An Assessment of Lake Area Shrinkage through Geospatial Approach: Case study of Phewa Lake of Kaski District, NepalDownload PDF
Lake area shrinkage has been severe throughout all ecological regions in Nepal. Sedimentation of lakes reduces both effective depth and surface area of lake, which ultimately reduce the effective life of the lake. Phewa Lake covering an area of about 439 hectares has been one of the prominent tourist attractions of Nepal. Remotely sensed data sets are emerging as better choice for managers to observe spatially explicit changes over the time period where a high repeat frequency is required. This study aims to determine the spatio-temporal change and assess the shrinkage rate of Phewa Lake area. Six temporal (November 1988 to October 2012) Landsat TM and ETM satellite images were used as primary data to detect change and calculate dimensions of the lake. ERDAS IMAGINE 9.2 and ESRI ArcGIS 9.3 were used for digital image processing such as projecting in common coordinate system, digitizing the lake boundary and calculating the area. Standard formula used to calculate annual shrinkage rate of the lake reveals this rate as 0.46% and the lake area as 410.5 ha. respectively. The mean annual decrease of the lake was about 2 ha. Shrinkage in the lake area has indicated that it could create potential threat of eliminating the lake in future. Thus, a detailed study and regular monitoring is recommended for controlling sedimentation problem in the lake.
Keywords: Spatio-temporal change, Sedimentation, Phewa Lake, Lake Area shrinkage