Water balance estimation under the challenge of data scarcity in a hyperarid to Mediterranean region |
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Authors: | Agnes Sachse Christian Fischer Jonathan B Laronne Hanna Hennig Amer Marei Olaf Kolditz Tino Rödiger |
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Institution: | 1. Department of Environmental Informatics, Helmholtz Centre for Environmental Research—UFZ, Leipzig, Germany;2. Lehrstuhl für Geoinformatik, Friedrich‐Schiller Universit?t, Jena, Germany;3. Department of Geography and Environmental Development, Ben‐Gurion University of the Negev, Beersheba, Israel;4. Department of Catchment Hydrology, Helmholtz Centre for Environmental Research—UFZ, Halle (Saale), Germany;5. Department of Earth and Environmental Sciences, Al Quds University, Jerusalem, Palestine, Israel;6. Applied Environmental System Analyses, TU Dresden, Dresden, Germany |
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Abstract: | Water budget analyses are important for the evaluation of the water resources in semiarid and arid regions. The lack of observed data is the major obstacle for hydrological modelling in arid regions. The aim of this study is the analysis and calculation of the natural water resources of the Western Dead Sea subsurface catchment, one which is highly sensitive to rainfall resulting in highly variable temporal and spatial groundwater recharge. We focus on the subsurface catchment and subsequently apply the findings to a large‐scale groundwater flow model to estimate the groundwater discharge to the Dead Sea. We apply a semidistributed hydrological model (J2000g), originally developed for the Mediterranean, to the hyperarid region of the Western Dead Sea catchment, where runoff data and meteorological records are sparsely available. The challenge is to simulate the water budget, where the localized nature of extreme rainstorms together with sparse runoff data results in few observed runoff and recharge events. To overcome the scarcity of climate input data, we enhance the database with mean monthly rainfall data. The rainfall data of 2 satellites are shown to be unsuitable to fill the missing rainfall data due to underrepresentation of the steep hydrological gradient and temporal resolution. Hydrological models need to be calibrated against measured values; hence, the absence of adequate data can be problematic. Therefore, our calibration approach is based on a nested strategy of diverse observations. We calculate a direct surface runoff of the Western Dead Sea surface area (1,801 km2) of 3.4 mm/a and an average recharge (36.7 mm/a) for the 3,816 km2 subsurface drainage basin of the Cretaceous aquifer system. |
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Keywords: | data scarcity Dead Sea hydrological model J2000g water balance |
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