Hard engineering involves the construction of hydraulic structures to protect coasts from erosion. Such structures include seawalls, gabions, breakwaters, groynes and tetrapods.
Hard engineering can cause unintended environmental consequences, such as new erosion and altered sedimentation patterns, that are detrimental to the immediate human and natural environment or along down-coast locations and habitats.
Seawalls and bulkheads may have multiple negative effects on nearshore ecosystems due to the way they reflect wave energy instead of dissipating it. Energy from reflected waves can cause a scouring effect on substrate below the structure, resulting in loss or displacement of sediment. Over time, this effect may lead to a decrease in the size of intertidal and nearshore habitats. This effect is also known as coastal squeeze. In addition, bulkheads and seawalls offer no filtering for surface runoff, this means that anthropogenic pollutants and chemicals in armored areas may enter coastal waters relatively quickly.
Hard engineering, also called shoreline armoring, comes with other ecological effects on top of habitat loss and increased surface runoff. Structures that are built between land and sea are usually made of material not native to shoreline ecosystems. For instance, most sea walls and interlocking coastal defense structures are made of concrete, which may lend itself as habitat for invasive species rather than native ones. These structures also impede shoreline access, blocking some or all species from accessing refuge on dry land. In these armored areas, nutrient exchange between tidal and riparian ecosystems is threatened or cut off entirely. These issues arise from hard engineered sea shores, and lead many to believe that living shoreline techniques are far more beneficial ecologically and in terms of long-term erosion control.
Examples of hard engineering include:
Groynes – Low walls constructed at right angles to retain sediments that might otherwise be removed due to longshore drift.
This page is automatically generated and may contain information that is not correct, complete, up-to-date, or relevant to your search query. The same applies to every other page on this website. Please make sure to verify the information with EPFL's official sources.
Coastal sediment supply is the transport of sediment to the beach environment by both fluvial and aeolian transport. While aeolian transport plays a role in the overall sedimentary budget for the coastal environment, it is paled in comparison to the fluvial supply which makes up 95% of sediment entering the ocean. When sediment reaches the coast it is then entrained by longshore drift and littoral cells until it is accreted upon the beach or dunes. While it is acknowledged that storm systems are the driver behind coastal erosion.
A coastal development hazard is something that affects the natural environment by human activities and products. As coasts become more developed, the vulnerability component of the equation increases as there is more value at risk to the hazard. The likelihood component of the equation also increases in terms of there being more value on the coast so a higher chance of hazardous situation occurring. Fundamentally humans create hazards with their presence.
Beach evolution occurs at the shoreline where sea, lake or river water is eroding the land. Beaches exist where sand accumulated from centuries-old, recurrent processes that erode rocky and sedimentary material into sand deposits. River deltas deposit silt from upriver, accreting at the river's outlet to extend lake or ocean shorelines. Catastrophic events such as tsunamis, hurricanes, and storm surges accelerate beach erosion. Beach accretion and erosion Tsunamis, potentially enormous waves often caused by earthquakes, have great erosional and sediment-reworking potential.
Concurrent rehabilitation alternatives were evaluated for a 1900 m reach of the River Etsch in northern Italy using a recently developed Hydro Morphological Index of Diversity (HMID) model. HMID is a new tool enabling quantitative assessments of river rest ...
Dams store water and trap sediment in their reservoirs. Downstream river segments, hence, are affected by a limited sediment dynamics. This becomes obvious by river bed incision, limited geomorphological variability and depletion of hydraulic habitats for ...
The objective of this paper is to examine the importance of sediment diffusion relative to advection in bed load transport. At moderate bottom shear stress, water turbulence is too weak for picking up and keeping particles in suspension and so shallow wate ...