CELPIP Reading Part 3Reading for Information Practice

A. Roofs, driveways, and pavement shed rainfall quickly because water cannot soak through their hard surfaces. The resulting runoff can overwhelm drains and carry sediment or residue toward nearby streams. A rain garden is a planted depression that receives water from a defined area and holds it temporarily. It differs from a permanent pond because most water disappears into soil or an outlet between storms. This combination helps explain why runoff problems and the rain garden concept cannot be understood from one feature alone or from one brief observation.

B. Designers place the basin where runoff can enter safely without threatening foundations or underground services. A gently shaped surface spreads water, while engineered soil may improve drainage where native ground absorbs slowly. Plants are selected for both short periods of flooding and dry intervals after the basin empties. Dense roots maintain pore spaces and help the soil resist erosion when water arrives rapidly. For design and function of urban rain gardens, relationships among these features matter because a change in one may influence several others within the same setting over time.

C. As runoff pools, its reduced speed allows sand and other suspended particles to settle. Water then filters through soil, where particles and some dissolved materials attach to mineral and organic surfaces. Plants and soil organisms can take up or transform certain nutrients before water continues underground. An overflow route carries exceptional rainfall away without washing out the garden or flooding adjacent property. Viewed together, details about temporary storage and filtration processes connect visible characteristics with processes that are less immediately obvious to an ordinary observer at first.

D. Leaves, litter, and sediment must be removed when they block inlets or bury the intended planting surface. Bare patches may need new plants or mulch before weeds and erosion become established. A rain garden treats only the drainage area and storm size for which it was designed. It works best as one part of a wider system that also reduces runoff and protects natural flow routes. Within design and function of urban rain gardens, the result is a system in which structure, timing, and local conditions remain closely connected throughout continuing development.

E. Not given in any of the above paragraphs.