Deducing the digital evaporation loss model of high dam reservoir

Abstract

Evaporation is the most negative phenomenon, causing huge losses in the water capacities of reservoirs. For example, evaporation at the High Dam (HD) reservoir (the water resources bank of Egypt that supplies Egypt with about 97% of its freshwater needs) which is characterized by its large water surface area (about 6000 km2 at water level 178 A.M.S.L). This reservoir, due its geographical location, is exposed to a range of climatic factors which increase evaporation rate annually, and consequently, increase the total loss of its capacity (about 10 Billion m3 of the HD reservoir capacity is lost annually due to evaporation phenomenon). Many organizations rely on an evaporation chart that gives the value of evaporation loss according to some climate variables. With respect to the problem of malfunctions of some stations, or in case of lack of data for any reason, it is important to have a digital evaporation loss model that gives the missed evaporation loss in the High Dam reservoir directly, according to two factors; the given month and the average monthly water level. This paper will explain how to get benefit from the available data of hydro-meteorological stations distributed within the High Dam reservoir, to predict the digital evaporation loss surface using the GIS prediction and conversion tools.