Hydrological Interaction between Surface Water and Ground Water in Vavuniya District of Sri Lanka

Abstract

Irrigation tanks are the only surface water resource in Vavuniya district. Households in this district are dependent on ground water sources to satisfy their domestic water needs. It has been experienced and reported by the households that the wells during the dry season especially during the months of June, July, and August became dry without water while there was little water in the irrigation tanks in this district. Hence, this study was carried out to understand the hydrological relationship between surface water and ground water. Three tanks namely Vavuniya tank, Pandarikulam tank and Paddanichchepuliyankulam tank were purposively selected as surface water source. 21 wells were selected from each Vavuniya tank and Padanichchepuliyankulam tank command area and 23 wells were selected from Pandarikulam tank command area as ground water source. The measurements of water level of tanks and wells were taken once in two weeks for six months from August 2013 to January 2014. The correlation coefficients of respective tank water levels Vs well water levels were estimated using Minitab 16 and found that the average correlation coefficient of the same of Vavuniya tank, Pandarikulam tank and Paddanichchepuliyankulam tanks were 0.88, 0.72 and 0.69 respectively. The strong positive correlation between the tank water level and well water level in the selected tanks confirmed that the increased tank water level would ensure the well water level. Any action taken towards tank maintenance and rehabilitation would ensure the sustainable water availability in the wells. Therefore maintaining sufficient water level in the tank would help to minimize water scarcity issues in Vavuniya.