A book on Water in Road Structures would not be complete without a brief description on the use of the pavement as a water store. Pervious pavements (see Chapter 5, Section 5.7) can be taken one step further and not only used to convey water away from the surface, but can also be used to temporarily store the water in the pavement. There are two principal reasons for doing this
• hydrograph attenuation and
• water quality improvement.
Here, the use of pervious pavements may only be briefly discussed, but interested readers may find out much more in the book devoted to the topic by Ferguson (2005). Typically they comprise highly permeable surfaces (e. g. of concrete blocks or stone cobbles) with a coarse, open-graded layer underneath that will act as a water storage and transport layer. It may also retain water that will, ultimately, soak away into the subgrade.
