Planform Changes in the Lower Mahaweli River, Sri Lanka Using Landsat Satellite Data

Major development projects along rivers, like reservoirs and other hydraulic structures, have changed not only river discharges but also sediment transport. Thus, changes in planforms can be observed such rivers. In addition, centerline migrations witnessed. The Mahaweli River is the longest Sri Lanka, having largest catchment area among 103 major basins country. has been subjected to many over last 50 years, causing significant discharge However, no research carried out evaluate temporal spatial planforms. current seeks qualitatively analyze planform of Lower (downstream Damanewewa) past 30 years (from 1991 2021) identify features their spatiotemporal lower River. Analyzing rivers requires long-term data with high resolution. Therefore, this research, remotely sensed Landsat satellite were used a considerably resolution (30 m). These images processed analyzed using QGIS mapping tool semi-automated digitizing tool. results show that occurred mainly most downstream sections selected segment. Further, curvature was comparatively river. An oxbow lake formation time part after 2011. Centerline migration rates calculated generated centerlines. It found generally than about m per year, except for at locations where meandering observed. main limitations study possible misclassifications due obstructions caused by cloud cover images. To achieve more accurate estimates, could developed further quantitative mathematical analysis considering dynamics