Stability of the shoreline

Stabihty of the shoreline is an important factor in determining the acceptability of a site, in particular for sites on the shores of large bodies of water. The stabihty of the shoreUne near the site should be investigated together with effects of the nuclear power plant on the stability. 

For a river site the stabihty of the river channel in extremely heavy floods should be considered. 

Early in the siting process the investigations should include the collection and analysis of all available historical data on the stabihty of the local shoreline. For sandy or silty beaches it is customary to evaluate the stabihty of the shoreline on the assumption of both the onshore-offshore movement and the littoral transport of beach materials. When the coast is formed by cliffs, changes may occur in the coastline over a long period and may be able to be deduced from historical maps. 

The effects of the plant structures on the littoral stabihty that are to be investigated include  

The longshore transport of sand in the littoral zone should be evaluated by studying the tidal currents and the climatological data for waves as they occur in the given segment of beach, with a knowledge of how the waves 

---

Erosion-control practices are required in many different circumstances. Agricultural practices for animal husbandry or to produce food crops can have significant adverse impacts on soil health if soil conservation techniques are not applied. Land development for residential housing or commercial and industrial facilities can have short-term erosion impacts during construction or long-term effects from rainwater or snowmelt on the sites. Recreational uses near lakes, streams, or oceans can affect the stability of the shoreline. Transportation systems may create unstable slopes with increased potential for landslides from cuts through hills for roads and rail lines. 

The actual computation of the longshore transport for determining the long term stability of the shoreline and its stability under severe flood conditions requires data on the heights, periods and directions of breaking waves, which should be evaluated by means of wave refraction diagrams, and the characteristics of beach sediments. 

Shoreline Fumigation - For rural sources within 3000 m of a large body of water, maximum shoreline fumigation concentrations can be estimated by SCREEN. A stable onshore flow is assumed with stability class F (A0/AZ = 0.035 K/m) and stack height wind speed of 2.5 m/s. Similar to the inversion break-up fumigation case, the maximum ground-level shoreline fumigation concentration is assumed to occur where the top of the stable... 

Dispersant is a common term used to label chemical spill-treating agents that promote the formation of small droplets of oil that disperse throughout the top layer of the water column. Dispersants contain surfactants, chemicals like those in soaps and detergents, that have molecules with both a water-soluble and oil-soluble component. Depending on the nature of these components, surfactants cause oil to behave in different ways in water. Surfactants or surfactant mixtures used in dispersants have approximately the same solubility in oil and water, which stabilizes oil droplets in water so that the oil will disperse into the water column. This can be desirable when an oil slick is threatening a bird colony or a particularly sensitive shoreline. 

Shoreline sensitivity — The susceptibility of a shoreline environment to any disturbance that might decrease its stability or result in short- or long-term adverse effects. Shorelines that are susceptible to damage from stranded oil are usually equally sensitive to cleanup activities, which may alter physical habitat or disturb associated flora and fauna. Marshes and lagoons are the most sensitive shoreline environments, while exposed coasdine subject to heavy wave action is generally the least affected by oil and cleanup activities. 

The mechanical IBL develops across the shoreline because of roughness changes. Mechanical turbulence overpowers thermal contrast to make the stability parameter, Z/L, close to zero, or neutral. As shown in Fig. 10a, the... 

Most of the applications of geotextile containment in coastal engineering belong to this type of shore protection i.e., the containment is built directly along the shoreline to prevent erosion and to stabilize a beach-dune system during storm surge (Fig. 21.7). For this purpose, different types of containments have been applied, very often as a last defense line in combination with beach nourishment. 

It is not known when this picture was taken, but with the two inlet jetties in place, the southern jetty can be applied to test the stability of Doran Beach at the time after the installation of these jetties. First, application of MEPBAY with the tip B renders the predicted static bay shape landward of the existing waterline. This is similar to that before the jetty construction, but this later static bay shape marked as B D is closer to the existing shoreline than the previous A D, hence, less potential erosion overall. It can be envisaged that beach may retreat if sediment supply reduces in the future. However, for a bay beach in dynamic condition, a... 

Beach nourishment provides an approach to beach stabilization that can enhance recreation, storm protection, and habitats for nesting sea turtles and other biota that reside in the beach and dune environment. The mechanics of beach nourishment along sandy shorelines can be represented in terms of the planform evolution and cross-shore processes. These two issues are usually considered separately in design with the recognition that profile equilibration normally occurs with a shorter timescale than the planform evolution and calculations of planform evolution are generally carried out as if the profile adjustment is instantaneous. 

Plume height is based on the assumed F stability and 2.5 m/s wind speed, and the dispersion parameter (o, ) incorporates the effects of buoyancy induced dispersion. If x , is less than 200 m, then no shoreline fumigation calculation is made, since the plume may still be influenced by transitional rise and its interaction with the TIBL is more difficult to model. 

Holding back the sea—as water levels continue to rise—may always be technically feasible however, it will not always be technically sound or economically practical. In areas where the long-range cost or the environmental damage due to shoreline stabilization is exorbitant, it will be prudent to move back from the shore. Planned retreat requires years of preparation. A retreat can occur as a gradual process, or as catastrophic land abandonment. 

---