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Depression focused recharge

Also referred to as depression focused groundwater recharge.

If water falls uniformly over a field such that field capacity of the soil is not exceeded, then negligible water percolates to groundwater. If instead water puddles in low lying areas, the same water volume concentrated over a smaller area may exceed field capacity and recharge groundwater. The larger the relative contributing runoff area is, the more focused infiltration is. Water tables rise under such depressions.

Depression focused groundwater recharge can be very important in arid regions. More rain events are capable of contributing to groundwater supply.

Depression focused groundwater recharge also profoundly effects contaminant transport into groundwater.

Deeper ponding exerts pressure that forces water into the ground faster. Faster flow dislodges contaminants otherwise adsorbed on soil and carries them along. This can carry pollution directly to the raised watertable below and into the groundwater supply. Thus the quality of water collecting in rapid infiltration basins is of special concern.

Pollution in stormwater runoff collects in retention basins. Concentrating degradable contaminants can accelerate biodegradation. However, where and when water tables are high this affects appropriate design of detention ponds, retention ponds and rain gardens.

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Depression_focused_recharge". A list of authors is available in Wikipedia.
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