One of the studies that we are conducting is for the ancient coastal city of Byblos, which is facing problems of soil erosion and sea level rise. We are looking at different mitigation methods to stop soil erosion and save one of the city’s major archaeological sites.
Soft and hard mitigation are available methods for mitigating erosion.
Soft methods tend to be inexpensive, small in scale and mostly eco-friendly; whereas hard methods do not solve the problem of erosion most of the times especially on the longer term, they aggravate the problem of soil loss. Some examples include seawalls, bulkheads, revetments, groins, jetties (made of rubble mound, concrete), etc. Seawalls interfere with local wave hydrodynamics and sediment movement, cause up-drift accretion, down-rift erosion, and put swimmers, divers and marine life at risk.
Focusing on the soft methods, they include dune rehabilitation/sand fencing, green belts, and artificial reefs/Biorock© Process
Dune rehabilitation: Drift fencing and dune re-vegetation prevent the loss of wind-blown sand inland and help with dune stability. One specific example could be the application of Sand Fencing. It is the process of reconstructing dunes by driving wooden pickets to about 2 m height, parallel to the shoreline at the end of the natural dune line. It requires time since sand accumulation along the fence is a slow process.
Green belts: series of trees in a number of rows to protect the coast from onslaught of waves. Examples of application are found in: Picchavaram in Tamil Nadu; Karnataka state in India (250 m from the sand zone); Sri Lanka (Pandunas). Failure of these implementations is usually due to poor maintenance.
Artificial reefs: recreation of the coral reefs colonies to dissipate wave energy by wave breaking and protect coasts. They also augment the amount of sea life such as fish, algae, barnacles, corals, oysters, and cause shoreline to accrete. What is important is to consider here the native sea ecosystem before introducing new species that might be invasive. One process within artificial reefs is Biorock© Process. It is a method of mineral accretion that grows coral reefs. It is applied to fish and shellfish mariculture, as well as to growing limestone breakwaters to protect islands and coastal areas from erosion and rising levels.
Below are images representing the soft solutions:
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