Water Resources Research Act Program

Details for Project ID 2008HI282S

Application of Radar Imagery as Input to a Rainfall-Runoff Model for the Kawela Watershed, Molokai

Institute: Hawaii
USGS Grant Number: 08HQAG0142
Year Established: 2008 Start Date: 2008-09-01 End Date: 2011-03-01
Total Federal Funds: $0 Total Non-Federal Funds: Not available

Principal Investigators: Aly El-Kadi

Project Summary: Spatial variability of rainfall is typically high and existing raingages usually are sparsely distributed on a watershed scale, which can lead to substantial over- and underestimation of total basin rainfall. Precipitation estimated from reflectivity measured by the NEXRAD radar promises spatially and temporally comprehensive coverage. Thus, hourly and daily radar rainfall was compared to raingage rainfall as potential input for a rainfall-runoff model in the Kawela watershed, Molokai, Hawaii. Rainfall rates from radar and raingages are log-normally distributed and correlate, although the relationship exhibits large scatter, especially at rainfall rates below 5 mm/day. Although radar rainfall is promising for the use in rainfall-runoff modeling, it is best to use radar rainfall to supplement areas without raingages or times without record as an addition to raingage data.