Dissertations / Theses on the topic 'Hydrological'

My work questions the ongoing dialogue between technology and nature. This dialogue is most evident in landscapes and their respective ecosystems, specifically rivers. These bodies of water are a fluid mirror reflecting a wavering view of ourselves, a constructed human presence within the natural environment. This thesis offers a way of understanding these pipelines, dams, canals and attendant infrastructures in a conceptual manner. These encapsulating forms that interrupt, shape and utilise the natural realm are the facades of a hydrological imaginary. ‘A Hydrological Imaginary’ addresses this field of tension between the river and its artificial counterparts - canals, pipelines and human-made containments. The core of the thesis is a discussion of rivers, dams and water-based infrastructure that illustrates how environmentally engaged art discourses respond to the technological and sociocultural elements of water. This paper discusses the strategies of artists that work with bodies of water through photography, such as Australian artist David Stephenson and German artists Bernd and Hilla Becher along with my own photographic work. Multi-disciplinary artists such as UK artists Simon Starling and Rachel Whiteread are also discussed, along with the work of American artist Robert Smithson and American artist John Roloff. These conceptual art practices are to be connected to American writer David E. Nye and Scandinavian Professor Terje Tvedt’s ideas on the underlying histories of geopolitics, the technological sublime and Australian writer Martin Thomas’ ideas on the role of environmentalism in art. Thus, this thesis illustrates how art agitates the hydrological realm and contributes to the creation of new reflections, meanings and possibilities from the narratives of contained water, submerged histories and sociocultural attributes to the landscape. I have used my practice to bring context to these concepts around the ideas of contained nature and the movement of water in two solo exhibitions that featured video, photographic and kinetic sculptures created in a range of staged encounters with rivers in Eastern Australia. Alongside my previous work based on the Yangtze River in China in 2012, and work made within the Blue Mountains in 2012 – 2015 prior to commencing this Masters project, this thesis is a distillation of these seemingly disparate bodies of water. It is a narrative on historic systems, aesthetics and possibilities of the natural and the assisted movement of water.

In seismology, the capability of an earthquake to induce other seismic events has been widely accepted for decades. For example, the term aftershock involves a strong relation of such a seismic event with the incidence of a main shock. Moreover, hydrological changes (water level in wells and streams, geyser eruption and remote seismicity) in response to remote earthquakes have been reported for many years. A matter of current debate concerns the spatiotemporal scale of interaction among seismic events. However, there appears to be no clear image of what is the exact method of transmission of the triggering energy for the phenomena listed above. It appears that the P-wave and the S-wave are inadequate in terms of ground strain magnitudes at teleseismic distances, while the amplitude of the surface waves generally decreases exponentially with depth in the Earth and could not be responsible for triggering deeper earthquakes or deep-seated fluid flow fluxes in 3-5 km deep reservoirs. This leaves some other wave as a possible triggering energy sources.

This thesis is based on a diffusion-dynamic theory that predicts a low velocity displacement wave, called a soliton wave, propagating in liquid-saturated porous media with velocity ~100-300 m/s, analogous to a tsunami that travels with the loss of little energy. This is hypothesized to be the mechanism for energy transfer that could be sufficient to promote changes in local pore pressure and therefore to alter the ambient effective stresses. It is also hypothesized that a soliton wave packet is emitted by a primary seismic event and may trigger sympathetic secondary earthquakes at a remote distance, fluid level fluctuation in wells, changes in geyser eruption behaviour, and changes in microseismic frequency, amplitude and patterns in appropriate places (e. g. under water reservoirs, in areas of active hydrothermalism, in tectonically active areas, and so on).

This thesis undertakes a review of some of these phenomena, and finds that the evidence as to what is the triggering mechanism is not clear. Also, it appears that the soliton hypothesis is not at all disproved by the data, and there may be some evidence of its existence.

To reveal the evidence of this kind of wave (soliton) in nature, real sequence and K-Q cases velocity data bases of earthquake interactions in the year of 2003 have been constructed by using information from Incorporated Seismological Research Institute (IRIS). The qualitative and quantitative analysis demonstrates that interactions between seismological and hydrological systems due to soliton waves are a definite possibility. However, the growth of fluid fluxes, geysers eruption and remote seismicity are controlled by both the principal stresses and the pore pressure. Hence, this interaction depends on the hydromechanical properties of rock such as permeability, compressibilities, and viscosities of fluids, saturations, and porosity. Perhaps the strongest argument in favour of a low-velocity soliton trigger is that the other seismic waves seem to be inadequate, and there is no evidence for their actions as a trigger.

The practice of detection and analysis of a soliton is not undertaken in this work. Because current devices are incapable to measure such a wave as they are on the surface and insensitive to liquid-solid coupling, sensitive and precise sensors in the low frequency range must be installed within the liquid saturated zone, preferably under the water table, to advance further work.

In response to sustainable land management requirements and catchment-scale hydrological modelling needs, scientific interest in hydrological'connec~ivity'hasgrown. However, little is ~ . known about how hydrological connectivity is impacted by management. While there has been much research into livestock grazing and soil erosion in the UK; relatively little research has been conducted to characterize the hydrological patterns of livestock impacts, especially in organic soils which might be more vulnerable to environmental degradation. This thesis examines livestock impacts, as a land use case study, to conceptualize the 'dynamic nature of hydrological connectivity and its potential changes on hillslope and catchment hydrology. Different grazing strategies on organic soils (blanket p~ats and peaty gleys) in the uplands of Upper Wharfedale and Teesdale and organo-mineral soils (stagnogleys) in lowlands at Kirkby Overblow, northern England are investigated. Field measurements and monitoriIig are combined with laboratory experiments and proces~-based distributed modelling. Results suggest that compaction effects from sheep differ between soil types and topographic context but that they were generally confined to the upper 20 cm of the soil profile but with greater impacts in the upper 5 cm. Light-medium grazing (-9 a ha-1 ) significantly raised mean bulk density compared to adjacent soils with no grazing in the upper 10 cm of the soil profile of'stagnogleys. The relatively heavy grazing associated with frequently trampled areas under sheep tracks on stagnogleys was associated with soils with a mean bulk density 10 % greater (in the upper 10 cm of the soil) than those in the surrounding lightly grazed soil for stagnogleys, 2 % in 0-5 cm arid 9 % in 5-10 cm layers of peaty gleys, and at least 50 % in the near surface of peats. The effects of sheep tracks on soil properties and hydrological function were found to extend by at least 2 m further either side ofthe track rather than just being a feature ofthe visible track alone. Removing sheep led to a substantial fall in compaction effects in peats (10.4-21.7 % in bulk ~ensity) and stagnogley soils (0.5 % in bulk density) within a short time period (4-6 years). There were also significant differences in jnfiltration rates between short-term exclosure sites ' and grazed sites. For peat soils differences between lightly graZed areas and the long-term ' exclosures (35-45 years) were not much greater than those between the lightly grazed areas and the short-term exclosures suggesting that soil response to removal of sheep can be rapid. This thesis demonstrated that both the value and actual spatial distribution of livestock may .significantly decrease vertical connectivity and increase lateral connectivity, and hence increase both the spatial and temporal frequency of overland flow. In the organic soils of the humid-temperate zone studied this is through alteration of saturation-excess processes rather than infiltration-excess flow generation; antecedenfwater stores or soil moisture content are therefore of great, importance in hydrological connectivity responses to livestock impacts. Sheep tracks can be crucial in producing more rapid and connected overland flow on peats and stagnogleys, and effects extend several metres ether side of the track. Blanket peats are more vulnerable to livestock grazing than stagnogleys. The modelling approach used on stagnogleys from Kirkby Overblow suggests that increasing sheep density in very wet environments would lead to enhanced flood risks in terms of overall runoff amount and more rapid response due to e$anced coupling of hillslope arid river corridors, especially in extreme rainfall conditions.

Due to an increase in impermeable hard surfaces, urbanization has led to the deterioration of urban watercourses and increased the quantity of stormwater runoff. It may be argued that the current norm of impermeable roofs represents a wasted opportunity. Green roofs have the potential to replace some of the hydrological characteristics of natural catchments that are normally lost as a consequence of urbanization and the removal of vegetation. The overall aim of this study was to develop a generic green roof rainfall runoff response model capable of predicting the temporal variations within any configuration of green roof in response to an arbitrary rainfall input. It was recognized that the preliminary investigations has led to the identification of a subset of processes/parameters for a green roof which warranted more detailed investigation. In this case the substrate moisture holding capacity and the losses due to evapotranspiration were identified as key controlling variables to be identified. To simulate the function of stormwater drainage, a direct observation of the system's behaviour is required. Hence, an established 'typical' small scale green roof (1.0 in x 3.0 m) on the roof of Sheffield University has been monitored with the intention to relate both retention and detention with fundamental, measurable, physical properties of the system. A continuous long time-series of data, in the period of 29 months, from the test rig was analysed and interpreted. Laboratory analyses on physical properties and evaporation of the substrates were undertaken and relationships between measureable physical properties and model parameter values were identified. The empirical (requiring site-specific calibration using monitored data) conceptual model now has been developed into a physically-based model. Although the model still needs to be refined, independent physically-based methods have been identified for defining two key parameters (evapotranspiration (ET) and the maximum moisture-holding capacity (WC,,, a,, )). ET can be estimated using a modified form of Thornthwaite's equation, and WC.., may be determined by physical laboratory assessment of the substrate. The proposed hydrological model has been shown to reproduce monitored data, both during a storm event, and over a longer continuous simulation period.

Water is one of the essential elements for the nature and human being. The development of good practise of managing water resources are necessary to maintain sufficient availability and to support socio-economic activities and preserve natural ecosystems. For these reasons, it is fundamental to improve the knowledge of cause-effect relations that drives hydrological cycle, which determines water availability. Climate and land use (LU) are two of the main drivers of the water cycle and indeed, the knowledge of their influence on hydrology is a fundamental research question. Of course, the future water availability is strictly related to future climatic and LU scenarios and then a critical role is assumed by the prediction and assessment of these two. A climate and LU change impact study will be developed to investigate the near-future water availability in the Mediterranean area. In detail, on the basis of the state of art and the actual knowledge, the main objective of this dissertation is to estimate the probability density function (pdf) of annual surface runoff Q in transient climate and LU conditions in the island of Sardinia (Italy). The study case has been selected due to the ongoing important process of climate change, overexploitation and degradation of natural resources affecting the entire island (see e.g. ISPRA, ENEA and CIRCE studies). These analyses might have a strategic importance for stakeholders and government agencies that are interested in the management of water resources due to the well-known issue of water availability in the Mediterranean area. The knowledge of the near-future impact of climate and LU change could be useful to establish regional guidelines and good practices to avoid the ongoing reduction of water resources in Sardinia. After a detailed review of the existing methodologies for describing and detecting climate and LU change and their influence in hydrological processes, a methodology based on the Budyko’s theory that aims at assessing near future Q pdf in a closed form has been adopted. Five parameters are requested, referring to mean and standard deviation of annual rainfall P and annual potential evapotranspiration PET and Fu’s parameter ω. Sets of these parameters will be assessed to define different climatic and LU scenarios for the near future. EUROCORDEX and Land Use CORINE projects will be used to represent climate and LU in the present and in the near future. Results showed that in the near future Q will decrease due to the reduction of P and the increase of PET. The variability of Q will decrease due the reduction of variability of P. Finally, it has been observed that in Sardinia the main driver in the change of Q pdf will be climate change, while the LU plays a secondary role.

Government Island, located in the Columbia River approximately 16 km (10 mi) upstream of the confluence with the Willamette River, is a wetland mitigation site prompted by expansion of the southwest quadrant of Portland International Airport. The purpose of the study is to predict water levels in two enclosed lowland areas, Jewit Lake and Southeast Pond, based on levels of the Columbia River, precipitation, and evapotranspiration. Mitigation is intended to convert 1.13 km2 (237 acres) of seasonally flooded wetland to 1.27 km2 (267 acres) of semi-permanently flooded wetland and seasonally flooded wetland. Flooding of the wetland is most likely to occur December through January and May through early June when Columbia River water levels at Government Island exceed 3.6 m (12 ft) m.s.l. Flooding of Jewit Lake occurs through a channel connecting the wetland to the Columbia River. A groundwater model (MODFLOW) was parameterized to simulate the hydrology of the wetland. Observations of the subsurface stratigraphy in 25 soil pits, bucket auger cores, and during installation of water monitoring devices were used to estimate thickness and lateral extent of a confining unit that overlies an aquifer. Climatological data for 1994 and water levels were entered into MODFLOW to calibrate rates of water movement through the subsurface. Periods of drying for Jewit Lake and Southeast Pond were predicted based on precipitation and actual evapotranspiration rates expected to be present in the study area between June and December. Results of groundwater modeling show that Jewit Lake will maintain surface water above 3.6 m (12 ft) in most years. Southeast Pond is expected to dry annually as mitigation is unlikely to change the hydrology of Southeast Pond. Groundwater modeling predicted the types of wetlands present at different elevations by evaluating periods of drying within the wetland using the U.S. Fish and Wildlife Service classification of wetlands method. Results suggest that Jewit Lake will be converted to semipermanently flooded wetland below 3.6 m (12 ft) in elevation. Southeast Pond will remain a seasonally flooded wetland as a result of mitigation.

This thesis aimed to study how different actors perform hydrological observations in Sweden. Target groups for the study were institutions that regularly measure water stage and river discharge, including water councils, water- and wastewater departments in municipalities, water authorities and hydropower companies. After the identification of the different actors, the study investigated how, where and why they perform hydrological observations as well as the way actors perceive the accuracy of these measurements. Information was collected through interviews and the development of a number of questionnaires. A total of 447 actors were contacted and 260 replied. The majority of them, 209, answered that they do not perform any hydrological measurements while the remaining 51 answered that they measure water stage. One of the main reasons for measuring is that many actors are facing water-rights court ruling. There were also several actors that stated that they perform hydrological measurements to make sure that the water body where water from wastewater treatment plants and storm water is emitted has sufficient water stage for environmental concerns. The hydropower companies replied that they, in addition to maintaining a water-rights court ruling, used water stage data to control the functioning of the plant. They also calculate river discharge based on production, floodgate position and stage. There were also seven municipalities, which stated that they had implemented a flood-monitoring model and that water stage data were used as input to the model. These municipalities and two other actors stated that they measure discharge or use a stage-discharge relationship (rating curve) to derive discharge data. However, in some cases, control measurements were lacking. Most actors used pressure sensors to measure stage. Their perceived levels of accuracy varied from ± 1 mm to ± 5 cm. Only five actors stated that they level their instruments regularly, which is a precondition for maintaining a correct data series. The results are useful for SMHI’s continued review of their hydrological network, although continued attempts to receive answers from all contacted actors would provide a more complete overview of hydrological observations. A study that thoroughly investigates how actors perceive the accuracy of their measurements would also give further knowledge in this field.
Examensarbetet syftade till att undersöka hur olika aktörer genomför hydrologiska mätningar i Sverige. Målgrupper för studien var aktörer vars verksamhet innefattar mätningar av vattenföring och vattenstånd. De målgrupper som identifierades var vattenråd, kommunala VA-avdelningar, vattenmyndigheter och vattenkraftbolag. När aktörerna identifierats undersöktes hur, var och varför aktörerna mäter samt hur de uppfattar noggrannheter i sina mätningar. Informationen samlades in genom frågeformulär och intervjuer. Totalt kontaktades 447 aktörer varav 260 svarade på frågorna som ställdes. Majoriteten, 209 aktörer svarade att de inte utför några hydrologiska mätningar medan resterande svarande att de mäter vattenstånd. Den anledning som flest aktörer gav till att de mäter var att de har en vattendom. Det var även flera aktörer som mätte för att försäkra sig om att recipienter för dagvatten och avloppsreningsverk hade tillräckligt högt vattenstånd för utsläpp. Vattenkraftproducenterna svarade att de, utöver att de har vattendomar, använder vattenståndsdata för att reglera kraftverken. De beräknade också vattenföringen utifrån lucköppningsgrad, vattenstånd och producerad effekt. Det var även sju kommuner som svarade att de hade implementerat modeller för översvämningsövervakning och använde vattenståndsmätningar som indata i prognosmodellerna. Dessa kommuner och två ytterligare aktörer svarade att de mäter vattenföring eller använder avbördningskurvor men i flera fall är kontrollmätningar av vattenföringen bristande. De flesta aktörerna använde tryckgivare för att mäta vattenståndet och de gav noggrannhetsintervall mellan ± 1 mm och ± 5 cm. Endast fem aktörer uppgav att de avväger mätinstrumentet vilket är en förutsättning för att upprätthålla en korrekt mätserie. Resultaten är användbar information i SMHIs utvärdering av sitt nätverk av hydrologiska mätstationer, dock skulle fortsatta försök att få svar från samtliga kontaktade aktörer ge en mer heltäckande bild av hydrologiska mätningar utförda av de olika målgrupperna. Det vore även intressant med en studie som går djupare in på hur noggrannhet uppskattas och uppfattas av de olika aktörerna.

Icings are common hydrological phenomena in arctic and subarctic regions. Their bodies are made up of the accumulation of ice layers formed by the freezing of overflow water during the winter season. Icing formation is a process involving a complex system of thermodynamics and hydrodynamics. In this thesis, the formation mechanics of river icings and ground icings are studied in terms of both thermal and hydrological processes.
The energy exchange systems during icing layer formation involve two ice water interfaces and some intra-layer water flow. Using energy balance analysis, this research finds that the outgoing energy components can be ranked according to their importance, with sensible heat being the most important component, radiation heat loss being of secondary importance, and latent heat loss being the least important factor. Further, this research illustrates that the heat conduction between the underlying ice and a newly formed icing layer is time dependent. For example, during the first half cycle of icing layer formation, heat is conducted into the underlying ice, but during the second half of the cycle the heat is conducted in an opposite direction.
During icing layer formation, the energy input is supplied mainly by water and incoming solar radiation. Intra-layer running water provides a significant amount of energy when air temperatures are milder, but its significance decreases when air temperatures become colder. Solar radiation during the day may also play an important role in the energy supply regime.
River icing formation involves several hydrological processes. The location of a river icing is basically controlled by the channel slope. The damming effect of icing mass plays a significant role in the extension of the icing body, especially in the upstream direction. River icings grow slowly, and generally experience three stages of development, namely the 'freeze-up' stage, 'obstruction' stage and 'overflow' stage, the third stage dominating icing growth. The formation of each icing layer is virtually a small-scale reproduction of these three stages. The model simulation shows that the thickness of icing accumulation increases with an increase in the initial water depth in the channel, but simulation also shows that there is a limiting threshold. The thickness of icing accumulation decreases when the initial channel water depth exceeds this threshold.
The growth of an icing is an event-dominated discontinuous process. Even during one icing layer formation, simultaneous growth occurs only within a very limited distance. At a specific location, icing growth is related temporally only over a short period of time. As a discontinuous process, icing spreading and thickening during an overflow event depends entirely on the climatic and topographical conditions.
Even though icing layering is influenced by many variables, under small discharge rates, as in the case of ground icing growth, statistical analyses show that the mean spreading length of an overflow event can be described efficiently by five variables: discharge, the temperature of the water, the product of air temperature and wind speed, air temperature and the icing surface slope previous to overflow. The maximum spreading length, however, may only be controlled by four variables: discharge, water temperature, air temperature and the product of air temperature and wind speed. Under field conditions, when wind speed is not measured, this wind related variable may be dropped with only a small decrease in confidence level.

Cette thèse, à travers une collection de cinq articles scientifiques, décrit et quantifie les processus de glace des cours d’eau à forte pente, donc à lit graveleux. Avant que ce projet de recherche ne soit entrepris, certains de ces processus étaient mal compris ou simplement absents de la littérature scientifique, et ce, alors que les cours d’eau à lit graveleux sont répandus en région froide. Les types de glace qui se forment le long de ces cours d’eau incluent la glace de fond, les seuils de glace, les barrages de glace, les champs de glaçage, les digues de glaçage, les couverts de glace suspendus et les carapaces de glace projetée. Certains processus de débâcle tels que les trains de glace et les embâcles sont également mentionnés dans la thèse, mais ne représentent pas son sujet principal. Cette recherche est le fruit de trois hivers d’observation et d’instrumentation sur le bassin versant de la rivière Montmorency. De manière spécifique, ce ne sont non pas quelques sites, mais plutôt plusieurs cours d’eau, d’un petit ruisseau de tête de bassin versant jusqu’à la rivière Montmorency, qui ont été visités quelque 120 fois, surtout durant la période hivernale. Les données recueillies ont permis de dresser un bilan des liens thermiques, cryologiques (glace) et hydrologiques qui existent entre ces cours d’eau. Ces liens forment ce que l’on appelle le continuum hivernal du bassin versant. Chacun des chapitres de cette thèse représente un ouvrage indépendant qui inclut une introduction, une revue de littérature, une conclusion et une bibliographie. Les quatre premiers articles présentent des sujets qui complémentent les chapitres précédents alors que la description qualitative fait progressivement place à l’analyse quantitative. La somme de ces articles contribue à faire de cette thèse un ouvrage complet sur les processus de glace sur les cours d’eau à forte pente. Le dernier chapitre, ou article, présente un modèle conceptuel des différents couverts et processus de glace observables le long de tout type de chenal sous n’importe quelle intensité hivernale.
This thesis, through a collection of five publications, describes and quantifies steep (gravel bed) channel ice processes. Before this research project was undertaken the literature on the topic was largely incomplete and ice processes taking place in gravel bed channels, which represent common cold region fluvial settings, could only be partly explained. Ice features forming along steep channels and described in the thesis include anchor ice accumulations, ice weirs, ice dams, icing fields, icing dikes, suspended ice covers, and spray ice shells. This thesis also approaches river ice breakup processes such as ice runs and ice jams. The findings presented in this work are the result of three winters of field observation and steep channels monitoring. Research sites were visited over 120 times, mostly during the winter period. Ice processes were not only described and monitored at a few sites but at the drainage system scale, from a small headwater channel down to the main river channel. The thermal, cryologic, and hydrological interactions between various steep channels of the Montmorency River watershed were analyzed. These links form what is referred to as the watershed continuum. Each chapter of this thesis is an independent publication that includes an introduction, a literature review, a conclusion, and a list of references. The first four articles present a topic that complements previous chapters. The sum of these chapters forms a comprehensive review of the ice processes taking place in steep channels as the qualitative description progressively evolves into a quantitative analysis. The last chapter (article) presents a global conceptual model on river ice types and processes taking place in any fluvial setting in any climate.

During last years extensive development of small hydropower plants has taken place, and many of that plants are frequently located in small catchments. Mainly there is no runoff data for these small catchments, because runoff gauging stations have been established in comparably larger catchments. For establishing runoff for small catchments it is common practice to downscale it from larger catchments – analogue catchments. For downscaling analogue stations should have nearly the same catchment characteristics, like area, lake percentage, elevation distribution, etc. Small hydropower catchments often don’t have lakes, it means that small catchments have faster runoff response and more “peaked” hydrographs, comparably to larger catchments. In this case scaling approach will lead to wrong design and disappointing results during operation. Underestimation of runoff data will lead to additional spill of water, and overestimation will bring to wrong installed capacity and may be would not be efficient at all. During past years consulting companies become very interested in more precise runoff data, even if it have been collected during not long time period. It has been decided to set a gauging stations near to projects and collect runoff data (even for short period). In the past 10 years SWECO AS company has collected runoff series for approximately hundred stations, which are located through all Norway. Collected runoff series are also very valuable for other hydrological computations, it could improve and adjunct NVE data for small catchment and supplement hydrological data where NVE has no stations. This study was made with permission of SWECO AS (Trondheim) and people who have paid for data collection.The objectives of the Thesis is to store all available runoff data to the database in proper format (using HEC-DSS programm), collect necessary information about each station and compute topographical and climatic parameters (using NVE Low-flow application), make a standardized description of each record (station) including all important information like location (GPS), map, photo, catchment characteristics, rating curve etc. and check the quality of data.In this project one of the objectives is to prepare runoff data series to transfer to NVE database in tidy and in the format that requested NVE.During Thesis work one of the objectives is to make an comparable analysis between SWECO stations data and NVE analogue stations. Data from NVE analogue stations was provided by NVE staff. Besides, relationship between topographical and climatic parameters with flow duration curves of selected SWECO stations should be estimated.

Technological advances in computer science, namely cloud computing and data mining, are reshaping the way the world looks at data. Data are becoming the drivers of discoveries and strategic developments. In environmental sciences, for instance, big volumes of information are produced by monitoring networks, satellites and model simulations and are processed to uncover hidden patterns, correlations and trends to, ultimately, support policy and decision making. Hydrologists, in particular, use models to simulate river discharges and estimate the concentration of pollutants as well as the risk of floods and droughts. The very first step of any hydrological modelling exercise consists of selecting an appropriate model. However, the choice is often made by the modeller based on his/her expertise rather than on the model's suitability to reproduce the most important processes for the area under study. Since this approach defeats the ''scientific method'' for its lack of reproducibility and consistency across experts as well as locations, a shift towards a data-driven selection process is deemed necessary. This work presents the design, development and testing results of a completely novel data mining algorithm, called AMCA, able to automatically identify the most suitable model configurations for a given catchment, using minimum data requirements and an inventory of model structures. In the design phase a transdisciplinary approach was adopted, borrowing techniques from the fields of machine learning, signal processing and marketing. The algorithm was tested on the Severn at Plynlimon flume catchment, in the Plynlimon study area (Wales, UK). This area was selected because of its reliable measurements and the homogeneity of its soils and vegetation. The Framework for Understanding Structural Errors (FUSE) was used as sample model inventory, but the methodology can easily be adapted to others, including more sophisticated model structures. The model configuration problem, that the AMCA attempts to solve, can be categorised as ''fully unsupervised'' if there is no prior knowledge of interactions and relationships amongst observed data at a certain location and available model structures and parameters. Therefore, the first set of tests was run on a synthetic dataset to evaluate the algorithm's performance against known outcomes. Most of the component of the synthetic model structure were clearly identified by the AMCA, which allowed to proceed with further testing using observed data. Using real observations, the AMCA efficiently selected the most suitable model structures and, when coupled with association rule mining techniques, could also identify optimal parameter ranges. The performance of the ensemble suggested by the combination of AMCA and association rules was calibrated and validated against four widely used models (Topmodel, ARNOVIC, PRMS and Sacramento). The ensemble configuration always returned the best average efficiency, characterised by the narrowest spread and, therefore, lowest uncertainty. As final application, the full set of FUSE models was used to predict the effect of land use changes on catchment flows. The predictive uncertainty improved significantly when the prior distributions of model structures and parameters were conditioned using the AMCA approach. It was also noticed that such improvement is due to constrains applied to both model and parameter space, however the parameter space seems to contribute more. These results confirm that a considerable part of the uncertainty in prediction is due to the definition of the prior choice of the model configuration and that more objective ways to constrain the prior using formal data-driven techniques are needed. AMCA is, however, a procedure that can only be applied to gauged catchment. Future experiments could test whether AMCA configurations could be regionalised or transferred to ungauged catchments on the basis of catchment characteristics.

The recent high profile flooding events – that have occurred in many parts of the world – have drawn attention to the need for new and improved methods for water resources assessment, water management and the modelling of large-scale flooding events. In the case of the Zambezi Basin, a review of the 2000 and 2001 floods identified the need for tools to enable hydrologists to assess and predict daily stream flow and identify the areas that are likely to be affected by flooding. As a way to address the problem, a methodology was set up to derive catchment soil moisture statistics from Earth Observation (EO) data and to study the improvements brought about by an assimilation of this information into hydrological models for improving reservoir management in a data scarce environment. Rainfall data were obtained from the FEWSNet Web site and computed by the National Oceanic and Atmospheric Administration Climatic Prediction Center (NOAA/CPC). These datasets were processed and used to monitor rainfall variability and subsequently fed into a hydrological model to predict the daily flows for the Zambezi River Basin. The hydrological model used was the Geospatial Stream Flow Model (GeoSFM), developed by the United States Geological Survey (USGS). GeoSFM is a spatially semi-distributed physically-based hydrological model, parameterised using spatially distributed topographic data, soil characteristics and land cover data sets available globally from both Remote Sensing and in situ sources. The Satellite rainfall data were validated against data from twenty (20) rainfall gauges located on the Lower Zambezi. However, at several rain gauge stations (especially those with complex topography, which tended to experience high rainfall spatial variability), there was no direct correlation between the satellite estimates and the ground data as recorded in daily time steps. The model was calibrated for seven gauging stations. The calibrated model performed quite well at seven selected locations (R2=0.66 to 0.90, CE=0.51 to 0.88, RSR=0.35 to 0.69, PBIAS=−4.5 to 7.5). The observed data were obtained from the National Water Agencies of the riparian countries. After GeoSFM calibration, the model generated an integration of the flows into a reservoir and hydropower model to optimise the operation of Kariba and Cahora Bassa dams. The Kariba and Cahora Bassa dams were selected because this study considers these two dams as the major infrastructures for controlling and alleviating floods in the Zambezi River Basin. Other dams (such as the Kafue and Itezhi-Thezi) were recognised in terms of their importance but including them was beyond the scope of this study because of financial and time constraints. The licence of the reservoir model was limited to one year for the same reason. The reservoir model used was the MIKE BASIN, a professional engineering software package and quasi-steady-state mass balance modelling tool for integrated river basin and management, developed by the Denmark Hydraulic Institute (DHI) in 2003. The model was parameterised by the geometry of the reservoir basin (level, area, volume relationships) and by the discharge-level (Q-h) relationship of the dam spillways. The integrated modelling system simulated the daily flow variation for all Zambezi River sub-basins between 1998 and 2008 and validated between 2009 and 2011. The resulting streamflows have been expressed in terms of hydrograph comparisons between simulated and observed flow values at the four gauging stations located downstream of Cahora Bassa dam. The integrated model performed well, between observed and forecast streamflows, at four selected gauging stations (R2=0.53 to 0.90, CE=0.50 to 0.80, RSR=0.49 to 0.69, PBIAS=−2.10 to 4.8). From the results of integrated modelling, it was observed that both Kariba and Cahora Bassa are currently being operated based on the maximum rule curve and both remain focused on maximising hydropower production and ensuring dam safety rather than other potential influences by the Zambezi River (such as flood control downstream – where the communities are located – and environmental issues). In addition, the flood mapping analysis demonstrated that the Cahora Bassa dam plays an important part in flood mitigation downstream of the dams. In the absence of optimisation of flow releases from both the Kariba and Cahora Bassa dams, in additional to the contribution of any other tributaries located downstream of the dams, the impact of flooding can be severe. As such, this study has developed new approaches for flood monitoring downstream of the Zambezi Basin, through the application of an integrated modelling system. The modelling system consists of: predicting daily streamflow (using the calibrated GeoSFM), then feeding the predicted streamflow into MIKE BASIN (for checking the operating rules) and to optimise the releases. Therefore, before releases are made, the flood maps can be used as a decision-making tool to both assess the impact of each level of release downstream and to identify the communities likely to be affected by the flood – this ensures that the necessary warnings can be issued before flooding occurs. Finally an integrated flood management tool was proposed – to host the results produced by the integrated system – which would then be accessible for assessment by the different users. These results were expressed in terms of water level (m). Four discharge-level (Q-h) relationships were developed for converting the simulated flow into water level at four selected sites downstream of Cahora Bassa dam – namely: Cahora Bassa dam site, Tete (E-320), Caia (E-291) and Marromeu (E-285). However, the uncertainties in these predictions suggested that improved monitoring systems may be achieved if data access at appropriate scale and quality was improved.

The main objective of this thesis is to characterize hydrological processes in a Mediterranean mountain catchment, by combining distributed hydrological measurements and environmental tracers in order to improve the understanding of catchment hydrological function. During the period 2009-2013 hydrological data were collected from the Vallcebre Research Catchments, monitored since 1996 by the Surface Hydrology and Erosion group of the IDAEA-CSIC. Data include, in addition to rainfall and discharge measurements, distributed hydrological measurements and environmental tracers (both geochemical and isotope ones) at different time scales (seasonal to event scale). With this information, this study first investigates the spatial and temporal variability of the depth to water table during rainfall-runoff events. The results show that the depth to water table did not rise uniformly throughout the catchment during rainfall-runoff events. The spatial variability of depth to water table was mainly controlled by location characteristics, especially the piezometer distance from the stream, which influenced the distribution of wetness conditions within the catchment. The wetness conditions in turn affected the timing of the water table response, as well as the magnitude of the streamflow response. Spatio-temporal water table variability during floods varied, depending on the catchment's antecedent wetness conditions Dissolved organic carbon (DOC) concentration dynamics in different hydrological compartments were also analysed (rainfall, soil water, groundwater and stream water) at different time scales (seasonal to event scale). The results show some seasonality in rainwater and soil water DOC concentrations, while no clear seasonality was found in stream water and groundwater, where DOC dynamics were strongly related to discharge and water table variations. During storm events, DOC concentrations increased systematically in stream water. In addition, for storm events with several discharge peaks, the slope of the discharge/DOC concentration relationship was higher for the first peak. The increase in stream water DOC concentration during floods suggested a relevant contribution of soil water, as well as the existence of stream water DOC sources near or in the stream bed. The rather similar dynamics of stream water DOC concentration in all floods contrasted with the diversity of hydrological processes observed. This raises the question of the origin of the rapid DOC increase found and the validity of the use of DOC as a tracer. Finally, water mean transit time (MTT) was calculated in different hydrological compartments of the catchment, using stable isotopes (δ18O and δ2H) and tritium. The use of δ18O signal variations in rainfall and in the sampled hydrological compartments showed some limitations on water age calculation in the catchment studied: it only indicated that MTT was greater than two years. The use of a new methodology (TEPMGLUE) to calculate MTT using tritium allowed consideration of different sources of uncertainty in water age determination, as well as evaluation of the benefit of using samples of different ages and of differing analytical quality. The results showed similar MTT calculations, whether including only the water samples taken in the 1990s or using all samples (1996-1998 and 2013). However, when calculating MTT with only high analytical quality samples taken in 2013, two different MTTs were obtained. The MTT results showed that, in the Vallcebre catchments, well water was the youngest, followed by stream and spring water. The study also showed the relevance of the rainfall tritium input function to MTT calculations. Finally, results showed that topography did not affect MTT spatial distribution, whereas geological settings did.
L'objectiu de la tesi doctoral és millorar la caracterització dels processos hidrològics de les conques mediterrànies de muntanya utilitzant mesures hidrològiques distribuïdes i traçadors ambientals, amb la finalitat de comprendre'n el funcionament hidrològic. Durant el període 2009-2013 es van recollir dades hidrològiques de les conques d'investigació de Vallcebre, monitoritzades des de 1996 pel grup d’Hidrologia Superficial i Erosió del IDAEA-CSIC. Les dades inclouen, a més a més de registres de precipitacions i cabal, mesures hidrològiques distribuïdes i de dades de traçadors ambientals (geoquímics i isotòpics) a diferents escales temporals (estacional i d'esdeveniment). A partir d’aquesta informació s'ha analitzat, en primer lloc, la dinàmica espaciotemporal del nivell freàtic durant els episodis de pluja. Els resultats mostren que, durant aquests episodis, el nivell freàtic no reacciona de manera homogènia a tota la conca. La variabilitat espaial del nivell freàtic està molt afectada per les característiques de la localització de cada piezòmetre, especialment la distància al torrent, que té un paper essencial en la distribució de les condicions d'humitat de la conca. Aquestes condicions d'humitat, a la vegada, afecten al temps de resposta del nivell freàtic i a la magnitud de la resposta hidrològica. Segons les condicions d'humitat de la conca, la variabilitat espaciotemporal del nivell freàtic durant esdeveniments és diferent. En condicions seques, la variabilitat espaciotemporal del nivell freàtic és alta al llarg de tot l'esdeveniment. L'escolament es genera principalment per la contribució de les àrees que estan a prop del torrent. En canvi, en condicions de transició i especialment en condicions d'humitat, la variabilitat espaciotemporal del nivell freàtic és menor i respon de forma més ràpida, i produeix una resposta hidrològica major a escala de conca. Tot seguit, s'ha analitzat la dinàmica de la concentració de carboni orgànic dissolt (DOC) en diferents compartiments hidrològics (aigua de pluja, aigua del sòl, aigua subterrània i aigua del torrent) i a diferents escales temporals (estacional i d'esdeveniment). Els resultats mostren una variació estacional de la concentració de DOC a l'aigua de pluja i a la del sòl; però no s'aprecia aquesta estacionalitat a l'aigua subterrània i a la del torrent, a causa de que la concentració de DOC als dos compartiments està relacionada amb la dinàmica del nivell freàtic i la del cabal. A escala d’esdeveniment s'observa un augment sistemàtic de la concentració de DOC al torrent. A més a més, en els esdeveniments de diversos pics de cabal el pendent de la relació cabal/concentració de DOC sempre és major al primer pic. Aquest augment de la concentració de DOC al cabal durant els esdeveniments suggereix una contribució rellevant de l’aigua del sòl, però també l'existència de fonts de DOC pròximes al torrent o del mateix llit del torrent. D'altra banda, la relativa semblança de la dinàmica del DOC en el torrent durant esdeveniments de diferent magnitud i amb processos hidrològics contrastats molt diferents, planteja la qüestió de l'origen de l'augment de DOC i el seu possible ús com a traçador. Per últim, s'ha realitzat el càlcul del temps mitjà de trànsit (MTT) de l'aigua als diferents compartiments hidrològics de la conca utilitzant, primer, els isòtops estables (δ18O i δ2H), i segon, el triti. L'ús de la variació del senyal isotòpic del δ18O a l'aigua de pluja i a diferents compartiments d'aigua mostrejats presenta limitacions a la conca d'estudi; únicament permet demostrar que el MTT de les aigües és major de dos anys. L'ús d'una nova metodologia (TEPMGLUE) per calcular el MTT, utilitzant el triti, permet considerar diferents fonts d'incertesa i avaluar l'ús de mostres d'edats diferents i de diferent precisió analítica. Els resultats revelen que s'obtenen valors de MTT similars, tant utilitzant mostres dels anys noranta, com totes les mostres disponibles (1996-1998 i 2013). En canvi, quan únicament es calcula el MTT utilitzant les mostres del 2013 s'obtenen dos valors de MTT molt diferents. Els resultats de l’estudi també mostren que a les conques de Vallcebre l'aigua més jove és la dels pous, seguida de l'aigua del torrents i la de les fonts. L'estudi també demostra el paper rellevant de la funció d'entrada de triti amb la pluja per calcular el MTT. Per últim, els resultats suggereixen que la topografia no afecta la distribució espaial del MTT de la conca, però sí la geologia. Tots els resultats d'aquesta tesi aporten informació addicional sobre el funcionament hidrològic de les conques de Vallcebre, i a més a més suggereixen noves línies d'investigació
El objetivo de esta tesis doctoral es mejorar la caracterización de los procesos hidrológicos de las cuencas Mediterráneas de montaña, utilizando mediciones hidrológicas distribuidas y trazadores ambientales, con la finalidad de comprender mejor su funcionamiento hidrológico. Durante el período 2009-2013 se recogieron datos hidrológicos de las cuencas de investigación de Vallcebre, monitorizadas desde 1996 por el grupo de Hidrología superficial y Erosión del IDAEA-CSIC. Los datos incluyen, además del registro de precipitaciones y caudales, mediciones hidrológicas distribuidas y datos de trazadores ambientales (geoquímicos e isotópicos) a diferentes escalas temporales (estacional y de crecida). Con esta información, se ha analizado en primer lugar la dinámica espacio-temporal del nivel freático durante las crecidas. Los resultados muestran que durante las crecidas el nivel freático no reacciona de forma homogénea en toda la cuenca. La variabilidad espacial del nivel freático está muy afectada por las características de la localización de cada piezómetro, especialmente la distancia al cauce que tiene un papel esencial en la distribución de las condiciones de humedad de la cuenca. Estas condiciones de humedad, a su vez, afectan al tiempo de respuesta del nivel freático y a la magnitud de la respuesta hidrológica. Según las condiciones de humedad de la cuenca la variabilidad espacio-temporal del nivel freático durante la crecida es diferente. En condiciones secas la variabilidad espacio-temporal del nivel freático es alta a lo largo de toda la crecida. En estas condiciones, la escorrentía se genera principalmente por la contribución de las áreas próximas al cauce. En cambio, en condiciones de transición y especialmente en condiciones húmedas, la variabilidad espacio-temporal del nivel freático es menor y su respuesta es mas rápida, produciendo una mayor respuesta hidrológica en la cuenca. Seguidamente, se ha analizado la dinámica de la concentración del carbono orgánico disuelto (DOC) en diferentes compartimentos (agua de lluvia, agua del suelo, agua subterránea y agua del cauce) a diferentes escalas temporales (estacional y de crecida). Los resultados indican una variación estacional de la concentración de DOC en el agua de lluvia y en la del suelo. Sin embargo, no se aprecia esta estacionalidad en el agua subterránea y en la del cauce, debido a que la concentración de DOC en estos compartimentos está relacionada con la dinámica del nivel freático y del caudal. Durante las crecidas se observa un aumento sistemático de la concentración de DOC en el cauce. Además en las crecidas con varios picos de caudal el pendiente de la relación caudal/concentración de DOC es siempre mayor en el primer pico. El aumento de la concentración de DOC en el cauce durante las crecidas sugiere una contribución relevante del agua del suelo, pero también la existencia de fuentes de DOC próximas al cauce o en el mismo lecho. La relativa similitud de la dinámica del DOC en el cauce durante eventos de distinta magnitud y con procesos hidrológicos contrastados muy distintos, plantea la cuestión del origen del aumento de DOC y su posible utilización como trazador. Por último, se ha realizado el cálculo del tiempo medio de transito (MTT) del agua, en diferentes compartimentos hidrológicos de la cuenca utilizando, primero, isótopos estables (δ18O y δ2H), y después el tritio. El uso de la variación de la señal isotópica del δ18O en el agua de lluvia y en los diferentes compartimentos de agua muestreados muestra sus limitaciones en la cuenca de estudio; solo permite demostrar que el MTT es mayor de dos años. El uso de una nueva metodología (TEPMGLUE) para calcular el MTT usando el tritio, permite considerar diferentes fuentes de incertidumbre y evaluar el uso de muestras de edades diferentes y con distinta precisión analítica. Los resultados revelan que se obtienen valores de MTT similares, tanto utilizando muestras de los años noventa, como todas las muestras disponibles (1996-1998 y 2013). Sin embargo, cuando se calcula el MTT utilizando solo muestras del 2013 se obtienen dos valores de MTT muy distintos. Los resultados de MTT muestran que en las cuencas de Vallcebre el agua es más jóven en los pozos, seguida del agua de los cauces y la de las fuentes. El estudio también demuestra el papel relevante de la función de entrada de tritio en la lluvia para el cálculo del MTT. Por último, los resultados sugieren que la topografía no afecta la distribución espacial del MTT en la cuenca, pero sí la geología. Todos los resultados de esta tesis aportan información adicional sobre el funcionamiento hidrológico de las cuencas de Vallcebre, además sugieren nuevas líneas de investigación.

In order to effectively manage river basin systems, a full understanding of the effects of land use change on hydrological processes, as well as knowledge on spatial heterogeneity of surface runoff with associated catchment characteristics, is required. This thesis employed the SWAT2009 model and SUFI-2 tool to understand the hydrological response to land use change in the Daning River catchment, Three Gorges Reservoir area, China. Firstly, appropriate landscape representations for the SWAT-based hydrological modelling were examined. DEM spatial resolution, catchment delineation scale and HRU definition were identified so that the inputs uncertainty could be reduced to a minimal level. Secondly, a consistent underestimation of discharge using station-based climatic records disclosed there was insufficient precipitation due to the location of the rain gauge at relatively low altitude. Considering the orographic effects on precipitation, Daning hydrological models were well calibrated and validated with the sparse climate observations. The model prediction uncertainty was also quantified. Thirdly, using the calibrated hydrological models of the Daning River catchment, this study quantified the effects of land use change (1990 and 2004) on the hydrological processes in the whole basin and sub-catchment levels. In 1982-1993, the change of land use pattern from 1990 to 2004 resulted in an increase of surface runoff, whereas, in 1996-2007 reverting the land use from 2004 to 1990 caused a slight decrease of river flows. Increased forest cover decreased surface runoff at the sub-catchment level. A concurrent increase of agricultural land, which brought about more surface runoff, weakened the forest‘s ecological function of water retention at the catchment scale. This thesis highlights that the strategy of land use exploration for human use along with the afforestation is not always effective in ecological protection. With the changing land use in future, composition of forests and agricultural land is a significant element being considered.

L’évaluation des modèles hydrologiques est généralement basée sur des comparaisons des séries de débit observées et simulées à l’aide de critères de performance tels que le Nash-Sutcliffe Efficientcy. Bien que cette approach fournisse des mesures pertinentes de la performance prédictive d’un modèle, elle ne fournit que très peu d’informations sur les raisons d’une bonne ou d’une mauvaise performance. Gupta et al. (2008) ont proposé d’utiliser plutôt des signatures hydrologiques, des indicateurs qui caractérisent le comportement d’un bassin versant. Étant donné que les signatures hydrologiques peuvent être liées aux processus hydrologiques, la comparaison des signatures hydrologiques observées et simulées permet l’évaluation du modèle tout en offrant des diagnostics, i.e. des indications sur les processus hydrologiques qui y sont bien ou mal représentés.Dans cette thèse de doctorat, nous nous concentrons sur l’interprétation et le pouvoir diagnostique des signatures hydrologiques et comment celles-ci peuvent être utilisées pour guider l’amélioration d’un modèle distribué. Nous présentons la construction d’un jeu de signatures hydrologiques, utilisant uniquement des données largement disponibles – précipitations, débit et température de l’air – pour caractériser le fonctionnement hydrologique de 4 sous-bassins versants (Sud-Est de la France) et 10 bassins versants de montagne à influence nival (Southern Sierra, Californie, États-Unis). Des signatures hydrologiques existantes et des nouvelles sont sélectionnées et/ou développées. Collectivement, elles permettent de caractériser le comportement de bassins versants dans une grande variété de contextes hydro-climatiques. En nous concentrant sur les processus de neige, des mesures de neige supplémentaires nous permettent d’évaluer la pertinence des signatures hydrologiques dédiées aux processus nivaux. Par ailleurs, le modèle J2000 est déployé sur le bassin versant de l’Ardèche et une analyse de sensibilité est réalisée afin de comprendre comment les signatures hydrologiques sont liées aux paramètres du modèle. Cela nous permet de déterminer la façon dont elles doivent être interprétées dans le contexte du modèle J2000 de l’Ardèche et permet l’évaluation de leur pouvoir diagnostic. Enfin, en combinant les résultats de l’analyse de sensibilité avec des comparaisons entre signatures observées et simulées, nous entreprenons un diagnostic approfondi du modèle afin de dériver et tester des recommandations pour son amélioration. Nous identifions des déficiences du modèle, principalement liées au stockage de l’eau souterraine et des sols, mettant en évidence des problèmes de représentation spatiale des propriétés géologiques et pédologiques
The evaluation of hydrological models is typically based on comparisons of observed and sim-ulated streamflow time series using performance metrics such as the Nash-Sutcli˙e Eÿciency. Although it provides relevant measures of the predictive performance of a model, this type of approach provides very little information on the reasons behind good or bad performance. Instead, Gupta et al. (2008) proposed to use hydrological signatures which are indicators that characterize catchment behaviors. Because they can be related to hydrological processes, using them when comparing observation with simulation enable the evaluation of the model while o˙ering diagnostics, i.e. indications on the hydrological processes that are well or badly repre-sented in the model.In this PhD thesis, we focus on the interpretations and diagnostic power of hydrological signatures and how they can be used to guide the improvement of a distributed model. We present the building of a set of hydrological signatures, using only widely available data – pre-cipitation, streamflow and air temperature – to characterize the hydrological functioning of 4 Ardèche sub-catchments (South East of France) and 10 snow dominated catchments of the Southern Sierra mountains (California, USA). Already existing and new hydrological signatures are selected and/or designed. Collectively, they can characterize catchment behavior in a wide variety of hydro-climatic contexts. We demonstrate the value of additional snow measurements to evaluate the information content of snow dedicated hydrological signatures. In the context of the Ardèche catchment, we set up the J2000 distributed model and use a sensitivity analysis to understand how the hydrological signatures are linked to the model parameters. This provides insights into how they are to be interpreted in the context of the J2000 Ardèche model and allows the assessment of their diagnostic power. Finally, combining the results of the sensi-tivity analysis with comparisons between observed and simulated hydrological signatures, we undertake an in-depth diagnostic of the model to provide and test recommendations for its improvement. Deficiencies of the model functioning are identified, mainly related to soil and groundwater storage and fluxes, highlighting issues in the spatial representation of soil and geological properties

The cryosphere is defined as the portions of the earth where water is in solid form. It represents a very important part of the hydrologic cycle, affecting ecological, human and climate systems. A number of component models describing the energy and mass balances of a snowpack have been developed and these component models are finding their way into watershed models and land surface schemes. The purpose of this thesis is to examine the incorporation of a number of snow processes in the coupled land-surface-hydrological model WATCLASS. The processes under consideration were mixed precipitation, variable fresh snow density, maximum snowpack density, canopy interception and snow-covered area (SCA). The first four of these processes were based on similar work done by Fassnacht (2000) on a watershed in Southern Ontario. In the case of this thesis, the work was completed on a basin in Northern Manitoba. A theory of the relationship between snow-covered area and average snow depth was developed and an algorithm was developed to implement this theory in WATCLASS. Of the five snow processes considered, mixed precipitation was found to have the greatest impact on streamflow while the new canopy interception algorithm was found to have the greatest impact on sensible and latent heat fluxes. The development of a new relationship between SCA and average snow depth was found to have a minimal impact in one study case, but a significant impact on the sensible and latent heat fluxes when snow fell on a pack that had begun to melt and was partially free of snow. Further study of these snow processes in land-surface-hydrologic models is recommended.

Low cost, low power wireless sensors (motes) promise to revolutionize environmental data collection, but are they currently refined enough for widespread use by hydrologists? Their viability as a replacement for traditional data collection techniques was investigated in a 7 ha forested watershed in south-western British Columbia. The watershed included 41 instrument clusters measuring air and soil temperature, humidity, throughfall, soil moisture content, overland flow and groundwater head. The foundation of each cluster was a data box containing a MDA300 data acquisition board and a MICA2 processor board from Crossbow Technologies, Inc.™ that allowed for short range wireless data collection. The 41 motes each recorded data every 15 minutes from July, 2006, to April, 2007. In addition to reporting on the reliability of the motes and sensors during the 10 months deployment, the high spatial and temporal resolution data collected by this study gave the opportunity for many analyses of catchment processes. As soil moisture and throughfall are two influential processes in the exchange of water between the earth and the atmosphere, these were the focus of the data analysis. The first analysis was a resampling experiment on seven different events selected from the full data set. Comparing 100 different subsamples each of 5, 10 and 20 points for throughfall and soil moisture showed if increasing the sample size eventually produced diminishing returns in the ability to reproduce the true catchment mean. With significant differences in prediction ability for both soil moisture and throughfall at times of differing hydrologic activity, this analysis provides further support for the theories of changing moisture states of soil moisture and threshold values for throughfall. The second analysis described how the organization of soil moisture and throughfall changed during a range of weather conditions and timescales. Spatial representation of normalized values and Pearson correlation coefficients showed that there were distinct differences between wet and dry periods for soil moisture and between long and short analysis periods for throughfall.

Most documented investigations of the effects of land-use change on hydrological systems have considered the modification of forest areas. In this thesis, a headwater area in the North York Moors is used to examine the consequences of maintaining a land management regime which has received comparatively little observation in this context: controlled heather burning (muirburn). The effects of coniferous afforestation are also evaluated for selected variables. Particular attention is given to the responses of soil, moisture and evapotranspiration and the relationship between these two components.Simulated soil moisture deficits derived from empirical models are tested against measured values. Predictions based on Penman-Monteith evapotranspiration and 'layer' moisture deficits, along with an optimised soil-drying parameter, were found to simulate observed conditions most closely. A land-use change from open heather moorland to burnt ground promoted reductions both in evapotranspiration levels, especially at potential demando and in moisture deficits. In contrast, following afforestation, deficits were maintained or enhanced throughout the year, with higher moisture losses to interception than found under heather, due to the higher aerodynamic resistance of the latter. Predictions of actual evapotranspiration, determined from soil moisture models, were generally found to be reliable estimates of those 'observed' from the moorland water balance.Antecedent catchment conditions and storm characteristics were used in analysis of runoff distribution over time, quantified in terms of 'unit hydrographs' and linear regression models. Land-use effects were manifested most significantly in a doubling of hydrograph peak discharge following muirburn, the lower measured soil moisture deficits under a burnt catchment rendering more water available for storm runoff. A secondary, underlying control, that of a slower response from a wet catchment, lent 'support to evidence for the existence of variable source areas.

Earth system modeling, climate modeling, water resource research as well as integrated modeling (e.g., climate impact studies) require the coupling of hydrological and meteorological models. The paper presents recent concepts on such a coupling. It points out the difficulties to be solved, and provides a brief overview on recently realized couplings. Furthermore, a concept of a hydrometeorological module to couple hydrological and meteorological models is introduced
Wasserresourcenforschung, Erdsystem- und Klimamodellierung sowie integrierte Modellierung (z.B. Klimafolgenforschung) erfordern das Koppeln von hydrologischen und meteorologischen Modellen. Dieser Artikel präsentiert Konzepte für eine solche Kopplung. Er zeigt die zu lösenden Schwierigkeiten auf und gibt einen kurzen Überblick über bisher realisierte Kopplungen. Ferner stellt er ein Konzept für einen hydrometeorologischen Moduls zur Kopplung von hydrologischen mit meteorologischen Modellen vor

Thesis: S.B. in Art and Design, Massachusetts Institute of Technology, Department of Architecture, February, 2021
Cataloged from the official pdf version of thesis.
Includes bibliographical references (pages 49-50).
The focus of this thesis is hydrological disasters and the question it attempts to answer is: how can we design and implement housing structures along U.S. coastlines that fully withstand hydrological disasters? Priority and severity is shown by increasing trends in natural disaster occurrence frequency and damage and reconstruction costs. Cost increase is due in part because disaster events are more destructive, but also because of overbuilding and high housing density located within high risk areas. First, using several literature sources, this thesis analyzes various aspects of natural disaster response and education. This paper achieves its goal to increase awareness about the flaws in government risk management and lack of disaster awareness and mitigation design curricula amongst architecture institutions. As a design thesis, alternative housing models are presented in the later sections. The design process begins with hazard-risk identification and then outlining important building regulations. FEMA Coastal Construction Manual along with other sources were useful in understanding necessary mitigation measures required for coastal development designs. After research, a new design solution is presented. Design inspiration was drawn from similar technology and the need for innovative, resilient, and economical designs. This thesis hopes to use idealized designs to start more conversation about natural disaster defensive architecture.
by Alejandro Gonzalez- Placito.
S.B. in Art and Design
S.B.inArtandDesign Massachusetts Institute of Technology, Department of Architecture

Earth system modeling, climate modeling, water resource research as well as integrated modeling (e.g., climate impact studies) require the coupling of hydrological and meteorological models. The paper presents recent concepts on such a coupling. It points out the difficulties to be solved, and provides a brief overview on recently realized couplings. Furthermore, a concept of a hydrometeorological module to couple hydrological and meteorological models is introduced.
Wasserresourcenforschung, Erdsystem- und Klimamodellierung sowie integrierte Modellierung (z.B. Klimafolgenforschung) erfordern das Koppeln von hydrologischen und meteorologischen Modellen. Dieser Artikel präsentiert Konzepte für eine solche Kopplung. Er zeigt die zu lösenden Schwierigkeiten auf und gibt einen kurzen Überblick über bisher realisierte Kopplungen. Ferner stellt er ein Konzept für einen hydrometeorologischen Moduls zur Kopplung von hydrologischen mit meteorologischen Modellen vor.

Weather radar has been widely used in hydrologic forecasting and decision making; nevertheless, there is increasing attention on its unceltainties that propagates through hydrologic models. These unceltainties are not only caused by radar itself in measuring and estimating rainfall (such as attenuation, extrapolation of the rainfall measured aloft to the ground, sampling methods and pmtial beam blocking, etc.), but also come from the complicated synoptic regimes (such as air motion, vertical variability of temperature, and conversion to and from different hydrometeors). This thesis aims to improve the quality of radar rainfall and describe its uncertainty. The Brue catchment (135 sq. km) in Southwest England covering 28 radar pixels and 49 rain gauges and a hilly area to the east and south of Manchester with around 5000 sq . km and 50 rain gauges are chosen as the experimental domains for this thesis. The studies are composed of three main pmts: Firstly, I propose a fully formulated uncertainty model that can statistically quantify the characteristics of the radar rainfall errors and their spatial and temporal structure, which is a novel method of its kind in the radar data unceltainty field. The uncertainty model is established based on the distribution of gauge rainfall conditioned on radar rainfall (GRJRR). Its spatial and temporal dependences are simulated based on the copula function. With this proposed uncertainty model, a Multivariate Distributed Ensemble Generator (MDEG) driven by the copula and autoregressive filter is designed. The products from MDEG include a time series of ensemble rainfall fields with each of them representing a probable true rainfall. As wind is a typical weather factor that influences radar measurement, this thesis introduces the wind field into the unceltainty model and designs the radar rainfall uncertainty model under different wind conditions. In addition, I also propose an Empirically-based Ensemble Rainfall Forecasts (ERFEM) model to measure and quantify the combined effect of all the error sources in the radarrainfall forecasts .. The essence of the unceltainty model is formulated into an empirical relation between the radar rainfall forecasts and the corresponding 'ground truth' represented by the rainfall field from rain gauges. In modelling the radar rainfall unceltainty, I find that the wind has a huge impact on radar-gauge comparison. Due to the wind effects, the raindrops observed by the radar do not always fall veltically to the ground, and the raindrops arriving at the ground cannot all be caught by the rain gauge. This thesis proposes a practical approach to simulate the movement of raindrops in the air and adjust the aforementioned wind-induced errors on radar bias correction procedure. This scheme is based on the numerical simulation of raindrop movements in the three-dimensional ' wind field. The Weather Research and Forecasting (WRF) model is used to downs.cale the reanalysis data ERA-40 to obtain the wind field with high spatial and temporal resolutions. A normalized gamma model is adopted to estimate the raindrop size distribution (DSD). This work is the first study to tackle both wind effects on radar and rain gauges, which could be considered as one of the essential components in processing radar observation data, which should be undertaken after the aforementioned physical processes and before bias correction. Finally, this thesis analyzes how the radar rainfall uncertainty propagates through a hydrological model (the Xinanjiang model) and investigates which features of the uncertainty model have significant impacts on flow simulation. The generated ensemble rainfall values by MDEG are input into the Xinanjiang model to produce uncertainty bands of the ensemble flows. Five important indicators are used to describe the characteristics of uncertainty bands. It is concluded that the Gaussian marginal distribution and spatio-temporal dependence using Gaussian copula is considered to be the preferred configuration of the MDEG model for hydrological model unceltainty analysis in the Brue catchment. Keywords: Multivariate Distributed Ensemble Generator (MDEG); Copula; flow simulation; Radar-Rainfall Estimates; Hydrological Model Uncertainty; wind-induced error; drop size distribution; WRF; wind-drift.

An improved understanding of the processes controlling the dynamics of the Greenland Ice Sheet is needed to enable more accurate determination of the response of the ice sheet to projected climate change. Meltwater produced on the ice sheet surface can penetrate to the bed and cause ice motion to speed up through enhanced basal sliding. However, the importance of coupled hydro-dynamics both to current ice sheet motion and future stability over the coming century is unclear. This thesis presents observations from the south-west Greenland Ice Sheet which improve our understanding of coupled hydro-dynamics. It commences with an investigation of the response of ice motion to exceptional meltwater forcing during summer 2012. Simultaneous field observations of ice motion (by GPS) and proglacial discharge show that, despite two extreme melt events during July 2012 and summer ice sheet runoff 3.9 s.d. above the 1958– 2011 mean which resulted in faster summer motion, net annual motion was slower than in the average melt year of 2009. This suggests that surface melt-induced acceleration of land-terminating regions of the ice sheet will remain insignificant even under extreme melting scenarios. The thesis then examines spatial variability in ice motion, in relation to an inferred subglacial drainage axis, using GPS and satellite radar observations from a land-terminating margin up to 20 km inland where ice is 800 m thick. Whilst spatial variability in subglacial drainage system configuration is found to control ice motion at short timescales, the proportional contribution of summer motion to annual motion is almost invariant. The structure of the subglacial drainage system does not therefore appear to significantly influence spatial variations in net summer speedup. Lastly, observations are made by applying feature tracking to 30 years of optical satellite imagery in a ~170 by 50 km area along the ice sheet margin (where ice reaches ~850 m thick) to examine whether coupled hydrology-dynamics affects inter-annual ice motion. Hydro-dynamic coupling resulted in net ice motion slowdown during a period of clear climate warming. Further increases in meltwater production may therefore reduce ice sheet motion. The thesis concludes that at land-terminating margins of the Greenland Ice Sheet, (1) larger annual meltwater volumes do not result in faster annual ice motion; (2) the detailed structure of the subglacial drainage network appears unimportant to the role of summer motion in determining annual motion; and (3) atmospheric warming over several decades has been accompanied by a slowdown in ice motion. As such, hydro-dynamic coupling is unlikely to form a significant positive feedback between surface melting and ice motion in response to projected climate warming. The wider relevance of these findings to tidewater systems requires further investigation.