River Bed Response to Sea Level Rise

Climate change is causing the global sea level to rise. Research and discussion of the effects of sea level rise are often focused along coastlines. However, the effects of higher water level and changing morphodynamics can reach far inland via rivers. This study uses a one-dimensional numerical model to analyze bed level response to sea level...

Adaptation of river channels to a wetter or drier climate: Insights from the Lower Pilcomayo River, South America

Climate change has a direct influence on both hydrology and floodplain vegetation of water courses, which are key players in river morphodynamics. The river system response to climate change is complex and the effects of non-linear interactions between alterations in water, sediment and vegetation remain incompletely understood. Which of...

Disentangling changes in the river bed profile: The morphological impact of river interventions in a managed river

The river bed level in low-land rivers like the Rhine branches in The Netherlands changes continuously on various spatial and temporal scales. Large-scale degradation occurs in many rivers due to river-wide engineering interventions, such as channelization, in the last decades and centuries. Local river interventions, such as the construction...

Numerical study on the transition between river bar regimes due to varying discharge

Propagation of sediment waves associated with coarse gravel nourishments

Sediment nourishments have become an increasingly attractive alternative to deal with continuous bed degradation problems in the river system. When supplied to the river, sediment nourishments induce a sediment wave that propagates through the system causing changes in bed level and bed surface texture. In the present study we use a one...

Schematisation of discharge time series in morphodynamic river models

River discharge is an essential parameter in morphodynamic modelling. It proves to be highly variable in both time and space. In this thesis the impact of the schematisation of time-dependent discharge series on morphodynamic change is studied. The impact is governed by several factors such as the long-term discharge statistics, and both short-...

Impact of flow variability and sediment characteristics on channel width evolution in laboratory streams

Alluvial rivers are shaped by sequences of water flows excavating their channels. Observations show that besides the magnitude, the frequency and duration of streamflow oscillations might also be important for the river channel formation. In addition, the river morphology appears influenced by both size and degree of uniformity of the...

Ill-posedness in modeling mixed sediment river morphodynamics

In this paper we analyze the Hirano active layer model used in mixed sediment river morphodynamics concerning its ill-posedness. Ill-posedness causes the solution to be unstable to short-wave perturbations. This implies that the solution presents spurious oscillations, the amplitude of which depends on the domain discretization. Ill-posedness...

Riverbank protection removal to enhance bar formation for habitat diversity

Over the past centuries natural riverbanks have been transformed into banks with artificial revetments or sheet piles to protect them from erosion, which led to disappearance of important river features for flora and fauna. River restoration projects show that the removal of man-made bank protections may lead to the formation of bars (e.g. Van...

Morphodynamic assessment of side channel systems using a simple one-dimensional bifurcation model and a comparison with aerial images

Side channel construction is a common intervention applied to increase a river's conveyance capacity and to increase its ecological value. Past modelling efforts suggest two mechanisms affecting the morphodynamic change of a side channel: (1) a difference in channel slope between the side channel and the main channel and (2) bend flow just...

Role of vegetation on river bank accretion

There is rising awareness of the need to include the effects of vegetation in studies dealing with the morphological response of rivers. Vegetation growth on river banks and floodplains alters the river bed topography, reduces the bank erosion rates and enhances the development of new floodplains through river bank accretion. The role of...

Five common mistakes in fluvial morphodynamic modeling

Recent years have seen a marked increase in the availability of morphodynamic models and a proliferation of new morphodynamic codes. As a consequence, morphodynamic models are increasingly developed, used and evaluated by non-experts, possibly leading to mistakes. This paper draws attention to five types of common mistakes. First, new...

Bank retreat study of a meandering river reach case study: River Irwell

Lack of data is often considered a limitation when undertaking morphological studies. This research deals with morphological studies of small rivers experiencing bank erosion processes when only limited data are available. A reach of the meandering gravel-bed river Irwell (United Kingdom) is taken as a case study in order to analyze the bank...