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Notice (8): Undefined variable: urlPrefix [APP/Template/Layout/printlayout.ctp, line 8]water-and-sanitation/check-dam-in-a-day-using-plastic-sheets-shree-padre-4676059.html"/> Water and Sanitation | Check dam in a day using plastic sheets -Shree Padre | Im4change.org
Resource centre on India's rural distress
 
 

Check dam in a day using plastic sheets -Shree Padre
-CivilSocietyOnline.com

Kasargod: In 2000, Pidamale Govinda Bhat, 63, a middle-class areca nut farmer, rigged up an experimental check dam with sand and plastic sheets. For decades, his family had been constructing a temporary check dam across the Okkethoor river with stones and soil to irrigate their farm.

“The government constructed a vented dam for us in place of our temporary check dam,” recalls Bhat. “But the sarkari dam leaked and leaked. By 2000 it had become virtually useless.”

Bhat knew very well that if the flow of water in the river wasn’t checked, the whole area would face drought in summer. That had happened in 1983. The check dam didn’t get filled, wells dried up too and farmers stared at crop loss.

So,in 2000, Bhat stepped in and invented his own dam with sand and plasticsheets. It served its purpose. This type of check dam can be rigged up in just one day with the help of an earth mover. Not much labour or skill is required.

Inventing low-cost check dams with locally available material seems to have caught on among farmers in the district. The dams are temporary, sturdy and the material used can be recycled the next year.  

The decline of the traditional katta dam seems to have sparked a small revolution in check dam technology. Until some decades ago, Dakshina Kannada district had thousands of kattas or temporary check dams. They had to be constructed every year. The process was laborious but farmers paid for their construction.

Whenthe monsoon begins in June, most of the stones and part of the soil used in kattas gets washed away in floods. Before that happens, farmers remove the soil and keep it for the next year’s katta. But in recent years both labour and skill started becoming scarce. So farmers began experimenting.

Bhat’s inventive dam appears to be replacing the katta. Its benefits are many. His innovative check dam captures about 10crore litres of water and irrigates around 120 acres on both sides of the river.  The income of the families here comes to  about  Rs 3 crore annually. They spend about Rs 60,000 on water. No family in the vicinitynow suffers from a shortage of drinking water.

To construct Bhat’s sand-and-plastic-sheet check dam, a solid foundation has to be built the previous summer. This is done by digging a trench at the site till the level of the bed rock or layer of soil devoid of any sand. The trench is extended a bit on both sides of the river’s banks to avoid seepage at a later stage. Then a plastic sheet is lowered into the trench before it is refilled. The upper end of the sheet is rolled like acalendar. Weights are placed above this roll so that the sheet doesn’t get damaged or dislocated during the monsoon.

After the monsoon is over and the flow of water in the river recedes, it’s time to construct the check dam. An earth mover is commissioned to heap the sandin a specific manner. A vent is provided for the water to flow out during the time of construction. After the earth mover heaps the sand like a small hillock nine feet high, a second, bigger, plastic sheet is spread from the inner side over the whole heap. The width of the check dam is 150 feet. The rolled upper edge of the plastic sheet used in the foundation is now joined with the inner free end of the new sheet. The two sheets are joined by rolling them together and stones are placed to weigh them down.  

The other end of the plastic sheet is used to cover the entire check dam. This is to prevent any damage if there is unexpected heavy rain or floods. “This year, there was a burst of rain and water overflowed like a waterfall for three weeks,” recalls Ramachandra Sharma, Bhat’s son. “But there was no damage to the check dam.”

Interestingly, there is very little seepage in this layman’s check dam. “Whatever seepage is there, we pump the water for irrigation instead of draining stored water from the check dam,” explains Ramachandra. Their 18-acre areca nut garden requires 350,000 litres of water a day. So, for the entire irrigation season of six months from December to May, their farm needs 60 million litres of water.

Apart from Bhat’s family, 12 families nearby use water from this check dam. More than 75 horsepower is used to lift water for irrigation of about 120 acres on both sides of the river. The water level increases to 2.5 km in length. The total water that is stored would be about 100 million litres. This works out to about `6 for a kilolitre of stored water.

The plastic sheet gets damaged every year because of the sand heaped on it. So the Bhats have to buy a new one every year. A 120 gsm (grams per square metre) sheet costs them Rs 20,000. The neighbours who use the water voluntarily pay Sharma. “This takes care of half the cost every year,” he says.

In contrast, the state government’s minor irrigation department constructed a new damto replace an old dilapidated cement vented dam last year at a cost of `1 crore. But the structure leaks very badly. “With just the interest from the money the department invests for such concrete dams, we could have constructed two to three dozen sand-and-plastic check dams that arefar more effective in checking water flow,” remarks Sharma.

Inspiredby Bhat’s check dam, two neighbours, Pidamale Govindaprasad and Balipaguli Rajaram, together constructed a sand-and-plastic-sheet check dam this year. It cost them very little and they are very happy with itsperformance.

Other farmers are innovating and building similar check dams in adjoining areas.

Onesuch successful effort is the Varanashi check dam invented by Dr Varanashi Krishnamurthy nearly a decade ago. The Varanashi Research Foundation (VRF), a charitable trust headed by Dr Krishnamurthy, named it the Varanashi check dam. The innovation is that, instead of using a lot of soil to stop seepage, a silpaulin sheet is used in this sandbag check dam.

Inspired by the Varanashi check dam, Vasanthkumar Darbe, a farmer, went a step ahead and stopped using sandbags to make the check dam. Instead, he constructed a sand-and-plastic-sheet structure. Noting his success, a few farmers near him followed suit.
 
CivilSocietyOnline.com, April, 2015, http://www.civilsocietyonline.com/pages/Details.aspx?727