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<br />Forest-Fire Devegetation and aasin Adjustments <br /> <br />steep slopes near the watershed headwaters (fig. 5). Erosion is greater in <br />regions undergoing rill et'osion than in areas eroded by sheetwash. In the <br />distal portion of the drainage basins, drainage lines incised. Channel inci- <br />sion caused accelerated hillslope erosion near the basin mouths. <br /> <br />The length of overland flow (maximum transport distance on the hills lopes ) <br />is gl:"eater .in the mid-basin regions than in the headwaters of watersheds for <br />the intense- and moderate-burn watersheds but is greatest in the headwaters <br />in light-burn watersheds (table 3). Sediment is removed from hilIslopes in <br />the upper and lower basin areas faster than from the mid-basin because of <br />shorter transport distances. Overland flow distances in the headwaters con- <br />tinue to decrease as rill development progres~es. Photography was used to <br />document the decrease in area between rills with time. Some headwater over- <br />land-flow distances have been reduced by one half their original distance. <br />Increased channel ways . in proportion to interfluve area. results in increased <br />effidency of sediment removal from the watersheds. <br /> <br />During the forest fire. impervious hydrophobic layers developed on the <br />colluvial and alluvial cover of the deforested areas. Hydrophobic layers are <br />chetnically and physically altered zones (Krammes and DeBano. 1965; DeBano <br />et al., 1970; Savage et al., 1972). The infiltration potential of soil and <br />colluvial cover was diminished because grain sizes were reduced by the fire <br />(Tarrant. 1956). Fines moved downward through the profile and filled voids. <br /> <br /> <br />Figure S. Rill development on the ashy, hydrophobic layer in the mid-basin <br />area of the intense-burn watershed, Burnt Mesa. <br /> <br />'^' <br />