DEVELOPMENT OF A HYDROLOGIC MODEL TO IMPROVE ESTIMATES OF RECHARGE AND RUNOFF USING REMOTE SENSING DATASETS

Research on the regional and local hydrology of many of the world's arid lands is hindered by the general paucity of data and the inadequate coverage or absence of monitoring systems. In these areas, the limited fresh water resources and the rising demands due to increasing population is leading to political, economical, and social instabilities. We present an integrated methodology to identify alternative renewable water resources; the advocated methodology heavily relies on satellite-based global data sets that are readily available world-wide. We adopt a catchment-based continuously distributed hydrologic model to quantify the spatial and temporal distribution of surface runoff and potential groundwater recharge. The model includes two modules: (1) automated data processing module, and (2) catchment-based distributed surface runoff module. The data processing module extracts precipitation, air temperature, surface temperature, soil moisture, solar radiation, and normalized vegetation difference index (NDVI) values from a suite of satellite data (TRMM, SSM/I, AVHRR, METEOSAT). This is enabled through a series of operations including assimilation, compilation, calibration, georeferencing, stacking, geographical sub-setting, and threshold filtering. The surface runoff module provides a continuous simulation of the overland flow, channel flow, transmission loss, evaporation on bare soils and evapo-transpiration (ET) on vegetated canopy, and potential recharge to shallow groundwater system. The developed procedures were applied to the Eastern Desert of Egypt (220,000 km2), an area where adequate hydrologic monitoring systems are absent. The following series of datasets were generated as inputs to our model: 1) 3-hourly precipitation data (1998-2005 – TRMM), (2) 4-hourly precipitation (1987-2005 – SSM/I), (3) NDVI Maps (1987-2005 – AVHRR), (4) Soil Moisture, (5) Land Surface Temperature Maps (1987-2005 – AVHRR), and (6) Lithologic Maps. The model automatically integrates these datasets to provide temporal and spatial estimates for runoff and recharge in the investigated basins (~ 6000) of the Eastern Desert. Similar applications for understanding the hydrology and dynamics of water systems in arid regions and water availability in these areas are clear.