Common Nature

Rain gardens are a vital part of municipal water handling plans.

https://www.horstexcavating.com/news-and-blog/are-rain-gardens-a-good-solution-for-stormwater-management/

They are also useful in private yards or farms for similar purposes.

https://lawnlove.com/blog/rain-garden-benefits/

I have one under my downspout just off the patio, because the trap collects dirt. Crocuses, and heuchera are up. The columbine got frostbitten so I don't know if it'll regrow. In summer I plant things like blue lobelia and other water-loving annuals. The whole thing is probably less than 2 feet per side, but it's pretty, and it discourages overflow from rain.