Vertical drainage

Vertical drainage

Vertical drainage is the system of boreholes for lands drainage, from which water is pumped out by pumps with submerged electric motors. Depending on the location of wells over a drained area, they distinguish systematic drainage (wells are equally spaced over the area) and linear drainage. The latter is applied for capture of groundwater flows. The water pumped out of the wells is diverted by open canals or pipelines to main canals and outfall drains.

The structure of vertical drainage wells depends on ground types and hydrotechnical conditions: well screens are installed within the range of water-bearing stratum (aquifer bed); their length is to be at least 10 m. Screens with gravel-sand package are the most efficient.

Well depth is up to 20…50 m. Screen diameter is 30…40 cm; package thickness is 10 cm and more. The more the screen diameter, the more the water inflow to the wells.

In addition to the wells, pumps, and electric motors, the structure of vertical drainage consists of a transformer substation, power transmission line, start-up instrumentation, and automation devices. Operation of vertical drainage can easily be automated. When groundwater level rises, the pumps are turned on; when it drops to drainage rates, the pumps are turned off. The water pumped accumulates in basins; during arid periods, it is used for water application.

Cost-effectiveness of vertical drainage depends generally on the structure of wells, their depths, pattern of use of water pumped and land.