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<br />Also, floodplains are often <br />valuable areas for scientific research. <br />For example, they often contain unique <br />wildlife habitats which make them ideal <br />areas for ecological study. <br /> <br />Agriculture <br /> <br />Many of the Nation's floodplains <br />contain prime agricul tural lands. <br />Floods periodically blanket the flood- <br />plain with nutrient-rich sediments, <br />maintaining the fertility needed for <br />high agricultural productivity. <br />Controlling floods provides certain. <br />benefits. However it may also interfere <br />with the cyclic restoration of <br />fertility and thus lower agricultural <br />productivity. <br /> <br />Water Quality Maintenance <br /> <br />Floodplain vegetation slows <br />runoff, causing the water to deposit <br />some of the sediment it carries. In <br />addition to adding nutrients to the <br /> <br /> <br />Floodplains have archeological <br />other cultural values that are <br />when development occurs. <br /> <br />and <br />lost <br /> <br />floodplain soil, sediment deposition <br />often removes certain disease causing <br />organisms from the water. Streambank <br />vegetation also shades the water and <br />decreases its daily temperature fluctua- <br />tions. This reduces stress on fish, <br />wildlife and plants. During floods, <br />heavy vegetation slows the flow and <br />provides areas of slack water where <br />aquatic life have a greater chance to <br />survive. In addition, floodplain vegeta- <br />tion reduces erosion and consequent <br />siltation in channels and reservoirs <br />downstream. <br /> <br /> <br />Loss of vegetation along a stream's <br />banks often leads to erosion. In <br />addition to loss of the land,. erosion <br />means poorer water quality and <br />downstream sedimentation. <br /> <br />Groundwater Recharge <br /> <br />The dry weather flow in streams <br />and the water level in lakes and ponds <br />is often regulated naturally by ground- <br />water. During wet periods, a portion of <br />the rainfall or snowmelt may enter the <br />groundwater system. This reduces the <br />amount of runoff. During dry seasons, <br />water may flow from the groundwater <br />system into streams and lakes, keeping <br />them from drying up. The slowing of <br />runoff and floodwater by vegetation <br />allows more water to seep down through <br />the floodplain soils and become stored <br />as groundwater. <br /> <br />12 <br /> <br />,.., <br /> <br />r <br /> <br /> <br />- <br /> <br />r- <br /> <br />, <br />" <br />