Search

The presence of water on Rosamond lake presents potential operational hazards and environmental issues for Edwards Air Force Base (EAFB). This research tests the utility of threshold precipitation in predicting inundation of Rosamond lake. Arcview v.3.2, with the ESRI extension ‘watershed delineator’ and detailed field investigations were used to delineate the watershed and determine elevation-bounded intervals based on soil types and vegetation types and densities. The natural resource conservation service curve number approach was used to estimate the initial abstraction of precipitation, infiltration, runoff, and estimate the threshold depth of precipitation. Climatic data from the western regional climate center and remotely sensed data from the USA Army Corps of Engineers Cold Regions Research and Engineering Laboratory were used to examine the association between winter precipitation events and surface water inundation. Visual_Data, a remote sensing analysis program, was used to analyze the Landsat multispectral images in the infrared (IR) bands and apply remote sensing techniques to determine the areal change of water on Rosamond lake over a defined temporal resolution. Threshold precipitation was then compared to precipitation events that occurred within the temporal resolution of the image subtractions to determine the association between precipitation and the inundation of Rosamond lake. The results of this study demonstrated that with refinement this approach could be used to predict the flow of water to a playa lake to predict the duration of inundation.

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.