Debris Flows in Small Mountain Stream Channels of Colorado and Their Hydrologic Implications

Research Article| August 01, 1981 Debris Flows in Small Mountain Stream Channels of Colorado and Their Hydrologic Implications JOHN E. COSTA; JOHN E. COSTA Department of Geography, University of Denver, Denver, CO 80208 *Also: United States Geological Survey, Mail Stop 415, Lakewood, CO 80225. Search for other works by this author on: GSW Google Scholar ROBERT D. JARRETT ROBERT D. JARRETT United States Geological Survey, Mail Stop 415, Lakewood, CO 80225 Search for other works by this author on: GSW Google Scholar Author and Article Information JOHN E. COSTA *Also: United States Geological Survey, Mail Stop 415, Lakewood, CO 80225. Department of Geography, University of Denver, Denver, CO 80208 ROBERT D. JARRETT United States Geological Survey, Mail Stop 415, Lakewood, CO 80225 Publisher: Association of Environmental & Engineering Geologists First Online: 02 Mar 2017 Online Issn: 1558-9161 Print Issn: 1078-7275 © 1981 Association of Engineering Geologists Environmental & Engineering Geoscience (1981) xviii (3): 309–322. https://doi.org/10.2113/gseegeosci.xviii.3.309 Article history First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation JOHN E. COSTA, ROBERT D. JARRETT; Debris Flows in Small Mountain Stream Channels of Colorado and Their Hydrologic Implications. Environmental & Engineering Geoscience 1981;; xviii (3): 309–322. doi: https://doi.org/10.2113/gseegeosci.xviii.3.309 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyEnvironmental & Engineering Geoscience Search Advanced Search Abstract Gaging-station records and onsite investigations indicate that debris flows in small mountain streams have been confused with waterfloods. Geomorphic, sedimentologic, and hydraulic evidence attributed to debris flows were found in five of seven areas studied, each with an area of less than 10 square kilometers (4 square miles) and an altitude greater than 2,300 meters, (7,500 feet) where floods resulting from intense rainfall had been reported. Evidence used to identify debris flows includes coarse, lobate, poorly sorted, unstratified, pebbly mudstone-like unconsolidated deposits with well-defined levees and terminal lobes, and the extent of ground-litter disruption below high-water marks. Debris-flow deposits are more poorly sorted than water-flood deposits. Although boulders as large as 1 meter (3.3 ft) in diameter were transported by these debris flows, small trees on debris fans were not severely scarred, and small willows had diverted the flows. Downstream, high-water marks and gaging-station records indicate that only a small percentage of the debris-flow discharge was water.The distinction between debris flows and waterfloods is important because: (1) Mitigating procedures for waterfloods, such as channelization and damming, may not be effective for debris flows; (2) peak discharge measurements made from evidence of debris flows lead to excessive estimates of floods for the Rocky Mountains; and (3) because of sparse rainfall data in mountain regions, indirect-discharge estimates have been used by some hydrologists and engineers to determine the amount of rainfall that occurred during a storm. This may lead to inaccurate estimates of rainfall and flood discharges that are used in the design of flood-control structures. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.