Does moving sand dunes affect flooding?

Yes, it may remove a natural barrier that protects inland properties.  Floodplain lands and adjacent waters combine to form a complex, dynamic physical and biological system found nowhere else.  When portions of floodplains are preserved in their natural state, or restored to it, they provide many benefits to both human and natural systems.  Sand dunes can reduce the severity of floods, helping handle stormwater runoff and minimizing non-point water pollution.