Forensic Analysis of Two Contrasting Satellite Rainfall Products for Detection of the July 2002 Flooding in South-Central Texas

摘要

This study is a forensic investigation of how two well-known satellite rainfall products, available at native scales that are much coarser than that ideally needed for detecting heavy rainfall-induced localized flooding, might have performed for July 2002 flooding in south-central Texas. These two products are: 1) the Global Precipitation Climatology Project (GPCP) rainfall product available at 1° and daily resolution; and 2) the Tropical Rainfall Measurement Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) product 3B42RT available at 0.25 degree and 3 hourly resolution. Both products are considered sufficiently coarse for the flooding that evolved in the typically Hortonian (infiltration-excess) catchments of south-central Texas. An error assessment was performed on these rainfall datasets based on ground validation (GV) data. Compared with the hydrographs of gauge points located within the flooding region, both satellite rainfall products showed promise in detecting the rising and receding trends of the flood events. However, compared with flood inundation maps from Dartmouth Flood Observatory, 3B42RT showed higher agreement in matching with flow accumulation pattern at the subgrid scale. This study shows that merged satellite precipitation products that are emerging today from the constellation of low-earth orbit passive microwave sensors have adequate information content at the native scale for application in providing guidance on localized flooding over ungauged basins.