Irregular land use changes and river bank erosion in Biyagama area: A case study in Kelani river basin

Abstract

Land erosion in Riparian areas is a main problem in Sri Lanka. Intensity of this environmental problem increases day by day in response to high population growth and development activities. This study area is located in an intensively developing area at Kelani valley. These development activities appear to be unsuitable for the future and a cause for changing land use patterns. Both primary and secondary data were used for this study. While primary data were collected through a questionnaire, field observations and community based discussions, secondary data were collected from grama niladari reports and Red Cross society reports. Spatial analysis was carried out using GIS software. The main objective of this study is to find causes of river bank erosion and to explore the reasons for erosion in riparian area of Kelani valley. River bank erosion has resulted in many kinds of environmental problems, for example, damaging houses and buildings, washing away or falling off large extent of agricultural and commercial lands (Malwana, Bogahamula, Raggahwaththa, Pattivila and Bollegala), and damaging Gampaha-Colombo main road (B-218) at several places. Three causes have been identified as the reasons for such environmental problems. They are sand mining in Kelani river, unsuitable construction practices, industrial and agricultural activities in riparian land. Eventually erosion problem could lead to evacuation of people living in the right bank and create several socio- economic problems.