Drainage, Case studies, Western Australia, Groundwater flow
Typically, deep, open drains are about 2 in deep and about 1 in wide at the base and dug with a backhoe or excavator. The movement of groundwater is controlled by two factors. One is the physical ability of the material to transmit fluid. Permeability is the measure used to describe the ability of a material to transmit fluid through pores and cracks. It depends largely upon porosity (the percentage of the total volume of thematerial that is pore space) and the degree of interconnectedness of the pore spaces. The other factor controlling groundwater flow is gradient. George (1985) found that it was important to detemine the factors or profile characteristics controlling groundwater flow, such asthe depth of permeable or impermeable layers, in order to calculate appropriate drain design.
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Speed, R J, and Simons, J A. (1992), Deep drains : a case study and discussion. Department of Agriculture and Food, Western Australia. Report 133, 12p.