Flood detection/intensity estimates are based on 13 years of retrospective model runs with TMPA input, with flood thresholds derived for each grid location using routed runoff statistics (95th percentile plus parameters related to basin hydrologic characteristics). The intensity value is the calculated water depth above the flood threshold. Other model calculations, including streamflow, streamflow values above a flood threshold determined from retrospective model runs, land surface water storage are also displayed. In addition, the latest maps of instantaneous precipitation and totals from the last day, three days and seven days are displayed. All the calculations are updated every three hours. Users can "zoom in" to an interested local area, time sequence the maps over the last few days or months and plot time sequences of data at a point.
The flood model is based on the University of Washington Variable Infiltration Capacity (VIC) land surface model (Liang et al., 1994) coupled with the University of Maryland Dominant River Tracing Routing (DRTR) model (Wu et al., paper in preparation). The flood detection algorithm is described in Wu et al. (2012). The real-time TMPA precipitation data product (Huffman et al., 2010) is obtained from the NASA Goddard TRMM/GPM Precipitation Processing System (PPS). An initial evaluation of the new GFMS based on 15-yr (1998~2012) retrospective simulation against gauge streamflow observations and reported flood event archives has been performed and presented recently in 2013 American Meteorological Society(AMS) Annual Meeting. The PDF file of the slides from the talk is available here
To facilitate a quick evaluation of the model performance, below are links of some USGS streamflow gauges over the IFloodS focal river basins. Click them to get the observed streamflow time series and also gauge information (e.g. gauge location, from the selection box on the top the USGS webpage you clicked into). The corresponding locations of these gauges represented in the VIC-DRTR model are also indicated in the blow table. Users can put these locations (lat/lon) into the boxes in the right column of the page to retrieve the time series calculated by the model. Note that the slight difference between the locations for 1 km resolution and 12 km resolution are caused by the upscaling issue (see Wu et al., 2012).
| River Basin | USGS Gauge | Drainage Area | Model Location (12km) | Model Location (1km) | |
| Iowa River basin | USGS 05454500 | 8471 km2 | 41.6, -91.6 | 41.66, -91.54 | Iowa River at Iowa City;Below Coralville Dam |
| Iowa River basin | USGS 05453100 | 7236 km2 | 41.81, -92.1 | 41.81, -92.1 | Iowa River at Marengo, IA;Above Coralville Dam |
| Cedar River basin | USGS 05465000 | 20168 km2 | 41.39, -91.3 | 41.39, -91.3 | Cedar River near Conesville, IA |
| Cedar River basin | USGS 05445000 | 16860 km2 | 41.93, -91.68 | 41.97, -91.68 | Cedar River at Cedar Rapids, IA |
| Turkey River basin | USGS 05412500 | 4001 km2 | 42.75, -91.4 | 42.74, -91.26 | Turkey River at Garber, IA |
References
Huffman, G.J., R.F. Adler, D.T. Bolvin, E.J. Nelkin, 2010: The TRMM Multi-satellite Precipitation Analysis (TMPA). Chapter 1 in Satellite Applications for Surface Hydrology, F. Hossain and M. Gebremichael, Eds. Springer Verlag, ISBN: 978-90-481-2914-0, 3-22.
Liang, X., D. P. Lettenmaier, E. F. Wood, and S. J. Burges, 1994: A Simple hydrologically Based Model of Land Surface Water and Energy Fluxes for GSMs, J. Geophys. Res., 99(D7), 14,415-14,428.
Wu H., R. F. Adler, Y. Tian, G. Huffman, H. Li and F. Policelli (2013),Real-time Global Flood Monitoring Using Satellite-based Precipitation and a Land Surface Model, Water Resour. Res. (in preparation)
Wu H., R. F. Adler, Y. Hong, Y. Tian, and F. Policelli (2012), Evaluation of Global Flood Detection Using Satellite-Based Rainfall and a Hydrologic Model. J. Hydrometeor, 13, 1268.1284.
Wu H., J. S. Kimball, H. Li, M. Huang, L. R. Leung, R. F. Adler (2012), A new global river network database for macroscale hydrologic modeling, Water Resour. Res., 48, W09701, doi:10.1029/2012WR012313.