<p>The old water system in Sala, formerly belonging to thesilver mine, is analysed with regard to dam safety focusing onthe hydrological aspects. The hydrological safety of the riskclass I dams in the area, built in the 16th century, is notconsidered adequate according to the Swedish guidelines fordesign flood determination. A review is made of internationalprinciples for design flood determination. The overview showsthat there is no common principle used internationally whendealing with design flood for dams. In some countries there isan ambition to implement risk assessment for evaluation ofhydrological safety. However, at present Australia is the onlycountry that has fully integrated risk assessment in theirdesign flood guidelines. A risk assessment of the water systemin Sala shows that neither increasing the spillway capacity norimplementing flood mitigation measures in the watershed haveany significant effect on dam safety in the area. Nothingindicates that watersheds with a high presence of mires, likein the Sala case, should be particularly well suited forimplementing flood mitigation in the watershed as a dam safetymeasure. In order to safely handle the design flood in Sala andavoid dam failure due to overtopping the flood needs to bediverted from the water system.</p><p><b>Key words:</b>dam safety; design flood; flood mitigation;hydrological; risk assessment</p>

A methodology is presented for forecasting the probabilistic response of salinity movement in an estuary to seasonal rainfall and freshwater inflows. The Gambia River basin in West Africa is used as a case study in the research. The rainy season is from approximately July to October. Highest flows occur in late September and early October. Agriculturalists are interested in a forecast of the minimum distance that occurs each year at the conclusion of the wet season between the mouth of the river and the 1 part per thousand (ppt) salinity level. They are also interested in the approximate date that the minimum distance will occur. The forecasting procedure uses two approaches. The first uses a multisite stochastic process to generate long-term synthetic records (100 to 200 years) of 10-day rainfall for two stations in the upper basin. A long-term record of 10-day average flow is then computed from multiple regression models that use the generated rainfall records and real-time initial flow data occurring on the forecast date as inputs. The flow series is then entered into a one-dimensional finite element salt intrusion model to compute the movement of the 1 ppt salinity level for each season. The minimum distances between the mouth of the river and the 1 ppt salinity front that occurred for each season in the long-term record are represented in a cumulative probability distribution curve. The curve is then used to assign probability values of the occurrence of the 1 ppt salinity level to various points along the river. In the second approach, instead of generating a rainfall series and computing flow from regression models, a long-term flow record was generated using a stochastic first-order Markov process. Probability curves were made for three forecast dates: mid- July, mid-August, and mid-September using both approaches. With the first approach, the initial conditions at the time of the forecast had a greater influence on the flow series than the second approach.

Extreme precipitation events that occurred between March 24 and March 26 of 2015 in the region of the Atacama Desert (26-29 degrees S) left around 30000 victims, being one of the biggest events over the past 50 years, with total a cost of reconstruction of about 1.5 billion dollars. The mudflows which increased during the flashflood inundated much of the city of Copiapo and Tierra Amarilla. This manuscript aims to model the mudflow of March 2015 in the Rio Copiapo, specifically in the towns of Copiapo and Tierra Amarilla. The modeling process is performed using the Rapid Mass Movement Simulation Model (RAMMS) that allows modeling the dynamics of the mudflow in two dimensions, only using the topographic features of the modeling domain. Calibration of the model was carried out successfully using data from inundation heights captured around the city after the 2015 event. A detailed analysis of the hydrometeorological event is carried out using satellite images obtained from Multi-satellite Precipitation Analysis (TMPA), and pluviometric and hydrographic data available in the Copiapo River basin. The simulation of the flood is reproduced with maps of inundation heights associated with two modeling scenarios. The maximum flood heights are ultimately used for developing risk maps at both sites. According to our results, the RAMMS model is an appropriate tool for modeling mudflow and mapping flood risk to improve hydrological risk management in arid and semiarid basins of Chile.

Delineating spatial patterns of precipitation isotopes (“isoscapes”) is important for studies including the hydrology of terrestrial systems, present and past interpretations of climate, and tracer-aided hydrological modelling, among others. However, the extent to which precipitation isoscapes can be predicted across Canada has not been fully articulated. This thesis combines isotopes in precipitation (δ18Oppt) observations from two regional and one global network to create long term and time series precipitation isoscapes for Canada and the northern United States. Multi-linear regressions of a small suite of geographic and climate variables generate the best performing long-term and seasonal models of δ18Oppt. These models are used to develop long term isoscapes for Canada, which capture the general spatial and seasonal trends in δ18Oppt, showing an improvement upon results from previous studies using global models. Building upon long-term δ18Oppt prediction, δ18Oppt observations alongside climatological and geographic predictors are used to create empirical time series prediction models. Five regionalization approaches are used to separate the study domain into isotope zones to explore the effect of spatial grouping on simulations. Generally, the models capture the timing and magnitude of intra-annual (seasonal) δ18Oppt cycles across the study domain while simulating moderate inter-annual variation; however often fail to capture the anomalies in observed δ18Oppt. Uncertainty in predictions is quantified spatially and temporally, and the Köppen-Geiger (Kpn) regionalization is selected as the preferred regionalization scheme for future applications due to adequate model performance and lack of border issues at regional boundaries. Finally, estimates of monthly δ18Oppt from Kpn models, long term annual averages, and daily REMOiso output are used to force an isotope-enabled hydrological model, isoWATFLOOD, in the Fort Simpson Basin, NWT, Canada. Results show streamflow simulations are not significantly impacted by choice of δ18Oppt input; however, oxygen-18 in streamflow and the internal apportionment of water (and model parameterizations) are impacted, particularly during large precipitation and snowmelt events. This work shows how isoWATFLOOD can be used in regions with limited δ18Oppt observations, and that the model can be of value in such regions. This study reinforces that a tracer-aided modelling approach works towards diagnosing issues surrounding model equifinality. / February 2017

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.

Philosophiae Doctor - PhD / Springs are an important natural resource in many rural spaces which, if utilised sustainably, can be an important source of livelihoods for rural communities. In Zimbabwe, the social aspects of springs and their waterscapes remain understudied. This includes an in-depth understanding of how communities have shaped their livelihoods around springs, the extent to which they have contributed to sustainable rural livelihoods, especially in water stressed parts of the country and the institutional framework shaping their access and utilisation. Using the sustainable livelihoods framework of analysis, the goal of this study was to investigate the role that springs and their resultant waterscapes have played in securing livelihoods for rural households in the Save Catchment of Zimbabwe. Methodologically, the research adopted the socio-hydrological approach which is a new and emerging discipline that aims at understanding the interactions and feedbacks between the human and natural processes that give rise to community water sustainability challenges. The socio-hydrological approach is informed by both the qualitative and quantitative research techniques of data collection and analysis. Two rural communities (Nyanyadzi and Maturure) of the Save Catchment were randomly selected for an in-depth study. The snowball sampling technique (non-probability) was utilised in the selection of the 100 participants for the questionnaire survey. Purposive sampling was used to select nine key informant interview participants. Secondary data collection was done through a systematic review of scholarly and policy literature. Qualitative data generated from primary and secondary sources were processed and analysed using qualitative techniques such as thematic ordering, systematisation and fine grain analysis. For quantitative data, descriptive statistics, such as frequencies, were used to summarise and analyse questionnaire data. Rural communities in the Save Catchment of Zimbabwe were observed to have developed livelihood strategies that were anchored on springs and their waterscapes. In the studied communities, springs were utilised for both commercial and subsistence purposes and livelihoods constructed around springs included; gardening, tourism, livestock production, brick kilning art and craft making. In the study, springs were also shown to be a very important component of sustainable rural livelihoods. However, most of them were perceived to be declining in both water quality and quantity, imposing complex livelihood conundrums for the rural communities and threatening the sustainability of livelihood strategies that they are supporting. Practices observed to be threatening the integrity of springs were encroachment of settlements, natural environmental changes, soil erosion and population pressure. Limited environmental awareness, poverty, poor implementation and enforcement of conservation laws has resulted in the adoption of practices that degraded springs. Institutions shaping spring utilisation were observed to be ineffective to a large extent due to lack of capacities and conflicting mandates but local traditional leadership and water committees were observed to have deeper community penetration and were the most effective in influencing access and effective management of springs and their related waterscapes.

Computerised integrated models from science contribute to better informed and holistic exante integrated assessments of multifaceted policies and technologies. This view has lead to considerable effort being devoted to developing integrated models to support decisionmaking under Integrated Water Resources Management (IWRM). Nevertheless, an appraisal of previous and ongoing efforts to develop such decision support systems shows that attempts to address the hydro-socio-economic effects on livelihoods have been deficient and fragmented. To date, no universal standard integration method or framework is in use. Existing integrated models application failures have pointed to the lack of stakeholder participation. In an endeavour to close this gap, this thesis focuses on an integrated model development with prediction capability, ICHSEA, developed in Avenues script language in ArcView 3.3, to take advantage of the mapping capability of ArcView. This model couples existing hydrology (SWAT), agronomy (PARCHED-THIRST) and socio-economic (OLYMPE) models to link livelihoods of resource-constrained smallholder farmers to water resources availability at catchment level in the semi-arid Olifants subbasin, South Africa. These three models were calibrated and validated using observed data and local stakeholder participation, prior to coupling in the integrated model. All the models performed well in representing the study conditions, as indicated by the statistical performance. The integrated model is generally applicable to any catchment. The study methodology was inspired by the need to enhance rural livelihoods and to close the gap of stakeholder involvement in building and applying integrated models to ensure acceptability and application in decision-making. Over 20 years, the predicted impacts of untied ridges and planting basins versus conventional rainfed tillage on surface runoff reduction were 14.3 % and 19.8 %, respectively, and about 41─46 % sediment yield reduction in the catchment. At 90 % confidence interval, family savings improved from US$ 4─US$ 270 under conventional rainfed to US$ 233─US$ 1 140 under supplemental irrigation. These results underscore the economic and environmental benefits that could be achieved by adopting the new crop management practices. A relationship between maize crop evapotranspiration and family savings under different crop management strategies was also derived for five farm typologies in the catchment.

Desequilíbrios ambientais provocados pela combinação de queimadas, desmatamentos e os fenômenos de ENSO (Oscilação Sul de El Nino) podem ser os responsáveis pelo aumento de períodos de seca na região Amazônica. Com o propósito de compreender as conseqüências que longos períodos de seca podem causar na Floresta Nacional de Tapajós, foi desenvolvido um modelo numérico que simula a dinâmica da água no solo e o Balanço Hídrico para um latossolo (Haplustox, na taxonomia Americana), muito comum na região Amazônica. As simulações foram realizadas para o período de 1999 a 2003, utilizando dados de precipitação, evapotranspiração, umidade do solo, curvas de retenção, propriedades físicas do solo coletadas no local de estudo. Este estudo integra o Projeto Seca-Floresta do grupo de pesquisa do LBA (Experimento de Grande Escala da Biosfera-Atmosfera na Amazônia) para o experimento de exclusão parcial da chuva no projeto na Floresta Nacional Tapajós no que diz respeito a componente de modelagem hidrológica. Os resultados mostraram que, mesmo com a diminuição da quantidade de água disponível para a Floresta, não houve mudanças significativas em relação ao balanço hídrico da floresta, mostrando que a floresta provavelmente se adaptou, para sobreviver a longos períodos de seca / Environmental instability caused by the combination of fire, deforestation and the ENSO phenomena (El Nino South Oscillation) can be the responsible for increases of dry periods in the Amazonian region. With the purpose of understanding the consequences that long dry periods can cause on the National Forest of Tapajós, a mathematical model that determines the water dynamics in soil and the hydrological balance was developed for a typical soil of the Amazonian region the Amazonianlatossol (Haplustox). The simulation were performed for the period from 1999 to 2003, using precipitation, evapotranspiration, soil moisture, retention curves and soil physical properties data obtained in the study area. The present study integrates the Dry-Forest Project of the LBA (Large Scale Biosphere-Atmosphere experiment in the Amazon) research group for the experiment of rainfall exclusion in the National Forest of Tapajos and concerns the hydrological modeling component of the project. The results showed that even with a decrease in the amount of water available to the Forest, significant changes in the hydrological balance of the forest did not occur, showing that the forest had probably adapted itself to survive to longer periods of drought

L'objet de la présente thèse est de caractériser, quantifier et modéliser les flux d'eau au sein de la Réserve Naturelle Nationale de la Tourbière des Dauges, située en Limousin (Massif Central, France) et qui inclue une tourbière acide de fond de vallon et son bassin versant. Un ensemble de techniques, incluant la description de coupes superficielles existantes, la réinterprétation de sondages géologiques profonds, la tomographie de résistivité électrique et une modélisation de la distribution spatiale des formations affleurantes, ont été utilisées pour caractériser la nature et la géométrie des formations d'altération du granite. Les dépôts alluviaux et tourbeux ont été caractérisés et cartographiés par sondage à la tarière et à la tige filetée, et leur conductivité hydraulique estimée par choc hydraulique. Les précipitations, les paramètres météorologiques nécessaires au calcul de l'évapotranspiration potentielle, les débits et niveaux dans les ruisseaux, et les niveaux piézométriques dans la tourbe et les formations minérales sous jacentes ont été mesurés en continu pendant trois ans. Le modèle hydrologique distribué à base physique MIKE SHE / MIKE 11 a été utilisé pour modéliser les écoulements et les niveaux piézométriques au sein de la tourbière et de son bassin versant avec un pas de temps quotidien et une résolution spatiale de IO m. Il est montré que les apports souterrains issus de la zone fissurée du granite et suintant au travers du dépôt tourbeux constituent une part quantitativement importante et fonctionnellement essentielle de la balance hydrique de la zone humide. La présence d'une nappe affleurante entraîne une évacuation rapide vers les cours d'eau des apports par ruissellement ou par précipitation directe du fait de la saturation des histosols. Toutefois, il est montré que le fonctionnement hydrologique à l'échelle locale peut s'éloigner de ce schéma général du fait d'une grande hétérogénéité du taux d'humification et de la conductivité hydraulique de la tourbe, de la présence de dépôts alluviaux très perméables sous ou au sein du dépôt tourbeux et de perturbations anthropiques passées. Une fois calibré, le modèle hydrologique, qui représente la zone fissurée du socle granitique comme un milieu poreux équivalent, donne des résultats satisfaisants à très bons selon les indicateurs de performance utilisés: il est capable de reproduire les débits dans les cours d'eau au niveau des quatre stations de jaugeage disponibles, et le niveau de la nappe dans la plupart des piézomètres installés. A l'échelle du bassin versant étudié, le niveau moyen de la nappe simulé par le modèle montre une très bonne concordance avec la distribution observée des végétations de zone humide, cartographiée de manière indépendante. Les analyses de sensibilité ont montré que la porosité efficace et la conductivité hydraulique horizontale de la zone fissurée du granite sont les paramètres auxquels les débits et les niveaux de nappe (y compris dans la tourbe) simulés par le modèle sont les plus sensibles, ce qui démontre l'importance d'une meilleure caractérisation des formations d'altération du granite dans tout le bassin versant pour la compréhension et la modélisation du fonctionnement hydrologique de ce type de zone humide. Le modèle a été utilisé pour simuler l'impact potentiel d'un changement d'occupation des sols au sein du bassin versant sur la balance hydrique et les niveaux de nappe dans la zone humide, ainsi que sur les débits dans les cours d'eau. Le modèle suggère que le remplacement des végétations conduirait à une réduction substantielle des apports de surface et souterrains à la tourbière et à un abaissement conséquent des niveaux de nappe dans les histosols en période estivale. / This thesis identifies, quantifies and models water fluxes within the Dauges National Nature Reserve, an acidic valley mire in the French Massif Central. A range of techniques were used to investigate the nature and geometry of granite weathering formations and of peat deposits. Rainfall, reference evapotranspiration, stream discharge, stream stage, groundwater table depths and piezometric heads were monitored over a three-year period. The distributed, physics-based hydrological model MIKE SHE / MIKE 11 was used to model water flow within the mire and its catchment. lt was shown that the mire is mostly fed by groundwater flowing within the densely fissured granite zone and upwelling through the peat deposits. Upwelling to the peat layer and see page to overland flow were highest along the mire boundaries. However hydrological functioning differs from this general conceptual model in some locations due to the high variability of the peat hydraulic characteristics, the presence of highly permeable alluvial deposits of past human interference including drainage. The equivalent porous medium approach used to mode groundwater flow within the fissured granite zone gave satisfactory results : the model was able to reproduce discharge at several locations within the high-relief catchment and groundwater table depth in most monitoring points. Sensitivity analyses showed that the specific yield and horizontal hydraulic conductivity of the fissured zone are the parameter to which simulated stream discharge and groundwater table depth, including in peat, are most sensitive. The model was forced with new vegetation pararneters to assess the potential impacts of changes in catchment land use on the mire hydrological conditions. Replacement of the broad leaf woodlands that currently cover most of the catchment with conifer plantations would lead to a substantial reduction in surface and groundwater intlows to the mire and to a substantial drop in summer groundwater table depths, particularly along the mire margins.

The Upper Niger Basins (UNB) and the Inner Niger Delta (IND) are integral parts of the Niger River Basin, which flows through 10 countries and constitutes the third longest river in Africa. Natural climate variability and human interventions are two major factors affecting the hydrological regime in the UNB and IND. This study focuses on the later factor, by assessing the hydrological impacts of key existing and planned manmade structures and irrigation schemes in the UNB: the Sélingué (existing dam in Mali), four variants of the Fomi/Moussako dam (planned in Guinea), and Office du Niger (irrigation scheme located in Mali). The Fomi /Moussako dam will be located in the headwaters of the UNB and therefore, is expected to alter the hydrological regime in large parts of the watershed. Expected impacts include a reduction of the flood peak which will adversely affect critical ecosystems in the IND, and higher flows directly downstream of the dams in the dry season to sustain irrigation. These higher flows will, however, be consumed by Office du Niger irrigation scheme, leading to possible severe water shortages downstream of the irrigation scheme and in the IND. This is likely to affect the Malian economy and the poorest parts of its population, as the IND is crucial for the socio-economic and ecological preservation and development of the population surrounding it. The hydrological impacts of the dams and the irrigation scheme were evaluated in this study by developing a model of the IND and UNB using SWAT (Soil and Water Assessment Tool). After the model was calibrated, the effects of the dams and the irrigation scheme on selected flow statistics (mean and standard deviation) were determined at fourteen hydrological stations. In general, the results have shown that (1) the Fomi/Moussako dam will noticeably reduce the downstream high flows, and reduce the average flow; (2) if the Fomi/Moussako dam was to be built, the alternatives with the least storage volume (Moussako 388.5') will have the least impacts on the downstream flows. To assist in related decision making for various users, a Decision Support System (DSS) was also developed. The goal of the DSS is to help users analyze the effects of dams and irrigation on the flow regime by performing a comparative analysis (presence and absence of dams and irrigation in the river). A number of potential adaptation measures were also proposed.