Canyon erosion control
Catchment devices and check-dams
The water from the eastern plateau of Auroville flowing down to the sea has created gullies and major erosion. In the past years the gullies (loftily labeled 'canyons' in Aurovilian parlance...) have widened, and the lands adjacent are now threatened. The canyons, which cut at length through the Auroville plateau and its bioregion, have their own beauty, but left unattended they are also environmental disaster areas, cutting ever deeper into the landscape and funneling precious rainwater and tons of topsoil every monsoon into the nearby Bay of Bengal.
To solve these environmental problems, Dutch Aurovilian Kireet, in collaboration with the Auroville Water Service 'Harvest', started building check-dams in several of the gullies, sponsored by the local District Rural Development Agency (DRDA).
As the Utility canyon is one of our major run-off channels, and has great potential to store water, several check-dams have been made during the past year, mainly for run-off, silting and erosion control. Since then we have decided to proceed with four more check-dams, this time in the Aspiration canyon for the same purpose.
In order to help in the very important water catchment system that Auroville has created during the years, we also envisage increasing the percolation rate via the dams. For this purpose, one barrage wall of 3m height and 10m length and one earthen dam of 2m height and nearly 35m length have been built for water storage and percolation, both in Utility canyon.
After several months of heavy work, with the help of an excavator, the above check-dams and barrage wall were finished, and the earthen dam is completed. Now these structures are ready for harvesting rainwater during the monsoons.
The first barrage wall stores 14,500 m3 of water in a relatively narrow portion of 400 metres length. The other one, just nearby, stores 10,000 m3 of water in a much wider area of 200 m length. This not only means that we are now capable of storing this amount of water, but has the added benefit of allowing it to infiltrate into the ground. To know how much more water can be conserved, we have to wait till the next monsoon when we'll do some work on site to check the infiltration rate. We will also try and determinate how quickly the storage capacities become overloaded, which will give us an idea of the real run-off rate in the area.
In case you pass by Auroville, come and have a look! The area is located near the coastal road, at the end of Utility canyon. In times of heavy rain, it ought to be an impressive place to visit..
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