Trophic classification and assessment of lake health using indexing approach and geostatistical methods for sustainable management of water resources

This study aims to analyse the spatio-temporal trends in water quality, trophic state, and organic contamination of an alpine lake in the Darjeeling Himalaya through field investigations and to portray a comprehensive picture using multivariate analysis. Analysed water parameters have shown notable seasonal variations and were within the acceptable range for inland surface water. Water quality index (WQI) and organic pollution index (OPI) values have displayed 'poor' to 'heavily polluted' status in the pre-monsoon season, with marginally better conditions during the post-monsoon studies. Trophic state indices (TSIs) values revealed 'eutrophic to highly eutrophic' conditions during the investigation period. The results of the PCA have depicted three major determining factors (i.e., anthropogenic contribution, geogenic or weathering, and seasonal/climatic factors) that control the overall pollution level in the lake water system. The current study can potentially be a benchmark for assessing and undertaking management and restoration measures for this nascent alpine ecosystem.

Automated summary

This study analyzes the spatio-temporal trends in water quality, trophic state, and organic contamination of an alpine lake in the Darjeeling Himalaya through field investigations and multivariate analysis. The study found seasonal variations in water parameters, with acceptable range for inland surface water. Water quality index (WQI) and organic pollution index (OPI) values showed poor to heavily polluted conditions before the monsoon season, with slight improvement during the post-monsoon studies. Trophic state indices (TSIs) values indicated eutrophic to highly eutrophic conditions throughout the investigation period. The study identified three major factors influencing the pollution level in the lake water system: anthropogenic contribution, geogenic or weathering, and seasonal/climatic factors. This study can serve as a benchmark for assessing and implementing management and restoration measures for this emerging alpine ecosystem.