Townley, L.R. (1998), Surface water - groundwater interaction, with implications for groundwater contamination, Stormwater Industry Association (SIA) 3rd Regional Conference on Stormwater Management, Perth, 27 October, 3 pp.

Stormwater may be defined as excess water at the land surface, due to heavy rainfall, which is typically carried by drains, either to receiving water courses such as rivers or estuaries, or to a low point in the landscape where it infiltrates into the subsurface.

A low point in the landscape may be dry at the beginning of a stormflow event (as in stormwater sumps with invert levels constructed well above the water table), or wet, due to the existence of a lake or wetland. In either of these cases, stormwater is likely to recharge the local groundwater system, with subsequent impacts on the receiving groundwater, due to the quantity and quality of the stormwater.

The extent to which recharge occurs depends on the hydraulic conductivity of surface soils. Interaction with groundwater is far more likely in Perth or Adelaide than in Sydney or Melbourne, where surface sandstones and clays are generally much less permeable.

The extent to which recharge occurs in a lake or wetland depends on the level and rate of movement of the water table, at the time of the storm event. Since surface runoff occurs much faster than groundwater levels rise, recharge will generally occur, even in areas where a gradual rise in the water table has led to saturation at the surface and subsequent flooding.

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Last revised: 29 December 2021