Sources of extent of groundwater pollution in shallow aquifer: A case study from Jaffna district in Sri Lanka.

Abstract

Twenty six countries including Sri Lanka now classified are water deficient, and nearly 230 million people are affected with water shortage. And prediction is that by 2025, one quarter of the world’s population will face severe water shortages. Groundwater is the only water source available in Jaffna peninsula for all the requirements with seasonal rainfall. Two villages namely Thirunelvely and Kondavil from Jaffna district were selected for the study because the areas are receiving much attention due to its significant groundwater resources, Which are being utilized for domestic. Agriculture and specially used for Jaffna municipal water supply. The possible contamination causes such as abstraction rate, actual Well depth, proximately to latrines, agriculture areas, lagoon and ponds, and animal raring houses were considered. Water samples will collect it at monthly Interval and analyzed for electrical conductivity (EC) chloride, nitrate and total hardness. A point interpolation what was done to interpret the extent of contamination for EC, chloride, nitrate-N and total hardness using Arc view 3.2. The survey conducted in the study areas regarding proximately to pit latrines revealed that 52.5% of wells did not satisfy the requirements even though the recommended distance is 15 m. Out of tested well 32.5 % of shallow wells all situated between 5 m or between the agricultural lands. Further 17.5 % wells are situated within 100 m from agricultural land. Very few wells in (2.5%) were found within the 500m from the lagoon whereas (2.5%) were found 100 m from the Ponds. There was no correlation between actual depths of the wells to contamination sources and correlation was observed between actual abstraction rate to chloride concentration and EC. The distance from agricultural areas, livestock raring areas and pit latrines to contamination source especially nitrate-N were observed. All the contamination sources are influenced by wet season. Hence, management of ground water source and protecting its quality from contamination source is therefore essential to preserve exciting potential ground water aquifers in the peninsula.