More than half a billion people around the world live near river deltas, which are slowly sinking due to human activities, sea level rise, and the settling of sediments. Subsidence of river deltas can have serious impacts on populations, including raising the risk of storm surge and infrastructure degradation. However, current methods of tracking delta subsidence—via tide gauges or scattered GPS devices—have not provided the spatial variability needed to take measurements that are of use to the public.
Higgins et al. used a satellite-based interferometry technique to map the subsidence of the Ganges-Brahmaputra river delta over a period of 4 years. The satellite readings covered more than 10,000 square kilometers and were validated against separate GPS readings.
The authors found that the Ganges-Brahmaputra river delta, which is home to a population of more than 150 million people, is subsiding at a rate of about 10 millimeters per year around Dhaka, Bangladesh’s capital, and about 18 millimeters per year outside of the city. The authors note that their results indicate that satellite interferometry can be a useful method in accurately gauging the subsidence in deltas. (Journal of Geophysical Research: Earth Surface, doi:10.1002/2014JF003117, 2014)
—JoAnna Wendel, Staff Writer
Citation: Wendel, J. (2015), Satellite imaging improves study of sinking river deltas, Eos, 96, doi:10.1029/2015EO022013. Published 10 January 2015.