Improved Resiliency through Detection of Flood-Producing Precipitation with Observational Networks Composed of Radar and Precipitation Gauges

Resiliency to flooding depends on efficient detection of flood-producing storms depends on observational sensor network density and modeling schemes capable of leveraging high-resolution precipitation and land surface characteristics. Real-time rainfall information is needed for making flood alert decisions in support of local organizations responsible for flood control, urban drainage, and stormwater. Climatic zones in this analysis include the semiarid Colorado Front Range and humid regions in the central US. A review of probability of detection of flood-producing events for these climatic zones will be examined. The observation network consists of dense networks of rain gauges combined with weather radar measurements, used to produce near-real-time estimates of rainfall maps over each district. Resiliency is often defined by precipitation exceedance probabilities, namely return intervals for specific durations such as the 10 or 100-yr 60-min or 24-hour duration at a point (rain gauge) location. Drainage infrastructure design and desired flood protection thresholds are based on flow and stage modeled using precipitation meeting these thresholds. Analysis of archival precipitation data reveals that extreme events are not always captured by the rain gauge network alone, and occur more often than expected from point probabilities. Rainfall between the rain gauges can be significant even with high densities found in urban rain gauge networks designed for flood alert applications. Results will be presented, demonstrating that rainfall patterns associated with extreme events are difficult to detect with rain gauges alone, and that climate plays a role in the precipitation characteristics and resulting success in flood detection by these networks. Design of flood alert rain gauge networks in combination with weather radar can improve reliability of flood detection and resiliency. The combination of rain gauges and weather radar improves real-time flood warning and our understanding of the frequency of high-impact storms.