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Water conservation

Some of the earliest major works in the Forest Park and the Children's park were the creation of a series of ponds that would be able to fill in the monsoon and thus recharge the groundwater, create further habitat for plant and animal life, and bring some added beauty into the parks. These ponds were dug almost entirely by hand. This meant working at a speed where the contours of the land and the rocks within could dictate the shapes of the ponds. The excavated silt and rocks came at a speed conducive to creative use in landscaping and gardening. Working by hand also meant spreading the cost of the ponds around many families for months, rather than one JCB owner and the petrol companies.

sieving sandWhile the ponds are lovely to see full of water after the monsoon, the real water conservation connected to our work is largely unseen. Prior to 2003, annual fires burned the covering vegetation from the hill slopes. This exposed the soil to summer sun, baking it hard. When the rains arrived the water ran off the steep, hard slopes, carrying with it precious soils. Streams ran fast, full of sand and silt, and quickly dried up when the rain ceased.

From 2004 onward, we noticed a dramatic change in this pattern. As each year the areas burned were reduced, so the streams took longer to begin flowing with the onset of the monsoon. The sediment they carried was dramatically less, and they flowed for longer after the rains stopped. On the slopes of the hill organic matter was being allowed to build up. This acts as a sponge to soak up the rain. Even in the absence of rain it protects the soil from the worst of the sun's heat, keeping it softer and more permeable. Soft soil with organic matter encourages more and more soil organisms. Their burrowing and turning of the soil makes it more permeable still, so that the water infiltrates deeply. This in turn encourages better plant growth, producing more organic matter, which absorbs more water, and on it goes. Humans aside, life almost always generates the conditions to further life.

The stream that flows through the park is the one that we have watched most closely. In 2004 we constructed a small check dam in the stream. With the the first big rain, the stream rushed down and the pond above the dam filled completely with sand. We emptied out and used this sand. With the next big rain, the process was repeated, and so on, at least four times through the course of the monsoon. The next year there was far less sand, and from the year following that, until now, almost none. It takes the stream at least 2 weeks of good rain to start flowing, and after the rains stop it continues to flow for more than a month.

saplings Preventing the fires that used to burn off the vegetation each summer has meant that the soils on the slopes of the hill are protected from the rain. Organic matter is allowed to build up. This acts as a sponge to soak up water and hold it in the soil. At the same time, soil organisms that feed on the organic matter multiply, and their actions lighten the soil, allowing the water to infiltrate deeply. More porous soil, with organic matter, holding more water for longer, promotes better growth in the plants. Their roots lighten the soil more, whilst holding it together and protecting it further. Life supports life.

In the early years of the project the changes that these processes caused in the flow pattern of the seasonal stream that runs through the park were dramatic. Where previously a single heavy storm would bring the stream rushing down, full of sediment, only to dry up again in a few days, we now have to wait through two weeks of rain at the beginning of the monsoon before the stream starts to flow. When it does begin to flow it no longer carries the sand and silt that it once did, and when the rains finish, the stream continues to flow for more than a month as the water slowly seeps through the soil and underlying rock.