Residents in large parts of the State are bracing themselves for the worst as the soaring summer heat begins to sap precious drinking water resources, leaving the administration struggling to cope with a looming water crisis. The widening gap between the demand and supply of potable water, especially in fast developing urban centres, has highlighted the need to identify alternative sources of fresh water.
Scientists feel that the pit lakes left behind after open- cut quarrying for hard rocks have the potential to be developed as alternative water sources.
A pilot study conducted by the Centre for Earth Science Studies (CESS) here has revealed that the pit lakes could be used to supply water to parched areas. The sprawling water bodies, some of them spread over hectares, are often considered a liability and danger by the local people. Scores of people have gone to a watery grave in the deep pit lakes.
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The study carried out by Sheikha E. John, Maya. K, Nisha K.V and Padmalal D notes that no attempt has been made to tap the pit lakes, despite the soaring demand for water triggered by the development activities in Kerala over the past two to three decades.
The scientists who analysed the water quality of the pit lakes in Parakadavu panchayat on the outskirts of Kochi city, presented their findings at a regional seminar on water quality assessment and management held here recently.
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According to Dr. Padmalal, the choice of Parakadavu was dictated by the emergence of Kochi as a potential metro city and the increasing demand for water. “The current water supply schemes can contribute only 489 MLD (Million Litres Daily) of fresh water, leading to a deficit of 200 MLD,” he points out.
Rock in peril
Characterised by rocky terrain, the Parakadavu panchayat has been a major supplier of building stones and aggregate materials to Kochi and its satellite towns for many years.
The operation of several quarries has severely degraded the Mailadum Para, a rock series of significance in the area.
Quarries mapped
The research team conducted systematic field surveys in the panchayat to collect primary and secondary data on quarrying activities as well as on the quality of water collected from the pit lakes, a nearby pond and open well.
A total of 31 rock quarries, both active and abandoned, were mapped during the survey. The collective volume of water held in the pit lakes was estimated to be 5,80,415 cubic metres in the dry months.
The pit lake at Elavoor was found to be the largest one in the area. The water in this quarry was used for irrigation while the other pit lakes were not being utilised.
The study revealed that all the water quality parameters fell well within the drinking water standards prescribed by WHO and BIS. The high concentration of chlorides, sulphates and nutrients was attributed to agricultural run-off.
State-wide survey
Highlighting the recommendations of the study, Dr. Padmalal said the pit lakes could be developed as alternative sources of fresh water for the developing urban centres in Kerala if quarrying was integrated with the regional development plan and regulated scientifically. “With each summer registering record mercury levels, it is imperative for Kerala to accord priority for such projects,” he feels.
The scientists have proposed a State-wide survey to assess the volume and quality of water in pit lakes. They also stress the need for a permanent mechanism to monitor the water quality.