Assessment and Mapping of Surface Water Quality Index for Irrigation Purpose: Case Study Northwest of Nile Delta, Egypt

Shortness and contamination of water become one of the most hazards facing Egypt nowadays. The irrigation water quality index (IWQI) was calculated in this research to classify surface water of some irrigation canals northwest of Nile delta, Egypt. For this purpose, 14 sites distributed within study area were selected to take water samples during October 2019. ArcGIS (10.4.1) spatial Analyst extension was used to produce high accuracy maps. The IWQI spatial distribution within the study area shows that, samples fell into four classes, low restriction (LR) moderate restriction (MR) High restriction (HR) severe restriction (SR) with an area 178,138, 92 and 249, Km2 respectively. The area of SR water quality would be sited in the northeast and southwest in resultant of increase the EC, SAR, (Na+) and (Cl-) ions in this direction. The descending order of water restriction use in the study area is SR˃ LR˃ MR ˃ HR. Thus, most of surface water in the study area (73%) may avoided its use for irrigation under ordinary conditions. It should be used with high permeability soil and with plants that appear high resistance for salinity with special salinity control practices.