Tree Selection for the Enrichment of Mahaweli River Basin in the Dry Zone, Sri Lanka

Presentation Abstract

Hirusha Randimal

Department of Forestry and Environmental Science

University of Sri Jayewardenepura, Sri Lanka

Mahaweli is the longest river in Sri Lanka the Mahaweli Development Project has been established by taking this river as the central component. Due to the topography, it carries a large sediment load and the lateral part of the River consists with large alluvium deposits. Mahaweli river basin in the dry zone divided Mahaweli plain, Bintanne plain, Nuwarakalawiya plain and Flood plain consist with Villus ecosystems The major land use around the Mahaweli river in the Dry Zone is paddy cultivation. The water management schemes established under the above project have changed the natural flow regimes, resulting in sometimes higher flood flows, lower dry season flows and degradation of riparian and wetland habitats in the lower catchment. River banks erode along with onset northeast monsoon and inter-monsoonal rains due to lack of riverine vegetation. In order to enrich the river banks of those areas, tree species should be selected which suit for riverine ecosystems as well as intermediate and dry agro-ecological zones. Terminalia arjuna (Kumbuk), Madhuca longifolia (Mee), Barringtonia acutangiila (Ela midella) and Diospyrous malabaria (Thimbiri) are some of the species which can use for enrichment. Further, eradication and management of invasive species such as Mimosa pigra  and also proper enrichment model should be implemented and continuous monitoring should done for such kind of degrading ecosystem. Through a proper management of the riverine vegetation, sustainable extraction of timber and other forest products from such ecosystems should be the longer-term goal.