Drainage Water Reuse under Water Scarcity

Abstract

Water resources management in arid regions and semi-arid such as Egypt is a continuous process for the achievement of rational use of the scarce water resources for the benefit of the national economy. Water scarcity in Egypt is a major challenge, which is annually increasing due to the high water demand of different sectors, while the share of Egypt from the Nile is fixed at 55.5 billion cubic meter (BCM). Non-conventional water resources, such as drainage water, are essential alternatives to improve the water use efficiency. In Nile Delta, a considerable number of reuse pump stations (RPSs) are distributed along the drains network already decades ago. But farmers are unofficially using small pumps to divert drainage water directly to their fields. The major concern in the reuse of agricultural drainage water is the build-up of salts. This research aims to assess the water balance in El-Behira governorate to reduce the negative impacts of water scarcity on the crop yield, soil deterioration, evapotranspiration. The model was calibrated using the water and agriculture data of the year 2014 which was used as a base year then it was validated using the data of year 2015. Two statistical goodness-of-fit coefficients [Nash–Sutcliffe model efficiency coefficient (NSE) and ratio of the root mean square error to the standard deviation of measured data (RSR)] were used to assess the re-calibration and validation of the model; where the results of the model showed good and very good performance with the observations. In addition; the water allocation of the study area was simulated by the SIWARE Model during the studied two years to assess the current water uses and soil conditions, while the results are visualized using Geographical Information System (GIS) as an essential tool for a decision support system. The simulation results indicated that the study area suffers from water stress that forces the farmers to unofficially reuse the drainage water. Electrical Conductivity (EC) of the unofficially reused water ranged between Medium and high hazard salinities that gives restrictions on the crop pattern, causes hygienic risks, and increases the pollution in the shallow aquifer.