The interaction between waves and shore is a complex system; a sea wall can prevent erosion at one point while exacerbating it elsewhere in the region. Scientists are developing permeable obstacles that slow down the ocean waves, to protect shore and land from erosion.

These measures can be effective against erosion, but not against inundation. Therefore, they are temporary expedients, presuming that we curb global heating and prevent the coming inundation.

Inland wetlands can buffer against floods and drought (and therefore also against fire).

I am skeptical of the "biodiversity net gain" requirement. Constructing a new wetland is surely not as simple as it sounds, so it is likely that businesses will often follow the rules but produce no real new wetland. If a development has destroyed an old wetland and failed to create a new one, what does the government do?