You may require this approval if you intend to construct or use flood works. Flood works help to manage water on floodplains.
Flood works are barrages, causeways, cuttings or embankments that are situated near a river, estuary or lake or within a floodplain, and are likely to affect the flow of water to or from a river, estuary or lake, or the distribution or flow of floodwater in times of flood.