IELTS Reading Diagram Labeling

Rain gardens are shallow planted areas designed to collect water from roofs, pavements or roads after heavy rain. Instead of sending all runoff directly into storm drains, a rain garden slows the flow and allows some water to soak into the ground. This can reduce local flooding and limit the amount of oil, metal particles and fertilizer that reaches streams. The first part of a rain garden is usually an inlet, such as a curb opening or a stone channel, that guides runoff into the planted basin. Designers often place flat stones near this entry point because fast-moving water can otherwise wash soil away. The stones spread the flow and protect the surface. Once water enters the basin, it passes through a layer of mulch. This layer traps leaves and larger particles while also helping the soil remain moist between storms. Beneath it is a sandy soil mix. The sand creates small spaces that allow water to move downward, while compost in the mix supports plant growth and helps hold some pollutants. At the lowest part of the system, plant roots and soil organisms continue the filtering process. Deep-rooted native plants are especially useful because their roots keep channels open in the soil. If the garden receives more water than it can absorb, an overflow pipe sends the excess to the drainage system after the first flush has been filtered.