At a global scale, deltas are vital economic hubs, in part due to the combination of their access to inland regions via river systems with their proximity to sea. However, with the sea in close vicinity also comes the threat of freshwater contamination by saline seawater, especially during droughts. This study explores the potential of a mitigation measure to estuarine salt intrusion, namely the construction of a (temporary) earthen sill—a measure implemented in the Lower Mississippi River near New Orleans (LA, USA). This study suggests design guidelines on how a sill can be used to mitigate estuarine salt intrusion: the design should focus on the longitudinal placement and the height of the sill, and the mitigating efficiency of the sill reduces with increasing tidal range. Overall, a (temporary) sill has great potential to reduce salt intrusion in salt wedge estuaries if there is sufficient water depth available.

Coastal managers worldwide increasingly recognize the importance of conservation and restoration of natural coastal ecosystems. This ensures coastal resilience and provision of essential ecosystem services, such as wave attenuation reducing coastal flooding and erosion. In the continuum from unvegetated tidal flats to salt marshes and mangroves, fundamental physical controls as well as biotic interactions, and feedbacks among them, determine morphology and vegetation distribution. Although these processes are well described in established literature, this information is rarely applied to understanding the role of these ecosystems as coastal defense. The focus is often on specific elements of the complex system, such as vegetation structure and cover, rather than on their complex natural dynamics. This review examines whether and how the dynamic nature of tidal flat - wetlands systems contributes to, or detracts from, their role in coastal defense. It discusses how the characteristics of the system adjust to external forcing and how these adjustments affect ecosystem services. It also considers how human interventions can take advantage of natural processes to enhance or accelerate achievement of natural coastal defense.

Deltaic and coastal ecosystems are changing in response to natural and anthropogenic forces that require ecosystem-level restoration efforts to avoid habitat degradation or loss. Models that link ecosystem components of hydrodynamics, morphodynamics, nutrient and vegetation dynamics to represent essential processes and feedbacks are advancing the field of environmental modeling and are vital to inform coastal restoration decisions. An Integrated Biophysical Model was developed by creating a new vegetation dynamics component and linking it to other primary ecosystem components that included essential feedbacks. The model performance was evaluated by applying it to a deltaic ecosystem that included marshes and estuaries. The Integrated Biophysical Model output captured the general temporal and spatial environmental trends of key variables. This integrated model is capable to perform long-term simulations to assess responses of deltaic and coastal systems to global change scenarios and can be used to inform restoration strategies in ecosystems worldwide.