New approach in estimation of seawater intrusion footprint (SWIF) for irrigated crops using coastal groundwater

Abstract

The ecological and environmental issues caused by seawater intrusion, economic losses should not be neglected, especially from a long-term perspective. This research presents a new approach to calculate the water footprint of the crops that irrigated by coastal groundwater aquifers, considering seawater intrusion is one of the effecting pollutants. Seawater intrusion footprint (SWIF) is a new term of water footprint that defines aquifer pollution due to the excessive withdrawal from the aquifer. The seawater intrusion footprint that defined as the amount of water needed to mitigate the impact of seawater intrusion is different from the grey water footprint, which is defined as the amount of water needed to mitigate the impact of pollutants generated during the life-cycle of a product. Using the new approach, the water footprint of 12 irrigated crops in the Nile Delta in Egypt that use the coastal groundwater was recalculated and compared with the currently published figures that do not consider the pollution caused by seawater intrusion. The main results are; the irrigation using only coastal groundwater, the total water footprint of some crops such as wheat, bananas, sugar cane, and apples increase by more than 80% of published figures for each crop to reach 3068,1079,345 and 1761 m3/ton, respectively. While using coastal groundwater with green water in rainy seasons, the total water footprint of the same crops increases to 2282,1038, 300, and 1617 m3/ton, respectively. Since seawater intrusion causes groundwater contamination and salinization, leading to decreases in agricultural production and ecological and environmental issues. So, the economic losses arising from seawater intrusion impacts should not be neglected, especially from a long-term perspective. Also, it is recommended to incorporate seawater intrusion footprint (SWIF) in the total water footprint for the crops that irrigated by coastal groundwater aquifer. Also, the study suggested applying the new approach whenever the coastal groundwater has been used near the coast or far away if there is a seawater intrusion.