Estimation of Regionally Specific Z-R Relationships for Radar-Based Hydrologic Prediction

Radar-based hydrologic prediction relies on available rain gauges to correct for bias in rainfall estimates. Standard Z-R relationships have been developed, which are characteristic of storm types, e.g. convective or tropical storms. However, the evolution of storm drop size distribution and radar-specific factors can affect the accuracy of these standard relationships. Deriving Z-R relationships from rain gauge observations for specific radars offers the potential for improved rainfall estimation. The derived Z-R relationship would be more representative of local climatology and radar characteristics, and can be used when rain gauges are not available in real-time for bias correction. The purpose of this study is to derive and evaluate regionally and seasonally specific Z-R relationships for use in rainfall estimation for the South Florida Water Management District (SFWMD). These regionally specific relationships are expected to reduce bias in rainfall estimates found when using standard Z-R relationships, and lead to improved rainfall estimation for operational decisions.