3.3 KiB
| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Beach evolution | 3/5 | https://en.wikipedia.org/wiki/Beach_evolution | reference | science, encyclopedia | 2026-05-05T07:34:26.041541+00:00 | kb-cron |
====== Concrete objects ====== These are complex reinforced concrete objects, such as A-jack, Akmon, Dolos, Honeycomb sea wall (Seabees), KOLOS, Tetrapod and Xbloc. Simple concrete blocks have been replaced by these complex concrete objects because these objects are more resistant to wave action and require less concrete to produce a superior result. These could be used to build seawalls, groynes, breakwaters, and other structures including residential buildings. Tetrapods used along Marine Drive, Mumbai are an example of complex concrete objects.
====== Gabions ====== Gabions are constructed by wiring boulders and rocks into mesh cages and placed in front of areas vulnerable to erosion, sometimes at cliffs edges or at right angles to the beach. When the ocean lands on the gabion, the water drains through leaving sediment, while the structure absorbs a moderate amount of wave energy. Gabions need to be securely tied to protect the structure. They can be used to build seawalls, groynes, breakwaters, revetments, buildings, underwater reefs, etc.,
==== Soft engineering methods ====
Soft engineering uses a "soft" (non-permanent) structure by creating a larger sand reservoir, pushing the shoreline seaward. It gained popularity because it preserved beach resources and avoided the negative effects of hard structures.
===== Managed retreat ===== Managed retreat means the shoreline is left to erode, while relocating buildings and infrastructure further inland.
===== Beach evolution ===== Beach evolution, also called "beach replenishment" or "beach nourishment", it involves importing sand from elsewhere and adding it to the existing beach. The imported sand should be of a similar quality to the existing beach material so it can meld with the natural local processes and without adverse effects. Without the groynes or scheme requires repeated applications on an annual or multi-year cycle. Beach nourishment can be used in combination with seaward curving half-moon shaped "headland breakwater" structure, this combining the benefits of breakwater and groyne structures.
===== Sand dune stabilization ===== Sand dune stabilization protects beaches by catching windblown sand, increasing natural beach formation. Fences can allow sand traps to create blowouts and increase windblown sand capture. Plants such as Ammophila (Marram grass) can bind the sediment.
===== Beach drainage ===== The beach face dewatering lowers the water table locally beneath the beach face. This causes accretion of sand above the drainage system.
=== Cost considerations === The costs of installation, operation and maintenance vary due to:
system length (non-linear cost elements) flow rates (sand permeability, power costs) soil conditions (presence of rock or impermeable strata) discharge arrangement /filtered seawater utilization drainage design, materials selection & installation methods geographical considerations (location logistics) regional economic considerations (local capabilities /costs, availability of local material and native skilled workforce) study requirements /consent process.
=== An illustrative example ===