详情

原文传递 Field Reconnaissance of Debris Flows Triggered by a July 21, 2007, Thunderstorm in Alpine, Colorado, and Vicinity.

题名：	Field Reconnaissance of Debris Flows Triggered by a July 21, 2007, Thunderstorm in Alpine, Colorado, and Vicinity.
作者：	coe, j. a. godt, j. w. wait, t. c. kean, j. w.
关键词：	surface water runoff, sediments, channel morphology, rainfall, landslides
摘要：	On the evening of July 21, 2007, a slow-moving thunderstorm triggered about 45 debris flows on steep mountain sides near the community of Alpine, Colorado. Most of the debris flows were initiated by surface-water runoff that eroded and entrained loose sediment in previously existing channels. About 12 of the debris-flow channels were located in the lower half of Weldon Gulch upslope from Alpine, which is on a debris fan at the mouth of the Gulch. Most of these channels were deeply incised by the flows, and many of the resulting oversteepened channel banks are now failing and beginning to refill the channels with sediment. Debris flows that emerged from the mouth of Weldon Gulch primarily flowed onto the eastern half of the debris fan and closed roads and damaged vehicles and structures. Debris-flow deposits on the fan generally become finer grained and thinner with distance from the head of the fan. Given the existing conditions in Weldon Gulch, it is estimated that the debris-flow hazard on the fan has neither decreased nor increased as a result of the July 21 debris flows. Preventive measures that need to be considered by Alpine residents and government officials concerned with safety on the fan include: (1) establishing a channel and(or) catchment/diversion structure on the fan that routes future water and debris flows in a manner that protects existing roads and structures, and (2) maintaining vigilance during rainstorms by watching and listening for unusual flows of water or debris that may indicate debris-flow activity upstream, particularly during the summer months when thunderstorms are common in the area. / NOTE: Open-file rept. / Supplementary Notes: Prepared in cooperation with Colorado Geological Survey, Denver. / Availability Note: Order this product from NTIS by: phone at 1-800-553-NTIS (U.S. customers); (703)605-6000 (other countries); fax at (703)605-6900; and email at orders@ntis.gov. NTIS is located at 5285 Port Royal Road, Springfield, VA, 22161, USA.
总页数：	u0817；28p
报告类型：	科技报告