A recent study of the beaches in the state of Delaware(1) weighs the cost of beach retreat against the cost of beach nourishment over the next 50 years. The study concluded that the cost of retreating from eroding coasts will be approximately four times the cost of renourishing the state’s beaches.
To reach this conclusion, the study considers four types of costs associated with a policy of retreat. The first is land loss. As the beach erodes, the coastline moves inland. Over the next 50 years, there will be a significant loss to the total acreage of the state of Delaware. While it is beachfront that will be eroded, the loss of land will reduce the amount of inland land. As the coastline moves in, some beach will always exist along the water’s edge. However, this beach will be created from land formerly used for residential, commercial and agricultural purposes. The second type of loss associated with beach retreat is capital loss. Capitol loss considers the extent to which beachfront structures are lost to the ocean as it migrates inland. These include homes, commercial buildings, boardwalks and parking lots. Capitol loss also includes costs for maintenance and adjustments to preserve the structures to extend their use before their inevitable loss. Proximity loss is the third cost of beach retreat.
Because people are aware of the eroding coastline, there will be less development near the beach. Proximity to beaches adds value to homes, there will be a loss of value due to development further away from the beach. In addition, beachfront structures along a retreating coastline will depreciate in value when compared with the value of the same structures along a stable coastline. As the final cost of beach retreat, the study cites transition loss. As the coastline moves inland, existing structures will have to be removed. If any structures are to be relocated further from the coastline, then transition loss accounts for the cost of moving them.
Next, these four costs are calculated over the next 50 years. Using the historic rates of erosion along the Delaware coastline, the study estimates the cost of beach retreat between 2000 and 2049 to be $291 million. The study concludes cost of beach nourishment is about $15 million dollars per decade. Therefore, the cost of replenishing the beaches is about $60 million over the next half century. This is a significant savings over retreat, and the most economically practical option.
(1) Parsons, George R. and Michael Powell. “Measuring the Cost of Beach Retreat”. Coastal Management, 29:91-103, 2001.