GIS-based assessment of lake morphometry, siltation, and LULC dynamics in Chilua lake, Tarai region, India

Aquatic ecosystems play a crucial role in regulating ecological processes, such as providing habitats for various flora and fauna, facilitating nutrient cycles, maintaining streamflow, regulating climate, and ensuring livelihood security. Morphometric parameters, land use/land cover analysis, and the eutrophication level of Chilua Lake were analyzed in this study. An analysis using geospatial techniques over a 97-year period (1922–2019) of Chilua Lake in the Tarai region revealed a concerning deterioration, with a 27.75% reduction in the lake’s surface water extent. Due to the shallow nature of this lake, for a period of 6 to 8 months, the lake bed becomes dry, resulting in the formation of water patches which are utilized by local inhabitants. Consequently, the lake bed functions as a stream-like storage system, with 20% of the area retaining water throughout all seasons, while 15% is covered by water patches during the dry season. Furthermore, the coverage of littoral plants, agricultural activities, and urban development accounts for 45%, 11%, and 0.3%, respectively, whereas 10% of the area remains a dry lake bed. Over the same period, the built-up area around Chilua Lake increased by 1.3%, as revealed through buffer analysis over 15 years (2004–2019). Consequently, the expansion of built-up areas, cultivation on the dry lake bed, and the disposal of solid waste along with sewage inflow have directly contributed to the eutrophic status of the lake, particularly at sites C1 (sewage sources) and C3 (agricultural practices). Therefore, this study aims to investigate the factors contributing to lake deterioration and to propose stewardship practices through Basin Lake Management Techniques (BLMT) and the Triple-P model.