Satellite Gauging Reaches.
This is experimental software. If you use it please let us know and check the paper describing the method:
Van Dijk, A. I. J. M., G. R. Brakenridge, A. J. Kettner, H. E. Beck, T. De Groeve,and J. Schellekens (2016), River gauging at global scale using optical and passive microwave remote sensing, Water Resour. Res., 52,doi:10.1002/2015WR018545.