IMPROVING REGIONAL ESTIMATION OF RENEWABLE WATER RESOURCES FOR SUSTAINABLE MANAGEMENT

Water shortages are major obstacles to sustainable development and poverty alleviation in arid and semiarid countries. To address a nation’s or a region’s water-related sustainability problems, one key element is characterizing and quantifying renewable water resources for better management. Because of limited access and monitoring systems, quantifying renewable water resources in arid and semiarid areas is a great challenge.

We developed an integrated approach to improve estimates of renewable water resources. The approach (1) applies spatial and temporal precipitation estimates from multi-satellite data, (2) extracts land use and land cover from remote sensing data, and (3) simulates all watersheds in the region by using a rainfall-runoff model based on interpretation of satellite data. We applied this integrated characterization method to the eastern desert of Egypt, a region where rain gauges and other monitoring systems are extremely sparse.

Several satellites, including TRMM, SSM/I, and geostationary IR satellites are currently used to estimate rainfall. NASA recently began producing a merged dataset from multiple satellites yeilding precipitation rate with a high temporal and spatial coverage. The TRMM products used include four data sets: (1) 3B40RT combined microwave; (2) 3B41RT, microwave calibrated to geo-IR; and (3) 3B42RT, merged microwave and geo-IR, (4) and the 3B42 multisensor estimates. We used these 1-hr or 3-hr precipitation rate estimates, produced with a 0.25 by 0.25 degree resolution, covering the entire eastern desert, to generate high-resolution precipitation patterns for the eastern desert for 2003 and 2004. These precipitation rates were validated by rainfall the few rain gauges located on the edges of the Eastern Desert.

The eastern desert of Egypt includes several large-scale watersheds. Spatial integration of remote sensing data (TM, MSS, MODIS) was used to identify land use and land cover (LCLU) and soil types for all watersheds. With improved spatial and temporal precipitation patterns as input, plus distributions of LCLU and soil types, we applied a rainfall-runoff model to determine temporal and spatial distributions for renewable water resources of meteoric origin in each watershed. This estimated overall water budget, based on renewable water resources, provides a quantitative basis for sustainable management.