inhibition and downdrift erosion. These activities interfere with the natural sediment flows either through dam construction (thereby reducing riverine sediment sources) or construction of littoral barriers such as jetties, or by deepening of inlets; thus preventing longshore transport of sediment. Types of shoreline protection approaches The coastal engineering for the shoreline protection involves: Soft engineering: Beach nourishment is a type of soft approach. it gained popularity because it preserved beach resources and avoided the negative effects of hard structures. Instead, nourishment creates a “soft” (i.e., non-permanent) structure by creating a larger sand reservoir, pushing the shoreline seaward. Hard engineering: Beach evolution and beach accretion can be facilitated by the four main type of hard engineering structures in coastal engineering are, namely seawall, revetment, groyne or breakwater. Most commonly used hard structures are seawall and series of "headland breakwater" (breakwater connected to the shore with groyne). Managed retreat, the shoreline is left to erode, while relocating buildings and infrastructure further inland. Approach Assessment Advantages Widens the beach. Protects structures behind beach. Protects from storms. Increases land value of nearby properties. Grows economy through tourism and recreation. Expands habitat. Only practical, environmentally-friendly approach to address erosional pressure. Encourages vegetation growth to help stabilize tidal flats. Disadvantages Added sand may erode, because of storms or lack of up-drift sand sources. Expensive and requires repeated application. Restricted access during nourishment. Destroy/bury marine life. Difficulty finding appropriate materials. Considerations Costs Nourishment is typically a repetitive process, since nourishment mitigates the effects of erosion, but does not remove the causes. A benign environment increases the interval between nourishment projects, reducing costs. Conversely, high erosion rates may render nourishment financially impractical. In many coastal areas, the economic impacts of a wide beach can be substantial. Since 1923, the U.S. has spent $9 billion to rebuild beaches. One of the most notable example is the –long shoreline fronting Miami Beach, Florida, which was replenished over the period 1976–1981. The project cost approximately US$ 86 million and revitalized the area's economy. Prior to nourishment, in many places the beach was too narrow to walk along, especially during high tide. In 1998 an overview has been made of all known beach nourishment projects in the USA (418 projects). The total volume of all these nourishments was 648 million cubic yards (495 m3) with a total cost of US$ 3387 million (adjusted to price level 1996). This is US$ 6.84 per