Development of a flood forecasting model for Flamingo Tropicana Watershed in the Las Vegas Valley

Floods are among the most frequent natural phenomenon that occur due to excessive precipitation. Accurate and current forecasting of floods is necessary to avoid social and economic losses. Forecasting floods in an event of intense rain allows the concerned agencies to adopt appropriate measures such as warnings and evacuations and to initiate corrective and remedial efforts before disaster strikes (Chapman and Canaan, 2001); Las Vegas has experienced rapid population growth since the 1990s. This has brought large-scale increase in impervious land surface due to the expansion of residential, commercial, and industrial area in the valley. The increase in impervious area produces more runoff volume and peak flows and consequently shortens the time that the floodwaters take to reach their peak (Hall, 1984). To effectively convey the runoff from the impervious land surface, the Clark County Regional Flood Control District (CCRFCD) has established regional flood control facilities. Most of the times, these facilities are adequate to protect human life and property. However, there still exist some areas of concern as recent rainfall events have caused flooding in part of the watershed thereby causing huge loss to properties and threat to lives; This research focused on developing a hydrologic model to be used in time of intense rainfall for real-time flood forecasting. The research was carried out in the Flamingo Tropicana watershed. The existing HEC-1 flood hydrograph model of the CCRFCD was utilized to develop the flood forecasting model using the HEC-HMS software developed by United States Army Corps of Engineers. The modeling was carried out using the real-time rainfall data available through the Flood Threat Recognition System (FTRS) of CCRFCD and the gridded radar rainfall data having different resolution. The simulated hydrographs using the different rainfall data were compared with the observed data at different places in the watershed. In overall the model predicted the time to peak very well. The analysis of the results indicated that the model can be used for real-time flood forecasting in the Flamingo Tropicana Watershed. The information provided by this research can be applied to develop an integrated flood forecasting model for the entire Las Vegas Valley