Analyzing natural bed‐level dynamics to mitigate the morphological impact of river interventions

Local river interventions, such as channel narrowing or side channels, are often nec-essary to maintain safety, ecology, or navigation. Such interventions have differenteffects on the river's bed morphology during periods of high- and low-dischargeevents. Mapping the bed-level variations for different discharge levels and under-standing these effects can provide new opportunities for the design of interventionsin multifunctional rivers. At any moment, the local bed level in a river is composed ofbed-level changes that occur at various spatial and temporal scales. These changesconsist of bed aggradation/degradation trends on a large scale, on an intermediatescale bed-level variations as a result of discharge fluctuations, and on small-scalemoving river bed forms like dunes. Using the river Waal in the Netherlands as a casestudy, we analyze the intermediate-term bed-level changes resulting from dischargefluctuations (dynamic component) and propose adaptations to the design of flood-plain interventions such that possible negative impact on the local bed-level changesis minimized. Time series of bed levels along two 10 km stretches of the case studyare considered for a period of 16 years (2005–2020). Using a wavelet transform, weisolate bed-level variations resulting from discharge events. These bed-level varia-tions are presented based on the magnitude of the discharge event and are compiledin an interactive atlas of river morphodynamics, allowing us to mitigate the impact ofinterventions. This will help river managers in the design of interventions and lead toimproved management, operation, and maintenance of multifunctional rivers.