It’s the worst of the time — the groundwater table in the city and rural areas of Madurai has gone down this year following failure of two consecutive monsoons. Buying water, which has been a practice for hotels and marriage halls, has become the order of the day for most of the apartments and thousands of independent houses as well.
It’s the best of the time — the city received the first showers in the recent days. Northeast monsoon, the most beneficial season for this part of the State, is round the corner. Harvesting the rainwater, which can be done in more than one way, will help recharge the groundwater and provide the best solution to the water woes.
Rainwater harvesting (RWH) was made mandatory in all households, commercial and industrial buildings in the State in 2003. Engineers say the system produced the desired results of augmenting the groundwater in the subsequent years, despite many having put up namesake RWH structures to escape penal action.
However, after a decade since its implementation, people and the government authorities have forgotten the project that was launched by the previous Jayalalithaa government. With no maintenance of the RWH structures like cleaning the silted up percolation structures or non-replacement of worn-out pipes, both by individuals as well as the government agencies, the structures have failed in serving the purpose for which they were installed.
“More than the erratic nature of the rainfall, the increased drawing of groundwater without putting any effort to recharge it, is felt to be the real reason behind the present water crisis,” a Public Works Department engineer says. He feels the State government should once again direct the local bodies to inspect all the RWH structures and ensure that they were effective in recharging the water by preventing rainwater from running off outside their premises.
Even in government buildings in District Revenue Officer (DRO) Colony, there is no proper rain water harvesting system, says its Residents’ Welfare Association secretary S. Kannan. “When borewells under the mini-power pump project were being sunk only for 350 to 400 feet, we sunk a borewell for 700 feet, as we had to cater to the water requirement of over 600 houses,” Mr. Kannan says.
Only two of the six borewells in the colony are functioning and the others have gone dry. Water for daily use (for other than drinking and cooking purposes) was being supplied only once in 15 days.
Stating that the colony was set up on a sprawling ground, the permanent solution to the water problem could be RWH structures near each of the borewells.
A former Chief Engineer, Ground Water Division, PWD, N. Arunachalam, says rooftop water tapped through pipelines should be led into a pit of three-feet diameter at 5 to 10 feet away from the borewells and open wells. Seven concrete rings of a feet high should be inserted and half the pit filled with pebbles. “This structure will filter the water and recharge the wells and borewells,” he says.
The same water could be collected in sumps through finer filtration structure. The roof water should be led into a percolation pit filled with pebbles in the bottom. It should have one layer each of sand of finer granules and charcoal powder. “If the sump is given a good coat of food-grade paint, the quality of water will not change for months,” he says. All the pipelines should be covered with fine nets so that rats and other reptiles do not enter them.
The surplus water, after the sump is filled, could be used for groundwater recharge. “We can re-pay Mother Earth with water which we had drawn over the years,” he says.
Storm water drains
One of the major reasons for the ground water depletion is the new storm water drainage (SWD) under construction in the city, complains Mr. Kannan. The Corporation is constructing SWD along all major roads and streets to prevent inundation during rain. However, the concrete bed of the SWD has prevented percolation of water into the ground, and drained the run-off water into the Vaigai.
Though, initially, the SWD were designed without RWH recharge pits, Mr. Arunachalam, as a consultant to the Madurai Corporation, had suggested putting up recharge pits for every 15 metres of the SWD. The Corporation did not follow the advice to dig one-and-a-half foot deep recharge pits with pebbles, he says.
However, Corporation City Engineer A. Mathuram says such pits were put up in the lined drainage channels. “Even in Chennai, such a design has not been implemented in the roadside drains,” he says.
The RWH system proposed to recharge the dry Mariamman Teppakulam remains only in paper. The Corporation and the Hindu Religious and Charitable Endowments department planned to tap the run-off water from the four wide roads around the Teppakulam. “The officials have been talking about the RWH in Teppakulam for years, but not have implemented it. At least now, when the ground water has sunk very low, the district administration should take up the project, before the monsoon sets in,” Communist Party of India (Marxist) MLA R. Annadurai says.
He points out that successful implementation of rainwater harvesting practices has resulted in the Mariamman Teppakulam in Virudhunagar having water throughout the year. If rainwater could be stored in Madurai Teppakulam, it would recharge the groundwater in Anuppanadi, Iravathanallur and Munichalai areas, he says.