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Egypt has recently inaugurated a mega development project aiming to alleviate the overpopulation along the Nile River and to meet the looming food gap. Toshka is a promising area where groundwater-dependent activities are being expanded adjacent to Lake Nasser. Thus, it is of utmost importance to provide a sustainable development approach and to assess the resulting environmental implications. Accordingly, a coupled groundwater flow and transport model was invoked. The generated model was successfully calibrated for the observed water levels and salinity. The proposed exploitation regime of 102 wells each pumping 1000 m3/day was simulated for a 100-year test period. The maximum resulting drawdown was about 25 m, compatible with the advocated sustainable restriction limit. Climate change (CC) impacts of reducing the lake’s storage and increasing the crops’ water requirements were investigated. The lake’s water level fluctuations were a key factor in the aquifer hydraulics and flow direction. The drawdown breakthrough considering the CC catastrophic scenario (RCP8.5) has increased by about 20%. The developed solute transport model was utilized to simulate the salinity spatial distribution and the lateral movement of leaking pollutants from the underway activities. Cultivation activities were found feasible up to 80 km away from the lake border where salinity does not exceed 2000 ppm. Yet, a protection strip of not less than 4.8, 6.0, and 7.2 km according to the lake operating condition is inevitable to ensure that pollutants do not intrude into the lake. These findings will assist the decision-makers in scheming environmental impact assessment criteria for sustainable development.

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This study aims at the evaluation of water resources use in Lake Tana sub-basin based on the status of eight development projects that are planned to be executed in this region. Remote sensing and satellite imaging have been used in addition to their product applications. This is vital due to its hydrological significance and direct impact on Egyptian water resources. The Normalized Difference Vegetation Index (NDVI) has been calculated, for the year 2017, to recognize the agriculture land use and land cover. Then, by integration with the potential agriculture projects basic data, such as water consumption and crop pattern, water resources use in the basin was evaluated and quantified. The analysis performed in this study showed the following: the Koga project was the only implemented project from the proposed eight irrigation and drainage projects; the Megech and SouthWest (SW) Tana projects are still under construction. The density of the vegetation cover varies yearly from 75% to 100% in the Gumera project, whereas it did not exceed 40% in the NorthEast and NorthWest Tana projects. It varies from 15% to 100% in the Megech, Ribb, SouthWest Tana, and Gilgel Abbay projects. Projects' calculated NDVI coverages reflect the behavior of the local community in cultivation depending on rainfall (green water), or by direct extraction from rivers as supplementary irrigation (Blue Water). This behavior may be based on their own interests and uses, not based on planning or investment, except for the Koga project. The water consumption from those projects is estimated at about 933 million m 3 /year.

Synthetic time series created from historical streamflow data are thought of as substitute events with a similar likelihood of recurrence to the real event. This technique has the potential to greatly reduce the uncertainty surrounding measured streamflow. The goal of this study is to create a synthetic streamflow model using a combination of Markov chain and Fourier transform techniques based on long-term historical data for the Nile River. First, the Markov chain’s auto-regression is applied, in which the data’s trend and seasonality are discovered and eliminated before applying the Pearson III distribution function. The Pearson III distribution function is substituted by a discrete Fourier transform (DFT) technique in the second approach. The applicability of the two techniques to simulate the streamflow between 1900 and 1999 is evaluated. The ability of the generated series to maintain the four most important statistical properties of the samples of monthly flows, i.e., the mean, standard deviation, autocorrelation lag coefficient, and cumulative distribution, was used to assess the quality of the series. The results reveal that the two techniques, with small differences in accuracy, reflect the monthly variation in streamflow well in terms of the three mentioned parameters. According to the coefficient of determination (R2) and normalized root mean square error (NRMSE) statistics, the discrete Fourier transform (DFT) approach is somewhat superior for simulating the monthly predicted discharge.