Eutrophication, Water Quality, and Ecosystem Services of Two Selected Urban Wetlands of Lalitpur District, Central Nepal

Eutrophication is a major cause of wetlands degradation worldwide. In Nepal, urban wetlands play a crucial role in delivering ecosystem services essential for maintaining biodiversity and supporting local livelihoods. Therefore, conservation, sustainable management, and wise use of wetlands are imperative. This study evaluates water quality, eutrophication status, and the ecosystem service of two urban wetlands- Nagdaha and Ankhidaha situated within the Kathmandu Valley, Nepal. Standard methodologies were followed to assess water quality parameters, while key informant interviews were conducted to evaluate ecosystem services. Temporal changes in Land use land cover (LUCC) for the years 2000, 2010, and 2020 were analyzed using Landsat-7 satellite imagery. The water quality index values of Nagdaha (50.15) and Ankhidaha (552.47) indicate poor water quality. Statistical analyses revealed a strong correlation between nitrate and dissolved oxygen levels in both wetlands- Nagdaha (t = 35.68, p<0.001) and Ankhidaha (t= 9.42, p<0.001). Dissolved oxygen levels in Ankhidaha for the years 2018, 2019, and 2021 were found to pose a substantial threat to aquatic life. The findings indicate that eutrophication is compromising wetlands quality, subsequently diminishing the provision of ecosystem services. Land use land cover analysis highlights rapid urbanization, leading to a decline in vegetated areas and a consequent deterioration in water quality. Nine ecosystem services were identified as relevant to both local and broader communities, with recreation and ecotourism, biodiversity conservation, and educational opportunities emerging as the most prioritized. These insights provide valuable guidance for urban wetlands management and ecological restoration efforts.