Estimating playa lake flooding: Edwards Air Force Base, California, USA

Playa, or terminal lakes are essentially flat surfaces with minimal topographic relief, and they are common in most semi and arid-environments. Both ground and surface waters can accumulate within a terminal basin and result in flooding of the playa. Within the boundaries of Edwards Air Force Base, located in Southern California, there are four playas: Rosamond, Buckhorn, Rogers, and Rich Dry Lakes. The Rosamond and Rogers playas are currently and have historically been used as runways, taxiways, and industrial areas by the US Air Force and National Aeronautics and Space Administration. A flood assessment of Rogers Dry Lake was mandated due to Air Force regulations concerning delineation of 100-year flood hazard zones, and US Federal regulations, which specify that playas are 100-year special flood hazard zones. From an environmental viewpoint, when water is present, playa lakes can also provide habitat for migratory birds. There is neither guidance nor a generally accepted approach for identifying flood hazards on playas. Therefore, an approach was developed to determine the 100-year regulatory floodplain associated with a dry lakebed, and this approach was used to define tile regulatory floodplain on Rogers and Rich Dry Lakes. This paper describes the application of the method developed to estimate the regulatory 100-year depth of water on Roger and Rich Dry Lakes.