Rainfall Interpolation Methods Evaluation

Rainfall Interpolation Methods Evaluation

Alejandra Rojas, Ph.D. StudentDept. of Civil Engineering, UPRM

Eric Harmsen, Associate Prof.Dept. of Ag. and Biosystems Engineering, UPRM

Real Time Flash Flood ForecastingReal 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).

Work in Process 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.

ResultsResults

• 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.

Interpolation MethodsInterpolation Methods

USGS Gauge

Precipitation average depth (mm)Area(Km²)IDW EW Thiessen

Añasco San Sebastián 112.71 80.75 138.34 254.96

Rosario near Hormigueros 131.88 135.4 138.34 43.00

Guanajibo near Hormigueros 171.35 193.6   138.34 309.36

Exponential Weighted Inverse Distance Weighted

Storm Total MapsStorm Total Maps

River Response to Rainfall River Response to Rainfall Añasco River discharge due to Interpolation Methods

0

100

200

300

400

500

600

700

11/10/2003 12:00

11/11/2003 0:00

11/11/2003 12:00

11/12/2003 0:00

11/12/2003 12:00

11/13/2003 0:00

11/13/2003 12:00

11/14/2003 0:00

11/14/2003 12:00

11/15/2003 0:00

11/15/2003 12:00

Flo

w (

m^3

/s)

Thiessen Average

EW Interpolation

IDW Interpolation

Guanajibo River discharge due to Interpolation Methods

0

50

100

150

200

250

300

350

11/10/2003 12:00

11/11/2003 0:00

11/11/2003 12:00

11/12/2003 0:00

11/12/2003 12:00

11/13/2003 0:00

11/13/2003 12:00

11/14/2003 0:00

11/14/2003 12:00

11/15/2003 0:00

11/15/2003 12:00

Flo

w (

m^

3/s

)

IDW Interpolation

EW Interpolation

Thiessen Average