Estimation of Seepage Loss from Nasser Lake to the Adjacent Nubian Sandstone Aquifer, Southern Egypt

There is considerable amount of Nasser Lake seeps to adjacent Nubian aquifer, therefore water loss from this huge fresh water reservoir became a critical national problem considering the current water shortage throughout the area. During the present study, total values of seepage from the lake to adjacent Nubian Sandstone aquifer, fossil groundwater reservoir, was calculated from 1965 up till 2014 (50 years). This work reveals that average value of water seeps to Nubian sandstone aquifer is 47.46106 m3/year. Maximum value of loss was estimated in 1976 as 68.48106 m3, when the lake storage was 108.4109 m3 and the flow to the lake from the Nile was 81.5109 m3. Minimum loss from the lake estimated as 26.44106 m3 in 1987, when the storage in the lake was 47.26109 m3 and the income water was 48.8109 m3. The results reveal that seepage loss from Nasser Lake is strongly affected by temporal changes in lake recharge, by the geology of the area and on extent to which the lake stages are above or below the level of the adjoining land. It was observed from the fluctuation of groundwater levels to the rise and drop of the lake levels that the degree to which the lake contributes water to the Nubian sandstone aquifer varies greatly from place to place along its eastern and western shorelines. The general trend in water seepage from Nasser Lake, over a 50-year period, shows continuous decrease relative to the first 10 years of the lake filling.