How do engineers design and construct sustainable coastal protection systems in civil engineering to mitigate the impacts of coastal erosion and sea$-$level rise? Discuss the use of natural and nature$-$based solutions, such as mangrove forests, dune restoration, and beach nourishment, to enhance coastal resilience and ecosystem services. How can innovative engineering techniques, such as offshore breakwaters, submerged reefs, and coastal wetlands, reduce wave energy and erosion rates while enhancing biodiversity and shoreline stability? How do integrated coastal zone management approaches, including shoreline setback policies and habitat restoration programs, support the sustainable development of coastal areas while preserving natural resources and cultural heritage?