Integrating mangrove growth and failure in coastal flood protection designs

Mangrove forests reduce wave attack along tropical and sub-tropical coastlines, decreasing the wave loads acting on coastal protection structures. Mangrove belts seaward of embankments can therefore lower their required height and decrease their slope protection thickness. Wave reduction by mangroves depends on tree frontal surface area and...

The influence of infragravity waves on the safety of coastal defences: a case study of the Dutch Wadden Sea

Many coastlines around the world are protected by dikes with shallow foreshores (e.g. salt marshes and mudflats) that attenuate storm waves and are expected to reduce the likelihood and volume of waves overtopping the dikes behind them. However, most of the studies to date that assessed their effectiveness have excluded the influence of...

Historic storms and the hidden value of coastal wetlands for nature-based flood defence

Global change amplifies coastal flood risks and motivates a paradigm shift towards nature-based coastal defence, where engineered structures are supplemented with coastal wetlands such as saltmarshes. Although experiments and models indicate that such natural defences can attenuate storm waves, there is still limited field evidence on how...

Salt marshes for flood risk reduction: Quantifying long-term effectiveness and life-cycle costs

Flood risks are increasing worldwide due to climate change and ongoing economic and demographic development in coastal areas. Salt marshes can function as vegetated foreshores that reduce wave loads on coastal structures such as dikes and dams, thereby mitigating current and future flood risk. This paper aims to quantify long-term (100 years)...

Voorlanden voor hoogwaterbescherming

In Nederland zijn honderden kilometers aan waterkering toe aan versterking. De aanleg van begroeide vooroevers, zoals schorren en kwelders, is een mogelijkheid om de belasting op dijken te verminderen. Daarmee dalen overstromingsrisico’s en gaan natuurwaarden omhoog.

Assessing safety of nature-based flood defenses: Dealing with extremes and uncertainties

Vegetated foreshores adjacent to engineered structures (so-called hybrid flood defenses), are considered to have high potential in reducing flood risk, even in the face of sea level rise and increasing storminess. However, foreshores such as salt marshes and mangrove forests are generally characterized by relatively strong temporal and...

Stem breakage of salt marsh vegetation under wave forcing: A field and model study

One of the services provided by coastal ecosystems is wave attenuation by vegetation, and subsequent reduction of wave loads on flood defense structures. Therefore, stability of vegetation under wave forcing is an important factor to consider. This paper presents a model which determines the wave load that plant stems can withstand before...

Probabilistic Assessment of Overtopping of Sea Dikes with Foreshores including Infragravity Waves and Morphological Changes: Westkapelle Case Study

Shallow foreshores in front of coastal dikes can reduce the probability of dike failure due to wave overtopping. A probabilistic model framework is presented, which is capable of including complex hydrodynamics like infragravity waves, and morphological changes of a sandy foreshore during severe storms in the calculations of the probability of...

Nature-based flood protection: Using vegetated foreshores for reducing coastal risk

Vegetated foreshores such as salt marshes, mangrove forests and reed fields can reduce wave loads on coastal dikes due to depth-induced wave breaking and wave attenuation by vegetation. Here we present field measurements of wave propagation over salt marshes during severe storm conditions, a modelling approach to describe the effect of...

Nature-based flood protection: The efficiency of vegetated foreshores for reducing wave loads on coastal dikes

This paper analyses the effect of vegetation on wave damping under severe storm conditions, based on a combination of field measurements and numerical modelling. The field measurements of wave attenuation by vegetation were performed on two salt marshes with two representative but contrasting coastal wetland vegetation types: cordgrass ...

Wave attenuation by salt marsh vegetation

Salt marshes are a characteristic feature of estuaries and coastal seas. They are found in the upper coastal intertidal zones between land and water, which are regularly flooded by tides and surges. They are covered with salt-tolerant vegetation types, such as herbs and grasses. Sheltering from continuous intense hydrodynamic forcing by waves...