Reading Comprehension

Read the text and answer the question.

Cities around the world are experimenting with so-called sponge parks to manage heavy rainfall. Instead of paving every surface, planners build sunken gardens, gravel beds, and shallow ponds that soak up storm water like a sponge. During a downpour, this water collects in the park rather than flooding nearby streets. Afterward, the stored water slowly drains into the ground or evaporates, and the plants help filter pollutants. Supporters argue that such parks are cheaper than expanding underground drains and that they give residents green space at the same time. Critics, however, warn that they need careful maintenance to keep working well.