Study of environmental isotope distribution in the Aswan High Dam Lake (Egypt) for estimation of evaporation of lake water and its recharge to adjacent groundwater

Abstract

Oxygen-18 ((18)0) and deuterium isotopes were used to estimate the evaporation from the Aswan High Dam Lake and to investigate the inter-relation between the lake water and adjacent groundwater.According to stable isotopic analysis of samples taken in 1988 and 1989, the lake can be divided into two sections. In the first section extending between Abu Simbel and a point between EI-Alaki and Krosko, a remarkable vertical gradient of (18)0 and deuterium isotopic composition was observed. The second northern sector extending to the High Dam is characterised by a lower vertical isotopic gradient. In this sector in general, higher values of (18)O and deuterium contents were found at the top and lower values at the bottom. Also a strong horizontal increase of the heavy isotope content was observed. Thus, in the northern section evaporation is of dominating influence on the isotopic composition of the lake water.With the help of an evaporation pan experiment it was possible to calibrate the evaporative isotope enrichment in the lake and to facilitate a preliminary estimate of evaporative losses of lake water. The evaporation from the lake was estimated to be about 19% of the input water flow rate.The groundwater around the lake was investigated and samples from production wells and piezometers were subjected to isotopic analysis. The results indicate that recent recharge to the groundwater aquifer is limited to wells near to the lake and up to a maximum distance of about 10 km. The contribution of recent Nile water to the groundwater in these wells was estimated to range between 23 and 70%. Beyond this distance, palaeowater was observed with highly depleted deuterium and (18)0 contents, which was also confirmed by 14c dating. The age of palaeo groundwater in this area can reach values of more than 26,000 years.Recommendations are given for efficient water management of the lake water.

The use of remote sensing and GIS for the estimation of water loss from Tushka lakes, southwestern desert, Egypt

“…The Palaeozoic and Mesozoic successions form productive aquifers and contain fossil ground water that was recharged during wet palaeoclimatic periods (Aly et al, 1993;RIGWA, 1998). The regional ground water flow is from southwest to northeast (Ball, 1927).…”

Groundwater-surface water interaction in Lake Nasser, Southern Egypt

“…Areas to the west of the Nakhlai‐Aswan uplift (see cross section 2 in Figure ) are principally composed of low‐productive aquifers with paleokarst features, whereas areas to the east of the uplift are largely composed of highly to moderately productive aquifers, formed of coarse‐ to medium‐grained Paleozoic and Mesozoic sandstone with minor intercalations of shales (RIGW, ; Kim and Sultan, ). Both kinds of aquifers contain fossil groundwater recharged during wet paleoclimatic periods (Aly et al ., ; RIGW, ; Kim and Sultan, ). However, areas east of the uplift could have been recharged more recently (Abdel Karim, ).…”

“…contain fossil groundwater recharged during wet paleoclimatic periods (Aly et al, 1993;RIGW, 1998a;Kim and Sultan, 2002). However, areas east of the uplift could have been recharged more recently (Abdel Karim, 1992).…”

Spatial characteristics of surface water and groundwater using water stable isotope in the Tarim River Basin, northwestern China

“…In Africa, Aly et al . () observed that evaporation from the Aswan High Dam removed approximately 19% of the input water flow. In North America, Gat et al .…”

“…These researchers observed that a 1% loss of River Murray water under summer conditions by evaporation resulted in a mean increase in the value of δD of approximately 0·6-1·0% in the surface water. In Africa, Aly et al (1993) observed that evaporation from the Aswan High Dam removed approximately 19% of the input water flow. In North America, Gat et al (1994) estimated the evaporation from the Great Lakes on the basis of the isotope method and observed that between 4·6% and 15·7% of the atmospheric water content came from lake evaporation during summer.…”