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.: <br /> <br />in the individual subbasins of the drainage, water floods are probably the <br />most common events for the basin as a whole. The debris that does come down <br />to the mouth of the creek is quickly eroded away by the combined waters of <br />Canyon Creek, Oak Creek, and the Uncompahgre River. Therefore, at the mouth <br />of Canyon Creek a small area of Moderate to Low Hazard is mapped, <br />Oak Creek: The Oak Creek fan appears not to be as active as most of the <br />other fans in the study area. However, it has the potential to produce <br />significant events as evidenced in 1971 when debris from Oak Creek dammed the <br />Uncompahgre River forming a lake, The fan is very steep and is severely <br />truncated by the river. A railroad bed has been benched into the outer part <br />of the fan. If the profile of the fan is projected, it shows that the fan was <br />once much larger. It has been eroded by the river, which has been pushed west <br />by the more active Portland Creek fan. <br />The area of the fan closest to the creek is placed in the Very High <br />Hazard Zone and the rest of the fan in the High Hazard Zone, <br />Bridalveil Creek: The Bridalveil Creek fan is more active than would be <br />suggested by the absence of published accounts. Inspection of the fan showed <br />numerous levees and lobes of all sizes, several well-defined channels, and <br />tree burial and scarring. Tree scarring was rarely noticed away from the main <br />channels, although levees and lobes were noted all over the fan, giving it a <br />corrugated appearance (Figs. 24, 25). <br />Airphotos taken in 1955 show a wide, fresh-looking debris-flow track to <br />the north of the current channel, According to the 1955 field-checked USGS <br />topographic map, the creek is running in that channel. It also appears on the <br />photos that a channel had also existed where the channel now is. This <br />indicates that the creek switched channels sometime prior to 1955 and again <br />since then, Linear stands of young aspen twelve to fifteen feet high <br />radiating from the apex of the fan to the south of both channels suggest an <br />event about ten to twenty years ago. The quick-growing aspen are usually the <br />first tree to revegetate a denuded area. The partial burial of trees less <br />__ than five feet tall in the same area indicates another small event probably <br />~, around 1981 or 1982, <br />\\ <br /> <br />_ ql <br />