Testing the potential of Near Infrared band for the estimation of flow duration curves

The flow duration curves (FDCs) represent the relationship between river discharges observed at a given cross-section and the percent of time (duration) they are exceeded, or equaled, over an historical reference period. The FDC provides a comprehensive description of the hydrological regime of a catchment and its knowledge is fundamental for many water-related applications (e.g., water management and supply, human and irrigation purposes, etc.). However, relying on historical streamflow records, FDCs are constrained to gauged stations and, thus, typically available for a small portion of the world’s rivers. In this context, satellite data can support our monitoring capability and being considered as a valuable and additional source for the observation of the Earth’s physical parameters.

Recent studies demonstrated the efficiency of the surface reflectance in the Near Infrared (NIR) for the river discharge estimation. The high temporal resolution (almost daily), the high-medium spatial resolution (10 - 300 m) and the global coverage observing in a continuous way the range of 90-90 latitude encourage to extend the use of the NIR bands also for hydrology-related purposes. Here we tested the potential of MODIS 500 m 8-day product in providing discharge estimation for the construction of FDCs at 13 sites along the Mississippi River. In particular, this work considers records of river discharge from January 2003 to December 2019, calibrating and validating the FDCs for a period of 13 and 4 years, respectively. The aim is to test the ability to estimate the hydrological regime of a river at a given location using satellite data.

Results highlight the potential of the NIR bands to provide a realistic reconstruction of the flow regimes at different locations. Higher errors are obtained at the FDC tails, where extremely high or low flows have a low likelihood of being observed, mainly due to the limit of the sensor to see below the clouds during the flood events or to capture small water body. Better performances are obtained for the medium flows, encouraging the use of the satellite for the water resources management at ungauged river sites.