Wednesday, December 03, 2008
Vignettes from The Mexicali Valley
The Hydrometric system was apparently donated or installed by the Americans, but I found that it was temporaly out of order. There was a rack with SCADA hardware, unconnected. The local professionals are working without resources, and taking into account the environment, doing a tremendous job.
The irrigation is by flooding, and some plots have been levelled by lasers and looked very good. They added sulphur to the water, possibly to change the permeability of clay soils.
The underground water flow coming from the North is being pumped out by a series of boreholes more or less connected into a network. The pumps suffer continuous breakdowns because of vandalism and stealing of the cables. No one saw anybody stealing anything. Surprisingly, the pumps had no pressure meters - manometers - and the steel spring served as pressure valve. The pumps last about two three years because of the sand, but they said the water came up very clean without any sand. No sand separation equipment was seen. Three or more pumps are being managed as a system, so when one is down, other can take its place. The whole operation is manual, they have a man whose job is to visit all the pumps once a day. The oiling of the pumps and maintenance is being done by the Sociedad de Responsabilidad Limitada, a second tier organization, and not by the Distritos de Riego.