Isn't there a Cantonese song with the lyrics "When the rain falls heavily, the streets are flooded"? If so, please tell me the name of the song.

The name of the song is "Falling Rain"

"Falling Rain" is a nursery rhyme that has been passed down from generation to generation in Cantonese, especially in the city of Guangzhou, depicting the scene of flooded streets in the Xiguan area, the old city center of Guangzhou, during a rainy day, with lyrics full of children's words and fun, as seen from a child's eyes. Along with another Lingnan nursery rhyme, "Moonlight", it is a must-sing children's song for several generations of children in the Pearl River Delta region of Guangdong,