water falling from the sky like rain, sleet, snow, hail

Water can not pass through

heavy rain, steep land, built up areas, cutting down trees, tributaries, impermeable rock

confluence

The flat land beside the river which may flood when the river overflows.

waterfall, gorge, v-shaped valley, interlocking spurs, meander, oxbox lake

Embankments (high banks), let nature help, take care where you build, dig new river channels, portable flood barriers, anti flood shutters on homes.

vapour (a gas)

The source

don't throw litter in rivers, don't put face wipes, hygiene items, cotton or food down toilets, don't dump oil, paint, weed killer, etc. don't waste water

the wide mouth of a river where the river water and sea mix.

water supply, generate electricity, farming, transport, leisure, factories