Efficient management in water supply: A study at Araly Water Supply Scheme, Jaffna Peninsula.

Abstract

The demands for water supply, irrigation, domestic and industrial water have increased considerably in recent past in Jaffna district. The shallow karstic aquifer in Jaffna peninsula is one of the six main groundwater aquifers of Sri Lanka. Jaffna peninsula is underlain by Miocene limestone formations which are generally 100 to 150 m thick.The karstic cavities result in a shallow groundwater table,recharged by rainfall, and groundwater forms a “lense” of fresh water floating over the saline waters.Groundwater is the major natural water source in the Jaffna peninsula and it is used for domestic, agricultural and industrial purpose. Safe drinking water supply is a vital important where the water resources are under vulnerable conditions.The vulnerability may arise from natural and anthropogenic effects including local climate, geology and agricultural practices. In Sri Lanka 40% of population has organized water supply facilities and 59.4% is depending on other sources such as wells,tube wells,streams and rivers,including 10% on unprotected sources.Water quality analysis is one of the most important phase in water supply schemes. Determination of physico-chemical characteristics of water is essential for assessing the suitability of water for various purposes like drinking, domestic, industrial and irrigation. National Water Supply & Drainage Board, Jaffna is supplying the drinking water for identified poor quality groundwater area and plays a major role in supply of drinking water for rural and urban population of peninsula by maintaining seven water supply schemes to fulfill their water requirements.Araly is the one of their scheme.It is the shallow well with the bottom depth of 4.30 m.The secondary data such as water level fluctuation, electrical conductivity of bottom and surface groundwater and production were collected analyzed on monthly basis from 2011 to 2013. Results show that during the wet season the water level varies 2.4 m to 3.8 m and during the dry season it varies as 0.3 m to 1.6 m. Electrical conductivity varies from 189 μS/cm to 6190 μS/cm.During the wet season the water quality parameters were nearly same at bottom and the surface of the well water but during the dry season those parameters show significant variation between the bottom and surface of the well water.Bottom quality 3 values were higher than the surface values.Average production of the groundwater was 820 m /month. Earlier the pumping was carried out for three hours continuously but now the pattern of pumping was altered and do not pump continuously,there was a resting time after pumping of every one hour.Now 3 the production was increased up to 2272 m /month.To protect the water quality deterioration and aquifer, alteration in the pumping pattern is a good practice and also usage of low pumping rate water pumps and floating foot valves during the pumping operations could facilitate further.