Using Geographic Information Systems (GIS) to Assess Lake Morphometry, Siltation-Induced Ecological Deterioration, and Land Use/ land cover practices on the Dry Bed of Chilua Lake, Tarai Region, India

Aquatic ecosystems regulate and play great ecological roles, for instance, provide habitats for flora and fauna, nutrient cycles, maintain stream flow, climatic control, and support livelihood security through fisheries, recreational activity etc. However, anthropogenic activities have dramatically deteriorated the aquatic ecosystem. Geospatial techniques are significant for the extraction of morphometric features of lake. An analysis of 97 years (from 1922 toposheets to Google Earth Images, 2019) of Chilua Lake in Tarai region , revealed deterioration scenario. The extent of Chilua Lake is reduced up 27.75% in 97 years from 1922 to 2019. As per the 500 m buffer analysis surrounds of lake Chilua, 1.3% built-up area increased around the lake within 15 years (from 2004 to 2019). For 6 to 8 months, the lake goes dry out and the water left behind in patches and engaged in various activities by the locals. Lake bed is covered by stream like storage (20%) and water is available during all seasons, water left in patches during dry season (15%), littoral plant coverage (45%), farming (11%), dry lake bed (10%), and built-up area (0.3%). Increasing built-up, farming on dry bed, dumping of solid waste and sewage entry have contributed directly pushed towards eutrophic status lake ecology at C1 (sewage entering sources) and C3 (agricultural practices) based on the BOD, BO, TP, NO ₃ , SD, GPP, Chla, etc. This study investigates factors of lake deterioration and suggest the practices of Stewardship in the way of basin lake management techniques (BLMT) and Tripple-P model.