The man who farms water
http://cals.arizona.edu/OALS/ALN/aln46/lancaster.html
His farm is on the slope of a hill facing north-northeast (providing good sun exposure to the site, as it is in the Southern Hemisphere). The top of the hill is a large, exposed granite dome from which storm runoff once freely flowed. The average annual rainfall is 570 mm (just over 22 inches). However, as Mr. Phiri points out, this is an average based on extremes. Many years are drought years when the land is lucky to receive 12 inches of rain. When he began, it was very difficult to grow crops successfully let alone make a profit, due to the frequent droughts and zero equipment or capital for irrigation from groundwater. He spent time observing what would happen when it did rain. In small depressions and upslope of rocks and plants, the soil moisture would linger longer than in areas where sheet flow went unchecked. Thus began his self education in rainwater harvesting-and his work. Over a period of 30 years, he has created a sustainable system that provides all his water needs from rainfall alone.
“You start catchment upstream and heal the young before the old/deep gullies downstream,” says Mr. Phiri. Beginning at the top of the watershed, he built unmortared stone walls at random intervals on contour (that is, along lines of equal elevation). These walls slow the flow of storm runoff as the water moves through the spaces between the stones. This makes the water running off the granite dome more manageable as it is directed to unlined reservoirs, which like everything else, were built with nothing more than hand tools and the sweat of Mr. Phiri and his two wives. The larger of the two reservoirs Mr. Phiri calls his immigration center. “It is here that I welcome the water to my farm and then direct it to where it will live in the soil,” he laughs.
(continued)
Posted in water conservation / harvesting, water management
