Assessment of groundwater quality for irrigation in the arid regions using irrigation water quality index (IWQI) and GIS-Zoning maps: Case study from Abu Dhabi Emirate, UAE

The present study developed an Irrigation Water Quality Index (IWQI) and GIS-Zoning maps for assessing groundwater resources for irrigation purposes in Abu Dhabi Emirate, UAE. The calculated IWQI values varied from 8.78 to 77.44 and 52% of the samples categorized under severe irrigation restrictions, where groundwater can be used for irrigation of high salt tolerance plants only. While, 44% of the investigated wells located within the high restriction category, 3% within moderate restriction, 1% within the low irrigation restriction category, and 0% within unrestricted category. Moreover, Wilcox and USSL diagrams confirmed IWQI results as the groundwater was classified mostly as unsuitable for irrigation purposes without prior treatment. It shows that waters classified either as Permissible to Doubtful or Good to Permissible are forming only 3% of the overall investigated wells and are located east to Abu Dhabi Emirate along the border with Oman. While, none of the samples fall in Excellent to Good region. Moreover, the combination of the irrigation water quality parameters such as Sodium Adsorption Ratio (SAR), Electrical Conductivity (EC), Sodium Ratio (%Na), Chloride concentration, and Permeability Index (PI) provided a guidance for evaluating the problems that might be developed in soil due to current irrigation practices in the study area. The spatial distribution (GIS zoning-map) of the IWQI provided a clear visualization of irrigation groundwater quality in the study area and can be used along with other water quality parameters and indices as useful tools for the decision makers to identify the “Red Zones” that suffer from over-extraction and as a guide for action toward a sustainable groundwater management plan for agriculture purposes. Additionally, GIS maps can be used as a guide to recommend the range of suitable crops that can be cultivated and used for the range of soils in the study area.