INVESTIGATION OF THE GROUNDWATER SUITABILITY FOR IRRIGATION PRACTICES IN AN ARID REGION: CASE STUDY

Abstract

Groundwater is an important source of acceptable water for irrigation in the arid regions and in particular in the United Arab Emirates (UAE). Demand for groundwater is increasing in the UAE due to population growth and significant economic advancement associated with political stability. As agricultural practices are the main land use in Al Hayer area, southeast UAE, majority of extracted groundwater from major aquifer is used to meet the increasing demands of irrigation. This study is aimed to assess the suitability of groundwater in the study area for irrigation practices using classifications of Sodium Adsorption Ratio (SAR), Soluble Sodium Percentage (SSP), Magnesium Adsorption Ratio (MAR) as magnesium hazard and Residual Sodium Carbonate (RSC). In addition to that, the quality is assessed using the Total Dissolved Solids (TDS) and Electrical Conductivity (EC) of collected groundwater samples. Assessing the quality of groundwater in the region will help the decision makers in determining appropriate actions and using the conventional management tools to protect groundwater from the possible contamination. The chemical results indicate that the groundwater of the study area contains excess of Na⁺ and Mg⁺². This is related to the weathering of Oman Mountains which are located to the east of the study area. The data analyses of salinity hazard suggested that about 44% of collected groundwater samples from the entire region are grouped as very high salinity and are not suitable for irrigation and about 56% are grouped as high salinity which is doubtful to be used for irrigation. The calculations of SAR reveal that the groundwater of the study area is good to excellent for crop production. While, the calculated magnesium hazard suggests that all samples are not suitable for irrigation purposes. The SAR-EC plot presents two groups of sampling points. The first group of groundwater can be used for irrigation of most crops in almost all soils, however, the second group of groundwater is not suitable for irrigation under normal conditions.