Salinity barrier across Nilwala stuck on the drawing boards

• Delay in deciding upon the barrier’s location endangers the area’s water supply scheme

Discussions on the erection of a salinity barrier across the Nilwala River at Matara, at an estimated cost of Rs 1,200 million, have run into snags, endangering the area’s water supply scheme.

The problem is whether to have the salinity barrier at Nadugala (5 km upstream from where the Nilwala flows into the sea), which is the ideal location, or at Kadduwa (about 17 km upstream), with serious consequences, the Sunday Times learns.

The consequences of having the salinity barrier at Kadduwa will be saline (salt) water infiltrating or seeping into, not only the ground water along the whole stretch, but also making the lands unsuitable for cultivation, a participant at the discussions said. If the ground water is affected, people in these areas will not be able to use their wells for their drinking water, while the lands sandwiching the river would gradually become barren due to salinity.

Delays and the location of the salinity barrier would have a major impact on the water supply to Matara and the adjacent areas, it is learnt. The salinity barrier across the Gin Ganga had been cited as an example, to portray the benefits of a similar one across Nilwala at Nadugala.

If the salinity barrier is located at Nadugala, the National Water Supply and Drainage Board (NWSDB) will be able to make maximum use of all three of its pumping and purification stations at Nadugala, Kadduwa and Balakawala, it is learnt.

Salinity barriers across rivers have been necessitated due to the scarcity of fresh water, caused by the rise in sea levels, further exacerbated by the deepening of river beds through unregulated sand mining.
Illicit sand-mining in Sri Lankan rivers is compelling the construction of salinity barriers at enormous cost, another source pointed out.

Discussions on the Nilwala salinity barrier, organised by the Ruhunu University’s Faculty of Agriculture, the Nilwala Area Water Partnership and the Sri Lanka Water Partnership, was chaired by the Dean- Faculty of Agriculture, University of Ruhuna and Chairman- Nilwala Area Water Partnership, Prof. Mangala De Zoysa. Participants at the discussions included representatives from the Irrigation Department, the NWSDB and stakeholders.