Connected or disconnected? Spatial and temporal patterns of river-floodplain connectivity

The boundary between a river and its floodplain is often viewed as a static feature which demarcates where the river ends and where the floodplain begins. This boundary, however, is a geomorphic transition whose spatial and temporal evolution controls the interaction of rivers and their floodplains. The transport of water, solutes, and solids across this geomorphic transition affects the functioning of rivers, floodplain sedimentation, carbon storage, and ecosystem functioning. Using examples from studies that combine remotely sensed observations, modeling, and field observations, I will discuss the exchange of fluxes across geomorphic transitions in the context of connectivity and its variability in space and time. We will analyze the role of various climate forcings as well as topography and vegetation patterns, and their effect on water connectivity and the connectivity of sediment and other materials. These connectivity patterns can be quite different from each other, suggesting that water exchanges are not always accurate proxies for sediment exchanges in river systems and their floodplains.