JAFFNA PENINSULA DRINKING WATER
Sri Lanka’s Miocene Jaffna Formation Fractured & Karstic Limestone Aquifer: the Sole Source of Drinking Water in the Jaffna Peninsula
Barney Paul Popkin
seawater intrusion. The aquifer is a shallow, generally flat, weathered and karstic limestone, whose few outcrops have mostly have been removed to create more agricultural land.
T
www.aipg.org Because it is relatively young, even though the climate is
tropical there hasn’t been sufficient time to create the huge caverns found in many other carbonate aquifers. Because it is not heavily faulted, its fractures are not well connected and its primary and secondary hydraulic conductivities are low. The aquifer receives most of its natural recharge during the Maha monsoon of November to December, and some during the gentle Yala monsoon in May to September. It is other- wise over-pumped during the long dry seasons and saturated during the monsoons. It also receives significant recharge from household sewage and seawater. It is heavily polluted by agricultural chemicals, leachate from garbage, industrial waste disposal, and septic tank seepage. Because of rising sea levels and uncontrolled seawater intrusion, it is becoming more and more saline.
Although the aquifer receives about 20 percent of the region-
al rainfall as groundwater recharge, it has a small storage capacity and cannot meet agricultural, industrial, municipal, and household water demand (the relevant climatic, aquifer, and demand parameters are summarized in Table 1 at the end of the article). Consequently, although most households have shallow hand dug or drilled boreholes for washing, cooking, and cleaning, and the National Water Supply and Drainage Board supply public water at public roadside stations located throughout much of the City, householders import their drink- ing water as purified bottled water. Many of the over 80,000 domestic wells have been developed by blasting the aquifer to increase its local permeability and water-storage capacity. The water wells are typically approximately up to 10 meters deep.
To counter municipal water scarcity, it is planned to build
a 35,000-cubic meters per day seawater desalination plant at Peaqpuchqkadu, located 70 km southeast of Jaffna City’s Central Business District. Construction of this plant will be
Figure 1 - The island nation of Sri Lanka. The city of Jaffna is circled. Courtesy Google Maps.
Oct.Nov.Dec 2020 • TPG 41 Jaffna Peninsula
his tropical coastal aquifer is the sole source of drinking water for the for the 120,000 people of Jaffna City and the 615,000 residents of the 850-square kilometer Jaffna Peninsula in coastal Sri Lanka (Figure 1) and is poorly studied. It is thin, with low perme- ability, and limited storage capacity. It is overused, and rapidly degraded from manmade pollution and natural
funded by an Asian Development Bank (ADB) loan In addition, there are many small to very large schemes of constructed freshwater lagoons and surface water tanks for supplementing irrigation water. They include a planned six square kilometer by six meters high constructed water tank (3.63 billion cubic meter capacity) at the far southeast Elephant Pass in the Jaffna Lagoon (Figure 4), to be funded by the Sri Lankan Irrigation Department.
These engineering innovations are being undertaken to
correct the municipal and irrigation freshwater deficits affect- ing the approximately 735,000 residents of Jaffna City and Peninsula.
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