Flood-inundation mapping of a steep, gravel desert stream in Death Valley National Park, California

In desert landscapes, flooding can result in dramatic changes to streams. However, the frequency, magnitude, and geomorphic effects of floods in such environments are less understood compared to wetter environments (Tooth, 2000). In desert landscapes, steep slopes and sparse vegetation result in runoff and flashy flood peaks, often lasting for only a few hours. Many floods are the result of isolated, convective thunderstorms that cannot be predicted easily in advance and frequently occur at night. Therefore, direct observations or measurements of streamflow during floods often are limited, with data collection mostly occurring after the event. In ephemeral streams, limited vegetation within channels and on overbanks result in large stream velocity and higher probability for erosion during flooding. Moreover, flood occurrence in desert streams is often highly variable and some sites may go for years without streamflow, complicating flood frequency analyses. Finally, data sets in desert environments are often short and have few long-term, systematic collection sites.