Remotely sensed rivers to account for geomorphic processes in river basins threatened by anthropic pressures and climate changes

Remote sensing since a few years are offering unprecedented opportunities to monitor the environment and its functioning. Fluvial geomorphology is affected by these advances. Nowadays we can address basin analysis of river geomorphic trajectories and simulate sediment connectivity and transport at the network scale thanks to available remotely sensed geomorphic datasets. However, these assessments and simulations present distinct limitations and must be integrated with field data and high-resolution datasets acquired in selected locations for validation purposes. Despite that, if properly managed the current ability to generate an understanding of river geomorphic functioning and sediment connectivity at the network scale is notable and can support modern river management in assessing scenarios of future strategic decisions such as, water resources issues, rehabilitation objectives and flood protection schemes. In this talk I will present two case studies where we have been applying such approaches. The first concerns the Mekong river, one of the largest and most threatened river system globally, and its strategic dam planning for the following 30-50 years. We have assessed sediment connectivity and transport for different scenarios of dam planning and estimate the risk of sediment starvation for the Mekong Delta at risk of drowning identifying more sustainable and less impacting dam locations compared to the existing ones. The second case is the Vjosa river, one of the last unpaired braided system in Europe, recently threatened by the possibility to build multiple dams along its course to produce hydroelectric energy. Here we have developed simulations able to link changes in sediment transport due to dam building with likely adjstments in river patterns and morphology with multiple consequences in terms of river equilibrium and ecosystem services provided. Finally, current capacity to understand river geomorphic functioning at the network scale will be discussed. Impacts of strategic management measures and climate changes can nowadays be predicted in terms of sediment transport and river geomorphic adjustment processes likely occurring in the coming years. Rarely modern management uses the full capacity of this discipline to address management decisions, and this lack of exploitation of available knowledge is a responsibility we need to correct as a community in the future.