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Show PART IV MEANS FOR MEETING NEEDS Other vegetal treatment practices include brush control through spraying, chaining, or cutting, tree and shrub planting, and fertilizing. These measures can all lead to relatively permanent watershed improvement as opposed to the stopgap measures of structural control of runoff with channel linings, drop structures, and revetments. Treatment measures include contour furrows, pits, and contour trenches that are designed to catch and store water at or near where it falls. They provide temporary storage and increase the infiltration period and also catch storm runoff that causes downstream damage. They are installed on gullied lands damaged by surface runoff from rainstorms or snowmelt. They serve as effective temporary measures to reduce on- site or off-site damage until the natural productivity and stability of the watershed are restored by proper revegetation and management. A total of 4,379,000 acres need treatment for reduction of erosion and sediment on federal land. Water Control Measures Some watersheds have deteriorated to a point where salvage of the land is now impossible. In these areas reliance must be made primarily on structures for control of water flow, as the land will not respond to treatment techniques. Water control measures, as used here, include detention dams and debris retention basins in any given watershed restoration program. In some programs, complete watershed restoration and control of dry mantle floods may be accomplished solely by land treatment measures on the watershed. In others, land treatment may need to be supplemented by water-control measures downstream. The need for such structures can be determined only after careful analysis of source areas, determination of probable benefits to be derived from land treatment measures, and an estimate of expected improvement by management on untreated slopes. A total of 53,300 water control struc- tures should be installed on federal land. In some areas of excessive streambank and lakeshore erosion treat- ment is needed to stabilize the shoreline. Measures such as special plantings, gabion emplacement, or revetment construction are effective in stabilizing the shorelines and reducing sediment production. It is established there are 1,200 miles of streambank and lakeshore needing stabilization in the region. |