More scientific research to consider:
From the National Park Service (US).
“Shore parallel structures include seawalls, bulkheads and revetments. These structures are designed to protect coastal property not the beach fronting the property. Development permits are relatively easy to obtain in many states because seawalls may be built above the high water mark, and they are relatively inexpensive (when compared to beach nourishment). However, seawalls may accelerate erosion on the beaches fronting properties they are intending to protect. Wave energy is reflected off of the seawall rather than absorbed by a soft sediment shoreline. The increased wave energy and sediment source trapped behind the sea wall often decrease the sediment supply near the seawall, increasing erosion on adjacent beaches. Therefore, alternatives to these hard structures are strongly encouraged and actively sought by the NPS.”