Suitability of groundwater for irrigation in Manmunai West Divisional secretariat area of Batticaloa District

Groundwater quality has become a critical issue due to fresh water scarcity. Suitability of irrigation water is directly influences on the plant growth and its development, yield of the plant and deteriorates soil fertility. Irrigation waters, pumped from wells contain appreciable quantities of chemical substances and always carry substances derived from its natural environment or from domestic and industrial effluents. In the present study, the physical and chemical parameters of well water from Manmunai West DS area were analyzed to find the quality and the suitability of well water for irrigation. Water samples from 80 randomly selected wells which are presently used for irrigating crops were collected during the period from July to September 2017. Collected water samples were tested for water quality parameters such as pH, Electrical Conductivity (EC), Total Dissolved Solids (TDS), Hardness, Sodium (Na), Pottasium (K), bicarbonate, carbonate and Total Suspended Solids (TSS). The relative proportions of sodium to other cations were determined by the Sodium Adsorption Ratio (SAR) and Soluble Sodium Percentage (SSP). Residual Sodium Carbonate (RSC) of the well water also determined using cation, bicarbonate and carbonate concentrations. According to the results, parameters such as pH, TDS, Mg, Bicarbonate, hardness and SAR were within the FAO recommended range for irrigation purpose while other parameters such as TSS, K, Na, Carbonate, RSC, SSP and EC were above recommended range. The study concluded that, about 85% of the well water of the study area is not suitable for irrigation in reference to Na, K, Carbonate, Bicarbonate, RSC, SSP and EC. Therefore, awareness on proper management of land against the poor irrigation water quality especially for sodium and bicarbonate hazards is important in the study area.