Kaveri pollution report

Introduction

The Kaveri River (also spelled Cauvery) is a critical water resource for South India, supporting an extensive irrigation system, hydroelectric power generation, and household consumption. The river basin spans approximately 72,000 km² and includes several major tributaries such as the Bhavani, Noyyal, Amaravati, Hemavati, and Kabini. Beyond its utilitarian value, the river holds significant cultural and religious importance, with numerous ancient temples lining its banks. However, rapid urbanization, industrialization, and population growth have led to the deterioration of water quality in specific stretches of the river.

Water Quality Assesment via Water Quality Index (WQI)

Studies utilizing the Water Quality Index (WQI) have classified the river’s water suitability for drinking and domestic use.

• Overall Status: The water quality of the main Kaveri River and the Bhavani tributary has been categorized largely as “Excellent” to “Good”. Research conducted during 2009 indicated that WQI values for these rivers were generally below 50, denoting “Excellent” status.

• Seasonal Variations: The river exhibits self-purification capabilities. While quality deteriorates after the confluence with the polluted Noyyal River, the Kaveri is able to regain its original state after a considerable distance during monsoon seasons due to dilution. However, further downstream, the inflow from the Amaravati River causes renewed degradation.

• Tributary Disparities:

  • Bhavani River: Consistently shows good surface water quality suitable for domestic and drinking purposes.
  • Amaravati River: Water quality fluctuates; it is generally good during the post-monsoon season but has been found unfit for drinking at certain locations during the Northeast monsoon.
  • Noyyal River: This tributary represents a severe pollution concern. All samples analyzed from the Noyyal River showed WQI values above 300, rendering the water “unfit for drinking” in all seasons. This is attributed to the heavy discharge of industrial effluents from the Tirupur region.

Physico-Chemical Parameters and Heavy Metals

• General Parameters: For the Kaveri River, most physico-chemical parameters (pH, TDS, etc.) generally remain within safe limits prescribed by the World Health Organization (WHO). However, exceedances in Sodium (Na+) and Total Dissolved Solids (TDS) have been observed at specific locations, particularly near municipal solid waste dumping yards.

• Heavy Metals: An analysis of trace elements—including Zinc (Zn), Copper (Cu), Chromium (Cr), Lead (Pb), and Cadmium (Cd)—revealed the following:

  • Cadmium and Lead: These were not detected in surface water samples during the study periods.
  • Chromium: Detected concentrations (mean 0.034 mg/L) were below the WHO maximum permissible limit of 0.05 mg/L.
  • Copper and Zinc: Mean concentrations were found to be well below the maximum acceptable limits (2.0 mg/L for Cu and 5.0 mg/L for Zn).
    • Sources: While levels are currently low, municipal effluents and solid waste leachates are potential contributors to copper levels in the river.

Sources of Pollution and Anthropogenic Impact

• Urbanization and Sewage: The primary driver of water quality deterioration is the discharge of untreated or partially treated sewage from increasing populations in the basin. Significant land-use changes between 2001 and 2019 saw the conversion of cropland and vegetation into settlements, exacerbating waste generation.
• Industrial Effluents: The Noyyal River serves as a major carrier of pollution into the Kaveri, loaded with huge volumes of industrial effluents from the textile hub of Tirupur. Polluted stretches have been specifically identified in Pallipalayam, Erode, Trichy, and Tiruppur.
• Mining Activities: In the Ariyalur region, limestone mining is prevalent. While the flow of the Kallar River (part of the regional hydrogeological system) opposes the dip of limestone beds—limiting direct hydrological connectivity—groundwater in mining vicinities shows signs of anthropogenic influence. Groundwater samples in these mining areas frequently exceed permissible limits for TDS (27.27% of samples) and Sodium (39.39% of samples).

Conclusion and Recommendations

While the upstream sections of the Kaveri and Bhavani rivers remain relatively clean, the downstream quality is compromised by the inflow of highly polluted tributaries like the Noyyal and Amaravati. The impact of human activity is severe regarding specific parameters, with the Noyyal River requiring “immediate attention”.

To sustain the river’s water quality, the following measures are recommended:

• Sewage Treatment: Implementation of stringent treatment protocols for sewage and industrial waste water before discharge into the river system is essential.
• Monitoring: Continuous monitoring of indiscriminate discharges and strict enforcement of environmental regulations are required to control pollution loads.
• Restoration: Ecological restoration and the construction of protective embankments are suggested for sensitive terrains, such as the limestone mining areas in the Kallar basin.