Meander plan, sinuosity and bank erosion along river Semliki in Ntoroko district, western Uganda.

Abstract

The study was conducted on River Semliki in Ntoroko District on the Ugandan side of the River. This River has severally bust its banks and is characterized by bank erosion which results into loss of land and the associated side effects. This study was therefore designed to (i) demonstrate changes in the plan and stream sinuosity over the periods between 1986-1990, 1990-2000, 2000-2010, 2010-2016, (ii) quantify the amount of land lost in the cut banks of the River (iii) examine the vegetation and soil characteristics along the River banks. This study used 30m resolution ortho-rectified Landsat TM/ETM images of the study area to map out the meander plan of the River, identify the hotspots of land loss and quantify the amount of land lost in those areas using ArcGIS software version 10.1. Vegetation and soil sampling was carried out in the hotspots of land loss and a control site all within four villages in Ntoroko District, The results obtained showed that River Semliki has continuously changed its meander plan (course) over the time series examined. The sinuosity of the River was majorly meandering. There was a glaring evidence of land loss on the Ugandan side of the River. The loss of land ranged from 10.06 ha in Nyakasenyi village, Butungama. Sub-County to 22.53 ha in Bweramure village, Bweramure Sub-County. The Riverine vegetation was mainly woodlands and grasslands with the major plant species being Phragmites maurilianum, Typha domingensis, Sporobolus pyramidalis, Echinochloa pyramidalis, Cynodon dactylon while the soil type was mainly the red brown loam soil. In order to safeguard the River its bank and the adjacent land, communities surrounding the River should be sensitized on the protection of River banks; enforcement. of the recommended 100m free zone along the River bank, reduction of land use pressure along the River banks especially that resulting from livestock by creation of valley dams for watering livestock; restoration of the degraded sections of the River using native plant species; riprapping meander bend walls with stones to stabilize and reduce the scouring effect of water On channel walls.