ESTUARIES are shallow coastal water bodies with river inflow shaped by biomorphological processes, with patterns of channels and shoals, sand/mud flats, tidal marshes, vegetated banks and peat. Development was influenced by early Holocene landscape that drowned under sealevel rise, and by human interference. Estuaries harbour highly productive natural habitats and are of pivotal economic importance for food production, access to harbours and urban safety. Accelerating sealevel rise, changing river discharge and interference threaten these functions, but we lack fundamental understanding and models to predict combined effects of biomorphological interactions, inherited landscape and changing drivers.We do not understand to what extent present estuary planform shape and shoal patterns resulted from biomorphological processes interacting with inherited conditions and interference. Ecology suggests dominant effects of flow-resisting and sediment de/stabilising eco-engineering species. Yet abiotic physics-based models reproduce channel-shoal patterns surprisingly well, but must assume a fixed planform estuary shape. Holocene reconstructions emphasise inherited landscape- and agricultural effects on this planform shape, yet fossil shells and peat also imply eco-engineering effects.My aims are to develop models for large-scale planform shape and size of sandy estuaries and predict past and future, large-scale effects of biomorphological interactions and inherited conditions.We will significantly advance our understanding by our state-of-the-art eco-morphological model, my unique analogue landscape models with eco-engineers and a new, automated paleogeographic reconstruction of 10 data-rich Holocene estuaries on the south-east North Sea coast. We will systematically compare these to modelled scenarios with biomorphological processes, historic interference and inherited valley geometry and substrate. Outcomes will benefit ecology, archeology, oceanography and engineering