Assessment of Ecological Conditions on Loktak Lake After Construction of Ithai Barrage

The construction of the Ithai BarrageBarrage construction on the Manipur River has significantly altered the ecological balance of Loktak Lake, prompting a need to assess its impact on the lake’s hydrology and ecology. This study systematically analyzes the spatiotemporal changes in surface water, land use/land cover (LULC), and ecological water conditions in Loktak Lake from 1976 to 2022, focusing on the influence of the barrage. Methodologically, the study employed Normalized Difference Water IndexNormalized difference water index (NDWI) and Modified NDWIModified normalized difference water index (MNDWI) for surface water mapping, utilizing thresholding techniques. LULC changes were assessed using random forest supervised classification. Additionally, water presence frequency was used to evaluate ecological water conditions, and statistical analyses were conducted to quantify the barrage’s impact. LULC dynamics shows an increase in agricultural ponds from 6.10 km2 in 1976 to 29.22 km2 in 2022 and an expansion of built-up areas from 2.28 to 5.41 km2 over the same period. PhumdiPhumdi coverage exhibited variability, with thick vegetation areas peaking at 58.76 km2 in 2007 before reducing to 19.96 km2 by 2022. Ecological water assessment indicates an increase in ‘Low Ecological WaterLow ecological water’ areas from 63.23 km2 in 1976 to 76.16 km2 in 2022, and in ‘Ecological Water’ areas from 6.10 to 29.22 km2, suggesting shifts in ecological conditions. Statistical analysis of the barrage’s impact showed an R2 of 0.5008 and 0.1786 for NDWINormalized difference water index and MNDWIModified normalized difference water index, implying a moderate correlation with time respectively. The LULC R2 values highlighted varied impacts across different land cover types. Therefore, the Ithai Barrage significantly influences Loktak Lake’s hydrologicalHydrological dynamics and ecological dynamics, underscoring the need for integrated management to mitigate disruptions while considering socio-economic benefits.