What do Drains do In Low Permeability Acid Sulfate Soils?

摘要

In a natural system, the main driving forces for waterable fluctuations are evaportranspiration and rainfall. Man-made drainage introduces another component into the water-balance/water-table system, the drainage flux. It has been assumed that drainage increases the initial rate of watertable draw-down, and when combined with the evapotranspiration, it causes the watertable to drop to a greater depth between rainfall events than evaporation alone. A model was developed that includes for both evaporation and drainage fluxes on watertable behavior. This shows that for soils with low permeability and wide drain spacings that the watertable fluctuations at the mid-point between the drains are mainly driven by evaporation. Further modelling shows that in such soils the influence of the drains on the watertable is generally < 10 m from the drain.