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<br />5 <br /> <br />~) The maximum rating af five is cansidered apprapriate in view af <br />~ recent research. <br />c.o <br />QJ Madificatian 9: It is prapased that the Sail (b) rating <br />descriptian in the text be madified to' emphasize that the entire <br />60 inch sail prafile is nat invalved in the sediment yield and <br />erasian pracess. The tap twO' to' three inches is generally all af <br />the sail prafile that isinvalved in cancentrated averland flaw <br />sediment yield. The sediment yield character,af these few inches <br />af sail is critical to' rating this factar. <br /> <br />Shauld gully erasian be daminant within an area, then the entire <br />sail and sediment prafile wauld be invalved in the sediment yield <br />and erasian pracess but the PSIAC sediment yield procedure would <br />not be the appropriate procedure to' characterize an area af <br />daminant gully erasian. The PSIAC pracedure shauld be used to' <br />characterize upland and channel erosian. A direct valume <br />sediment yield pracedure (USDA, SCS, 1983) shauld be used .ta <br />characterize an area daminated by gully sediment yield. Tagether <br />the twO' pracedures wauld serve to' characterize the sediment yield <br />af the area. <br /> <br />Madificatian 10: It is prapased that the Tapagraphy (e) be rated <br />-by a weighted average far slape-area in conjunctian with the <br />characterizatian in PSIAC (1968, pages 5-6). The weighted slape- <br />area average can be based an field abservatian, planimeter work <br />ar GIS data. The geomarphic unit shauld be divided intO' general <br />slape-related subunits. Then the area af the subunit and the <br />characteristic slape shauld be determined. The geamarphic unit <br />average slape may then be calculated by the fallawing example: A <br />butte, mesa, bench and escarpment topagraphy characteristic of <br />the Colarada Plateau may have 15% af the area with a <br />characteristic slape af 70%; 35% af the area with a <br />characteristic slape af 5% and 50% af the area with a <br />.characteristic slape af 10%. . The averall average slape far a <br />geamarphic unit is abtained by multiplying the percent af the <br />area by its average slape percent; this shauld be dane far all <br />the individual slape-areas in the geamarphic unit. These values <br />are then added tagether to' give the weighted average slape <br />percent far the geamarphic unit; which in the case af this <br />example is 17.25% ar 17%. A weighted slope average calculatian <br />table and a slape percent rating chart is included on the revised <br />PSIAC Rating Chart. <br /> <br />The rating af this factar shauld be based an the watershed <br />cansideratians as dacumented in the PSIAC (1968, pages 5-6) as <br />well as the weighted slape average. Experienced judgement in all <br />PSIAC ratings is critical to' the abtaining the best results. <br /> <br />Madificatian 11: It is prapased that the factar (f) tapic name <br />be revised to' read EFFECTIVE GROUND COVER and it is praposed that <br />the Effective Graund Caver (f) rating farmat be madified to' <br />specifically state that vegetatian, litter and rack fragments <br />each be rated by determining the percentage af effective ground <br />