Restoring riparian vegetation – a promising means to ensure clean waterwca2014-2183 Kamal Melvani 1,* 1Managing Director, Neo Synthesis Research Centre, Sri Lanka, Kotte, Sri Lanka
Forest cover in Sri Lanka has declined of which riverine forests form a substantial part. Aside from stabilizing stream banks, controlling soil erosion, providing shade and habitat for surface and aquatic biodiversity, their importance as riparian buffers to mediate the inflow of polluted surface water or in bio remediating ground water must not be underestimated.
The most serious loss was experienced in the upper watersheds where montane forests were cut to plant tea. Current land use in these areas is dominated by tea and vegetable cultivation that use massive amounts of agrochemicals. Many agrochemicals produce and disseminate xenobiotics and their metabolites that may result in dangerous health issues both in the area of application and downstream. Current research suggests that the use of reservoir water might be a cause for acute chronic kidney disease in downstream communities.
Parallel to their impact on surface water quality, the impact of agrochemical leaching into ground water is equally serious. The experience in Kalpitiya where nitrogen based fertilisers has contaminated the prevailing Gyben Herzberg type aquifer is well known.
The Neo Synthesis Research Centre (NSRC) has from 2001 to date been engaged in the restoration of riparian vegetation alongside banks and gullies in the upper reaches of the Mathatilla Oya, Maragala Oya, Bolgoda Ganga, Hulu Ganga, Rakwana Ganga, Lemastote Oya and Maha Oya as well as around Lake Richmond in Haputale. The vegetation used in the landscape design of the riparian buffer zone mimicked the natural forest vegetation of the area. If the buffer zone was inhabited with people who had tea, home or vegetable gardens, efforts were made to induce trees in the area adjacent to the water body and convert cultivation to adopt organic regimes. However, most of these areas also suffer from a lack of sanitation. Hence issues include the intrusion of faecal coliform bacteria into surface water bodies, compounding water quality further. Toilets have been constructed though many more are required. Restoration has, in all instances been undertaken with the participation of the community.
Restoration of riparian vegetation around and along surface and ground water bodies may be a promising and low cost solution to averting the contamination of water resources.