Spatio- temporal Evaluation of Physico-chemical Parameters of selected Wetlands of Hajo of Lower Brahmaputra Region, Assam, India

Abstract

Wetlands are important components of fluvial landscapes, providing ecological services and supporting the lives and livelihoods of rural communities. The Brahmaputra valley of Assam contains numerous wetlands with diverse characteristics, and Hajo Revenue Circle in the lower Brahmaputra region includes several wetlands that serve local communities. However, urbanisation, industrialisation, agricultural runoff and settlement growth have contributed to wetland degradation and declining water quality. This study assessed the spatio-temporal patterns of water quality in four selected wetlands, namely Gaurjan beel, Digholi beel, Barbeel and Nitai beel, from December 2022 to October 2023. Monthly water samples of 1 litre were collected and analysed for 11 physicochemical parameters: turbidity (NTU), pH, total hardness (TH, mg/L), iron (Fe, mg/L), chloride (Cl, mg/L), fluoride (F, mg/L), total dissolved solids (TDS, mg/L), calcium (Ca, mg/L), magnesium (Mg, mg/L), sulphate (SO4, mg/L) and total alkalinity (TA, mg/L), following standard analytical procedures. Statistical techniques, including correlation analysis and Principal Component Analysis (PCA), along with the Water Quality Index (WQI), were used to interpret the data. The WQI results indicated that the selected wetlands ranged from poor to very poor water-quality status. Correlation analysis showed interrelationships among the physicochemical parameters, while PCA identified calcium, total hardness, alkalinity and chloride as major contributors to the first principal component. Gaurjan and Barbeel wetlands were particularly affected by human activities, including agricultural runoff. The findings provide useful evidence for water-quality monitoring and wetland management strategies in the study area.