The potential impact of sea level rise on Lake Ellesmere - Te Wiahora and the subsequent effect on the efficiency and performance of the L2 Drainage network was investigated in relation to the operation of the L2 Drainage scheme. Lake Ellesmere is currently manually opened for drainage to the sea when the lake levels reach 1.05 m above mean sea level (asl) in summer and 1.13 m asl in winter. With a rise in sea level, the lake opening levels for both summer and winter would have to increase in order to maintain the current hydraulic gradient. Higher lake levels would impact drainage schemes such as the L2 drainage network. An integral research approach was used to study this potential impact, including fieldwork, analysis of data, hydrologic and hydraulic modelling. Both the hydrologic and hydraulic response of the L2 catchment and river were reproduced with reasonable accuracy by the use of computational models. Simulations of 2, 10 and 20 year annual recurrence intervals (ARI) rainstorm events coupled with higher lake levels show increase flooding along the length of the river. An increase in the lake opening levels, coupled with south-easterly wind was shown to have increased the degree of flooding on adjacent farmlands, but only a 3.50 per cent increase of water level (for all conditions simulated) 3.5 km upstream of the L2 River. The study clearly shows that weed growth within the L2 River plays an important part in controlling the water level within the channel. Results show it was responsible for an observed water level rise of 0.30 m from the winter to summer season. The combined use of hydraulic and hydrological models provides an effective tool to study future impacts on the drainage efficiency and performance of the L2 drainage scheme and other similar systems. The potential for both models to be used as a predictive tool for improving the operation of the L2 scheme and Lake Ellesmere was only limited by the difficulty in estimating model parameters especially for the hydrologic model.

Traditional hydrological model inputs are often deemed inadequate in areas where stations are sparse, such as the northern extents of the Canadian Prairie basins. The Canadian Precipitation Analysis (CaPA) combines GEM (Global Environmental Multi-scale model) data and available observation data to provide enhanced precipitation estimates. The CaPA analysis has recently been extended to produce high-resolution precipitation data over the Canadian Prairies, encompassing the Nelson-Churchill River Basin. Manitoba Hydro and other water practitioners in Manitoba have expressed interest in potentially using CaPA precipitation as hydrological model forcing for Prairie watersheds. A three step validation approach was designed and applied to assess CaPA for hydrologic modelling applications in the Nelson-Churchill River basin. Results of validation show that the quality of CaPA data varies among regions and seasons, with CaPA proving beneficial in both data-sparse regions and winter seasons most prominently. Overall, CaPA shows promise for water resource application in the Canadian Prairies.

A SWAT hydrological model is developed to evaluate the individual and combined impacts of urbanization and climate change on water quantity (discharge) and quality (N and P) of the watershed of Carp River in Ontario, Canada. Seven numerical experiments (scenarios) were developed to represent the different configurations of the watershed in terms of land use (either current or projected) and climate regime (current or future, observed or simulated). The reference period is 1990-2018, and the future period is 2021-2050. The 2017 land use was used to represent the reference period. The future land use is the projected 2050 land use obtained from the City of Ottawa. The future climate was obtained by downscaling the outputs of nine (9) Regional Climate Models (RCMs) under two Representative Concentration Pathways (RCPs): RCP4.5 and RCP 8.5. The developed scenarios are the following: • S0o (baseline scenario) corresponding to the current land use map and the observed climate regime on the reference period • S0m is similar to S0o except that RCM outputs are used instead of the observed climate on the reference period • S1 corresponds to the future land use and historical climate regime on the reference period. • S0M45/S0M85 corresponds to the current land use and the future climate regime under RCP4.5 (S0M45) and RCP8.5 (S0M85) • S1M45/S1M85 corresponds to the future land use map and future climate regime under the two RCPs. The changes or impacts on quantity and quality in each scenario were estimated by comparing the results with the baseline scenarios S0o/m (reference) at two levels: globally (at the main outlet) and locally (at the outlet of an upstream sub-watershed). For a consistency purpose, S0o is used when assessing land-use change scenario while S0m was the reference in climate change and combined effects scenario. This allowed the comparison to be consistent with the same climate data frame. The results showed that climate change is likely to be the most dominant factor affecting discharge and nitrogen, while urbanization will control the quantity of phosphorus. Unsurprisingly, the combined effect had a more significant impact on water quantity and quality. However, the impact is not additive, and the relationship is not linear. Compared with S0, the annual average discharge increased by 1.57%, 5.49%, 7.52%, 6.75%, and 9.34% in S1, S0M45, S0M85, S1M45, and S1M85, respectively. In comparison, the change for annual N load was estimated at -1.88%, 29.62%, 2.03%, 24.84%, and -1.20% respectively. Change in annual average P was respectively 26.49%, 1.07%, -4.49%, 23.81% and 19.15%. Local impact assessment indicates the impact in upstream sub-watersheds may differ from the main outlet's impact in terms of magnitude and direction of change. Therefore, only considering global change may lead to a wrong interpretation of the impacts over the watershed. It is, therefore, necessary to evaluate the impacts at the local level as well.

Water is key in climate change adaptation. The impacts of climate change will primarily manifest themselves through water, with changes in the frequency and intensity of extreme hydroclimatic events such as floods and droughts. Understanding climate change influence is crucial for assessing future water availability and developing sustainable management plans. Vulnerability to these changes differs by region and community, geographic location, nature of climate change impacts, and human factors. The Nunavik region in northern Canada is experiencing some of the most rapid changes in climate in the world, with disproportionately large temperature increases, alterations in precipitation regimes, and thawing of permafrost, among others. This investigation aims to evaluate the impact of climate change on water availability in the Umiujaq community (Nunavik) and propose strategies to reduce the effects of these impacts. In order to achieve these goals, a hydrological model of the basin has been developed and calibrated using the Soil and Water Assessment Tool (SWAT), satellite and local data, and the SWAT Calibration and Uncertainty Programs (SWAT-CUP). Due to a lack of data, a model was first developed for the Grande Riviere de la Baleine watershed (Kuujjuarapik) and then transposed to Umiujaq. The hydrological model was successfully calibrated and validated (NSE = 0.81, RSR = 0.43, PBIAS = 5.2: NSE = 0.68, RSR = 0.56, PBIAS = 0.9). Then, the model was forced with Canadian downscaled climate data (CMIP5) under three emission scenarios (RCP 2.6, RCP4.5, and RCP8.5) to develop a quantitative analysis of the future water cycle's evolution. The results showed a slight increase in precipitation with global warming and a considerable reduction in snow content due to the higher temperatures. A faster and easier snow melting would happen yearly, bringing an earlier streamflow peak in the river. In the worst-case scenario (RCP8.5), the peak streamflow will move from June 17 to May 8 (40 days), which could result in lower water availability during the summer. To address these impacts, two strategies were analyzed: increase the storage capacity of the community and resort to an alternative water source, i.e., groundwater. The first one could be a solution in the short term, while the second one would be more reliable in the long term. However, the community is already facing difficulty in providing a reliable water supply throughout the year, so swift and concerted action from both the community and relevant authorities is of the essence in tackling this issue head-on.

Flooding is a major concern for Canadian society as it is the costliest natural disaster type in Canada. Southern Ontario, which houses one-third of the Canadian population, is particularly affected by early spring floods following snowmelt. During the last three decades, there has been a shift in flooding events from March-April to earlier months due to earlier snowmelt coupled with extreme rain events. Hydrological models run with different scenarios of climate change suggest further enhancement of this shift in the future. These projections of streamflow are associated with a cascade of uncertainties due to the choice of Global Climate Models (GCM’s), climate change scenarios, downscaling methods or hydrological models. A large part of the uncertainty is also associated with internal variability of climate due to the chaotic nature of the climate system. Despite these uncertainties, little is known about the impact of atmospheric circulation on past streamflow in southern Ontario and how the internal variability of climate is expected to impact the overall uncertainties in the projections of the future hydrological processes. In this thesis, the Precipitation Runoff Modelling System (PRMS), a semi-distributed conceptual hydrological model, was established in four watersheds in southern Ontario to assess the impact of atmospheric circulation on the modulation of streamflow and number of high flows. Recurrent meteorological patterns (Or Weather regimes), based on 500hPa geopotential height (Z500), have been first identified in Northeastern North America using the k-means algorithm. The occurrences of these weather regimes patterns were used to create a regime-normalized hypothetical temperature and precipitation dataset that have been used as input in PRMS. Then, to investigate the future evolution of the hydrological processes, PRMS was forced with temperature and precipitation from the 50-members Canadian Regional Climate Model Large Ensemble (CRCM5-LE), a dynamically downscaled version of CanESM2-LE. The 50-members were classified into different classes of similar change in average temperature, precipitation and streamflow to identify the corresponding large-scale patterns. The specific focus of this analysis was on winter high flows, with the identification of a heavy rain and warm index, that can help to explain the generation of winter high flows in southern Ontario. The future evolution of these hydrometeorological extreme events, calculated for each member of CRCM5-LE, was analyzed with respect to the corresponding k-means weather regimes calculated for each member of CanESM2-LE. Finally, the uncertainties in the projections of the hydrometeorological extremes from the 50-members ensemble were compared to other sources of uncertainties using an analysis of variance applied to 504 simulations in the Big creek watershed. The high flows were projected using seven sets of PRMS parameters, 11 CMIP5 climate models forced with 2 scenarios of climate change and the 50 members of CRCM5-LE. The results, focusing on the winter season, showed that weather regimes High-Pressure (HP) and southerly winds (South) are associated with a higher average streamflow volume and high-flows frequency in the historical period. Regime HP is characterized by high geopotential height anomalies on top of the Great Lakes region together with higher temperature and precipitation amounts. Regime South is characterized by high Z500 anomalies in the Atlantic east coast and is associated with stronger southerly winds and higher precipitation amount in southern Ontario. The temporal increase in HP in the past contributed more than 40% of the increase in average streamflow in winter. In the future, all 50 members of CRCM5-LE ensemble produce an increase in January-February streamflow. 14% of the ensemble depict a larger streamflow increase due to increase in Z500 anomalies in the east coast. This pattern, well defined by the regimes South, is expected to become a major contributor in the generation of hydrometeorological extreme events in Southern Ontario in the future. Regime HP is expected to contribute less to the high-flows due to the disappearance of snow. Overall, the contribution of internal variability of climate to high flows will be stable through the 21st century, primarily due to an increase in rainfall as generators of high flow events. The results suggest that the regional representation of rainfall in the GCMs-RCMs chains will be a critical area to improve with great societal implications for floods. / Dissertation / Doctor of Science (PhD)

<p>In order to find effective measures that meet the requirements for proper groundwater quality and quantity management, there is a need to develop a Decision Support System (DSS) and a suitable modelling tool. Central components of a DSS for groundwater management are thought to be models for surface- and groundwater flow and solute transport. The most feasible approach seems to be integration of available mathematical models, and development of a strategy for evaluation of the uncertainty propagation through these models. The physically distributed hydrological model ECOMAG has been integrated with the groundwater model MODFLOW to form a new integrated watershed modelling system - ECOFLOW. The modelling system ECOFLOW has been developed and embedded in Arc View. The multiple-scale modelling principle, combines a more detailed representation of the groundwater flow conditions with lumped watershed modelling, characterised by simplicity in model use, and a minimised number of model parameters. A Bayesian statistical downscaling procedure has also been developed and implemented in the model. This algorithm implies downscaling of the parameters used in the model, and leads to decreasing of the uncertainty level in the modelling results. The integrated model ECOFLOW has been applied to the Vemmenhög catchment, in Southern Sweden, and the Örsundaån catchment, in central Sweden. The applications demonstrated that the model is capable of simulating, with reasonable accuracy, the hydrological processes within both the agriculturally dominated watershed (Vemmenhög) and the forest dominated catchment area (Örsundaån). The results show that the ECOFLOW model adequately predicts the stream and groundwater flow distribution in these watersheds, and that the model can be used as a possible tool for simulation of surface– and groundwater processes on both local and regional scales. A chemical module ECOMAG-N has been created and tested on the Vemmenhög watershed with a highly dense drainage system and intensive fertilisation practises. The chemical module appeared to provide reliable estimates of spatial nitrate loads in the watershed. The observed and simulated nitrogen concentration values were found to be in close agreement at most of the reference points. The proposed future research includes further development of this model for contaminant transport in the surface- and ground water for point and non-point source contamination modelling. Further development of the model will be oriented towards integration of the ECOFLOW model system into a planned Decision Support System.</p>

This thesis presents the development of a dual-isotope simulation in a hydrological model, and its application to the lower Nelson River basin. The purpose of this study is to find if the simulation of stable water isotopes aids in hydrological simulation, and if a dual-isotope simulation is an improvement over a single-isotope simulation. The isoWATFLOOD model was enhanced to include δ2H and improve physical representativeness. The model was calibrated using various isotope and flow simulation error functions. Internal hydrologic storages and fluxes were verified by comparing simulated isotope values to observed isotope data. Adding isotope error to the calibration resulted in small but consistent improvements to the physical basis of calibrated parameter values. Isotope simulation error was found to be the best predictor of streamflow simulation performance beyond the calibration period. The dual-isotope simulation identified a number of model limitations and potential improvements from the verification of internal hydrologic storages. / October 2016

O uso de imagens de satélite tem aprimorado o estudo da dinâmica do uso do solo. Os mapeamentos da cobertura da terra se tornaram instrumentos fundamentais na avaliação das alterações na paisagem provocadas pela ação antrópica e sua influência sobre o planejamento regional e urbano. A utilização de ferramentas computacionais como os Sistemas de Informação Geográfica e os modelos hidrológicos têm auxiliado essas avaliações. O modelo hidrológico SWAT (Soil and Water Assessment Tool), desenvolvido pelo Departamento de Agricultura norte-americano, é um modelo de base física e parâmetros distribuídos, auxiliado por uma interface gráfica de software GIS. Por seu valor ambiental e econômico, a caracterização ambiental da área de drenagem da Represa de Itupararanga, com 936,54 \'KM POT.2\', localizada no estado de São Paulo, tem fundamental importância e a utilização de dados atuais permite que o estudo da área seja mais preciso no que diz respeito aos seus resultados. A partir de imagens do sensor Liss 3 do satélite ResourceSat-1, foi produzido o mapa atual de uso e ocupação do solo através da classificação supervisionada de máxima verossimilhança, validada por coletas de campo de ponto de controle com índice Kappa de 0,64 e índice de exatidão global de 71%. Os parâmetros morfológicos demonstraram que a área de estudo é bem drenada e possui baixa probabilidade de enchentes. A modelagem hidrológica foi calibrada para o período de janeiro de 2005 a dezembro de 2008 e resultou em coeficiente de eficiência de 0,41 e tendência percentual de 0%. A validação alcançou resultado de 0,301 e 5,5% para estes avaliadores, valores de ajuste considerados aceitáveis. Foram encontrados os valores de 9,66 e 1,5 para nitrogênio e fósforo, respectivamente, em kg/ha.ano, para os valores de poluição difusa, resultados elevados na comparação entre pesquisas com este foco. A comparação entre cenários identificou a necessidade de adotar práticas conservacionistas através do planejamento da ocupação para tornar sustentáveis as atividades dentro bacia e atenuar as pressões sobre os recursos naturais. / The use of satellite images has improved the study of the land use dynamics. Land cover mapping have become fundamental tools in the assessment of landscape changes caused by human action and its influence on regional and urban planning. Computation tools such as Geographic Information Systems and hydrological models have supported these findings. The hydrological model SWAT (Soil and Water Assessment Tool), developed by U. S. Agriculture Department, a model physically based and semi-distributed parameters with a GIS graphical interface. Due your environmental and economic value, the morphologic characterization of Itupararanga watershed, with 936,54 \'KM POT.2\', located in São Paulo state, have fundamental relevance and use of current data alows the study be more accurate. From images of Liss 3 sensor of ResourceSat-1 satelite, the current land use map was produced through supervised classification by maximum likelihood method and validated by control points on field collection, resulting in Kappa coefficient of 0.64 and overall accuracy rate of 71%. The morphological parameters showed that watershed is well drained and has low probability of flooding. The hydrological modeling was calibrated from January of 2005 to December of 2008 and had efficient value of 0.41 and trend rate of zero. Validation reached results of de 0.301 and 5.5% for these coefficients, considered acceptable for adjust values. Were found values of 9.66 and 1.5 for nitrogen and phosphorus, in kg/ha.year, respectively, for the values of diffuse pollution, high results in comparison between studies with this focus. The comparison between scenarios indentified the need to adopt conservation pratices through occupation planning to make the activities inside the basin and mitigate the pressure on natural resources.

Les systèmes aquifères constituent la partie souterraine du cycle hydrologique. Ils transfèrent les pluies infiltrées à travers les sols sur des distances variables. Après un temps caractéristique de l’ordre du mois au millier d’années, les eaux souterraines regagnent la surface en alimentant les rivières et en satisfaisant en partie l’évapotranspiration. Les aquifères sont ainsi une ressource en eau majeure pour l’Homme et les écosystèmes. La prédiction de leur réponse aux pressions anthropiques et climatiques se heurte à deux difficultés (1) la faible densité d’informations directes sur les milieux géologiques et leur grande hétérogénéité (2) la complexité des échanges entre la surface et la profondeur. L’enjeu est donc de développer des modèles représentant au mieux les processus aux différentes échelles spatiotemporelles. Pour aborder cette question, nous étudions le contenu informatif de différents types d’observables (piézométrie, débit de rivière, déformation de surface...) afin de déterminer comment ils peuvent améliorer la paramétrisation des modèles. Notre travail s’appuie sur la modélisation hydrologique du site de Ploemeur (échelle locale) et du bassin du Rhin (échelle continentale). Dans les deux cas, des modèles simples sont développés en utilisant des solutions analytiques et numériques. Le modèle ModFlow a également été couplé à un modèle hydrologique. À petite échelle, les résultats illustrent l’intérêt de différents types de données transitoires pour contraindre les processus. À grande échelle, le modèle développé ainsi que les observables permettent d’affiner le rôle des systèmes aquifères dans la disponibilité de l’eau en surface. Les deux approches illustrent un contrôle des flux à différentes échelles par la topographie, la géologie et l’hétérogénéité. / Groundwater systems (GW) constitute an important part of the hydrological cycle. GW transfer water infiltrated through soils on variable distances. After a characteristic time ranging from the month to thousand of years, GW reach the surface supporting rivers and evapotranspiration. Thus, they are a major resource for human and ecosystems. PredictingGWresponse to human and climate pressures is limited by (1) the scarcity of direct information on the highly heterogeneous geological media (2) the complexity of surface-depth exchanges. So, it seems necessary to develop models representing at best the processes at different spatiotemporal scales. To address this issue, we study the informative content of different observation types (piezometry, streamflow, surface deformation. . . ) to assess how they can improve models parametrization. Our work is based on GW modeling of the Ploemeur site (local scale) and of the Rhine basin (continental scale). For both approaches, simple models are developed, using analytical or numerical solutions. Also, the ModFlow model was coupled to an hydrological model. At small scale, results show the interest of temporal and multidisciplinary data to better constrain processes. At large scale, the developed model, as well as observations, allows to precise the role ofGWfor water availability on surface. Both approaches highlight a flows control at different scales by topography, geology and heterogeneity.

O modelo Soil and Water Assessment Tool (SWAT) tem sido utilizado para avaliar os impactos do uso e manejo da terra nos recursos hídricos, sedimentos e agroquímicos em diversas escalas e condições ambientais em todo o mundo. Entretanto, pelo fato de ter sido desenvolvido em centros de pesquisa norte-americanos, alguns parâmetros e rotinas de simulação não refletem adequadamente determinados processos de bacias localizadas em regiões tropicais. Nesse sentido, o presente trabalho visou aprimorar a modelagem hidrológica do SWAT através da revisão e modificação de processos relacionados à simulação da evapotranspiração. Os procedimentos propostos incluíram a alteração das rotinas de dormência vegetal no código fonte do modelo e a modificação dos cronogramas de operações de manejo e parâmetros do banco de dados de crescimento das plantas, visando reproduzir com maior precisão o ciclo das culturas em bacias tropicais. As modificações foram testadas em cinco bacias localizadas no Estado de São Paulo, com áreas entre 42 e 5.959 km², sendo comparados os resultados obtidos antes e depois da implementação das mesmas. Com as alterações, a análise do balanço hídrico anual evidenciou um aumento nos valores de evapotranspiração de cerca de 61% nas bacias, aproximando-se dos totais anuais de evapotranspiração calculados através de métodos empíricos, bem como houve redução significativa do escoamento superficial. Verificou-se uma melhoria da simulação de vazão em todas as bacias, sendo obtidos valores superiores para o Coeficiente de Eficiência de Nash-Sutcliffe (NSE) quando comparados à simulação sem as alterações. A calibração e validação foram realizadas com base na simulação modificada, sendo obtidos valores de NSE mensais entre 0,71 e 0,93 na calibração e 0,53 e 0,88 na validação, enquanto os valores diários de NSE situaram-se entre 0,51 e 0,82 na calibração e 0,38 e 0,83 na validação. A calibração a partir de uma simulação na qual as distorções dos processos hidrológicos da bacia estivessem previamente minimizadas resultou em bons resultados sem alteração excessiva dos parâmetros, indicando uma simulação hidrológica de melhor consistência. / The Soil and Water Assessment Tool (SWAT) has been used to predict the impact of land management practices on water, sediment, and agricultural chemical yields in a wide range of scales and environmental conditions across the globe. However, originally developed in the United States, some parameters and routines are unrealistic for simulating in tropical watersheds. In this sense, this work aims to improve the hydrologic modeling of SWAT model by reviewing and modifying parameters and routines related to evapotranspiration process. In order to adequately represent crop growth in tropical basins, the proposed procedures included changes in dormancy routines of SWAT source code and modifications of scheduled management operations and plant growth database parameters. These modifications were tested in five different basins at São Paulo State, Brazil, with areas ranging from 42 to 5959 km², by comparing the results before and after their implementation. Annual water balance analysis showed an increase in evapotranspiration about 61% for basins, approaching the total annual evapotranspiration estimated by empirical methods. Hence, it was observed that surface runoff and base flow components showed a decrease. The modifications resulted in improved flow simulation for all basins, showing better Nash-Sutcliffe Efficiency Coefficient (NSE) values compared to the unchanged simulation. Calibration and validation processes used the modified simulation database, being achieved monthly NSE between 0.71 &#8211; 0.73 at calibration and 0.53 &#8211; 0.88 at validation, while daily NSE were 0.51 &#8211; 0.82 at calibration and 0.38 &#8211; 0.83 at validation. Overall, minimizing distortions in hydrological processes at pre-calibration step resulted in good estimations without excessive modification of parameters at calibration, attesting a consistent hydrological modeling for the basins analyzed.