Integrated Water Quality Index and Multivariate Statistical Assessment of Surface Water Ponds Across Heterogeneous Land-Use Systems in Trivandrum District, Kerala, India.

Abstract

Surface water ponds embedded within heterogeneous land-use systems are highly susceptible to physicochemical alteration and microbial contamination. The present investigation evaluates the integrated water quality status of eight representative ponds located in Neyyattinkara Taluk, Thiruvananthapuram District, Kerala, India, influenced by distinct anthropogenic activities including hospital discharge, temple use, aquaculture, cattle farming, agricultural runoff, laundry effluent, oil milling, and automobile service activities. Monthly sampling from February 2022 to January 2023 assessed pH, electrical conductivity (EC), total dissolved solids (TDS), turbidity, biological oxygen demand (BOD), and total coliform. Water Quality Index (WQI) was calculated using the weighted arithmetic method, and multivariate statistical analyses including Pearson correlation, Principal Component Analysis (PCA), Hierarchical Cluster Analysis (HCA), and regression modelling were applied. Electrical conductivity and TDS showed significant spatial variability, reflecting ionic enrichment under industrial and agricultural influence. BOD and total coliform concentrations were elevated in cattle farming, laundry, and automobile service ponds, indicating strong organic and faecal contamination. WQI classification ranged from good in temple and aquaculture ponds to very poor in automobile and laundry-impacted systems. PCA identified mineralization, organic pollution, and runoff influence as dominant factors controlling water chemistry. The study demonstrates that land-use intensity governs pond water quality deterioration and highlights urgent need for decentralized management interventions.