River refers to water currents, flowing waters (rivers, creeks, streams). Rain makes reference to the meteoric waters, waters that fall (rain, rain).
See River, rain.
River is when it rains and stormwater is water from rivers or arrollos
River: adj. relative to the rivers: the river navigation is not possible in shallow rivers.RAIN: adj. relative to the rain or rain waters: in the cities the stormwater drainage system serves to collect the rain water.