Temporal Variability of Physicochemical Water Quality Parameters in the Kalpathy River, Palakkad District, Kerala

Abstract

This study investigates the seasonal variations in the water quality of the Kalpathy River from 2022 to 2024, focusing on physical, chemical, and biological parameters across the pre monsoon, monsoon, and post-monsoon seasons. Monthly water samples were collected at a depth of 0.5 meters using sterilized plastic bottles. The key parameters analysed included temperature, dissolved oxygen (DO), electrical conductivity (EC), pH, nitrates, total coliforms (TC), faecal coliforms (FC), faecal streptococci (FSC), phosphates, total dissolved solids (TDS), total suspended solids (TSS), chemical oxygen demand (COD), and biochemical oxygen demand (BOD). Standard laboratory procedures were followed to ensure the accuracy of results and minimize contamination. The results revealed consistent seasonal trends in water quality. Temperature remained stable across seasons, with a slight decrease in the post-monsoon period. DO levels peaked during the monsoon, likely due to increased water turbulence. EC, TDS, and phosphate concentrations were highest during the monsoon, driven by runoff from agricultural and urban areas. Microbiological parameters, including TC, FC, and FSC, showed elevated levels throughout all seasons, with significant spikes during the monsoon, suggesting contamination from untreated sewage and agricultural runoff. COD and BOD values were highest in the pre monsoon period, decreasing in the monsoon and post-monsoon due to dilution from rainfall.

Introduction

Kerala, in southern India, is known for its rich biodiversity, tropical climate, and extensive network of rivers, lakes, and backwaters, which are vital for ecological balance, agriculture, domestic use, and transportation. Among these, the Kalpathy River is important for human consumption, agriculture, aquatic habitats, and local livelihoods, but faces ecological stress due to natural and human-induced pressures. Seasonal variations, especially during the monsoon, influence water quality through increased runoff, nutrient loading, and pollutant influx.

Materials and Methods:

• Water samples were collected monthly from Kalpathy River over two years (2022–2024), covering pre-monsoon (Feb–May), monsoon (Jun–Sep), and post-monsoon (Oct–Jan) seasons.

• Sampling depth: 0.5 m. Samples were analyzed within 24 hours for physical, chemical, and biological parameters.

• Parameters analyzed: Temperature, Turbidity, pH, Dissolved Oxygen (DO), Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Coliforms, Fecal Coliforms, Fecal Streptococci, Total Dissolved Solids (TDS), Total Fixed Solids (TFS), Total Suspended Solids (TSS), Nitrate, Phosphate, Sulphate, and Electrical Conductivity.

Results and Discussion:

• Temperature: Relatively stable (28–29.5°C) across seasons; slight post-monsoon decrease due to rainfall.

• Dissolved Oxygen (DO): Highest during monsoon (6.68 ± 1.03 mg/L) due to increased water aeration, supporting aquatic life.

• pH and Electrical Conductivity: Within safe ranges for freshwater ecosystems.

• Nutrients: Nitrate and phosphate levels increased sharply during monsoon, likely from agricultural runoff.

• Microbial Indicators: Total and fecal coliforms were high throughout the year, indicating contamination from sewage and urban runoff; fecal streptococci also increased during monsoon, highlighting potential health risks.

• BOD and COD: Low levels indicate minimal organic pollution.

• TDS, TFS, TSS, and Sulphate: Seasonal variations observed, but mostly within acceptable limits.

• Turbidity: Slightly increased during monsoon but remained within safe limits.

References

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Copyright

Copyright © 2026 Binumol M., Nisy S., Shahana Shirin C., Vinaya V. . This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.