Abstract
The purpose of this paper is to estimate the water balance in a semi-arid environment with limited in situ data using a remote sensing approach. We focus on the Lake Manyara catchment, located within the East African Rift of northern Tanzania. We use a distributed conceptual hydrological model driven by remote sensing data to study the spatial and temporal variability of water balance parameters within the catchment. Satellite gravimetry GRACE data is used to verify the trends of the inferred lake level changes. The results show that the lake undergoes high spatial and temporal variations, characteristic of a semi-arid climate with high evaporation and low rainfall. We observe that the Lake Manyara water balance and GRACE equivalent water depth show comparable trends; a decrease after 2002 followed by a sharp increase in 2006–2007. Our modeling confirms the importance of the 2006–2007 Indian Ocean Dipole fluctuation in replenishing the groundwater reservoirs of East Africa. We thus demonstrate that water balance modeling can be performed successfully using remote sensing data even in complex climatic settings. Despite the small size of Lake Manyara, GRACE data showed great potential for hydrological research on smaller un-gauged lakes and catchments in similar semi-arid environments worldwide. The water balance information can be used for further analysis of lake variations in relation to soil erosion, climate and land cover/land use change as well as different lake management and conservation scenarios.
Highlights
We investigate the water balance for a lake and its catchment, located in a semi-arid hydrological setting using a hydrological model driven by remote sensing data
0.05 to 1 degree with the following objectives: (a) to quantify the water balance components in the lake and the overall basin; (b) to test the applicability of the J2000g hydrological model in a data poor semi-arid lake basin; and to (c) test the usability of gravimetry recovery and climate experiment (GRACE) satellite gravimetry total water storage (TWS) data on small un-gauged lake catchment basins and minor lakes that are not included in the global satellite altimetry mission network
We examined the applicability of the J2000g hydrological model in a data poor semi-arid lake basin
Summary
We investigate the water balance for a lake and its catchment, located in a semi-arid hydrological setting using a hydrological model driven by remote sensing data. Quantifying the hydrological budget in arid and semi-arid regions is important as the scarcity of water and climatic variability lead to conflicts related to water use [1,2]. Water resources in semi-arid regions have received slight consideration principally due to their complexity and a lack of in situ data [3]. The hydrological dynamics of a semi-arid catchment basin as expressed by both direct and base flow is affected by a number of factors including the spatial variation of topography, soils, vegetation, land use, river topography, structural geology and the spatial temporal variation of climate [4]. In many semi-arid regions of the world surface reservoirs provide the major source of water [2]
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