Issue link: https://read.dmtmag.com/i/59336
Wichita, Kan., Levee Recertification LIDAR has become a widely accepted tool to generate accurate digital terrain models (DTMs) used in a variety of water-resource applications, including stormwater manage- ment, flood mapping, levee recertification and emergency-response applications. Wichita, Kan., located at the populated junction of the Arkansas and Little Arkansas River Valleys in south-central Kansas, con- sistently experiences heavy rainfall in the spring and fall months. The area has a large number of canals that move water dur- ing base flow and flooding, and there are approximately 100 miles of levees cutting across the city. The levees were constructed in the 1950s and were in need of recertification by the Federal Emergency Management Agency. LIDAR was selected as the technology of choice for elevation data acquisition. The data eventually would be used for levee recertification, urban management, homeland security and other infrastructure needs. The project also developed a hydro geodata- base using the LIDAR DTM to determine the flow of water and drainage area over the landscape. TECHNOLOGY USED: LIDAR PROJECT OBJECTIVE: Acquire and process data for the recertification of existing levees in a flood-prone region. The city of Wichita, Kan., relies on levees constructed in the 1950s, which are prone to flooding during especially heavy rainfall years (left). A bare-Earth LIDAR DTM (center) shows the levees found throughout the city, and an Arc Hydro model (right) shows catchments (red lines) and drainage lines (blue). U.S. Dept. of Agriculture, Natural Resources Conservation Services, Dam Rehabilitation Part of the NRCS agency mission is to assist TECHNOLOGY USED: LIDAR PROJECT OBJECTIVE: Provide LIDAR data for use in generating digital elevation models and contours for use in hydraulic/hydrologic models. state and local governments in assessing, designing and managing construction of new or rehabilitated dams or other water-resource projects as part of the Watershed Protection and Flood Prevention Act as well as the Emergency Watershed Protection Program. For the assessment portion, LIDAR is used to collect data to provide descriptions of cur- rent conditions, breach-inundation maps and site-specific restraints for rehabilitation. Beyond assisting with NRCS' rehabilitation efforts, the data also are valuable in generating Emergency Action Plan evacuation maps as well as other conservation activities and efforts. These programs include the Environmental 28 GEO W ORLD / MA R CH 2O12 Quality Incentive Program, the Wetland Reserve Program and the agency's basic Conservation Technical Assistance. High-resolution digital elevation data developed from LIDAR, for example, cover approximately 11,000 square miles of various watersheds in Oklahoma. The data are being collected and processed over a five-month period and will be used to generate digital elevation models and contours for use in hydraulic/hydro- logic models. The LIDAR data were collected at an average point density of 1.4 meters and will meet or exceed a vertical accuracy of 12.5 centimeters. Merrick ground-survey crews also supported aerial acquisition by establishing more than 700 check points across the state. Case Studies