HR: 0800h
AN: H11C-0639    [Abstracts]
TI: Effect of impervious area estimation methods on simulated peak discharges
AU: * Kargar, M
EM: kargar@rohan.sdsu.edu
AF: San Diego State University, Civil and Environmental Engineering, 5500 campanile Drive, San Diego, CA 92182, United States
AU: He, Y
EM: yhe@mail.sdsu.edu
AF: San Diego State University, Civil and Environmental Engineering, 5500 campanile Drive, San Diego, CA 92182, United States
AU: Beighley, R E
EM: beighley@mail.sdsu.edu
AF: San Diego State University, Civil and Environmental Engineering, 5500 campanile Drive, San Diego, CA 92182, United States
AB: Knowing the percentage of a watershed covered with impervious area is critical for understanding its runoff characteristics and flooding potential. However, there are several available methods for estimating watershed imperviousness (IMP). The objective of this research is to understand the effect of the IMP estimation method on simulated flood frequency distribution. This research compares three common methods for estimating imperviousness: (1) directly measured from high-resolution aerial photographs, (2) derived from satellite imagery, and (3) estimated using lookup tables linking land use/land cover categories to IMP values. The HEC- HMS model is used to simulate rainfall-runoff and assess the effects of the estimated IMP on the flood frequency distribution for the Mission Creek Watershed in Santa Barbara, CA. The Mission Creek watershed drains 31 sq km and is approximately 55 percent developed. Basin-wide imperviousness ranges from 13 to 17 percent depending on the selected IMP estimation method. Results for each IMP estimation method are also presented for the sub-watershed (0.3 to 4.1 sq km) scales showing internal variations ranging from approximately +/- 15 percent IMP. The resulting impacts on the flood frequency distribution are highlighted using the 2- and 100-year flood discharges. Preliminary results show the effects of IMP variation are greatest for the 2-year flood and decrease with increasing return period. Simulation results are used to identify the range of IMP values where the estimation method is most influential on simulated flood discharges. A secondary finding is the identification of specific land use/land cover categories having the greatest variability in estimated IMP.
UR: http://spatialhydro.sdsu.edu
DE: 1803 Anthropogenic effects (4802, 4902)
DE: 1805 Computational hydrology
DE: 1821 Floods
DE: 1855 Remote sensing (1640)
SC: Hydrology [H]
MN: 2007 Fall Meeting