Academic literature on the topic 'HBV hydrological model'

Abstract. The most important climatological inputs required for the calibration and validation of hydrological models are temperature and precipitation that can be derived from observational records or alternatively from regional climate models (RCMs). In this paper, meteorological station observations and results of the PRECIS (Providing REgional Climate for Impact Studies) RCM driven by the outputs of reanalysis ERA 40 data and HadAM3P general circulation model (GCM) results are used as input in the hydrological model. The objective is to investigate the effect of precipitation and temperature simulated with the PRECIS RCM nested in these two data sets on discharge simulated with the HBV model for three river basins in the Hindukush-Karakorum-Himalaya (HKH) region. Six HBV model experiments are designed: HBV-Met, HBV-ERA and HBV-Had, HBV-MetCRU-corrected, HBV-ERABenchmark and HBV-HadBenchmark where HBV is driven by meteorological stations data, data from PRECIS nested in ERA-40 and HadAM3P, meteorological stations CRU corrected data, ERA-40 reanalysis and HadAM3P GCM data, respectively. Present day PRECIS simulations possess strong capacity to simulate spatial patterns of present day climate characteristics. However, also some quantitative biases exist in the HKH region, where PRECIS RCM simulations underestimate temperature and overestimate precipitation with respect to CRU observations. The calibration and validation results of the HBV model experiments show that the performance of HBV-Met is better than the HBV models driven by other data sources. However, using input data series from sources different from the data used in the model calibration shows that HBV-Had is more efficient than other models and HBV-Met has the least absolute relative error with respect to all other models. The uncertainties are higher in least efficient models (i.e. HBV-MetCRU-corrected and HBV-ERABenchmark) where the model parameters are also unrealistic. In terms of both robustness and uncertainty ranges the HBV models calibrated with PRECIS output performed better than other calibrated models except for HBV-Met which has shown a higher robustness. This suggests that in data sparse regions such as the HKH region data from regional climate models may be used as input in hydrological models for climate scenarios studies.

Abstract. This paper presents the hands-on modeling toolbox, HBV-Ensemble, designed as a complement to theoretical hydrology lectures, to teach hydrological processes and their uncertainties. The HBV-Ensemble can be used for in-class lab practices and homework assignments, and assessment of students' understanding of hydrological processes. Using this modeling toolbox, students can gain more insights into how hydrological processes (e.g., precipitation, snowmelt and snow accumulation, soil moisture, evapotranspiration and runoff generation) are interconnected. The educational toolbox includes a MATLAB Graphical User Interface (GUI) and an ensemble simulation scheme that can be used for teaching uncertainty analysis, parameter estimation, ensemble simulation and model sensitivity. HBV-Ensemble was administered in a class for both in-class instruction and a final project, and students submitted their feedback about the toolbox. The results indicate that this educational software had a positive impact on students understanding and knowledge of uncertainty in hydrological modeling.

Abstract. This paper presents a hands-on modeling toolbox, HBV-Ensemble, designed as a complement to theoretical hydrology lectures, to teach hydrological processes and their uncertainties. The HBV-Ensemble can be used for in-class lab practices and homework assignments, and assessment of students' understanding of hydrological processes. Using this model, students can gain more insights into how hydrological processes (e.g., precipitation, snowmelt and snow accumulation, soil moisture, evapotranspiration and runoff generation) are interconnected. The model includes a MATLAB Graphical User Interface (GUI) and an ensemble simulation scheme that can be used for not only hydrological processes, but also for teaching uncertainty analysis, parameter estimation, ensemble simulation and model sensitivity.

Applying hydrological models for river basin management depends on the availability of the relevant data information to constrain the model residuals. The estimation of reliable parameter values for parameterized models is not guaranteed. Identification of influential model parameters controlling the model response variations either by main or interaction effects is therefore critical for minimizing model parametric dimensions and limiting prediction uncertainty. In this study, the Sobol variance-based sensitivity analysis method was applied to quantify the importance of the HBV conceptual hydrological model parameterization. The analysis was also supplemented by the generalized sensitivity analysis method to assess relative model parameter sensitivities in cases of negative Sobol sensitivity index computations. The study was applied to simulate runoff responses at twelve catchments varying in size. The result showed that varying up to a minimum of four to six influential model parameters for high flow conditions, and up to a minimum of six influential model parameters for low flow conditions can sufficiently capture the catchments' responses characteristics. To the contrary, varying more than nine out of 15 model parameters will not make substantial model performance changes on any of the case studies.

Abstract. The most important climatological inputs required for the calibration and validation of hydrological models are temperature and precipitation that can be derived from observational records or alternatively from regional climate models (RCMs). In this paper, meteorological station observations and results of the PRECIS (Providing REgional Climate for Impact Studies) RCM driven by the outputs of reanalysis ERA-40 data and HadAM3P general circulation model (GCM) results are used as input in the hydrological model. The objective is to investigate the effect of precipitation and temperature simulated with the PRECIS RCM nested in these two data sets on discharge simulated with the HBV model for three river basins in the Hindukush-Karakorum-Himalaya (HKH) region. Three HBV model experiments are designed: HBV-Met, HBV-ERA and HBV-Had where HBV is driven by meteorological station data and by the outputs from PRECIS nested with ERA-40 and HadAM3P data, respectively. Present day PRECIS simulations possess strong capacity to simulate spatial patterns of present day climate characteristics. However, there also exist some quantitative biases in the HKH region, where PRECIS RCM simulations underestimate temperature and overestimate precipitation with respect to CRU observations. The calibration and validation results of the HBV model experiments show that the performance of HBV-Met is better than the HBV models driven by the PRECIS outputs. However, using input data series from sources different from the data used in the model calibration shows that HBV models driven by the PRECIS outputs are more robust compared to HBV-Met. The Gilgit and Astore river basin, which discharges are depending on the preceding winter precipitation, have higher uncertainties compared to the Hunza river basin which discharge is driven by the energy inputs. The smaller uncertainties in the Hunza river basin may be because of the stable behavior of the input temperature series compared to the precipitation series. The resulting robustness and uncertainty ranges of the HBV models suggest that in data sparse regions such as the HKH region data from regional climate models may be used as input in hydrological models for climate scenarios studies.

The study of climate change on hydrological response is a crucial as climate change impact will drive the change in hydrological regimes of river. Upper Ciliwung watershed is one of the critical rivers in Java Island, which has been affected by climate change. This study aims to: (i) simulate the discharge flow using the Hydrologiska Byrans Vattenbalansavdelning (HBV) model; (ii) simulate future flow using three general circulation models (GCM) namely Commonwealth Scientific and Industrial Research Organisation (CSIRO) Mk.3.6.0, Model for Interdisciplinary Research on Climate version 5 (MIROC5), and Geophysical Fluid Dynamics Laboratory-Coupled Model generation 3 (GFDL-CM3); (iii) determine the changes of extreme hydrological index during historical period (2001-2015) and projected period (2031-2045). The historical year simulation and projections are used to determine eight hydrologic extreme indices for high flow and low flow. We calibrated the HBV model for two years (2001-2002) and validated it for two years (2003-2004). Our model performed well in discharge simulation as shown by the NSE values (0.66 for calibration and validation). Then we calculated the indices for each period used (historical and projected). To show the changes in hydrological regimes, we compare the indices between two periods. Changes in the index of the two periods tend to decrease in value on the index parameters that characterize the minimum extreme events. Hence, that it is possible in the projected period there will be extreme hydrological events in the form of drought.

Ungauged basins are challenges for hydrological study, the key discipline to analyse for planning and the operation of water resources projects. Several river basins have no hydrologic measurements where there is feasibility of promising water resources schemes. This study deals with use of the Hydrologiska Byråns avdeling for Vattenbalans (HBV) hydrological model to generate stream flow time series and other hydrological variables. The model was calibrated successfully in the Sanghutar catchment of the Likhu River of Nepal, and then used to simulate runoff series at the proposed intake site of Likhu HEP, where the gauging station has not been installed. The model can be used to generate runoff of other ungauged catchments which have similar catchment characteristics.DOI: http://dx.doi.org/10.3126/hn.v8i0.4910 Hydro Nepal: Journal of Water, Energy and Environment Issue No. 8, 2011 JanuaryPage: 38-43Uploaded date: 17 June, 2011

Depending on the purpose of the study, aggregated hydrological models are preferred over distributed models because they provide acceptable results in terms of precision and are easy to run, especially in data scarcity scenarios. To obtain acceptable results in terms of hydrological process representativeness, it is necessary to understand and assess the models. In this study, the relative importance of the parameters of the Hydrologiska Byråns Vattenbalansavdelning (HBV) model is analyzed using sensitivity analysis to detect if the simulated processes represent the predominant hydrological processes at watershed scale. As a case study, four watersheds with different hydrological regimes (glacial and pluvial) and therefore different dominant processes are analyzed. The results show that in the case of the rivers with a glacial regime, the model performance depends highly on the snow module parameters, while in the case of the rivers with a pluvial regime, the model is sensitive to the soil and evapotranspiration modules. The results are directly related to the hydrological regime, which indicates that the HBV model, complemented by sensitivity analysis, is capable of both detecting and representing hydrological processes at watershed scale.

Hydrological models are widely used tools to solve a broad range of hydrological issues. Each model has its own structure defining inter-relationships of hydrological balance components, and comparative differences in the models’ inner structure must be taken into account when discrepancies result from the same data. Results of base flow simulation by three different models BILAN, FRIER and HBV-light were compared based on knowledge of the models’ internal structure. It was proven that the courses of modelled parameters are quite similar, but that the respective values differ. The highest base flow values were simulated by the BILAN model, due to the threshold value of the soil moisture storage incorporated within this model’s structure. The lowest values were obtained by HBV-light model. Simulated base flow values were compared with groundwater heads and minimum monthly discharges. This comparison showed that the base flow values in the Nitra catchment at Nedožery profile simulated by BILAN and FRIER models are closer to the reality than those, simulated by HBV-light model.

The aim of this thesis was to test and evaluate whether parameter regionalization of a hydrological model can be used to model the impact of forest clearcutting on streamflow in Sweden. This is an important task to be able to perform water management and impact assessments adequately. The HBV conceptual rainfall-runoff model was applied for 218 Swedish catchments of different sizes that were spread across the country and covered a wide range of different forest cover percentages. The modelling approach included calibration of the model for each catchment using a genetic algorithm and then associating the resulting optimal parameter values with the percentage of forest cover. The obtained relationship between different model parameters and forest cover was validated with help of a paired catchment study site in northern Sweden where a clear cut was done in 2006: calibrated optimal parameter sets of pre- and post-clearcutting conditions were compared to parameter sets obtained from the Sweden-wide analysis. Correlations were found for about half of the fifteen hydrological model parameters, but the validation with the paired catchment study site could only partially confirm these obtained relationships. The results suggest that the adopted parameter regionalization approach is too basic. However, some of the results seem promising and emphasize the need for further research and development of the approach to provide a more reasonable method to model the impact of forest clearcutting on streamflow.
Det huvudsakliga målet med detta examensarbete var att testa och utvärdera om parameterregionalisering av en hydrologisk modell kan vara en lämplig metod för att modellera och kvantifiera påverkan från skogsavverkning på vattenbalansen i Sverige. Detta är en viktig uppgift för att kunna hantera våra vattenresurser och utföra konsekvensanalyser på ett tillfredsställande sätt. En konceptuell hydrologisk modell tillämpades på 218 avrinningsområden av olika storlekar och som var geografiskt utspridda i hela Sverige där även andelen skog i avrinningsområdena hade ett brett spektrum. Den använda modelleringsmetoden innefattade kalibrering av varje avrinningsområde genom att använda en genetisk algoritm, varefter de optimala parametervärdeana korrelerades mot andelen skog i avrinningsområdet. Idén med denna metod är att använda dessa potentiella samband för att justera modellparametrarna och därmed simulera en skogsavverkning. De erhållna sambanden mellan modellparametrarna och skogstäcket validerades med hjälp av data från en försöksstudie i norra Sverige där en skogsavverkning gjordes under 2006. Skillnaden mellan de bäst fungerande parametervärdena före och efter skogsavverkningen jämfördes med de tidigare sambanden från andra avrinningsområden i Sverige. Signifikant korrelation hittades för ungefär hälften av de 15 hydrologiska modellparametrarna, men valideringen mot den riktiga skogsavverkningen kunde bara delvis bekräfta de erhållna sambanden. Resultaten visar att detta sätt att använda parameterregionalisering antagligen är för grundläggande. Vissa resultat är ändå lovande och fortsatt forskning och utvidgning av metoden är nödvändig för att kunna tillhandahålla en rimlig metod för att kvantifiera en skogsavverknings effekter på vattenbalansen.

Snowmelt runoff in the mountainous eastern part of Turkey is of great importance as it constitutes 60-70% in volume of the total yearly runoff during spring and early summer months. Therefore, forecasting the amount and timing of snowmelt runoff especially in the Euphrates Basin, where large dams are located, is an important task in order to use the water resources of the country in an optimum manner. The HBV model, being one of the well-known conceptual hydrological models used more than 45 countries over the world, is applied for the first time in Turkey to a small basin of 242 km2 on the headwaters of Euphrates River for 2002-2004 water years. The input data are provided from the automatic snow-meteorological stations installed at various locations and altitudes in Upper Euphrates Basin operating in real-time. Since ground based observations can only represent a small part of the region of interest, spatially and temporally distributed snow cover data are acquired through the use of MODIS optical satellite. Automatic model parameter estimation methods, GML and SCE_UA, are utilized to calibrate the HBV model parameters with a multi-objective criteria using runoff as well as snow covered area to ensure the internal validity of the model and to generate a Pareto front. Model simulations show that the choice of study years and timing of satellite images affect the results and further suggest that more study catchments and years should be included to achieve more comprehensible conclusions. In the second part of the study, the calibrated HBV model is applied to forecast runoff with a 1-day lead time using gridded input data from numerical weather prediction models of ECMWF and MM5 for the 2004 snowmelt period. Promising results indicate the possible operational use of runoff forecasting using numerical weather prediction models in order to prevent or at least take precautions before flooding ahead of time.

I denna rapport undersöks hur mängden organiskt kol, TOC (Totalt organiskt kol), varierar i tid och rum i Mälarens avrinningsområde, samt vad det är som styr TOC-halten i Mälaren. Det är viktigt att förstå dynamiken hos TOC i Mälaren och i dess avrinningsområde eftersom ökat TOC i vattnet påverkar vattenkvaliteten och orsakar problem vid beredning av dricksvatten. TOC kan bland annat reagera med klor/UV-ljus och bilda cancerframkallande ämnen. Det kan också öka antal mikrober i vattnets distributionssystem. Arbetet omfattar analys av samband mellan elementen, transportberäkningar per ytenhet av elementen till Mälaren och en modelleringsansats för ett av avrinningsområdena. Rapporten innehåller även en jämförelse mellan de olika vattenföringsmodellerna samt uppmätt vattenföring för analys av eventuella systematiska skillnader mellan dessa som påverkar beräkningen av TOC och de andra elementens transport till Mälaren. Analysen av sambanden mellan variablerna TOC (mg/l), kaliumpermanganat förbrukning (KMnO4, mg/l), absorbans_F (F=filtrerad), järn (mg/l), mangan (mg/l) och SO4_IC (sulfat mätt med hjälp av jonkromatografi, mg/l), visade att vissa av dessa variabler är korrelerade med varandra. TOC mot KMnO4 och TOC mot absorbans_F hade de bästa anpassningarna med respektive R2- värden 0,65 och 0,59 och p-värden <0,001. Årsnederbörd är positivt korrelerad med TOC per ytenhet för Kolbäcksån med R2-värde 0,63 och p-värde <0,01, vilket innebär att sambandet är signifikant. Ökad årsnederbörd leder till ökad tillförsel av TOC till Mälaren. Det finns däremot inget signifikant samband mellan TOC-transport per ytenhet och årsmedeltemperatur. Arealflödesberäkningar tyder på att den största tillförseln av TOC- transport per ytenhet kommer från den nordöstra delen av Mälaren. Fyrisån står för den största tillförseln av TOC. Hydrologiska, kemiska och meteorologiska data inkluderades i modeller för att kunna skatta TOC-halten i Mälaren. Temperatur-, evapotranspirations- och nederbördsdata användes i en hydrologisk modell, HBV- modellen, för att simulera vattenföringen från avrinningsområdet. Sedan användes en processbaserad modell, INCA- C, som drivs av hydrologisk data och beräknade grundvattenbildning och markfuktighet för att simulera tidsmässiga mönster i TOC. Invariablerna till INCA-modellen, markfuktigheten och HER (grundvattenbildning), simulerades med hjälp av HBV- modellen. Dessa modeller tillämpades i Kolbäcksån (ett av Mälarens största avrinningsområden). Modelleringen av Kolbäcksåns TOC- halt resulterade i en modell som anpassade dynamiken mellan 1996 och 2009, men missar den mellan 2009 och juni 2010, med bäst anpassning mellan 2006 och 2008. R2- och NS värden som erhölls för modellen var 0,086 och -0,059.
In this report, it has been investigated how the amount of organic carbon, TOC, varies in time and space in the basin of Mälaren, and what controls the TOC content in the lake. It is important to understand the dynamics of the TOC in the lake and its catchment because increased TOC in the water affects water quality and causes problems in the preparation of drinking water. Particularly, it can react with chlorine / UV- light and form carcinogenic substances. It can also increase the number of microbes in water distribution systems. In addition the work includes analysis of the relation between water chemistry variables, annual fluxes calculations (g/m2/year) of element flows to the lake and a modeling approach to a watershed. Annual fluxes calculations (g/m2/year) indicate that the largest supply of TOC to the lake comes from the northeast of the lake. Fyrisån accounts for the largest input of TOC to the lake. The high TOC-flux is due to a small proportion of open water in the catchment. Hydrological, chemical and meteorological data have been included in models to estimate the TOC content in the Mälaren. Input data processing, especially precipitation data, has been an important part of the work as it affects the whole model. Temperature, evapotranspiration and precipitation data were used in a hydrological model, HBV model, to simulate the flow from the catchment area. Then a process-based model, INCA-C, operated by the hydrological data and soil moisture, has been used to simulate the temporal patterns in TOC. The input variables to INCA-C- model, soil moisture and HER (Hydrological effective rainfall), have been simulated using the HBV- model. Those models were applied in Kolbäcksån, one of the lake's largest catchments. The modeling of Kolbäcksån resulted in a model that captured the dynamics of a few periods of the whole time series. The modeling of Kolbäcksån TOC-concentration resulted in a model that captured the dynamics between 1996 and 2009, but misses it between 2009 and June 2010. R2 and NS values obtained for the model were 0.086 and -0.059, respectively.

Water infrastructures have been implemented to support the vital activities of human society. The infrastructure developments at the same time have interrupted the natural catchment response characteristics, challenging society to implement effective water resources planning and management strategies. The Telemark area in southern Norway has seen a large number of water infrastructure developments, particularly hydropower, over more than a century. Recent developments in decision support tools for flood control and reservoir operation has raised the need to compute inflows from local catchments, most of which are regulated or have no observed data. This has contributed for the motivation of this PhD thesis work, with an aim of improving runoff estimation at ungauged catchments, and the research results are presented in four manuscript scientific papers.  The inverse distance weighting, inverse distance squared weighting, ordinary kriging, universal kriging and kriging with external drift were applied to analyse precipitation variability and estimate daily precipitation in the study area. The geostatistical based univariate and multivariate map-correlation concepts were applied to analyse and physically understand regional hydrological response patterns. The Sobol variance based sensitivity analysis (VBSA) method was used to investigate the HBV hydrological model parameterization significances on the model response variations and evaluate the model’s reliability as a prediction tool. The HBV hydrological model space transferability into ungauged catchments was also studied.  The analyses results showed that the inverse distance weighting variants are the preferred spatial data interpolation methods in areas where relatively dense precipitation station network can be found.  In mountainous areas and in areas where the precipitation station network is relatively sparse, the kriging variants are the preferred methods. The regional hydrological response correlation analyses suggested that geographic proximity alone cannot explain the entire hydrological response correlations in the study area. Besides, when the multivariate map-correlation analysis was applied, two distinct regional hydrological response patterns - the radial and elliptical-types were identified. The presence of these hydrological response patterns influenced the location of the best-correlated reference streamgauges to the ungauged catchments. As a result, the nearest streamgauge was found the best-correlated in areas where the radial-type hydrological response pattern is the dominant. In area where the elliptical-type hydrological response pattern is the dominant, the nearest reference streamgauge was not necessarily the best-correlated. The VBSA verified that varying up to a minimum of four to six influential HBV model parameters can sufficiently simulate the catchments' responses characteristics when emphasis is given to fit the high flows. Varying up to a minimum of six influential model parameters is necessary to sufficiently simulate the catchments’ responses and maintain the model performance when emphasis is given to fit the low flows. However, varying more than nine out of the fifteen HBV model parameters will not make any significant change on the model performance.  The hydrological model space transfer study indicated that estimation of representative runoff at ungauged catchments cannot be guaranteed by transferring model parameter sets from a single donor catchment. On the other hand, applying the ensemble based model space transferring approach and utilizing model parameter sets from multiple donor catchments improved the model performance at the ungauged catchments. The result also suggested that high model performance can be achieved by integrating model parameter sets from two to six donor catchments. Objectively minimizing the HBV model parametric dimensionality and only sampling the sensitive model parameters, maintained the model performance and limited the model prediction uncertainty.

Cette étude porte principalement sur l’évaluation d’estimations de précipitations par satellite à haute résolution pour l’hydrologie du bassin central de lacs de la vallée du Rift en Éthiopie. La première partie est consacrée à la correction du biais de pluie par satellite pour la simulation du débit et du bilan hydrique au niveau des lacs. Ensuite, l'impact du captage d'eau et d'autres facteurs sur le bilan hydrique du lac, en particulier sur le niveau et la variation du volume de l'eau, sera étudié. Enfin, l’étude quantifiera les demandes actuelles et futures et évaluera ainsi l’impact de différents scénarios de développement des ressources en eau sur le bilan hydrique du lac. Dans cette étude, nous avons évalué la performance et la correction de biais du satellite CHIRP (Satellite Hazards Group) pour la simulation pluie-ruissellement. Nous avons également évalué les effets des paramètres et des performances du modèle calibrés à la suite de différentes entrées de précipitations. Nous avons appliqué une méthode de puissance non linéaire pour corriger le biais de la CHIRP dans la simulation du débit des bassins versants de Meki et Katar à l'aide du modèle Hydrologiska Byråns Vattenbalansavdelning (HBV). Ensuite, un ensemble de données de précipitations corrigées de biais a été simulé dans une modélisation pluie-ruissellement, où l'écoulement simulé a été utilisé pour la simulation du niveau d'eau du lac Ziway dans le modèle de bilan hydrique du lac. Ensuite, nous avons mené une enquête sur les prélèvements d'eau (WAS) afin d'estimer les prélèvements d'eau réels dans le lac et un modèle de bilan hydrologique pour évaluer l'impact isolé des prélèvements d'eau sur le volume et le niveau de l'eau du lac. L'impact probable de trois voies de développement sur le stockage du lac et le niveau de l'eau a été évalué. L'étude a également appliqué un modèle d'évaluation et de planification de l'eau (WEAP) pour évaluer la demande en eau existante et future afin d'évaluer l'impact du développement des ressources en eau sur le lac, sur le niveau et le volume de l'eau du lac. Dans les simulations, le bassin versant est divisé en différents sous-bassins principaux où les nœuds de l'offre et de la demande sont localisés dans l'espace et modélisés. Les secteurs de l’eau en concurrence sont le développement de l’irrigation, les utilisateurs domestiques et les besoins en matière de débits environnementaux identifiés pour l’abstraction. En conséquence, à partir des résultats de la simulation, le captage annuel moyen total du volume d’afflux et de la disponibilité en eau sera évalué en fonction de la couverture de la demande et de la fiabilité. Ainsi, l’étude identifiera les facteurs possibles d’attribution du bilan hydrique du lac et fournira des informations aux décideurs, aux planificateurs et aux utilisateurs d’eau pour une meilleure gestion des prélèvements d’eau du lac
Des changements importants ont été observés dans le bilan hydrique du bassin des lacs de la vallée centrale du Rift (CRV) en Éthiopie au cours des dernières décennies, ce qui entrave leurs services pour une grande variété d'écosystèmes. Cependant, les contributions des composantes du bilan hydrique n'ont pas encore été quantifiées en raison du manque de disponibilité continue des données et de réseaux de pluviomètres suffisants. Dans cette étude, nous avons utilisé l'estimation des précipitations par satellite du groupe Climate Hazards Group InfraRed Precipitation (CHIRP) en utilisant la modélisation des précipitations et du ruissellement où le ruissellement simulé a servi d'entrée à la simulation du niveau de l'eau. La thèse se compose de quatre étapes ultérieures. Les deux premiers se concentrent sur l'évaluation et la correction des biais des précipitations du satellite CHIRP pour simuler le débit et le niveau de l'eau du lac en utilisant le modèle Hydrologiska Byråns Vattenbalansavdelning (HBV). Le troisième se concentre sur la quantification du prélèvement d'eau réel et de son impact sur le bilan hydrique du lac à partir des données des relevés de captage d'eau. Dans la dernière étape, nous avons évalué la demande d'eau actuelle et future à l'aide du modèle d'évaluation et de planification de l'eau (WEAP) et évalué les impacts probables du développement des ressources en eau sur le niveau d'eau des lacs CRV. Les résultats montrent que CHIRP a des biais à différentes échelles spatiales et temporelles. Cependant, la correction du biais de l'estimation satellite a considérablement réduit le biais et a révélé de meilleures simulations de ruissellement. Le ruissellement simulé pour les bassins versants de jauge Meki et Katar a contribué respectivement à 855 mm et 524 mm à l'afflux du lac. Le ruissellement des bassins versants non jaugés est d'environ 182 mm, ce qui représente 8,5% de l'apport total du lac. La simulation du niveau d'eau du lac montre une bonne concordance de 1986 à 2000, mais une détérioration de la concordance après 2000, qui est principalement attribuée à une erreur dans l'un des termes du bilan hydrique et aux influences anthropiques. Dans l'ensemble, cette étude indique l'applicabilité de l'estimation des précipitations par satellite CHIRP pour les études du bilan hydrique des lacs dans la région où les données sont rares dans la vallée centrale du Rift en Éthiopie. L'estimation du prélèvement d'eau réel du lac Ziway a montré que chaque année 37 Mm3 d'eau sont prélevés pour l'état actuel. Lorsque les futurs plans de développement seront pleinement mis en œuvre, la quantité annuelle estimée de captage d'eau augmentera de 2,5 fois (soit 94 Mm3), ce qui entraînera une baisse du niveau d'eau du lac de 0,94 m et une réduction de la surface de 38 km2. Cela entraînera par conséquent une réduction de 26% du volume de stockage réel par rapport à l'état naturel de base. Les résultats de la simulation WEAP pour l'ensemble du bassin des lacs CRV ont révélé que pour le développement à long terme une moyenne de 223,02 Mm3 de demande en eau et 176,6 Mm3 d'eau détournée du lac et de ses affluents. Cela donnera une demande annuelle non satisfaite de 46,5 Mm3 dans le bassin central des lacs de la vallée du Rift. Il a également constaté que la plupart des programmes de développement des ressources en eau dans tous les bassins versants auront des demandes non satisfaites dans les scénarios à long terme plus élevés que dans le développement actuel. Cela a donc révélé une baisse annuelle moyenne du niveau de l'eau du lac de 2, 0,97 et 2,1 m pour le lac Ziway, Langano et Abiyata, respectivement. Par conséquent, cette étude indique que les impacts actuels du développement des ressources en eau autour du lac sont substantiellement importants et vont s'accentuer dans les futurs plans de développement. Par conséquent, l'étude suggère une gestion intégrée de l'eau du lac et de ses bassins versants

A changing climate can severely perturb regional hydrology and thereby affect human societies and life in general. To assess and simulate such potential hydrological climate change impacts, hydrological models require reliable meteorological variables for current and future climate conditions. Global climate models (GCMs) provide such information, but their spatial scale is too coarse for regional impact studies. Thus, GCM output needs to be downscaled to a finer scale either through statistical downscaling or through dynamic regional climate models (RCMs). However, even downscaled meteorological variables are often considerably biased and therefore not directly suitable for hydrological impact modeling. This doctoral thesis discusses biases and other challenges related to incorporating climate model output into hydrological studies and evaluates possible strategies to address them. An analysis of possible sources of uncertainty stressed the need for full ensembles approaches, which should become standard practice to obtain robust and meaningful hydrological projections under changing climate conditions. Furthermore, it was shown that substantial biases in current RCM simulations exist and that correcting them is an essential prerequisite for any subsequent impact simulation. Bias correction algorithms considerably improved RCM output and subsequent streamflow simulations under current conditions. In addition, differential split-sample testing was highlighted as a powerful tool for evaluating the transferability of bias correction algorithms to changed conditions. Finally, meaningful projections of future streamflow regimes could be realized by combining a full ensemble approach with bias correction of RCM output: Current flow regimes in Sweden with a snowmelt-driven spring flood in April will likely change to rather damped flow regimes that are dominated by large winter streamflows.

Представлены результаты использования данных полевых наблюдений для моделирования речного стока малого водосбора в верховьях р.Уссури. В качестве входного потока данных в гидрологическую модель HBV об эвапотранспирации применены оригинальные данные о стволовом сокодвижении, пересчитанные в объем влаги, транспирируемого древостоем. Показано, что расчетные методы определения эвапотранспирации (Пенмана-Монтейса и Л.Одина) завышают оценки испарения: разница с данными стволового сокодвижения достигает 100 мм слоя за теплый период. Надежной связи между расчетными значениями суточного испарения и измерениями не обнаружено. Выявлено повышение качества расчетов стока при использовании данных стволового сокодвижения в качестве входного потока в гидрологическую модель. The results of applying the field observation data for hydrological modeling in the Upper Ussuri river are presented. The original data of sap flow measurements (recalculated to the evapotranspiration volume of forest stand) was used as input to the HBV model. It is shown that the calculation methods for determining evapotranspiration (Penman-Monteith and L.Oudin) overestimate the daily evaporation volume. In comparison with sap flow data difference reach 100 mm during the warm period. No reliable relationship was found between the calculated values of daily evaporation and measurements. An increase in the quality of runoff calculations is reported while using data from stem sap flow as an input to a hydrological model.