Nagaland University Study Exposes Land Use as Key Driver of Water Pollution in Loktak Lake Catchment

Research finds agricultural runoff, human settlements, and shifting cultivation severely degrading river water quality; Nambul and Khuga rivers identified as most polluted due to extensive land-use disturbances.

 A groundbreaking study by Nagaland University has revealed a strong correlation between land use changes and deteriorating water quality in the Loktak Lake catchment area of Manipur– raising fresh concerns for India’s only floating national park and the endangered Sangai deer habitat.

The research, led by Dr. Eliza Khwairakpam, Assistant Professor, Department of Environmental Science, found that agricultural runoff, expanding settlements, and shifting cultivation are directly contributing to the degradation of rivers feeding the lake. The Nambul and Khuga rivers were identified as the most polluted due to extensive land-use disturbances.

Loktak Lake, a Ramsar Site known for its rich biodiversity with 132 plant species and 428 animal species, supports fisheries, hydropower, transport, and tourism. However, the study warns that unchecked human activity in its catchment could further threaten its fragile ecosystem, already listed under the Montreux Record for wetlands facing ecological damage.

Field sampling was conducted across nine rivers — Khuga, Western, Nambul, Imphal, Kongba, Iril, Thoubal, Heirok and Sekmai. Using Land Use Land Cover (LULC) mapping, the study established that water quality indicators such as dissolved oxygen and biological oxygen demand were closely tied to surrounding land activities.

“The findings confirm that land use decisions across villages and forest landscapes upstream are directly impacting water quality downstream,” said Dr. Eliza Khwairakpam. “Sustainable land management, stricter control of agricultural runoff, and regulated Jhum cycles are crucial to safeguard Loktak Lake’s ecosystem and the livelihoods dependent on it.”

Nagaland University Vice Chancellor, Prof. Jagadish K. Patnaik, lauded the research as a vital step toward environmental stewardship. “This study highlights the pressing challenges posed by agricultural runoff and human settlements, reinforcing the need for policy-driven, community-based conservation,” he stated.

The study, published in the International Journal of Environment and Pollution (https://doi.org/10.1504/IJEP.2025.148717), was supported by the Forest Department, Government of Manipur, and the Manipur Pollution Control Board, with collaborative inputs from IIT Delhi.

Researchers noted that while rivers like Iril and Thoubal maintained better water quality due to dense forest cover, the Nambul River’s poor oxygen levels and high organic contamination were linked to 47% agricultural and 11% settlement areas in its sub-catchment.

Calling for urgent, catchment-wide action, the study underlines that protecting Loktak’s wetlands is not only an ecological imperative but also a safeguard for the cultural and economic lifeline of Manipur’s people.