Land system transformations govern the trophic status of an urban wetland ecosystem: Perspectives from remote sensing and water quality analysis
Shahid Ahmad Dar, Irfan Rashid, Sami Ullah Bhat
Abstract
Abstract Globally, urban wetlands are facing immense pressure from land use land cover changes (LULCCs) and associated water quality degradation that is severely affecting the trophic status of these ecosystems. This study analyzed water quality degradation resulting from land system changes in the vicinity of Khushalsar, an urban Wetland, in Srinagar City from 1980 to 2017. The analysis of satellite data indicated that this Wetland lost ~18.1 ha from 1980 to 2017. During the same period, the urban area within the Wetland increased from 0.2% to 16.5%. The land cover changes assessed in the vicinity of Wetland indicated an increase of 119% and 62.8% in built‐up and roads respectively. The analysis of surface water quality of the Wetland showed widespread degradation. The Trophic state index ranged from 73.4 to 84.6 indicating hyper‐eutrophic waters. A snapshot of comparative water quality data from 2002 to 2018 revealed that the mean concentration of NO 3 − ‐N increased from 219 to 433 μg L −1 and that of total phosphorus increased from 135.4 to 1,236 μg L −1 indicative of continuous nutrient enrichment. Hierarchical cluster analysis (HCA) grouped eight sampling sites into four clusters based on likeliness of water quality characteristics. Similarly, discriminant analysis showed the formation of similar patterns of clusters, corroborating the HCA. Principal component analysis suggested three principal components accounting for a cumulative variance of 90.61%. The unplanned land system changes vis‐a‐vis human‐induced water quality degradation together with the lack of a monitoring mechanism have brought the Khushalsar Wetland to its current hyper‐eutrophic state.