Stone and rock parapet of artificial water threshold. Water threshold on the river in the flooding. Barrier over a large river. Control flood waters and reduce water’s speed. Aerial footage from drone. Small dam set embankment barrier dike weir wall seawall riverwall barrage stream current flow effluent brook potamic fluvial rivulet watercourse riverbed overhead nature natural flood control waterfall foam froth suds lather scum white spume water jumping drop splash river floor river barrier and sparkling threshold 4K UHD 3840×2160.