1. Rainfall Interpolation Methods Evaluation Alejandra Rojas, Ph.D. Student Dept. of Civil Engineering, UPRM Eric Harmsen, Associate Prof. Dept. of Ag. and Biosystems Engineering, UPRM

2. Real Time Flash Flood Forecasting The principal goal of this study is development an operational real time flash flood forecasting in western Puerto Rico within the Collaborative Adaptive Sensing of the Atmosphere (CASA) Test-bed located in western Puerto Rico. “NETRAD” scan the lower troposphere, high resolution data for detecting. The NEXRAD data needs to be adjusted because in May 2001, a flooding event in Puerto Rico caused over $150 million in damage and killed two people and the Storm Total Precipitation Estimates from Doppler Radar data underestimated the rainfall by up to 66% in some areas (NOAA, 2006).

3. Work in Process The hydrologic model used is a fully distributed model where each cell have soil, land use characteristics and rainfall information. Remote sensing images of the area, soil characteristic measures, digital infrastructure elevation models (CRIM-PR data or LIDAR survey), adjusted NEXRAD data, and revised river and stream flow data will be used to develop a flash flood simulation tool. Sensitive Analysis, and real time abilities.

4. Results Preliminary a simulation was made with rain gauge interpolated data for November 11th to 13th 2003 and average hyetograph weighed with Thiessen polygons, the inverse distance weighted and the exponential weighted interpolations were used to improve the flow prediction.

5. Interpolation Methods USGS Gauge Precipitation average depth (mm) Area (Km²) IDWEWThiessen Añasco San Sebastián112.7180.75138.34254.96 Rosario near Hormigueros131.88135.4138.3443.00 Guanajibo near Hormigueros171.35193.6 138.34309.36 Exponential WeightedInverse Distance Weighted Storm Total Maps

6. River Response to Rainfall