Nagaland University researchers have uncovered alarming evidence linking land use patterns to worsening water pollution in Loktak Lake’s catchment area in Manipur. Their findings point to agricultural runoff, expanding settlements, and shifting (Jhum) cultivation as key factors degrading the rivers that feed India’s largest freshwater lake.

Led by Dr Eliza Khwairakpam, Assistant Professor at the Department of Environmental Science, the study assessed nine major rivers — including Nambul, Khuga, Imphal, Iril, and Thoubal — using Land Use Land Cover (LULC) maps to correlate human activity with water quality indicators such as dissolved oxygen and biological oxygen demand.

Results showed the Nambul River as the most polluted, with high organic contamination and low oxygen levels, influenced by 47% agricultural land and 11% settlement coverage. The Khuga River ranked next, despite higher forest cover, due to widespread Jhum cultivation across 42% of the region. Conversely, rivers flowing through forest-dominated landscapes, like Iril and Thoubal, recorded better water quality, underlining the ecological importance of vegetation.

Dr Khwairakpam emphasised that “land use decisions across villages and forest landscapes upstream are directly impacting water quality downstream,” calling for community-based land management and stricter control of agricultural runoff. She added that sustainable practices and controlled Jhum cycles were vital to safeguarding Loktak Lake — home to the endangered Sangai deer and India’s only floating national park.

The research, published in the International Journal of Environment and Pollution, was supported by the Forest Department of Manipur, the Manipur Pollution Control Board, IIT Delhi, and Nagaland University.