Groundwater Balance in Jaffna Peninsula Facing Crisis Due to Depletion of Limestone Through Overuse


Dilrukshi Handunnetti

COLOMBO] The single limestone aquifer, which is the main source of freshwater in Sri Lanka’s northern Jaffna peninsula, is gradually depleting through overuse, researchers say.

“The area suffers from severe groundwater imbalance which might reach crisis proportions in the future,” Shanti de Silva, one of two scientists who carried out the research for the agricultural department of the University of Jaffna, told SciDev.Net.

At a presentation of the research results last month (18 April), de Silva called for a regulatory framework to optimise groundwater use in Jaffna peninsula — which was captured by the Sri Lankan army from separatist rebels in May 2009, ending decades of civil strife.

Originally published in Tropical Agricultural Research (in December 2012), the results showed that the potential recharge of the aquifer in the dry season was approximately 14 per cent of that in the wet season — showing up a serious contrast between the two main seasons.

“Water resources of the basin remain almost constant while the demand for water continues to increase. Moreover, due to uneven distribution of rainfall, water resources lack replenishment,” the report said.

Kusum Athukorala, who heads the Network of Women Water Professionals and is the winner of the 2012 Women in Water award, told SciDev.Net that with thousands of people returning to settle in the former warzone, groundwater extraction is bound to increase. “Since this will create more imbalances, some regulation will help prevent a future crisis,” she said.

The researchers recommend extraction of 50 per cent of the annual recharge to prevent a severe imbalance developing in the aquifer, the main resource for agriculture, domestic use and water supply on the Jaffna peninsula.

Aquifers are layers in underground rock, capable of trapping water that can be pumped out for domestic consumption, agriculture and industry.

Since high water usage was observed in farming, conservation practices need to be implemented to increase water use efficiency, including correct selection of crops and irrigation methods, the researchers said.

Farm-level organisations, policies to renovate existing surface tanks, restrictions on the use of mechanical pumps and regular monitoring of the ground water table are among measures suggested to reverse a worsening situation.

The researchers have also suggested construction of rainwater reservoirs in public places and sensitising farmers against over extraction as ways to ensure adequate replenishment of the Jaffna aquifer.