Over development of groundwater environment could lead to drying up of wells and decrease in water levels. It could also result in drying up of streams and lakes apart from causing induced pollution, Arun P.R., a scientist at the Centre for Water Resources Development and Management, Kunnamangalam, says.
Of the 152 block panchayats in Kerala, 22 have been categorised as semi-critical in terms of ‘stage groundwater development and water level trend’ based on studies. Three blocks – Kasaragod, Malampuzha and Kodungallur – are in ‘critical’ category while one block – Chittur – is classified as overexploited. Fifty blocks have reached more than 70% development of groundwater, Mr. Arun told The Hindu.
“People should abstain from concreting the surface of house compounds. If they want to cover the surface, interlocking bricks could be used so as to allow water to reach the ground. Similarly, using concrete on the sides of roads should be avoided.,” he said.
One of the problems related to development of groundwater in the coastal areas is salinity. The length of saline water intrusion is 250-600 metres from the coast now. The intrusion can spread to wider areas if groundwater is overdeveloped. The coastal topography consists of ridges, having thick sandy alluvium, and runnels with lesser thickness of sand. Excessive pumping and deeper extraction result in salinity influx during dry season in coastal areas.
High iron content in borewells and bacteriological contamination in certain areas could be a cause of concern in several areas. “Ferrous sulphate is unstable and precipitates as insoluble ferric hydroxide, which settles out as rust coloured silt. Water gets a bad taste and odour. It is unpalatable, even at low concentration (0.3mg/litre). Excess iron promotes growth of iron bacteria and they deposit slimy coating.”
Fluoride found in groundwater in Alappuzha and Palakkad districts was another issue that merited observation. “Sources of fluoride in groundwater are minerals such as calcium fluoride, apatite, cryolite, and fluorspar. Fluoride is present in deeper aquifer in and around Alappuzha district as well as shallow and deeper aquifers along eastern parts of Palakkad,” he said.