18 Years Rainwater Harvesting and Erosion Control
Welcome.
I have been asked to show you some spots where I have been hanging out.
During more than 40 years I have had the privilege to observe the development of Auroville’s ecologic evolution. I arrived May 21, 1972 early morning after a hectic night in the bus from Bangalore. I walked in bliss in a red desert and I felt coming home. But where did I come? I was looking for Ruud Lohman, whose book about Auroville had inspired me. I found him in a big hole, the foundation of Matrimandir.
Matrimandir is about 50 mm above the sea, so we are on a slope. Deforestation during the last hundred years helped to erode the lands and create a barren and desert like landscape with many canyons.
I saw the bunding and the planting of trees by the first pioneers in 1975. In 1976 I stayed for a short time in Utility. There was no road, so we walked through the Utility canyon. I felt strongly that there should be a dam in this canyon.
In 1985/86 I Shaw the first results of bunding and tree planting. Serious dam building has been done. It inspired me a lot and I was sure Auroville could be green again.
In 1996 I could selttle down. From the rooftop of Gaia’s Garden everything looked green, so I thought the job was done.
But the monsoon in 1997 showed an enormous run off; bunds were breaking and the rainwater flowed though the canyons in the Bay of Bengal. The sea was bleeding with tons of laterite soil.
I climbed down the canyon looking for the dam I envisioned in 1976. I did not find that dam, but up stream I found many broken dams. They were made by the government, but broke down soon in the coming monsoons.
Michael Mason was repairing them and he and Jaap inspired me. They taught me the first principles and I stared repairing old ones and then building new ones.
By doing I developed a system. First I made the apron, so no cement got wasted and by mixing the cement on it strengthen the apron. Then the foundation of the spillway and the toe. Last the wing walls.
Before starting a new dam I walked and surveyed the canyon for the right location. The right location was extremely important.
For the construction we used granite and concrete, as the flow of water in the canyons was a destructive force. Martanda is standing on the spillway. Under the apron and the toe.
After some years and seeing a dam regularly overflowing I raised the dam.
Here we see the basin being filled up. Village kids came to swim.
About 5 years ago a benign cyclone gave abundant rains and all the basins filled up.
The observations of the monsoons learned me a lot and kept me busy to improve.
Here you see a dam near Bommyarpalyam with I raised twice. It is made for the special occasions when the rains are extremely torrential.
Trying to catch as much water as possible and using all existent gullies and holes.
Each monsoon is a challenge and after a good rain it is worthwhile to go and have look what is happening. If this dam starts overflowing, it is becoming interesting.
Then I will start looking further.
Granite and concrete check dams are expensive. And in order to have no sleepless nights they have to be very strong. In the Success canyon we tried for the first time an earth dam. As it proved successful and the tree main canyons were canalized I stopped with my team and just hired a JCB for landscaping.
The Utility canyon had enough capacity to store all, but the Aspiration canyon is narrow and when it rains torrentially it will overflow near Quiet.
The landscaping started in Sadhana Forest. The sandy soil erodes quickly and the underlying Manaveli clay prevents a quick percolation.
Buddha garden has the same soil structure.
Where ever there is laterite soil the percolation goes very fast. Like here in Discipline forest.
The International Zone keeps its water long near Visitors Centre, but after the American house it percolates fast. With a normal monsoon the I.Z has no run-off. But it is important to clean and maintain the ponds annually.
Recent work in Hermitage. From top to bottom.
As said in the beginning the pioneers did next to bunding and tree planting serious dam building. Here a dam in Aurodam, made by hand.
Still in a very good shape, but was asked to raise it in order to extend its capacity.