Scale-independent assessment of discharge reduction and riparian disconnectivity following flow regulation by dams

Research Article| July 01, 2003 Scale-independent assessment of discharge reduction and riparian disconnectivity following flow regulation by dams Francis J. Magilligan; Francis J. Magilligan 1Department of Geography, Dartmouth College, Hanover, New Hampshire 03755, USA Search for other works by this author on: GSW Google Scholar Keith H. Nislow; Keith H. Nislow 2U.S. Department of Agriculture Forest Service, Northeastern Research Station, Amherst, Massachusetts 01003, USA Search for other works by this author on: GSW Google Scholar Brian E. Graber Brian E. Graber 3Watershed Restoration Specialist, Madison, Wisconsin 53703, USA Search for other works by this author on: GSW Google Scholar Geology (2003) 31 (7): 569–572. https://doi.org/10.1130/0091-7613(2003)031<0569:SAODRA>2.0.CO;2 Article history received: 14 Jan 2003 rev-recd: 31 Mar 2003 accepted: 04 Apr 2003 first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Francis J. Magilligan, Keith H. Nislow, Brian E. Graber; Scale-independent assessment of discharge reduction and riparian disconnectivity following flow regulation by dams. Geology 2003;; 31 (7): 569–572. doi: https://doi.org/10.1130/0091-7613(2003)031<0569:SAODRA>2.0.CO;2 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 SocietyGeology Search Advanced Search Abstract By using the established hydraulic relationships among flood frequency, flood magnitude, and river-channel capacity, we develop a scale-independent assessment of the hydrogeomorphic impacts of 21 dams across the United States that have broad ranges in function and contributing drainage area. On the basis of generalized extreme value (GEV) analysis of pre- and post-dam hydrologic records, our analysis indicates that the 2 yr discharge has decreased ∼60% following impoundment, exceeding the magnitude of climatically triggered discharge reductions occurring during the Holocene. Reductions in the frequency of the pre-dam 2 yr discharge have been equally profound. The pre-dam 2 yr flood has occurred on average twice per site, whereas statistical analysis indicates that it should have occurred ∼20 times. Furthermore, floods greater than bankfull have been essentially eliminated by dams, completely disconnecting the riparian zone from riverine influence. Our analyses herein suggest that a critical threshold of disconnectivity exists and corresponds approximately to the pre-dam 5 yr flood. This similar recurrence probability exists independent of region, dam type, or catchment size. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.