HR: 1340h
AN: GC33B-1259    [Abstracts]
TI: Critical Climate Controls and Information Needs for the Glen Canyon Adaptive Management Program and Environmental Assessment in the Grand Canyon Region
AU: * Melis, T S
EM: tmelis@usgs.gov
AF: USGS/Grand Canyon Monitoring and Research Center, 2255 N. Gemini Dr., Flagstaff, AZ 86001
AU: Jain, S
EM: Shaleen.Jain@noaa.gov
AF: NOAA-CIRES Climate Diagnostics Center, 325 Broadway, Boulder, CO 80305
AU: Topping, D J
EM: dtopping@usgs.gov
AF: USGS/Grand Canyon Monitoring and Research Center, 2255 N. Gemini Dr., Flagstaff, AZ 86001
AU: Pulwarty, R S
EM: Roger.Pulwarty@noaa.gov
AF: NOAA-CIRES Climate Diagnostics Center, 325 Broadway, Boulder, CO 80305
AU: Eischeid, J K
EM: Jon.K.Eischeid@noaa.gov
AF: NOAA-CIRES Climate Diagnostics Center, 325 Broadway, Boulder, CO 80305
AB: Climatic drivers of episodic to interdecadal variations to the observed changes in the flood magnitude, timing and spatial scales affect the sediment inputs to the Colorado River ecosystem. Since the 1963 closure of Glen Canyon Dam, the dominant sole major supplier of sand to the Colorado River in the upper portion of Grand Canyon is the Paria River, which supplies about 6% of the pre-dam supply of sand at the upstream boundary of Grand Canyon National Park. Sand is delivered by the Paria River during short-duration (< 24 hours), large magnitude (up to 300 cubic meters/second) floods that occur primarily during the warm season (July-October). The planning and decision processes in the Glen Canyon Dam Adaptive Management Program (GCD-AMP) strive to balance numerous, often competing, objectives, such as,water supply, hydropower generation, low flow maintenance, maximizing conservation of the tributary supplied sediment, endangered species recovery, and cultural resources. In this work, we focus on a key concern identified by the AMP, related to the timing and volume of sediment input into Grand Canyon. Adequate sediment inputs into the river ecosystem Canyon combined with active flow management, of the timed in the form of strategically timed bypass releases from Glen Canyon Dam, support the restoration and maintenance of sand bar habitats and instream ecology. Variability in regional precipitation distribution on multiple time scales is diagnosed with emphasis on understanding the relative role of East Pacific tropical storms, North Pacific sea surface temperatures, and subtropical moisture sources. On longer time scales, structured variations in the sediment supply imply a changing baseline for mean ecological and geomorphological conditions in the Canyon, counter to the static view taken in the current environmental impact assessments. Better understanding of the coupled climate-hydrologic variations on multiple time scales is increasingly recognized as critical input for adaptive management (both passive and active). In collaboration with the GCD-AMP, this work deliberately identifies the entry-points for predictive hydroclimatic information at appropriate lead times. From the standpoint of this active adaptive management program, lead climate information allows scientists and managers to anticipate geomorphic response from critical tributaries, that in turn trigger large-scale, experimental releases from Glen Canyon Dam. Similar future studies are planned for the Little Colorado River, as flood frequency in that larger drainage is tied to both the ecosystem's sand supply and the spawning success and recruitment of endangered humpback chub.
DE: 1840 Hydrometeorology
DE: 1862 Sediment transport (4558)
DE: 6309 Decision making under uncertainty
DE: 6344 System operation and management
SC: Global Climate Change [GC]
MN: Fall Meeting 2005