A 3-step framework to consider hydrosedimentary dynamics in river crossing management.

English Abstract:

In rivers with high bed load transport, morphological changes result in considerable cost for managing river crossing. In Québec, managers lack the tools to anticipate river change driven by hydrosedimentary dynamics. Simple rules are hard to provide because of river complexity and of contingency in river behaviour hence the need for a framework that is adjustable to both river character and management needs. We propose three fundamental steps that can lead to a relevant diagnostic of hydrosedimentay dynamics in support of river crossing management. The first step provides geomorphological context and first-hand understanding from river styles. The second step details historical trajectories and identifies relevant controls. The third step aims at defining sediment connectivity, from sediment sources to sinks, which can be quantified through sediment budget analysis. Taken together, the three steps provide an efficient understanding of hydrosedimentary dynamics and lead to management strategies that can address sediment-related problems. The 3-step framework will be illustrated using several cases of high sediment load rivers in eastern Quebec where river crossing issues emerge from intense hydrosedimentary dynamics.