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Underwater sonar survey using Side Scan Sonar (SSS) and Single beam Echo-sounder (SBES) was used for the investigation of the old Nubian archaeological villages buried within the bottom topography of Nasser Lake. The research objective involved emphasizing the efficiency of marine geophysical techniques in the detection of the submerged old Nubian Villages in Nasser Lake behind the High Dam, the study also aimed to study riverbed topography and determining the old course of the Nile River in the area. The resulted bathymetric maps showed that the two former banks of the Nile River in the study area were characterized by two distinct natures, while the shoreline has retreated with different extents starting from 250 m at the southern regions up to 3 km in the northern parts. The high-resolution sonar images of the bottom uncovered distinctive acoustic patterns according to difference in the returned backscatter strength. Submerged Nubian houses were detected along some areas of the eastern bank, which were found either standing over elevated rocky cliffs or built on multiple tiered levels. Precise target measurements were applied on the detected houses and different dimensions were obtained, which suggest that these houses were built according to the availability of suitable land to construct such dwellings. [ABSTRACT FROM AUTHOR]

This study aims to compare the changes in the physicochemical and biological characteristics simultaneously in Nasser Lake as lentic water and the main Nile River as lotic water due to the construction of the Aswan High Dam. Therefore, water samples were seasonally collected from four sites along the lentic water and five sites along the lotic water. The results showed an increase in the water temperature and pH in the lentic than the lotic waters, while TSS, nutrients, BOD, and TDS showed a reverse trend. Furthermore, zooplankton recorded 45 taxa; 31 rotifers, 7 cladocerans, and 3 copepods, in addition to 4 taxa represented in rare groups. Rotifera dominated the main river water, while Copepoda dominated Nasser Lake water. Twenty-two holozooplankters appeared only in the main river water, while three holozooplankters appeared in the lake water and 20 holozooplankters were shared in both waterbodies. The appearance of Ptygura libera in the river for the first time proved that the lake is the source of some zooplankters in the river. According to the trophic state index and the river pollution index calculations, the two waterbodies categorized as eutrophic and unpolluted, respectively. [ABSTRACT FROM AUTHOR]

Heavy metals (HMs) pollution of water is a continuous worldwide issue in both developing and developed countries. HMs are resistant and non-degradable elements that are introduced to the water bodies via natural and anthropogenic processes. The main anthropogenic sources are agriculture, industrial and domestic wastes that are increased due to the increase of the global population. The existence of HMs at high levels, both essential and nonessential HMs can cause dangerous complications in the aquatic system, plants, animals and human health. Nasser Lake and the Nile River are the main sources of freshwater in Egypt. Anthropogenic heavy metals may pass to Nasser Lake via the discharged of pollutants into the Nile upstream of the lake. Despite that, the Nile River in Egypt receives different wastes from point and non-point pollution sources along its banks, the levels of most HMs decline and are within the national and global permissible levels in the areas far from the hot spots (pollution sources). The present article's interest is in the nature, sources and effects of the HMs in the aquatic environment in addition to the long-term changes of HMs content in the water and sediments of Nasser Lake and the Nile River in Egypt. [ABSTRACT FROM AUTHOR]

Summary: This paper examines the sensitivity and uncertainty of evaporation estimates from Nasser Lake, south of Egypt using data collected at the floating station Raft, 2km upstream of the Aswan High Dam, and 12 evaporation models. Based on their approach the evaporation models were ranked in five classes, respectively the Bowen ratio energy budget (BREB) approach, three energy–aerodynamic based methods, a mass transfer method, two temperature and five solar radiation–temperature approaches. State dependent parameter models were used to estimate the sensitivity indices of the different evaporation estimation methods at daily and monthly frequencies. A drastic reduction in the cost of the sensitivity analysis was obtained when coupled with efficient sampling methods, producing quasi-Monte Carlo sequences (Latin Hypercube samples). Analysis of the sensitivity indices (Si ) revealed that the energy and advective parameters (Qx and Qv ) in the Bowen ratio energy budget method most strongly affect evaporation estimates. The most sensitive parameters for the energy–aerodynamic methods (Penman, Priestley–Taylor and the deBruin–Keijman methods) are the change in heat storage (Qx ) and solar radiation. For the other methods the most sensitive parameters were solar radiation, air temperature and vapour pressure, but with lower sensitivities. After investigation of the first and second-order sensitivity indices, it was found that the first-order sensitivity indices capture more than 90% of the total variance of the evaporation estimates. Interactions between input parameters were found limited with a maximum contribution to variance of less than 3.3% for daily frequency and less than 8.5% for the monthly frequency. Results indicated that many parameters in the 12 evaporation models could be fixed without appreciably affecting the output of these models. This helped to reduce the computational load of these models. The uncertainty results show that the Dalton group is subject to the highest error. The overall uncertainty ranged from 9% (BREB method) to 15% (mass transfer method) of the mean evaporation rate. [Copyright &y& Elsevier]

Abstract: In Egypt, the Nile River water is the main source of water, providing nearly 95% of water requirements. The Nile water is impounded in Lake Nasser (LN) in the south of Egypt by the High Aswan Dam (HAD). In this study, we presented the radioactivity levels in LN sediments over the time period 1992–2000 and the distribution pattern of the measured radionuclides (238U series, 232Th series, 40K and 137Cs). In addition, the uranium concentration in water samples was measured. The distribution pattern of these radionuclides in sediments reflects the geochemical behavior and weathering processes of uranium series, thorium series and the heavy minerals in the Nile pathway and in Nasser Lake. [Copyright &y& Elsevier]