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<br />101 <br /> <br />It should be clear that the elimination, of wetland: acreage in <br />watersheds that have little wetland or lake area may have a greater 1mpact <br />on stream flow and flood flow modification than wetland: losses from basins <br />with a large percentage of wetland and lake area. Likewise the lo<:ation and <br />distribution of wetlands can strongly influence the flclw distribution and <br />the time/flow response of flood waters. Wetl.ands located on smallE!r <br />tributaries generally desynchronize tributary and main channel peak flows <br />whereas wetlands and lakes with restricted outlets may retain and delay <br />flood waters and thereby attenuate peak flood flows (Carter et al. 1978). <br /> <br />Natural Ground Water RecharKe <br /> <br />Ground water is water found underground in porous rock, gravel, sand, <br />or other areas called aquifers. Depending on the geomclrphology, ground <br />water may be trapped in an aquifer or move sl.owly. The movement of ground <br />water in aquifer& is des.:ribed by "Darcy' s l.~w," which states that the rate <br />of flow of water is proportional to the hydrologic gradient (Lohman 1972) <br />and appears to apply to mos t if not all aquifers (Figur e 6). Standard <br />techniques are used to determine the directiclD and rate of ground ..ater <br />flow, the head, aquifer porosity, water yield, etc. <br /> <br /> <br />~/ET1..AND <br />OFF..snEA,H <br />STORAGE <br /> <br />.m? <br /> <br />lip... 6. hlatloaahlp between .tna flows, ,...thlld off-eU... .to...... <br />aad arouad vater ..achar.e flow of tv_ .tr.... <br /> <br />The :novem~nt of water from a wetland into an aquifer is called <br />(aquifer) recharge and some recharge of aqulfers from >letlands doe,; occur. <br />However, not all wetlands are recharge areas (Carter et al. 1978). .'here <br />recharge does take place, it may occur as infiltration from the surface <br />through the unsaturated soil zone to the water table, as seepage from a <br />stream or lake, or as seepage through a confining bed Int:o an aquifer. <br />Ground water may move between a shallow water table and deeper, confined <br />aqui fers depending upon the hydrologic gradi.!nt. Some recharge may occur <br />where water moving onto the flood plain rechllrges the ,",'ater table aquifer. <br />Such recharge is often called overbank ~~ (Mundorf 1950). Re,~harge may <br />also occur through the bottoJ:lS of some western strealllll (Leopold and MIller <br />1961) . <br />