Storm drains: when they are blocked with leaves, they are not able to effectively do their raison d'etre. In autumn, deciduous trees, of which there are a few in Nashville, shed their leaves. Said leaves usually are not resistant to gravity, so they land on the ground. Many of those leaves are carried by rain runoff to storm drains. But, leaves tend to not actually go down the drain, so they stay in small piles around the drains, preventing the runoff from actually entering the drain.
Since water, too, is not usually resistant to gravity, it will then flow down hill. Often times, that is into the streets. Then we get what is known as "urban flooding," which, in many cases, is completely preventable.
Hey, Public Works: would you mind greatly ensuring storm drains are kept free of obstructions so that the streets don't flood? That'd be great, thanks.