URBAN STORMWATER INFILTRATION PERSPECTIVES

In urban areas there are many problems with water management: combined sewer overflows, peak flows, man-induced droughts, consolidation of the soil, damage from frost penetration, etc. It is preferable to look at all these problems In relation to each other, according the concept of integrated water management. This paper focuses on the possibilities for urban stormwater infiltration. The results of three studies are presented. The first study concerns the flooding of the Shirako River in Tokyo. It is shown that with the help of stormwater infiltration the floods can be reduced remarkably. The second study concerns combined sewer overflows and the discharge from treatment plants for catchments in Denmark and the Netherlands. When looking at the total yearly discharge from the combined sewer and the treatment plant. it is shown that infiltration is more effective than detention. The third study shows the impact of urban stormwater infiltration on the groundwater flux in an area in the south of the Netherlands. To relate the different results from the three studies an analogy is introduced with the human body. The combination of problems results in a so-called urban hang-over. It is shown that the positive effects of urban stormwater infiltration within an integrated approach are more significant than looking at all the effects separately.