Lisanne Braat

European Space Agency | ESA

Studies of fluvial landforms on the surface of Mars have become more detailed since rover data became available of areas altered by water (e.g. water-deposited sediment in Gale crater by Curiosity and the Jezero delta by Perseverance). As surface interpretations become more detailed, we need to pay more attention to the differences between Earth an...

Estuaries are dynamic landscapes with complex bar and channel patterns formed by interactions between tidal and fluvial currents. River discharge dampens the tidal wave, enhances the ebb flow, and supplies sediment to the estuary. However, it is largely unknown how river discharge influences overall estuary morphology. The objective of the current...

Rivers and estuaries are flanked by floodplains built by mud and vegetation. Floodplains affect channel dynamics and the overall system's pattern through apparent cohesion in the channel banks and through filling of accommodation space and hydraulic resistance. For rivers, effects of mud, vegetation and the combination are thought to stabilise the...

Mud plays a pivotal role in estuarine ecology and morphology. However, field data on the lateral and vertical depositional record of mud is rare. Furthermore, numerical morphodynamic models often ignore mud due to long computational times and simplifications of mixed depositional processes. This study aims to understand the spatial distribution, fo...

Rivers and estuaries are flanked by floodplains built by mud and vegetation. Floodplains affect channel dynamics and the overall system's pattern through apparent cohesion in the channel banks and through filling of accommodation space and hydraulic resistance. For rivers, effects of mud, vegetation and the combination are thought to stabilise the...

On the list of challenges facing the world largest deltas, increased saline water intrusion (SWI) in the surface water system and its role in jeopardizing freshwater supply are often ranked very high. Yet, detailed process-based studies of SWI at the whole delta scale are limited, and the trends are regularly associated with global sea level rise....

In the list of challenges facing the world largest deltas, increased salt intrusion and its role in jeopardizing freshwater supply is often ranked very high. Yet, detailed process-based studies of salt intrusion at the whole delta scale are limited and the trends are regularly associated to global sea level rise. Here, using field measurements and...

Mud accretion and establishment of biostabilizers, such as microphytobenthos and saltmarsh vegetation, govern the development of estuarine morphology. Mud facilitates saltmarsh survival and microphytobenthos growth, which in turn promotes sedimentation and reduces mud erosion. Consequently, an increasing extent and thickness of mud cover might lead...

Mud plays a pivotal role in estuary ecology and morphology. Effectsof mud are often ignored in morphodynamic studies due to longer compu-tational times and limited field data. This study aims to understand thespatial distribution of mud layers in tidal bars, their formative conditions,preservation potential and their effects on the morphology of ti...

The cover image is based on the Research Article Effects of estuarine mudflat formation on tidal prism and large-scale morphology in experiments by Lisanne Braat et al., https://doi.org/10.1002/esp.4504.

The planform of estuaries is often described with an ideal shape, which exponentially converges in landward direction. We show how growing topographically forced nonmigratory (i.e., anchored) bars determine the large-scale estuary planform, which explains the deviations observed in the planform of natural estuaries filled with bars compared to the...

Vegetation enhances bank stability and sedimentation to such an extent that it can modify river patterns, but how these processes manifest themselves in full-scale estuarine settings is poorly understood. On the one hand, tidal flats accrete faster in the presence of vegetation, reducing the flood storage and ebb dominance over time. On the other h...

The interaction of marine (tides and waves) and fluvial processes determines the sedimentary fill of coastal systems in the fluvial-tomarine (FTM) transition zone. Despite frequent recognition of tidal and wave influence in modern and ancient systems, our understanding of the relative importance of marine processes and their impact on mud depositio...

Human interference in estuaries has led to increasing problems of mud, such as hyper‐turbidity with adverse ecological effects and siltation of navigation channels and harbours. To deal with this mud sustainably, it is important to understand its long‐term effects on the morphology and dynamics of estuaries. The aim of this study is to understand h...

Human interference in estuaries has led to increasing problems of mud, such as hyper‐turbidity with adverse ecological effects and siltation of navigation channels and harbours. To deal with this mud sustainably, it is important to understand its long‐term effects on the morphology and dynamics of estuaries. The aim of this study is to understand h...

Cohesive floodplain sediment and vegetation are both thought to cause meandering river patterns. Our aims are to compare the isolated and combined effects of mud and vegetation on river planform and morphodynamics in the setting of intermediate‐sized valley rivers. We use a numerical model for century‐scale simulation of flow, sediment transport an...

The planform of estuaries is often described with an ideal shape, which is exponentially converging in landward direction. We show how growing forced bars determine the large-scale estuary planform, which explains the deviations from the ideal planform for natural estuaries filled with bars. Experiments were conducted in a 20~m long, 3~m wide tilti...

Vegetation enhances bank stability and sedimentation to such extent that it can modify river patterns, but whether similar strong biogeomorphological feedbacks exist in estuarine environments is poorly understood. On the one hand, tidal flats accrete faster in the presence of vegetation, reducing the flood storage and ebb-dominance over time, while...

Analogue models or scale experiments of estuaries and short tidal basins are notoriously difficult to create in the laboratory because of the difficulty to obtain currents strong enough to transport sand. Our recently discovered method to drive tidal currents by periodically tilting the entire flume leads to intense sediment transport in both the e...

Alluvial river estuaries consist largely of sand but are typically flanked by mudflats and salt marshes. The analogy with meandering rivers that are kept narrower than braided rivers by cohesive floodplain formation raises the question of how large-scale estuarine morphology and the late Holocene development of estuaries are affected by cohesive se...

Estuaries typically show converging planforms from the sea into the land. Nevertheless, their planform is rarely perfectly exponential and often shows curvature and presence of embayments. Here we test the degree to which the shapes and dimensions of tidal sand bars depend on estuary planform. We assembled a dataset with 35 estuary planforms and pr...

Alluvial river estuaries consist largely of sand but are typically flanked by mud flats and salt marshes. The analogy with meandering rivers, that are kept narrower than braided rivers by cohesive floodplain formation, raises the question how large-scale estuarine morphology and late Holocene development of estuaries are affected by cohesive sedime...

Analogue models or scale experiments of estuaries and short tidal basins are notoriously difficult to create in the laboratory because of the difficulty to obtain currents strong enough to transport sand. Since Osborne Reynolds' experiments over a century ago, experimental tidal flow has been driven by periodic sealevel fluctuations. Recently we di...

Scour holes often form in shallow flows over sand on the beach and in morphodynamic scale experiments of river reaches, deltas and estuarine landscapes. The scour holes are on average 2 cm deep and 5 cm long, regardless of the flow depth and appear to occur under similar conditions as current ripples: at low boundary Reynolds numbers, in fine sand...

Alluvial fans develop their semi-conical shape by quasi-cyclic avulsions of their geomorphologically active sector from a fixed fan apex. On debris-flow fans, these quasi-cyclic avulsions are poorly understood, partly because physical scale experiments on the formation of fans have been limited largely to turbidite and fluvial fans and deltas. In t...

Predicting debris-flow runout is of major importance for hazard mitigation. Apart from topography and volume, runout distance and area depends on debris-flow composition and rheology, but how is poorly understood. We experimentally investigated effects of composition on debris-flow runout, depositional mechanisms and deposit geometry. The small-sca...

For the execution of field measurements around the Sand Engine during MegaPEX2014 there was a need for operational model predictions. Local river outflow causes non-uniform velocities and spatially complex current patterns near the Sand Engine. For assessing the optimal timing and location of the instruments and GPS drifters, information on the pre...