Questions 31 to 40 Complete the notes below. Write ONE WORD AND OR A NUMBER for each answer.
Stormwater Sponge Streets
Urban stormwater problem • Heavy rain overwhelms the drainage [31] __________ in older neighbourhoods • Run off from roads often contains [32] __________ from vehicle brakes and tyres
Core design features • replacing sealed surfaces with permeable [33] __________ • planting lines of street trees in soil filled [34] __________ • adding small channels called [35] __________ to guide water into planted areas
How sponge streets work • first stage is temporary storage in the surface [36] __________ • water then filters through layers of sand and [37] __________ • excess water is carried away through an underground [38] __________
Benefits • can reduce local flooding by up to [39] __________ percent in pilot streets • improves summer comfort by lowering street [40] __________
Keys
31 system 32 metals 33 paving 34 trenches 35 swales 36 layer 37 compost 38 pipe 39 30 40 temperature
Transcripts
Part 4 You will hear a lecture about stormwater sponge streets in cities.
In this lecture, I will describe the idea of stormwater sponge streets and explain why they are becoming increasingly important in modern cities. Sponge streets are a type of street design that helps manage heavy rainfall by absorbing, storing and cleaning water close to where it falls, rather than sending it quickly into underground drains.
Many older neighbourhoods were built with drainage systems designed for a very different climate and a much smaller population. As cities have grown, these systems have been put under increasing pressure. During periods of intense rain, the drainage system can become overwhelmed. Water then flows across roads and pavements and, in some cases, enters nearby buildings, causing damage and disruption.
Another related problem is water quality. When rain falls on roads, it collects pollutants before flowing away. A common example is metals, which come from vehicle brakes and tyre wear. When this polluted water enters rivers without treatment, it can harm plants and animals living there and reduce overall water quality.
Sponge streets aim to address these problems by changing how streets are built. One core design feature is replacing sealed surfaces with permeable paving. This allows rainwater to pass through the surface instead of running off immediately. As a result, water can be managed more slowly and safely.
A second key feature is planting lines of street trees in soil filled trenches. These trenches are designed to hold water for short periods and then release it gradually. Although some people worry that trees might be damaged by excess water, the soil mix used in these trenches is specially designed to drain effectively while still supporting plant growth.
A third feature involves adding small open channels, known as swales. These channels guide water into planted areas where it can be absorbed naturally. Some swales are clearly visible along the edge of the street, while others are shallow and blend into the surrounding landscape, making them less noticeable to pedestrians.
To understand how sponge streets work in practice, it is helpful to look at the different stages involved. The first stage is temporary storage in the surface layer. This surface layer often includes gravel beneath the paving, creating space where water can be held briefly during heavy rainfall.
After this, water filters through layers of sand and compost. The sand helps slow the movement of water, while the compost supports plant roots and helps remove pollutants. This natural filtering process improves water quality before it moves further through the system.
If rainfall exceeds the capacity of the sponge street, excess water is carried away through an underground pipe. This pipe connects to the wider drainage network and prevents water from building up on the road surface. In this way, sponge streets work alongside existing infrastructure rather than replacing it completely.
So what benefits do sponge streets offer. Evidence from pilot projects suggests that local flooding can be reduced by up to 30 percent during heavy rain events. The exact figure depends on factors such as street design, soil conditions and the intensity of rainfall, but the results are generally positive.
There are also additional benefits beyond flood reduction. Increased tree cover and moist soil can help cool the surrounding air. This improves comfort during hot weather by lowering street temperature, which is particularly important for people who walk or cycle in urban areas.
Many cities are now using sponge streets as part of wider climate adaptation plans. These projects are often tested on a small scale first, before being applied to larger areas. Engineers and planners work together to adjust designs based on local conditions and results. Over time, this approach allows cities to improve performance without major disruption. This gradual process also helps build public support, as residents can see clear benefits before larger changes are introduced.
In addition, lessons learned from early projects can be shared between cities, leading to more effective designs over time. Such collaboration helps avoid repeating mistakes and allows successful ideas to spread more quickly across different regions.
In summary, stormwater sponge streets offer a practical response to the challenges of heavy rainfall in cities. By absorbing, filtering and managing water more effectively, they help reduce flooding, improve water quality and create more comfortable urban environments for the future.
