What effect can heavy rainfall have on river water level?

Correct answer: Water level can rise

The direct answer is C: heavy rainfall can raise the water level of a river. A river receives water from rainfall falling directly into its channel and from runoff flowing over the surrounding land. Rain may also enter through small streams and tributaries. If the amount of incoming water becomes greater than the amount flowing away, the river level rises. Step by step: heavy rain falls; water runs over the land and enters streams; streams and tributaries carry extra water into the main river; the main river’s discharge and level increase; if the increase is extreme, flooding may occur. The word ‘can’ is important because the exact effect depends on soil, slope, vegetation, river size, dams, drainage, and the duration of rain. Option A is wrong because rainfall does not make a river’s level always zero; it normally adds water. Option B is wrong because a river does not disappear merely because rainfall is heavy. Option C is correct because increased inflow can raise the water level. Option D is wrong because ordinary heavy rain does not freeze water into ice; freezing requires sufficiently low temperatures. Memory cue: more rain means more runoff, and more runoff can mean a higher river level.