Urban creep, also known as urban sprawl, is the gradual expansion of urban areas into previously rural or natural areas. This can have a significant impact on drainage design and soakaway design calculations, as it can increase the amount of impervious surface (such as paved roads and buildings) and reduce the amount of permeable surface (such as soil and vegetation) available to absorb and store water.
When urban areas expand, they often replace natural landscapes with buildings, roads, and other hard surfaces, which can lead to an increase in surface runoff and a decrease in infiltration. This can put a strain on existing drainage systems, which may not have been designed to handle the increased volume of water. As a result, urban creep can lead to an increased risk of flooding and water pollution.
One way to mitigate the impact of urban creep on drainage systems is to incorporate green infrastructure (GI) into the design. GI is a network of natural and semi-natural features such as parks, gardens, streets, and green roofs that can provide a range of benefits including improving air and water quality, reducing flood risk, and providing habitats for wildlife. By incorporating GI into the design, urban areas can become more resilient to the impacts of climate change, such as heavy rainfall and sea level rise.
It’s important for urban planners and drainage design consultants to consider the potential impact of urban creep when planning new developments, and integrate strategies to reduce its impact on drainage systems.
For more information on urban creep and its impact on drainage design, you can visit the following websites:
- Natural England: https://www.gov.uk/guidance/green-infrastructure-gi-and-urban-sprawl
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Climate change and drainage design
Climate change is one of the most pressing issues of our time, and its impact on drainage design, and also highway design, is becoming increasingly apparent. With rising temperatures and more intense rainfall events, traditional drainage systems are becoming less effective in managing water flow and preventing flooding.
One of the main impacts of climate change on drainage design is the increase in the frequency and intensity of heavy rainfall events. This means that traditional drainage systems, which were designed to manage the average rainfall, are now overwhelmed by the increased volume of water. As a result, the risk of flooding is increasing, and traditional drainage systems are becoming less effective at preventing damage to property and infrastructure.
Another impact of climate change on drainage design is the increase in sea levels. This means that coastal areas are at a higher risk of flooding from storm surges and tsunamis. This requires drainage systems to be designed to a higher standard, with greater capacity and better protection against flooding.
To address these challenges, drainage designers are turning to a sustainable drainage strategy, better known as Sustainable Urban Drainage Systems (SuDS), which mimic natural drainage systems and reduce the risk of flooding while also improving water quality. SuDS include permeable surfaces, retention and detention ponds, rain gardens, and swales, which are all designed to slow down and spread out the flow of water, reducing the risk of flooding.
Climate change is also likely to lead to changes in land use and vegetation patterns, which in turn can affect the runoff characteristics of the land. Drainage systems should be designed to be adaptable to these changes, and may need to be modified or reconstructed in the future.