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Salt of the sea

30/01/2007 | Down To Earth

Disasters often help science researchers to understand natural phenomenon closely, and the Asian tsunami is no different. High waves from the ocean has brought saltwater deep into the land, at places upto 2 kms, which left soil, groundwater saline for a long time. The urgency to manage the crisis has helped scientists understand the salinity problem. Coastal agriculture was the first victim of salinity. Certain places around Batticaloa in the eastern coast suffered 4-25 times more salinity than unaffected areas. Paddy when flowering and tillering were heavily affected by salinity. The ripening crop was not. The government has recommended farmers to plant salinity tolerant varieties in this region in future. An assessment by FAO and the Sri Lankan government has expressed concern about extensive destruction of kitchen gardens as they supply basic nutrition, fruits and vegetables to the rural poor.

However, scientists were certain that soil salinity would normalise after a few monsoons. In fact, heavy rainfall after the tsunami had helped large parts of coastal soil to regain normalcy.

salt graph


But the larger problem was salinity in groundwater. Most of the coastal rural population depends on wells for drinking water. Seawater seeped into groundwater through open wells in the flooded areas. Also, seawater, held in depressions, permeated through sandy soil. People desperate for drinking water started pumping it out from the wells. "But in most cases they dumped the water next to the well. This did not solve the matter,' observes Karen Villholth, a prominent groundwater researcher from the International Water Management Institute in Colombo. Her research in the east coast shows that salinity became almost normal after rainfall in November 2005. Another research project by Janitha Liyanage of Kelaniya University, Colombo, does not show much reduction of salinity in wells in the southern coast, with high rainfall around Weligama, even after two years. "We are still trying to understand the geology and reason for this. it may happen as the region is trapped between a river and the sea', she points out. As expected, the region has an acute shortage of safe drinking water.

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