floodplain
noun
- area of land adjacent to a stream or river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge
Wiktionary
Pronunciation: /ˈflʌdˌpleɪn/
noun
Etymology: From flood + plain.
- A low-lying plain adjacent to a river subject to flooding during periods of high rainfall or at high tide.
“Near-synonyms: bottomland, bottomlands”
“tidal floodplain”