HR: 1330h
AN: H12B-1001    [PDF]
TI: Wavelet analysis of the hydrologic effects of Glen Canyon Dam on the Colorado River at Lees Ferry, Arizona
AU: * White, M A
EM: mikew@cc.usu.edu
AF: Utah State University, Aquatic, Watershed, & Earth Res. 5210 Old Main Hill, Logan, UT 84322 United States
AU: Schmidt, J C
EM: jschmidt@cc.usu.edu
AF: Utah State University, Aquatic, Watershed, & Earth Res. 5210 Old Main Hill, Logan, UT 84322 United States
AU: Topping, D J
EM: dtopping@usgs.gov
AF: United States Geological Survey, WRD 2255 N. Gemini Drive, Flagstaff, AZ 86001 United States
AB: Continuous wavelet transformation is a powerful analytical tool with which to analyze the hydrologic effects of dam construction and operation on river systems, an issue of great managerial, political, and social interest in the western United States. Using continuous records of instantaneous discharge from the Lees Ferry gaging station and records of daily mean discharge from upstream tributaries, we conducted a continuous wavelet transformation (CWT) analysis of the pre- and post-dam hydrologic structure of the Colorado River in Grand Canyon, downstream from Glen Canyon Dam. CWT of mean daily discharge provided a highly compressed and integrative picture of the near-total elimination of pronounced annual and sub-annual wavelet features after dam construction. Events such as droughts, managed floods, and uncontrollable snowmelt-driven discharge were also visible. The continuous record, interpolated to consistent hourly intervals, revealed a much finer scale image of river conditions. Prior to dam construction, the CWT showed the influence of warm season peak discharge periods, discharge driven by the monsoon and dissipating tropical storms, and annual droughts. In the post-dam period, strong wavelet signals related to diurnal power generation, weekly shutdowns in power generation, shifts in daily discharge management, and the 1996 experimental flood were dominant. The CWT approach appears to represent well-known features of dam operation without generation of spurious results. Thus, CWT, with quantitative statistical significance tests, should be a promising tool for assessing (1) dam operation in less well-studied regions and (2) real-time success or failure of management attempts to reconstruct desired flow characteristics.
DE: 1803 Anthropogenic effects
DE: 1821 Floods
DE: 1860 Runoff and streamflow
SC: Hydrology [H]
MN: 2003 Fall Meeting