Most properties which some people consider to be waterfront properties now are from this level, where they buy properties around water areas, sand fill some of the areas and leave others to preserve nature, which they can later develop those sand-filled lands and build on it and leave the view on. Those areas are most times more expensive than land situated in dry ground; no place is hard to develop.
Truly no place is easy to develop but one key thing most investors normally does when it comes to land is that they knows that money spent on a worthy asset like land is worth it, and land is one property that appreciate in value overtime and it can never be sold at a loss, the worst possible scenario is reselling it back at the same price you bought it, so wether it's a riverine area or not, any money spent on achieving something big that will be much more beneficial in the future will be worth it.