Utilization of Satellite Altimetry for Bangladesh Flood Forecasting and Warning System (May, 2015)

Monday, May 11, 2015

Satellite altimetry is typically used to measure the height of the ocean, but it can also be used to measure the heights of rivers and lakes. In areas that experience monsoonal rain this can provide life saving information. Currently Bangladesh has implemented a system that uses Jason-2 to forecast river heights, such as the Ganges River (Figure 1), up to 8 days ahead of time. This system was developed by Faisal Hossain, at University of Washington in collaboration with the Flood Forecasting and Warning Center (FFWC), the Institute of Water Modeling in Bangladesh and International Center for Integrated Mountain Development (ICIMOD). FFWC functions as the key government agency of Bangladesh with the national mandate to make flood forecasts available for the public. The development work was part of SERVIR, a joint program between NASA and USAID to use Earth observing satellite data to help developing countries make informed decisions on environmental matters.

Figure 1. Upper row: The Ganges Brahmaputra Meghna (GBM) river basins and the Ganges-Brahmaputra (GB) delta. Bottom row: The many river deltas (shown as a triangle in each region) located in large remote river basins that lack information for modeling rivers and water management. [Image Credit: NASA SERVIR]
Figure 2. Map of Bangladesh showing
OSTM/Jason-2 tracks in black and
Saral/AltiKa in magenta.



During this upcoming monsoon season measurements from the joint French and Indian altimetric mission, SARAL, will be integrated into the operational flood forecast system maintained by FFWC (Figure 2). While both Jason-2 and SARAL were designed to measure the sea surface (Figure 3), they also contain information on the heights of rivers. This is done by taking the distance measured by the altimeters from it and the surface of the Earth and correcting for various atmospheric properties that will degrade the altimeter’s measurement. Collectively the satellites will provide a more comprehensive observational system of river dynamics.






Figure 3. Sea surface height measured by OSTM/Jason-2 and SARAL/AltiKa. This shows
the world coverage of the two satellites combined. [Image Credit: sealevel.jpl.nasa.gov]




PO.DAAC Science Team in collaboration with Dr. Faisal Hossain (Univ. Washington)