Laserfiche WebLink
<br />8 <br /> <br />~~ control depending on construction, design and maintenance. The <br />t.C' rating line should read "Roads in need of maintenance or need, <br />to drainage control design.". Excessive concentrated road drainage <br />~, can lead to significant gullying and damaging concentrated flow <br />erosion. If road bank erosion is significant, it can be <br />characterized by the direct volume method (USDA,SCS, 1983). <br /> <br />In the 10 point and 0 point categories there should be items <br />involving the badlands land type. The 10 point rating line <br />should read "Almost all of the area is badlands with minimal <br />armoring.". The 0 point rating line should read "almost all of <br />the area is badlands with 50% armor on slopes.". Badlands is a <br />land type that is not accounted for in the .PSIAC (1968) <br />procedure. Not all badlands are in a high yielding condition. <br />For instance the Book Cliffs region of utah is a badlands <br />escarpment composed of a sandstone caprock underlain by hundreds <br />of feet of highly erosive Mancos Shale on steep slopes. The <br />sediment yield from the Book cliffs varies greatly with the . <br />amount of natural armoring that has occurred.from the weathering <br />of the overlying sandstone caprock. <br /> <br />Based on the above discussion, it is proposed that this category <br />be renamed LAND TYPE AND MANAGEMENT QUALITY. This change is <br />necessary because badlands is a land type (not a use), wildfire <br />burned areas are a management problem with high sediment yield <br />rates (not a land use) and grazing, overgrazing, historic <br />overgrazing, logging and roads relate to sediment yield in terms <br />of land management (not as a land use). <br /> <br />Modification 13: It is proposed that in the Upland Erosion (h) <br />the. reference to rill erosion be eliminated and replaced with the <br />term "concentrated flow erosion". Rill erosion in the last.20 <br />years has become predominantly associated with cultivated <br />cropland erosion in the phrase "sheet and rill erosion" and the <br />USLE. Concentrated flow erosion is defined as storm related <br />natural flow paths where sediment is eroded and transported <br />during storm events. These paths are not gullies but can <br />eventually become gullies in some cases. The flow paths can <br />laterally develop as well as developing more tributary paths. <br />These flow paths enter into major channels or gUllies or may <br />distribute into lower sloping depositional zones. The result can <br />be significant sediment loss over a wide area of land. This is <br />the type of sediment yield and erosion process that the PSIAC <br />sediment yield procedure was developed to characterize. <br /> <br />The reference to landslide erosion should be eliminated. This <br />type of erosion can be characterized by a direct volume <br />measurement estimate method and should not be included in the <br />PSIAC procedure. <br /> <br />In the 10 point category the (b) wind erosion portion should be <br />eliminated. If wind erosion is a significant problem, then a <br />wind erosion equation (USDA, SCS, 1984) should be used to <br />characterize the problem. The wind erosion values can be used in <br />