| Popis: |
The plains of Clarendon, in south Jamaica, have always suffered from irregular and inadequate rainfall, with long periods of drought, and a scheme to irrigate the area from surface sources proved a failure. Geological investigations have revealed that there are two subsurface water-bearing horizons, separated by an impermeable clay. The upper horizon, consisting of alluvial gravel, and drawing its water from the rainfall on the plains themselves, yields only limited supplies; the lower horizon, however, which is in the Tertiary limestone underlying the clay, provides an abundance of water. This is derived from rainfall on the surrounding limestone hills, which are intensely karstified, so that almost all the precipitation disappears underground and makes its way below the Clarendon Plains. This water is tapped by means of borehole wells, and distributed through irrigation canals. Thus this formerly arid area has been transformed, and its sugar production has increased more than seven-fold. |
