Configurational stability in gravel-bed rivers Simon Dadson (1) and Michael Church (2) (1) Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ. United Kingdom. (2) Department of Geography, University of British Columbia, Vancouver, British Columbia, V6T 1Z2. Canada. Gravel-bed rivers derive stability from the configuration of grains on the channel bed. Grains interact with each other to form clusters which are more stable together than their constituent grains would be individually. Here, a model is presented for the configurational stability of river beds which shows that structured gravel requires an order of magnitude greater shear stress for entrainment than unconfined material. These results are then used in ensembled monte-carlo simulations to investigate the growth of gravel-bed stability, and changes in sediment transport rate over time as configurational stability develops. The predictions made agree qualitatively with previously published field and experimental observations. These theoretical and observational findings are discussed in the context of related work on structures and jamming in granular media.