Satellite data for the integrated modelling of Watershed-Coast System morphodynamics in a changing climate: a critical review and a structured framework

Watershed-Coast Systems (WACS) integrate the watershed and the coast as a coupled geomorphological entity whose evolution depends on climate, terrestrial, and marine drivers acting at very different scales. Modelling the morphodynamics of WACS in a changing climate is a recognised but uneven endeavour: satellite-data use has matured for inland hydrology and for coastal observation taken in isolation, but the role of satellite data as the connective tissue between the two – the integration component of recent WACS frameworks – remains comparatively underdeveloped. This review addresses that asymmetry. It synthesises the literature on the use of satellite data for each component of an established WACS modelling framework (climate, watershed, coastal, and integration), with particular attention to the river-mouth, estuary, and delta interface where satellite observations bridge terrestrial and marine processes. A structured methodological framework is then proposed that operationalises the use of satellite data within the WACS modelling workflow; the framework is organised and visualised by matrices connecting essential aspects to satellite-product families, to modelling roles, and to spatial and temporal scales. The framework foregrounds the modelling roles (forcing, parameterisation, calibration, assimilation, validation, assessment, communication) and explicitly identifies where current missions are productive and where gaps remain, with the recent wide-swath altimetry mission offering a particularly clear opportunity for transitional-zone modelling. The review is intended for scientists, engineers, and modellers working on integrated watershed–coast modelling, and for coastal and river managers and policymakers concerned with WACS resilience.