A geospatial approach for limnological characterization of Nigeen Lake, Kashmir Himalaya

The lakes of Kashmir Valley show multiple signs of deterioration. This study integrated multiple datasets pertaining to the land system, lake bathymetry and water quality in GIS environment to limnologically characterize the Nigeen Lake. Settlements in the vicinity of the lake were mapped using high-resolution satellite data of 2003 and 2016. Lake depths measured at 235 points spread across the lake surface were used to produce the detailed bathymetry of Nigeen Lake. Surface water quality data at five sites pertaining to 22 physico-chemical parameters was analyzed for limnological characterization of the lake. The quality of lake water is within the permissible limits as per the drinking water standards set forth by World Health Organization (WHO); however, the values of secchi-disc transparency (0.52-1.39 m) and total phosphorous (184-687 μg L^-1) indicate hypereutrophic state of the lake. The settlements in the lake vicinity expanded by 30% from 2003 to 2016. The bathymetry analysis revealed that the lake depth varied from 1.02 to 6.07 m. The reckless urbanization and inadequate sewage treatment system together with high residence time of water in the Nigeen Lake are responsible for enhanced nutrient enrichment and deterioration in water quality.