Groundwater quality deterioration evaluation for irrigation using several indices and geographic information systems: A case study

Groundwater in the Al-Burayhi and Hethran Basin, Taiz, Yemen, it is important source of irrigation water. However, its quality faces threats from both natural and human activities. This study aims to assess the potential deterioration of groundwater for irrigation purposes using several indices and Geographic Information System (GIS) software. Indices, including salinity (electrical conductivity), sodium hazard (Sodium Adsorption Ratio and Permeability Index), combined salinity and sodium hazard index (electrical conductivity and sodium percentage), magnesium hazard index, and chloride content index. The results indicate that 24.14 % of the samples showed high salinity, while 75.86 % showed very high salinity according to the electrical conductivity indices. For sodium hazards, 79.3 % of the samples posed a medium hazard to soil permeability in the long term based on the Permeability Index. Regarding the combined salinity and sodium hazard, 69 % of the samples were of poor quality for irrigation. For magnesium hazards, 55.17 % of the groundwater samples were of poor quality for irrigation. Concerning chloride content, 72.41 % of the samples exceeded the permissible limits according to Yemeni and international standards (350 mg/L). Therefore, using groundwater in the study area for irrigation impedes crop growth and productivity, leads to soil salinization and/or physical degradation due to increased alkalinity, and necessitates costly soil treatments to restore its productivity. Nevertheless, groundwater in the study area can be conditionally used for irrigation by considering all factors affecting the use of low-quality groundwater for irrigation.