Using groundwater quality index for categorizing the groundwater suitability for irrigation in the south Nile Delta region, Egypt

Abstract

Groundwater is considered one of the most important sources of water all over the world. It can be used for different purposes of life, depending on its quality. The quality can be categorized for irrigation based on many items such as sodium percentage, permeability index (PI), magnesium hazard (MH), Kelley ratio (KR), and water quality index (WQI). Those items can be expressed and presented in Geographic Information System (GIS) format. This study aims to compare the WQI with the other items for expressing the suitability of groundwater for irrigation in GIS format. This study is conducted in the south Nile Delta region, Egypt. Seventy-two groundwater samples are collected and analyzed for pH, EC, total dissolved solids, soluble cations and soluble anions, iron, and manganese. These parameters are used to calculate the WQI considering their permissible limits of FAO, while the other items were calculated using some parameters based on their equations. The results reveal that, due to sodium percentage, there are three orders from five orders, of which 53% are good, 39% are permissible, and 8% are doubtful. Considering PI, the results were 7% for class 1 and 93% for class 2. Regarding MH, the results ranged between 6% (not suitable for irrigation) and 94% (suitable for irrigation). Depending on KR, 82% of the samples are suitable for irrigation, while 18% are not suitable for irrigation. The results of WQI illustrate that 76.4% of the total studied samples are excellent for irrigation and 23.6 are good for irrigation. All the results are represented using ArcGIS 10.1 program to clear the spatial distribution of the groundwater suitability for irrigation. The use of WQI with GIS is considered the best tool to represent and categorize the suitability of groundwater for irrigation.