What can one person do to reduce Thampanoor’s infamous problem of water-logging? For an answer, let’s turn to Kapil Sreedhar, a resident of East Thampanoor. He, with the technical support of Communication and Capacity Development Unit (CCDU), has built a cost-effective flood control gallery in his compound. It ensures that rainwater is not drained into the road.
In addition to contributing less to the Thampanoor flash floods, the gallery has also resolved the water-logging issue inside his compound. “I approached CCDU because earlier when it would rain, it would take hours for the water to drain out. Now, after the construction of the gallery, it does not take more than 20 minutes. I am planning to correct the compound’s slope further, so that more water is channellised to the gallery,” says Kapil.
Building the percolation pit cost Kapil almost `10,000, of which around `6,000 was spent on labour - 3-4 hands hired for four days. CCDU director Subhashchandra Bose hopes that more people will follow his example. “Thampanoor water-logging can be mitigated to a large extent if several others follow his example. If similar galleries are constructed for 1,000 houses, the total cost would come around Rs 1 crore. Compare that to the many crores spent on Thampanoor water-logging,” says Bose.
The watershed management expert also suggests the revival of four ponds in Thiruvananthapuram to reduce surface run-off and increase groundwater run-off. These are Thamarakulam in Armed Reserve Camp, Nandavanam; Erumakkulam, near Chengalchoola; Pathrakkulam, at East Fort; and Manjalikulam.
The objective of all groundwater recharge systems is to decrease the velocity of water flow as well as increase infiltration rate and time of concentration. “In addition to merely recharging groundwater, some can resort to rooftop rainwater harvesting mechanisms,” suggests Bose.
As per Kerala Municipality Building (Amendment) Rules, 2004, the civic bodies are bound to enforce ground water recharging arrangements as an integral part of all new building constructions, through collection of roof top rainwater. Moreover, all new residential building constructions with a floor area of 100 sq m or more and plot area of 200 sq m or more should have rooftop rainwater harvesting arrangements.
Since Kapil’s building is old, it is not mandatory for him to build a rainwater harvesting mechanism. He says, “I wish to construct an underground harvesting system. But, it would cost me Rs 1.5 lakh. If the government gives some kind of subsidy for people like me, who have to rely on a fixed income, it will be very helpful.”
In the state, rainwater harvesting is yet to find many takers, especially for houses constructed before it became mandatory to have provisions for rainwater harvesting. Adding a harvesting mechanism to the existing structure costs higher than building one during the construction stage. Moreover, most feel that the system could turn out to be an eyesore.
CCDU offers a few smart ideas to conceal rainwater harvesting tanks. These have been implemented by city residents and found to be effective.
Under the Garden
No one who sees Leena’s garden at her home in Vazhuthacaud will be able to guess that underneath it is a 10,000-litre rainwater harvesting system. Under the lush green lawn, there is a sump. Water from the rooftop of the house gets collected here and is pumped back to the roof to be sprinkled on a rooftop garden. The cost of the structure was Rs 40,000.
Those who are planning to add a car shed to their houses can consider adding an underground rainwater harvesting system to it. This works similar in principle to the garden rainwater harvesting system. Das Antony, a resident of Vazhuthacaud, has built an 80,000-litre rainwater harvesting system.
The cost of a rainwater harvesting system is roughly calculated as Rs 4 for every litre. Ferro-cement is used in the place of RCC for cost-effective harvesting.