The value of cities varies from country to country due to various factors; historical legacy, artistic and cultural heritage, and in cases of more recent cities, it depends on the degree of equipment and the quality of their infrastructure. Sustainable drainage is a solution that is justified by long-term environmental and social factors. It is linked to decisions about how our cities should be in the context of the broader challenges of climate change.
Drainage systems can contribute to sustainable development and improve the cities where we live by balancing the different opportunities and challenges that influence urban design and the development of communities. There is a growing acceptance that we need a more sustainable approach to managing surface water. Therefore, if surface water is a valuable resource, it must be managed efficiently for maximum benefit.
In this context, Sustainable Urban Drainage Systems (SUDS) mimic natural drainage processes to reduce the effect on the quality and quantity of runoff from developments and provide attractiveness and desirability of an area and biodiversity benefits. These have advantages in the hydrological, environmental, landscape and economic fields.
The hydrological benefits derive from the maintenance of the natural flow of water streams in the urban environment. This results in less interference in the natural regimes of receiving water bodies, both in quality and quantity. The key point is that by favoring the infiltration of run-off water, it becomes a local water resource available for reuse, in green area irrigation, for example.
The increase of permeable surfaces mitigates the temperature increase caused by asphalted surfaces by evaporative cooling. This guarantees a reduction of the "heat island" effect. On the other hand, by preventing floods and allowing rainwater collection, they help to cope with the effects of climate change. Sustainable drainage systems help to create natural environments that improve the aesthetic, landscape and environmental quality of the urban areas where they are located.
As an economic benefit, we can point out lower investment and operational costs due to the decrease of treated water compared to conventional systems. On the other hand, as precipitation water becomes an available resource and is included in water resources management, expenditure on water harvesting and other water works decreases. This is compounded by the decline in economic losses caused by floods. In short, we are faced with a system with a lower life-cycle cost than other alternatives that justifies its economic sustainability. As a positive externality, we can point out the increase in the added value of the urban areas where they are located, due to the above-mentioned improvements in the landscape.
For all these aspects, SUDS are an important solution to make rainwater management a valuable asset in our cities, enhancing the urban development’s where they are integrated.