HR: 1340h
AN: H33D-0504    [Abstracts]
TI: Airborne Laser Altimetry (LIDAR) Support of Floodplain Inundation Modeling of Arid Southwest Stream Systems to Predict WoUS Boundaries
AU: * Finnegan, D C
EM: david.finnegan@erdc.usace.army.mil
AF: Cold Regions Research and Engineering Laboratory, 72 Lyme Road, Hanover, NH 03755 United States
AU: Lichvar, R W
EM: robert.lichvar@erdc.crrel.usace.army.mil
AF: Cold Regions Research and Engineering Laboratory, 72 Lyme Road, Hanover, NH 03755 United States
AU: Ericsson, M P
EM: michael.ericsson@erdc.crrel.usace.army.mil
AF: Cold Regions Research and Engineering Laboratory, 72 Lyme Road, Hanover, NH 03755 United States
AB: The U.S. Army Corps of Engineers (COE) is actively involved in floodplain management and regulation of dry wash floodplains in the western United States. The COE also regulates "Waters of the United States" (WoUS) under Sec. 404 of the Clean Water Act by determining the extent of surface indicators related to "ordinary" flood discharges known as Ordinary High Water Marks (OHWM). Currently, the return interval for inundation to the WoUS boundary is not well understood. Large flood inundation models (50, 100 yr flood events) currently available do not reflect features found in the field useful for placement of OHWM. At the present time, COE hydrologic models such as HEC-1 and HEC-RAS require detailed site information for rainfall and stream flow characteristics as well as on-site surveys to determine channel morphology, width, fluvial patterns, slope and other physical attributes. Typically, the fine-scale resolution necessary for 1-D hydrologic models is obtained from a limited number of channel cross sections obtained with survey equipment. The focus of this research is to develop a quantitative method to accurately reproduce determined flood return inundation levels in support of identifying the events that best represent the extent of the "ordinary" high water using high-resolution topography acquired through Light Infrared Detection and Ranging (LIDAR). Using NASA's Airborne Topographic Mapper (ATM) as a source of high-resolution topographic data we were able to acquire highly precise horizontal (~10cm) and vertical height locations (~5-10 cm) at several arid stream test reaches throughout the Mojave Desert, California. By incorporating LIDAR data into HEC-RAS models at a non-interpolated 2m cross section spacing our results have shown that 1-D flood inundation models that are typically used for high-flow events is capable of determining the geomorphic signature, extent and inundation frequency of "ordinary" flood events.
DE: 1821 Floods
DE: 1824 Geomorphology (1625)
DE: 1860 Runoff and streamflow
DE: 1894 Instruments and techniques
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting