While Karnataka and Tamil Nadu fight over Cauvery water, what has become evident is the poor quality of the water at the centre of the controversy. Researchers from the University of Mysore evaluated the impact of human activity around Karnataka’s Krishna Raja Sagara (KRS) dam on the Cauvery river and found that water at most of the sampling stations was of “very poor quality” and only “partially suitable” for human consumption.
“The growing population, a rise in living standards, urbanisation, intensive agricultural practices, industrialization, and various other demands, has increased the demand for water. Municipal and industrial activity on the bank of rivers constantly discharge degraded water at all seasons and pollute the river water artificially. Hence, variation in water quality is the most important factor to assess in water resources research and risk management. In this research, an assessment of water quality in the Cauvery river was carried out, in order to understand the impact of human activity,” said the paper, published in the International Journal of Research and Scientific Innovation.
The study identified 15 sampling sites, which includes Sagara Katte, Venugopalaswamy Temple, KRS Dam, Balamuri, Yedamuri, Belagola, Pump House, Ranganathitthu, Srirangapatna, Mahadevapura, Gendehosahalli, Rangasamudra, Bannur, Somanathapura and T Narasipura.
What they found
Assessment of heavy metal parameters shows that the concentration of iron and copper in all sampled locations, both pre-monsoon and post monsoon, was on the higher level because of sewage discharge and corrosion of water-supplying pipes from the locality. The concentration of zinc exceeded the FAO (Food and Agricultural Organisation of the United Nations) standards due to the improper management of fertilisers in the agricultural area of the river basin in the pre- and post-monsoon season, said the research team. However, except at T Narasipura, lead and chromium were not detected in any of the samples.
The researchers said that the percentage of sodium in water is a parameter computed to evaluate suitability for irrigation. Excess sodium in water produces the undesirable effects of changing soil properties and reducing soil permeability, so the assessment of sodium concentration is necessary, they said.
Further, while phosphate itself does not have notable adverse health effects, phosphate levels greater than 1.0 may interfere with coagulation in water treatment plants, they added. The last sampling point of T Narasipura recorded a maximum of 100.6 and Srirangapatana 12.1 mg/L in both sodium and potassium analysed samples.
“Present investigation of both sodium and potassium were shown at the limit in the Cauvery river, due to improper urban management as well as agricultural run-offs,” said the paper.
Total hardness is defined as the sum of calcium and magnesium concentrations. Evaluation reveals that total hardness, including calcium and magnesium, was high and unsuitable for anthropological activities. Further, turbidity — which is caused by a variety of suspended matter — was greater in urban areas of the Cauvery river basin as compared with the agricultural irrigated area, because of direct sewage discharge, said the paper.
The researchers also tested the dissolved oxygen, which measures the amount of life-sustaining oxygen dissolved in the water. “A certain minimum amount of oxygen must be present in water for aquatic life to survive. This oxygen is available for fish, invertebrates, and all other aquatic animals. Collected sample from Ranganathitthu shows maximum (dissolved oxygen) and Pump House sample shows minimum due to harsh agricultural activities from localities,” said the research team.
They added, “Biochemical Oxygen Demand (BOD) is a measure of the amount of biological pollution as bacteria utilise organic matter in their respiration and remove oxygen from the water. All respective samples in the analysed seasons are within permissible limits, except at T Narasipura.”
The researchers have recommended immediate mitigation measures along with long-term monitoring to avoid further contamination of the “life-river of south”.
Credits Bangalore Mirror