Laserfiche WebLink
<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />II <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I, <br />I <br />I <br /> <br />O~1797 <br /> <br />3.3. Land Use <br /> <br />Land use within the project reach consists primarily of ranching, which includes <br />floodplain irrigation and grazing activities. Irrigation diversions are located at several <br />locations within the project reach, including RM 9.3L, RM 6.2R, RM 3.3R, and RM <br />2.8R. Each of these diversions convey Arkansas River water to adjacent floodplain <br />areas; additional floodplain area is commonly accessed by natural secondary channels. <br />Although floodplain irrigation has the potential to enhance vegetative reinforcement of <br />floodplain soils, concentrated return flows can be erosive. There is no observed <br />indication that floodplain irrigation is causing floodplain erosion; rather, aerial <br />photographs indicate the ditches have transported fine sediment onto the floodplain <br />surface. The unvegetated condition of some of these deposits suggests that they may be <br />geochemically degraded; if so, floodplain deposition via the irrigation ditches may <br />ultimately reduce floodplain vegetation, and thereby reduce the erosion resistance of the <br />floodplain surface. <br /> <br />Grazing pressures are variable within the project reach. In the channel reaches between <br />the Lake Fork confluence and Highway 24 Bridge, grazing is active, and vegetative vigor <br />is limited. Willow regeneration has been limited due to active browsing and trampling. <br />The most distinct direct impact of grazing on the system has been the acceleration of <br />channel widening due to gravitational failure of undercut channel banks. <br /> <br />May 7, 1999 <br /> <br />Fluvial Geomorphological Assessment <br />Upper Arkansas River <br /> <br />Page 13 <br />