Optimizing Water Conservation and Crop Yield: Evaluating the Blue Water Saving Potential of Deficit Irrigation and Mulching in the Nile Basin

This study aims to investigate the potential water savings achieved through implementing deficit irrigation (DI) combined with mulching in the Nile Basin countries. The study analyzes the effects of blue water consumption and water footprint (WF) on various crops in the Nile basin countries. We utilized the AquaCrop-OS model to evaluate the effects of blue crop water use and water footprint of dominant crops. Changes in blue crop water use (CWU) varied between countries and crops, ranging from -34% to -1%. Yield varied in the simulations, with some decreases and some increases compared to the reference (R). The blue water footprint exhibited relative changes ranging from -47% to 35%. The changes in blue water footprint (measured in m³/y) resulting from deficit irrigation and mulching impacted production while maintaining a constant irrigation area. In South Sudan, for cotton, Deficit irrigation (DI1) resulted in a -12.5% relative decrease in blue WF compared to R. However, the reduction in blue WF was more significant (-37.2% relative decrease) when DI1M compared to R. Other countries also experienced varying reductions in blue WF for crops. These findings show the possibility of saving water while keeping production levels stable. In Egypt, DI1 resulted in an 8.0% reduction in blue WF compared to R. Combining DI1M led to a more significant reduction of 37.2%. This study provides useful information for water conservation decision-makers in the Nile Basin countries.