HR: 09:15h
AN: G11B-06    [Abstracts]
TI: The use of Airborne Laser Swath Mapping Data in Watershed Analysis to Guide Restoration Priorities: the Napa River Watershed Study
AU: * Dietrich, W E
EM: bill@eps.berkeley.edu
AF: Dept. Earth and Planetary Science, University of California, Berkeley, CA 94720
AU: Bellugi, D
EM: dino@eps.berkeley.edu
AF: Dept. Earth and Planetary Science, University of California, Berkeley, CA 94720
AU: Real de Asua, R
EM: raf@stillwatersci.com
AF: Stillwater Sciences, 2855 Telegraph Avenue, Berkeley, CA 96079
AU: Iordache, I
EM: ionut@eps.berkeley.edu
AF: Dept. Earth and Planetary Science, University of California, Berkeley, CA 94720
AU: Allen, D
EM: allen@eps.berkeley.edu
AF: Dept. Earth and Planetary Science, University of California, Berkeley, CA 94720
AU: Napolitano, M
EM: MBN@rb2.swrcb.ca.gov
AF: Regional Water Quality Control Board, 1515 Clay Street, Oakland, Ca 94612
AU: Trso, M
EM: martintrso@sbcglobal.net
AF: Trso, 1768 Oxford street, Berkeley, CA 94709
AB: A necessary step in the management and restoration of ecosystem functions in a watershed is to quantify the linkages between landuse practices and channel habitat. With the advent of widely available digital elevation data, increasing numerical skills, and increasing insight about physical and ecological processes, models are being built that explore these linkages. Development and application of these models, however, strongly depends on the resolution of the toporgraphic data. Critical details of hillslope topography are not captured by the highest resolution USGS data (10 m), and, impotantly, channel banks are not a topographic feature in the digital elevation model. Instead the position of the main channels are delineated from hand mapped "blue lines" of USGS topographic quadrangle and then the smaller channels are typically estimated to occur at grid cells receiving drainage area exceeding some critical amount. High-resolution airborne laser swath mapping data (ALSM)) captures much of the finer scale topography, including that of channel banks, but introduces new challenges in both accuracy determination and GIS applications. As part of work to guide development of a Total Maximum Daily Load Analysis of the Napa Watershed, ALSM data were acquired for the entire 1100 km2 Napa River (California) watershed by the University of Florida. The filtered bare earth data set exceeded 1 billion points and gave an average data density of 1.5 m with areas in grasslands dropping below 1 m. Many GIS tools exist to analyze digital elevation data, but we have found many of them inadequate for the large, detailed data set. A central goal of the data acquisition was to create an accurate delineation of the channel network and to estimate channel morphology and grain size to help define the extent of available habitat for salmon. Over 400 on-channel dams and 4000 channel road crossings were identified, which create topographic barriers of significance to modeling and watershed management efforts. Each barrier had to be eliminated to pass drainage area downstream. Furthermore, standard GIS tools treat channels as single cells bearing some drainage area in excess of a critical amount. Such tools are inappropriate where the grid cell is much smaller than the channel width and the channel banks are topographically distinct. A new method of channel delineation needs to be developed. Nonetheless, the single cell approach allowed us to estimate extent of habitat using a channel classification based on a slope and an estimate of median grain size from slope and hydraulic geometry relationships. Mapping and modeling revealed potential salmonid habitat is constrained to the mainstem Napa River and the mainstem's of its major tributaries. Reservoirs, which reduce this habitat, have been built at a rate of about 20 per year for 50 years, leading to increasing conflict between habitat needs of fish and the demand for water. The 1m data of the entire Napa watershed are available at http://calm.geo.berkeley.edu/website/NapaDwnldRaw/ as part of the NSF-supported Center for Airborne Laser Altimerty (NCALM).
UR: http://calm.geo.berkeley.edu/website/NapaDwnldRaw/
DE: 1815 Erosion and sedimentation
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting