Water is the main component of the integrated and sustainable development, the expansion in various fields is linked to the ability of countries to provide the water needed for this expansion. In recent years Water supply issues are creating unprecedented pressures because of increasing population and economic demands. As irrigated agriculture represents 70 % of global water consumption, managing water resources is a major concern in maintaining sustainable agricultural practices. The economics of water use and its long-term future requires the search for alternatives and determine the amount of available water resources at the present time. Egypt and countries that share the Nile Basin show interest in studying how to determine manage and develop water resources. Accurate information on the water balance components of lakes and reservoirs is deemed necessary for managing demand. Satellite data are found very useful in natural resource monitoring and management, since it provides a wide spatial extent and temporal coverage. Unlike traditional field survey, mapping using remote sensing is not constrained by rough inaccessible terrains or geopolitical boundaries and it provides access to extensive historical data archives for retrospective studies. Also In-situ hydrological measurements of reservoirs are usually not publically available. Remote Sensing is up to date, cost effective, non-destructive and timely. In this paper, Water balance equation and its components illustrated and focused on how open-access Satellite Remote Sensing measurements data can be used replacing field measurements. Then an assessment of TRMM (Tropical Rainfall Measuring Mission) data with respect to rain gauge data within Lake Tana in the period from 2000 to 2002 and the result have a good performance with RMSEr about 25 mm within period of high precipitation about 500 mm in August and finally Satellite Radar Altimetry data were validated by directly comparing the Satellite Radar Altimetry data -based water levels with the in-situ water levels from gauge measurements over Lake Nasser made by Nile Research Institute of the Ministry of Water Resources and Irrigation (NRI) over three different years 1993-2000-2009 period, RMSEr equal to 0.99 m, 0.88 m and 0.46 m, respectively. |
