Abstract
Abstract. Availability of in situ river monitoring data, especially of data shared across boundaries, is decreasing, despite growing challenges for water resource management across the entire globe. This is especially valid for the case study of this work, the Brahmaputra Basin in South Asia. Commonly, satellite altimeters are used in various ways to provide information about such river basins. Most missions provide virtual station time series of water levels at locations where their repeat orbits cross rivers. CryoSat-2 is equipped with a new type of altimeter, providing estimates of the actual ground location seen in the reflected signal. It also uses a drifting orbit, challenging conventional ways of processing altimetry data to river water levels and their incorporation in hydrologic–hydrodynamic models. However, CryoSat-2 altimetry data provides an unprecedentedly high spatial resolution. This paper suggests a procedure to (i) filter CryoSat-2 observations over rivers to extract water-level profiles along the river, and (ii) use this information in combination with a hydrologic–hydrodynamic model to fit the simulated water levels with an accuracy that cannot be reached using information from globally available digital elevation models (DEMs) such as from the Shuttle Radar Topography Mission (SRTM) only. The filtering was done based on dynamic river masks extracted from Landsat imagery, providing spatial and temporal resolutions high enough to map the braided river channels and their dynamic morphology. This allowed extraction of river water levels over previously unmonitored narrow stretches of the river. In the Assam Valley section of the Brahmaputra River, CryoSat-2 data and Envisat virtual station data were combined to calibrate cross sections in a 1-D hydrodynamic model of the river. The hydrologic–hydrodynamic model setup and calibration are almost exclusively based on openly available remote sensing data and other global data sources, ensuring transferability of the developed methods. They provide an opportunity to achieve forecasts of both discharge and water levels in a poorly gauged river system.
Highlights
Introduction and backgroundThis study shows how river water-level measurements from the drifting-orbit radar altimetry mission CryoSat-2 can be used in combination with hydrodynamic river models
The method developed in this study, combining altimetry data from two missions with different orbits with a hydrologic–hydrodynamic model allows the calibration of cross sections in a 1-D hydrodynamic river model without precise knowledge of topography or bathymetry
This results in a model that accurately simulates water levels, which is an important achievement if poorly gauged river basins are to be modelled
Summary
This study shows how river water-level measurements from the drifting-orbit radar altimetry mission CryoSat-2 can be used in combination with hydrodynamic river models. This new type of satellite altimetry data, providing river waterlevel profiles with unprecedented spatial resolution, was used in combination with conventional data from Envisat, providing water-level time series at virtual stations. The combination of these two datasets allowed accurate calibration of water-level dynamics – both absolute water levels as well as water-level amplitudes – along a continuous stretch of a 1-D hydrodynamic model of the Brahmaputra River This is obtained without precise knowledge of topography or bathymetry
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
