4 times more sediment discharge, with the annual hydrological regime radically altered with increased flooding throughout the year, particularly in winter months and a lack of a sustained discharge peak in the ‘melt’ months. This has implications for the projected environmental changes over the coming decades. The simulated effects of increased precipitation, reduced forest cover and snow-free conditions, in combination, point to increased amounts of coarse sediment discharge within the channels. Broad estimations show that a 20% reduction in forest cover or snow-free conditions can result in an additional 1m of sediment moving through the system and accumulating in the lake with potentially large impacts on flooding, in-channel fauna, benthic-dwelling lake fauna, aquatic macrophysics and water quality and water availability for storage and local power generation.
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Jonczyk, Jennine. "Processes leading to nutrient pollution at the field and sub-catchment scale." Thesis, University of Newcastle Upon Tyne, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442220.
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Dayawansa, Nandani Dhammika Kumari. "The development of nutrient pollution models for use at the catchment scale." Thesis, University of Newcastle Upon Tyne, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391963.
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Boyce, Daniel J. B. "Micro-component water demand scenario modelling for catchment scale residential water use." Thesis, Cranfield University, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.443748.
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Harrison, Rebecca Victoria. "An investigation of spatial and temporal pesticide dynamics at the catchment scale." Thesis, University of Bristol, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.682555.
Full textAbstract:
Pesticides are an essential component of modern agriculture and large quantities are applied annually on a global basis to arable land to prevent crop loss. After application, pesticides can be taken up by plants, degraded or distributed in the environment between the soil and in surface water or groundwater. Transport of pesticides in runoff and subsurface flow during rainfall events poses a significant concern for water quality with adverse effects on drinking water and aquatic life. Establishing the links between pesticide applications, hydrology, soil properties and erosion dynamics is key to understanding the fate of pesticides in the environment. This study has used a multi-scale approach combining laboratory experiments with a focused field campaign in a lowland agricultural catchment to investigate spatial and temporal pesticide dynamics at the catchment scale. The research provides methodological development for analysis of pesticides in soil, an understanding of the behaviour of pesticides in the soil and water environment after application due to rainfall and a catchment scale study of pesticide transport and distribution annually, seasonally and during individual storm events. First order controls on pesticide transport have been identified to partly explain the distribution of pesticides through a catchment and the upstream conditions required for pesticide movement. These include timing of application, quantity of pesticide available, antecedent soil moisture and rainfall, storm event characteristics, land use and season. An investigation of sediment-associated pesticides showed no significant quantities in stream-bed, reservoir bed or suspended sediment during storm events. The major risk factor for pesticide movement was found to be dissolved pesticides in storm event runoff. Results of this research can be used by farmers, water companies, regulatory bodies and scientists to improve water resource protection from field to catchment scales.
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Sjöblom, Viktor. "The role of catchment scale for determining hydrological flow paths during spring flood /." Umeå : Sveriges lantbruksuniversitet, 2005. http://epsilon.slu.se/10048534.pdf.
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Haas, Marcelo [Verfasser]. "Nitrate processes investigation for improved ecohydrological modeling at the catchment scale / Marcelo Haas." Kiel : Universitätsbibliothek Kiel, 2016. http://d-nb.info/1117540774/34.
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Shepherd, Barry. "The application of remotely sensed data to a catchment-scale nutrient transport model." Thesis, University of Leicester, 2003. http://hdl.handle.net/2381/29844.
Full textAbstract:
Nutrient transport models are being used increasingly as a tool for the research and management of nutrient enrichment (eutrophication) of freshwaters. Phosphorus is seen as the main cause of freshwater eutrophication. A nutrient transport model was acquired that could simulate the movement of phosphorus through a catchment. The SWAT model from the US Department of Agriculture, Agricultural Research Service appeared to suit the requirements of a catchment-scale, continual time model that was distributed in nature. It is based on physical processes in order that predictions could be made for land management practices or environmental conditions that had been absent in calibration processes.;Remote sensing technology has the potential to improve on estimates of distributed variables based on spot measurements and interpolative techniques. The initial intention of this project was to estimate several parameters from remote sensing images and use them as input to the chosen nutrient transport model. The SWAT model is only able to utilise mapped data for soil types and land cover. Whilst the latter can be extracted from various remote-sensing devices the former cannot. Synthetic aperture radar (SAR) has the potential to estimate several of the parameters considered influential to the movement of nutrients in a catchment. This study utilised five SAR images to investigate the potential of extracting: (i) land cover data, (ii) soil moisture, (iii) soil surface roughness, (iv) soil organic matter content (v) oilseed rape leaf area index and (vi) oilseed rape biomass. No significant relationships were found between any of the soil parameters and radar backscatter using linear regression. It is thought that this may be due to the excessive moisture levels at the time of sampling, but sampling intensity could also have been better. Likewise no significant relationships were found between the botanical parameters and radar backscatter. Wheat and oilseed rape characteristics were also collected and applied to the MIMICS model to assess the technology of radiative transfer models in the UK. There was a significant correlation between the backscatter values obtained through the MIMICS model and the backscatter from mature wheat to the SAR images to but not to green wheat or oilseed rape.;A land cover map was generated using a multi date composite of three of the SAR images. The images were acquired in May, July and August of 1999. Land-classes were assigned using supervised maximum likelihood estimation (MLE) and unsupervised training. Out of 11 classes of land cover found on the Stonton Brook, 11 were identified using the supervised training and MLE and only seven using the unsupervised training. The former method acquired a total accuracy of 46 % against the latter's 53%. On applying the classification schemes to a field boundary map the total accuracies improved to 58 % and 54 % respectively. Both maps were regarded as moderately accurate and both were used in the SWAT model.
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Kazemi, Alamouti Hamideh. "Development of a Hybrid Conceptual-Statistical Framework to Evaluate Catchment-Scale Water Balance." Thesis, Curtin University, 2021. http://hdl.handle.net/20.500.11937/84108.
Full textAbstract:
The study introduces a novel framework that combines conceptual, hydrological and statistical models to study water resources on short-term and long-term scales. It improves the performance of a common conceptual model and its extended version to estimate water balance components of the case studies. Moreover, a conceptual-statistical model is developed to further increase the performance of the original models. The proposed method is a useful approach for other catchments particularly, where limited data is available.
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Teutschbein, Claudia. "Hydrological Modeling for Climate Change Impact Assessment : Transferring Large-Scale Information from Global Climate Models to the Catchment Scale." Doctoral thesis, Stockholms universitet, Institutionen för naturgeografi och kvartärgeologi (INK), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-84197.
Full textAbstract:
A changing climate can severely perturb regional hydrology and thereby affect human societies and life in general. To assess and simulate such potential hydrological climate change impacts, hydrological models require reliable meteorological variables for current and future climate conditions. Global climate models (GCMs) provide such information, but their spatial scale is too coarse for regional impact studies. Thus, GCM output needs to be downscaled to a finer scale either through statistical downscaling or through dynamic regional climate models (RCMs). However, even downscaled meteorological variables are often considerably biased and therefore not directly suitable for hydrological impact modeling. This doctoral thesis discusses biases and other challenges related to incorporating climate model output into hydrological studies and evaluates possible strategies to address them. An analysis of possible sources of uncertainty stressed the need for full ensembles approaches, which should become standard practice to obtain robust and meaningful hydrological projections under changing climate conditions. Furthermore, it was shown that substantial biases in current RCM simulations exist and that correcting them is an essential prerequisite for any subsequent impact simulation. Bias correction algorithms considerably improved RCM output and subsequent streamflow simulations under current conditions. In addition, differential split-sample testing was highlighted as a powerful tool for evaluating the transferability of bias correction algorithms to changed conditions. Finally, meaningful projections of future streamflow regimes could be realized by combining a full ensemble approach with bias correction of RCM output: Current flow regimes in Sweden with a snowmelt-driven spring flood in April will likely change to rather damped flow regimes that are dominated by large winter streamflows.
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Apelu-Uili, Toiata. "Working together as one?Exploring the implementation and community perception of catchment management in Samoa." Thesis, University of Canterbury. Waterways Center for Freshwater Management, 2015. http://hdl.handle.net/10092/11260.
Full textAbstract:
Water is a constantly changing resource by way of the hydrological cycle. It is unevenly distributed and crosses boundaries of all kinds i.e. political, social, cultural and natural.
Samoa is a small developing state in the Pacific Region that is facing rapid pressure with its water resource availability. Consequently, access to and use of water resources has created tensions between water resources regulators, water utilities and villages. Therefore, managing and governing of water becomes a challenging process that has to take into account the complexity of both nature and society. With the emergence of the Integrated Water Resources Management (IWRM) framework, a greater social acceptance and importance has been given to catchment scale management and governance. Nowadays, many countries including Samoa, have embraced this appealing concept where catchments are seen as natural units for water governance and management.
This study used a social qualitative approach, aimed to investigate the implementation of catchment management and examine local community perceptions of catchment management, using Apia Catchment as case study. It is based on a conceptual framework of the concept of scale i.e. set out in recent debates and ideas in the arena of catchment scale water governance and management. The primary data was collected from community focus groups within two villages of Apia Catchment, and semi-structured interviews with government agencies involved in the Water and Sanitation Sector programmes.
The findings revealed a shift in water resources management and governance and a spatial scale mismatch in Apia Catchment management. According to government officials, the catchment approach is a ‘management tool’ adopted to improve the coordination between water users and to promote local ownership of catchment activities amongst individual villages. However, several challenges arose around land ownership, monetary cost, community resistance and issues outside of catchment areas when implementing catchment management. Despite the challenges that government officials encountered and the concerns raised by the communities, catchment scale management is still being adopted in Samoa. With the adoption of catchment management, many individual villages within Apia Catchment are expected to make decisions collectively. However, some local groups have concerns about the use of the term ‘boundary’, the possibility of the government taking over their land and the proposed catchment-based authority taking precedence over pre-existing cultural hierarchy.
Overall, this research reveals that catchment management is often viewed or seen by government as a ‘one size fits all’ notion that ignores the range of the socio-ecological realities on the ground. This study shows that in order to design better water resources policies and strategies that are fully applicable and workable for Samoa, it is very important to identify these mismatches in scales (e.g. spatial and administrative) and levels (e.g. national and local). Understanding scales and associated levels is critical to understanding the whole system and can reduce possible consequences of mismatches due to lack of interaction and collaboration between levels and scales. Local villages have expressed their opinions on how to enhance catchment management and this could perhaps be useful for government in terms of implementation. Based on the results, recommendations are made for water resources managers to assess the importance of different levels and their interactions but, more importantly, to consider how local communities perceive catchment management.
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Papacharalampou, Chrysoula. "Integrated water resources and asset management at a catchment scale : a life-cycle improvement approach." Thesis, University of Bath, 2017. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.723320.
Full textAbstract:
In the water utility sector, traditional asset management focusses on the maintenance and provision of physical assets (infrastructure) that allow water companies to deliver their services, meet their customers’ expectations and achieve their economic objectives. Nevertheless, the serviceability of the sector heavily depends on natural elements (e.g. rain, land). The importance of Natural Capital (i.e. the natural systems and their deriving ecosystem services) has been at the core of policy recommendations which have shaped regulatory changes in the water sector of England and Wales. Water companies are now required to explicitly account for and report their inter-dependencies on the natural environment and adopt systems-oriented approaches in their Asset Management Programmes (AMPs). These reforms will enable the sector to become resilient to the environmental and societal challenges faced at urban and rural contexts. Responding to the regulatory demands, the research introduces a novel and structured approach for integrating natural capital in the asset management portfolio of the water industry. The work is built on a transdisciplinary research framework and demonstrates that a new scale needs to be considered for the implementation of Holistic Asset Management: the water basin or catchment. A Catchment Metabolism modelling schema was created, grounded on the principles of Integrated Catchment Management and ecosystems services. The schema is based on the robust synthesis of concepts, tools and methods from a spectrum of disciplines. These include Industrial Ecology, Water Accounting, Environmental Regional Input-Output Analysis, hydrology, software engineering and functional modelling. Catchment Metabolism introduces a holistic perspective in asset management and expands its scope. The schema enables the conceptualisation, modelling and management of catchments as complex asset systems. It, thus, forms the ground for structured collaboration among experts for integrated water resources planning and decision-making. The schema allows for the design and implementation of catchment-based strategies and the assessment of their environmental performance. An industrial case study for a pilot catchment system (Poole Harbour Catchment) is used to demonstrate the application of the Catchment Metabolism. Alternative strategies for nitrogen pollution mitigation are assessed. The application of winter cover crops across the catchment appears to be the optimum strategy. The case study demonstrates the practical and modular implementation of the schema, reveals its methodological strengths and limitations and evaluates its applicability in the asset management planning and decision-making of the water sector.
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Whitehead, Jodie. "Integrated catchment scale model of a lowland eutrophic lake and river system : Norfolk, UK." Thesis, Cranfield University, 2006. http://hdl.handle.net/1826/1109.
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Shallow lakes are ecologically and economically important; many users are interested in methods to assess their response to restoration measures and in tools to predict the impact of specific measures. These users include: local and governmental authorities, private companies
or nature conservation organisations.
This research is centred on the Broads. The Broads are shallow, eutrophic lakes, probably the result of medieval peat workings, concentrated in the Ant, Bure, Thurne and Yare river valleys. These man made lakes and their surroundings are unique in Europe in terms of both ecology and landscape, forming one of the few remaining large areas of lowland river grassland in the UK.
A catchment scale model, SWAT, has been used to model past and future land use and
climate scenarios for river basins supplying water and nutrients to the Broads. SWAT is a
comprehensive model that requires a diversity of information including climate, topography, soil, land use, agricultural practices, water abstraction and discharge data.
Future scenarios run with SWAT suggest that increases in rainfall and temperature through
climate change and changed land use increase nutrient and sediment yields and runoff. Future scenarios therefore suggest increased eutrophication problems for both the rivers and Broads within the study area and an increase in the already high risk of ecological failure to the Broads.
Various management scenarios based on erosion control measures were designed to alleviate nutrient and sediment yields and increased run-off to the system. SWAT modelling showed the best-case future scenario in terms of land management was to convert the area to grassland. Where land is still used for agriculture erosion control, measures such as cover crops and conservation tillage should be employed.
Overall, the work has increased the understanding of water quality, water movement, nutrient and sediment dynamics and agricultural management practices within the study area. The environmental implications of different future scenarios and erosion control measures on the ecology of the Broads provide a basis for management of the area.
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Lindgren, Georg. "Physical process effects on catchment-scale pollutant transport-attenuation, coastal loading and abatement efficiency." Doctoral thesis, KTH, Mark- och vattenteknik, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3900.
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Pollutants follow various subsurface and surface water pathways from sources within a catchment to its outlet and may cause detrimental effects on downstream water quality and ecosystems. Along their different transport pathways through a catchment, pollutants may be attenuated subject to different physical and biogeochemical processes. In this thesis, physical process effects on such catchment-scale pollutant transport and attenuation, resulting coastal pollutant loading and its efficient abatement are investigated. For this purpose, pollutant transport-attenuation is modeled both generically using a Lagrangian Stochastic Advective-Reactive (LaSAR) approach and site specifically for the Swedish Norrström basin using the GIS-based dynamic nitrogen transport-attenuation model POLFLOW. Furthermore, the role of such modeling for catchment-scale pollutant abatement is also investigated by use of economic optimization modeling. Results indicate that appropriate characterization of catchment-scale solute transport and attenuation processes requires accurate quantification of the specific solute pathways from different sources in a catchment, through the subsurface and surface water systems of the catchment, to the catchment outlet. The various physical processes that act on solute transported along these pathways may be quantified appropriately by use of relevant solute travel time distributions for each water subsystem that the pathways cross through the catchment. Such distributions capture the physical solute travel time variability from source to catchment outlet and its effects on reactive pollutant transport. Results of this thesis show specifically that neglect of such physical solute travel time variability in large-scale models of nitrogen transport and attenuation in catchments may yield misleading model estimates of nitrogen attenuation rates. Results for nitrogen abatement optimization in catchments further indicate that inefficient solutions for coastal nitrogen load reduction may result from simplifying physical transport assumptions made in different catchment-scale nitrogen transport-attenuation models. Modeling of possible future nitrogen management scenarios show also that slow nitrogen transport and reversible mass transfer processes in the subsurface water systems of catchments may greatly delay and temporally redistribute coastal nitrogen load effects of inland nitrogen source abatement over decades or much longer. Achievement of the national Swedish environmental objective to reduce the anthropogenic coastal nitrogen loading by 30% may therefore require up to a 40% reduction of both point sources, for achieving a fast coastal load response, and diffuse sources, for maintaining the coastal load reduction also in the long term.QC 20100908
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Anderson, Brett Gordon. "Quantifying the interaction between riparian vegetation and flooding : from cross-section to catchment scale /." Connect to thesis, 2006. http://repository.unimelb.edu.au/10187/2086.
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This study investigates whether the flood regime in a catchment is sensitive to the condition of riparian vegetation along the river network. The research is based on a comprehensive assessment and synthesis of field and laboratory measurements of vegetation flow resistance. A new numerical model is developed to estimate the roughness characteristics of multi-species riparian assemblages at a cross-section. Reach-scale and catchment-scale flood routing models are then applied to estimate the impact of vegetation on flood characteristics at successively larger scales. The investigation reveals that when riparian vegetation is removed at catchment-scale, peak stage declines as channel capacity increases but is also increased as the upstream catchment responds more rapidly to rain. In fact, the two competing impacts tend to cancel out leaving flood peak stage relatively insensitive to riparian condition. However, the overbank duration of a flood and flow speeds (including wave celerity) were both found to be sensitive to vegetation condition; respectively increasing and decreasing with density of vegetation. The first stage of this research examines the magnitude of the vegetation contribution to overall channel roughness, and established a means to predict it. The features of the flow resistance generated by six plant types (mature trees; grasses; aquatic plants; flexible saplings; and large woody debris) were distilled from a comprehensive review of over 160 existing publications (Chapter 2).
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Lindgren, Georg A. "Physical process effects on catchment-scale pollutant transport-attenuation, coastal loading and abatement efficiency /." Stockholm : Department of Land and Water Resources Engineering, Royal Institute of Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3900.
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Holleran, Molly E. "Quantifying catchment scale soil variability in Marshall Gulch, Santa Catalina Mountains Critical Zone Observatory." Thesis, The University of Arizona, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1538334.
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The quantification and prediction of soil properties is fundamental to further understanding the Critical Zone (CZ). In this study we aim to quantify and predict soil properties within a forested catchment, Marshall Gulch, AZ. Input layers of soil depth (modeled), slope, Saga wetness index, remotely sensed normalized difference vegetation index (NDVI) and national agriculture imagery program (NAIP) bands 3/2 were determined to account for 95% of landscape variance and used as model predictors. Target variables including soil depth (cm), carbon (kg/m2), clay (%), Na flux (kg/m 2), pH, and strain are predicted using multivariate linear step-wise regression models. Our results show strong correlations of soil properties with the drainage systems in the MG catchment. We observe deeper soils, higher clay content, higher carbon content, and more Na loss within the drainages of the catchment in contrast to the adjacent slopes and ridgelines.
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Loschko, Matthias [Verfasser], and Olaf A. [Akademischer Betreuer] Cirpka. "Stochastic Framework for Catchment-Scale Reactive Transport Simulations / Matthias Loschko ; Betreuer: Olaf A. Cirpka." Tübingen : Universitätsbibliothek Tübingen, 2018. http://d-nb.info/1171795009/34.
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Pearce, Richard John. "A generic approach to the assessment of cross-media pollution within catchment scale landscapes." Thesis, Cranfield University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.401678.
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Alvarez-Zaldívar, Pablo. "Pesticide degradation and transport at catchment scale : compound-specific isotope analysis and numerical modelling." Thesis, Strasbourg, 2019. http://www.theses.fr/2019STRAH010.
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Les herbicides sont une importante technologie de protection des cultures de l'agriculture moderne. Cependant, leur application sur de vastes étendues de terre génère des sources de pollution diffuses qui sont non seulement difficiles à surveiller et à contrôler, mais qui menacent également la qualité des ressources humaines en eau et des écosystèmes fluviaux dans le monde entier. Bien que des évaluations sur le terrain et des essais en laboratoire soient nécessaires avant l'introduction de matières actives sur le marché, le devenir et l'étendue de la dégradation des pesticides et de leurs métabolites dans l'environnement sont sujets à de grandes incertitudes. Ce travail de thèse établit une preuve de concept pour l'application de l'analyse isotopique des composés spécifiques (AICS) pour surveiller la dégradation et le transfert des pesticides à l'échelle du bassin versant. La thèse comprend à la fois la caractérisation sur le terrain et la modélisation numérique pour étudier la valeur de l'AICS comme outil de surveillance et comme technique de réduction de l'incertitude du modèle. Des expériences en laboratoire sont également utilisées pour appuyer l'interprétation des données sur le terrain et valider l'élaboration de structures de modèles numériquesHerbicides are an important crop protection technology of modern agriculture. However, their application over large extensions of land generates diffuse pollution sources that are not only difficult to monitor and control, but also that threaten the quality of human water resources and river ecosystems world-wide. Although field assessments and laboratory tests are required before active ingredients are introduced to market, the fate and degradation extent of pesticides and their metabolites in the environment is subject to significant uncertainty. This thesis work establishes a proof of concept for the application of compound specific isotope analysis (CSIA) to monitor pesticide degradation and transfer at catchment scale. The thesis includes both field characterization and numerical modelling to investigate the value of CSIA as a monitoring tool and as a model uncertainty reduction technique. Laboratory experiments are further employed to support interpretation of field data and validate numerical model structure development
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Adamovic, Marko. "Development of a data-driven distributed hydrological model for regional scale catchments prone to Mediterranean flash floods. Application to the Ardèche catchment, France." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENU039/document.
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L'objectif scientifique de la thèse est de progresser dans la modélisation hydrologique spatiale régionale dans le contexte de crues éclairs qui représentent l'une des catastrophes naturelles les plus destructrices dans la région Méditerranéenne. L'accent est mis sur les questions de mise à l'échelle des bassins versants et la dérivation des équations et des modèles applicables aux bassins de milieu simplifiées de grande taille pour mieux décrire l'hétérogénéité du paysage et de la complexité du processus. Telles sont les questions clés pour faciliter le modèle mis en place dans le contexte de l'ensemble du bassin versant et d'essayer son application dans les bassins non jaugés trop. Pour répondre à ces questions, une modélisation hydrologique spatiale simplifiée sur les sous-bassins versants est d'abord proposé où les paramètres sont essentiellement tirées de l'information disponible (surtout cartographique). La méthode de Kirchner (WRR, 2009) qui suppose que le débit à la sortie est la seule fonction de stockage du bassin versant, est spécifiquement étudiée dans le cadre des bassins versants Méditerranéens. L'étape suivante consiste à créer un nouveau modèle hydrologique SIMPLEFLOOD distribué sur la base de « top down » méthodologie de Kirchner dans la plateforme de modélisation JAMS. Les paramètres du modèle simple sont estimés à des endroits calibrés et une régionalisation se fait en fonction de la géologie. Le bassin versant est discrétisé en sous-bassins versants d'environ 10 km2. La dernière étape consiste à procéder à un couplage de données avec le modèle hydraulique MAGE 1D développé à IRSTEA HHLY tenir compte des effets de propagation de la rivière sur les hydrogrammes simulés. Le couplage est externe, ce qui signifie que les sorties du modèle hydrologique dans le système de modélisation de JAMS deviennent les entrées du modèle MAGE hydraulique. Les sorties sont les débits qui sont transférés dans le modèle de MAGE soit comme flux latéraux (provenant des terres adjacentes) et /ou entrées d'eau locales. L'application de la thèse est le bassin versant de l'Ardèche (2388 km ²), qui est l'un des sites pilotes français pour le programme international HyMeX (cycle hydrologique dans l'expérience de la Méditerranée, http://www.hymex.org/). La thèse proposée contribue également au projet FloodScale (multi-échelle d'observation hydrométéorologique et de modélisation pour la compréhension et simulation des crues éclairs (http://floodscale.irstea.fr/). L'application de la méthodologie Kirchner (2009) montre que les résultats de simulation des débits sont bonnes pour les bassins de granit, trouvés à être caractérisée principalement par des processus excès de ruissellement et d'écoulement sous la surface de saturation. L'hypothèse simple de système dynamique fonctionne particulièrement bien dans des conditions humides (pics et les récessions sont bien modélisés). D'autre part, la performance du modèle est moins bien représentée à l'été et les périodes de sécheresse où l'évapotranspiration est large et observations de bas-débits sont inexactes. Dans le bassin versant de l'Ardèche, les précipitations simulées correspondent bien à de stations de jaugeage observés et données de réanalyse SAFRAN pendant les périodes de non-végétation. Le modèle doit encore être amélioré pour inclure une représentation plus précise de l'évapotranspiration réelle, mais fournit un résumé satisfaisant du fonctionnement du bassin versant pendant les périodes humides et d'hiver. Le couplage du modèle hydrologique obtenue avec le modèle hydraulique MAGE 1D fournit des résultats satisfaisants mais les résultats sont si réciproques comme dans le cas du modèle hydrologique ou une équation d'onde cinématique simple pour le routage des flux existe. On peut dire que dans les situations ou débordement de la rivière est significative, le couplage serai crucialThe scientific objective of the thesis is to progress in regional spatial hydrological modeling in the context of flash floods that represent one of the most destructive natural hazards in the Mediterranean region. Emphasis is put on catchment scaling issues and derivation of simplified equations and models applicable to basins of medium to large size to best describe landscape heterogeneity and process complexity. These are the key issues in facilitating the model set up in the context of the whole catchment and trying its application in ungauged catchments too. To address these issues, a simplified spatial hydrological modeling over sub-catchments is first proposed where parameters are essentially derived from available information (cartographic utmost). For this purpose, the Kirchner (WRR, 2009) method that assumes that discharge at the outlet is only a function of catchment storage is specifically studied in the context of Mediterranean catchments. The next step is to create a new distributed hydrological model based on the data driven methodology of Kirchner within the JAMS modeling framework. The parameters of the simple model are estimated at the gauged locations and a regionalization is done according to geology. The catchment is discretized into sub-catchments of about 10 km2. The final step is to proceed with data coupling with the MAGE 1D hydraulic model developed at HHLY to consider river propagation effects on the simulated hydrographs. The coupling is external, meaning that outputs from the hydrological model in JAMS modeling system become inputs to the hydraulic model MAGE. Outputs are discharge rates in the reach network that are transferred into the MAGE model as either lateral flows (coming from adjacent land) and/or local inflows. The case study of the thesis is the Ardèche catchment (2388 km²), which is one of the French pilot sites for the HyMeX international program (Hydrological Cycle in the Mediterranean Experiment, http://www.hymex.org/). The proposed thesis also contributes to the FloodScale project (Multi-scale hydrometeorological observation and modeling for flash floods understanding and simulation, http://floodscale.irstea.fr/ ). The application of the Kirchner (2009) methodology shows that resulting discharge simulation results are good for granite catchments, found to be predominantly characterized by saturation excess runoff and sub-surface flow processes. The simple dynamical system hypothesis works especially well in wet conditions (peaks and recessions are well modeled). On the other hand, poor model performance is associated with summer and dry periods when evapotranspiration is high and operational low-flow discharge observations are inaccurate. In the Ardèche catchment, inferred precipitation rates agree well in timing and amount with observed gauging stations and SAFRAN data reanalysis during the non-vegetation periods. The model should further be improved to include a more accurate representation of actual evapotranspiration, but provides a satisfying summary of the catchment functioning during wet and winter periods. The coupling of the resulting hydrological model with the MAGE 1D hydraulic model provides satisfying results. However, the results show that the timing and magnitude of simulated discharge with coupled model is as good as by the hydrological model with a simple kinematic wave equation for flow routing. We argue that in situations when there is a significant overflow in the floodplain the interest of the coupling with the hydraulic model becomes crucial
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Sokrut, Nikolay. "The Integrated Distributed Hydrological Model, ECOFLOW- a Tool for Catchment Management." Doctoral thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-237.
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Busche, Henning [Verfasser]. "Modeling hydrological processes in a semi-arid mountainous catchment at the regional scale / Henning Busche." Bonn : Universitäts- und Landesbibliothek Bonn, 2013. http://d-nb.info/1044974346/34.
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Meyles, Erik W. "Hillslope and watershed scale hydrological processes and grazing management in a Dartmoor catchment, Southwest England." Thesis, University of Plymouth, 2002. http://hdl.handle.net/10026.1/387.
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Concerns have been raised on the deterioration of heather moorland due to management in the UK. A study was therefore conducted on the impacts of moorland management on the soils and hydrology of a catchment on Dartmoor. Soil moisture was measured gridwise using TDR on 19 occasions. At 23 sites within this grid, physical properties of the topsoil were obtained. At three locations, tensiometer nests were installed, recording soil suction at 10 cm depth intervals. At the catchment scale, stream discharge and rainfall were recorded. Grazing densities within the watershed were estimated and the observed patterns were related to vegetation types. Results from the TDR grid showed that in dry conditions, soil moisture patterns are heterogeneous in contrast to a more uniform pattern in wet periods. A threshold soil moisture content of about 0.60 cm3 cm-3 divides the two conditions. The exponential relationship between average hillslope soil moisture content and stream discharge also revealed the division between wet and dry states. A regression analysis showed that during dry conditions, the vegetation plays a significant role in determining the soil water status. During wet conditions, topography becomes more important. In these conditions, the soil water movement is mainly lateral, whereas in the dry state, this is vertical in the soil profile. Tensiometer data showed that most soil water movement is in the topsoil. Analyses suggested that soil moisture under vegetation classes associated with higher grazing pressures is higher in similar topographic conditions. Soil bulk density is higher and the total porosity is lower near the soil surface. This suggests that less rainfall is required to reach the soil moisture threshold and water will be transported laterally down the slope. A heather burning experiment revealed that the direct effect of temperature is shallow. Soil moisture levels do not change over the course of the burn. However, in dry situations during summer, soil moisture contents under burned plots are higher than under unburned vegetation probably due to reduced transpiration. If this effect is similar at the hillslope scale, when the soil is wetting up, the soil moisture threshold value could be reached at an earlier stage and accelerated lateral water movement could be the result. It can be concluded therefore, that moorland management could accelerate water movement on the hillslopes causing higher discharge peaks in wet periods and consequently low flows in summer. However, the effects are subtle and encouraging vegetation heterogeneity could play a role in buffering water to prevent loss to the stream.
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Olen, Stephanie Verfasser], and Manfred [Akademischer Betreuer] [Strecker. "Understanding Himalayan denudation at the catchment and orogen scale / Stephanie Olen ; Betreuer: Manfred R. Strecker." Potsdam : Universität Potsdam, 2016. http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-91423.
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Norouzi, Moghanjoghi Karim [Verfasser], and Todd [Akademischer Betreuer] Ehlers. "Physics-Based Modelling of Erosion in Catchment Scale / Karim Norouzi Moghanjoghi ; Betreuer: Todd A. Ehlers." Tübingen : Universitätsbibliothek Tübingen, 2016. http://d-nb.info/119961596X/34.
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Condon, Katherine Elyse. "Quantifying Catchment-Scale Particulate Organic Matter (POM) Loss Following Fire, Relative to Background POM Fluxes." Thesis, The University of Arizona, 2013. http://hdl.handle.net/10150/301557.
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This study investigates translocation of particulate carbon and nitrogen from burned and unburned catchments within New Mexico's Valles Caldera National Preserve following severe wildfire. My research questions are: (1) how much carbon and nitrogen is eroded from burned slopes and re-deposited in debris fans? and (2) how do these quantities compare to fluvial export of particulate carbon and nitrogen from nearby unburned catchments? Results indicate that the ~200 kg ha⁻¹ of nitrogen per depositional area on the debris fans represents ~50 to 100 years' worth of atmospheric inputs. In total, 124 times more carbon and 21 times more nitrogen were deposited on the two fans than was exported in particulate form from all three unburned catchments combined in water year 2012. My findings suggest that post-fire erosion may increase nitrogen loading to downslope environments, with the potential to alter the biogeochemical budgets of both aquatic and terrestrial systems.
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Norouzi, Moghanjoghi Karim Verfasser], and Todd [Akademischer Betreuer] [Ehlers. "Physics-Based Modelling of Erosion in Catchment Scale / Karim Norouzi Moghanjoghi ; Betreuer: Todd A. Ehlers." Tübingen : Universitätsbibliothek Tübingen, 2016. http://d-nb.info/119961596X/34.
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Olen, Stephanie [Verfasser], and Manfred R. [Akademischer Betreuer] Strecker. "Understanding Himalayan denudation at the catchment and orogen scale / Stephanie Olen ; Betreuer: Manfred R. Strecker." Potsdam : Universität Potsdam, 2016. http://d-nb.info/121840082X/34.
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Switanek, Matthew. "Improving Seasonal to Annual Predictions of Climate Variability and Water Availability at the Catchment Scale." Thesis, The University of Arizona, 2008. http://hdl.handle.net/10150/193313.
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In a water-stressed region, such as the southwestern United States, it is essential to improve current seasonal hydroclimatic predictions. Typically, seasonal hydroclimatic predictions have been conditioned by standard climate indices, e.g., NINO3 and PDO. In this work, a methodology called basin-specific climate prediction (BSCP) is proposed to improve hydroclimatic predictions. The method analyzes the statistically unique relationships between sea surface temperatures (SSTs) and a basin's hydroclimate. The oceanic region which maximizes the correlation is subsequently used as a predictor for hydroclimate. BSCP is used to perform hindcasts for the hydroclimate in the Little Colorado River basin and the results are compared to those using standard climate indices as predictors.
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Zehe, Erwin, and Günter Blöschl. "Predictability of hydrologic response at the plot and catchment scales: Role of initial conditions." Universität Potsdam, 2004. http://opus.kobv.de/ubp/volltexte/2012/6011/.
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This paper examines the effect of uncertain initial soil moisture on hydrologic
response at the plot scale (1 m2) and the catchment scale (3.6 km2) in the presence of threshold transitions between matrix and preferential flow. We adopt the concepts of microstates and macrostates from statistical mechanics. The microstates are the detailed patterns of initial soil moisture that are inherently unknown, while the macrostates are specified by the statistical distributions of initial soil moisture that can be derived from the measurements typically available in field experiments. We use a physically based model and ensure that it closely represents the processes in the Weiherbach catchment, Germany. We then use the model to generate hydrologic response to hypothetical irrigation events and rainfall events for multiple realizations of initial soil moisture microstates that are all consistent with the same macrostate. As the measures of uncertainty at the plot scale we use the coefficient of variation and the scaled range of simulated vertical bromide
transport distances between realizations. At the catchment scale we use similar statistics derived from simulated flood peak discharges. The simulations indicate that at both scales the predictability depends on the average initial soil moisture state and is at a minimum around the soil moisture value where the transition from matrix to macropore flow occurs. The predictability increases with rainfall intensity. The predictability increases with scale with maximum absolute errors of 90 and 32% at the plot scale and the catchment scale, respectively. It is argued that even if we assume perfect knowledge on the processes, the level of detail with which one can measure the initial conditions along with the nonlinearity of the system will set limits to the repeatability of experiments and limits to the predictability of models at the plot and catchment scales.
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White, Alissa Marie. "Examining the Impacts of Wildfire on Throughfall and Stemflow Chemistry and Flux at Plot and Catchment Scales." Thesis, The University of Arizona, 2015. http://hdl.handle.net/10150/595818.
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This study investigates the effects of fire on the chemistry and flux of precipitation diverted to the forest floor as stemflow and throughfall by observing the impact of the June 2013 Thompson Ridge Wildfire in the Jemez River Basin of New Mexico. The loss of canopy cover from wildfire drastically modifies landscapes and alters ecosystems as fire replaces leafy canopies with charred branches and trunks, changes soil composition and erosion processes, and affects hydrologic flow paths and water chemistry. In order to track these changes, throughfall and stemflow collectors were installed beneath burned and unburned canopies in two catchments impacted by the Thompson Ridge Fire. Throughfall, stemflow, and open precipitation samples were analyzed for major cations, anions, dissolved inorganic and organic carbon, trace metals, and rare earth elements to determine how fire affects the chemical composition of the precipitation that interacts with burned canopies. Precipitation samples collected from both burned and unburned sites during the 2014 summer monsoon season show variations across burn severity, specifically in calcium, strontium, phosphate, and dissolved inorganic carbon concentrations, and across collector type with stemflow concentrations generally higher than throughfall and open precipitation concentrations. A stem count model was used to determine tree density for individual plots and catchments from LiDAR images taken before the 2013 fire. The stem count model was used to upscale event and monsoon season solute fluxes from plot to catchment scale. Higher nutrient concentrations combined with higher volumes of precipitation diverted as stemflow in burned forests have a multiplicative effect resulting in greater nutrient fluxes via stemflow creating nutrient hot spots surrounding burned tree trunks. Upscaling these plot scale concentrations and solute fluxes allows this study to represent changes to an entire catchment and quantify effects of wildfire on chemical loads and water chemistry.
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Vogt, Esther. "Nitrogen fluxes at the landscape scale : a case study in Scotland." Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/6244.
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Nitrogen (N) fluxes show a substantial variability at the landscape scale. Emissions are transferred by atmospheric, hydrological and anthropogenic dispersion between different landscape elements or ecosystems, e.g. farms, fields, forests or moorland. These landscape N fluxes can cause impacts to the environment, such as loss of biodiversity. The aim of this study is to illustrate how landscape N fluxes can be quantified by integrating atmospheric and fluvial fluxes in a Scottish landscape of 6 km x 6 km that contains intensively managed poultry farming, extensively managed beef and sheep farming, semi-natural moorland and woodland. Atmospheric ammonia (NH3) emissions of two deep pit free range layer poultry houses were estimated by high time-resolution measurements of NH3 concentrations and meteorological variables downwind of layer poultry houses and the application of an inverse Gaussian plume model. Atmospheric NH3 concentrations and deposition fluxes across the study landscape were studied at a resolution of 25 m x 25 m. The approach combined a detailed landscape inventory of all farm activities providing high resolution NH3 emission estimates for atmospheric dispersion modelling and an intensive measurement programme of spatial NH3 concentrations for verifying modelled NH3 concentrations. The spatially diverse emission pattern resulted in a high spatial variability of modelled mean annual NH3 concentrations (0.3 to 77.9 μg NH3 m-3) and dry deposition fluxes (0.1 to >100 kg NH3-N ha-1 yr-1) within the landscape. Annual downstream fluxes and variation in spatial concentration of dissolved inorganic nitrogen (NH4 + and NO3 -) and dissolved organic nitrogen (DON) were studied in the two main catchments within the study landscape (agricultural grassland vs. semi-natural moorland catchment). The grassland catchment was associated with an annual downstream total dissolved nitrogen (TDN) flux of 14.4 kg N ha-1 yr-1, which was 66% higher than the flux of 8.7 kg ha-1 yr-1 from the moorland catchment. This difference was largely due to the NO3 - flux being one order of magnitude higher in the grassland catchment. The contribution of DON to the TDN flux varied between the catchments with 49% in the grassland and 81% in the moorland catchment. Fluvial and atmospheric N fluxes were combined to derive N budgets of the two catchments. Agricultural activities accounted for the majority of N input to the catchments, with atmospheric deposition also playing a significant role, especially in the moorland catchment. Both catchments showed large stream export fluxes compared to their net import which suggests that their capacity of N storage is limited. This thesis quantifies major N fluxes in a study landscape and shows their large spatial variability. Agricultural activities dominate landscape N dynamics. The work demonstrates the importance of considering landscape N variability when attempting to reduce the environmental impact of agricultural activities.