Public: Water
Underground Flood Meadows   (+1)  [vote for, against]
Connect disused underground mines to the river system via sluice gates

Queensland has recently experienced an increase in mining activity.

As part of the rehabilitation process once those mines are mined out, dig a connecting pipe or trench from the nearest river system, with a sluice gate to be owned by, say, the State Emergency Service. In high-rainfall conditions, open the sluice gate and divert part of the flood-water into the underground mine.

Depending on the characteristics of the country rock, the intervening drought periods (southern Queensland has just been through a seven-year drought) will see the water either seep into the surrounding water table or become available for pumping out for irrigation (or a bit of both). These are both better outcomes than evaporation or flushing out to sea.
-- pertinax, Jan 17 2011

Compared to the volume of water in the floods, mines would only be able to sink a tiny amount.

Drilling many, many small, deep "dry" boreholes to allow water to sink into permeable strata during flooding might, however, have some benefit in containing runoff.
-- 8th of 7, Jan 17 2011

Have we done solutions involving jello? There are some polymers which will gel at very, very low concentrations. A few tons dumped in a line parallel to the river would slow the flood down impressively. It could even be flavoured.
-- MaxwellBuchanan, Jan 17 2011

random, halfbakery