Stormwater Management in Urbanised Areas

Presently, stormwater in built-up areas and other areas with closed surfaces can hardly find a natural path to reach the natural water cycle. This may result in gradual, long-lasting changes in soil structures and water regimes, entailing a reduction in the natural local groundwater replenishment and impacts upon the chemical and biological conditions over and under the ground. Furthermore, harmless drainage of surface runoffs, in particular extreme runoffs during heavy rain events, calls for substantial technical and financial considerations during the stage of designing, construction and operation of sewer systems and wastewater treatment plants. However, despite all technical measures, some extreme runoffs do reach surface water. This may result in flood events, or increased pollution in small water courses in catchment areas with a major share of urban development. Considering the potential pollution that may be released in the drained area, the reintroduction of stormwater into the natural water cycle as close as possible to the point of its impact is an objective that is meaningful in environmental, water management and technical terms, and may also be advantageous in terms of the national economy. Therefore, while taking into account the local conditions, it is vital to primarily pursue the surface runoff reduction and its local infiltration, and, secondly, resort to conveying stormwater in sewer systems.