Efective drainage of rainwater from roads by rain garden-strips in the concept of the city-sponge

Abstract

Today there is a problem of flooding of urban areas with rainwater and their slow drainage to rainwater sewage and further to the distribution collectors. There are several ways to ensure the resilience of urban areas to heavy rains and downpours. One of the current methods is "green" roofs (horizontal or sloping) ith green plantings, which is capable to absorb water. A certain amount of water is absorbed by the plants, its certain amount remains in the substratum, and the rest is filtered by several layers of the structure under the plants, which throttles the movement of it to the storm-water sewage. The second method is to collect rainwater in special storage tanks, which are located on the roof or near to the building or in the soil structure in the yard. The accumulated water is used for household needs: watering lawns, washing, flushing toilets, washing floors, cleaning pavements, etc. The third method is to absorb water and drain it by natural biological terrestrial sponge facilities: permeable surfaces, sloping terrain, natural vegetation, green structures, rain gardens, etc. These correspond to the modern concept of "sponge city". The authors propose a method of rapid drainage of rainwater using special "green structures" – rain-garden bands along the roadways. The ability to capture water by rain-garden bands has been confirmed on the example of most of the regional centres of Ukraine in case of the strongest observed precipitation. Such rapid drainage becomes especially important in the transition from cities for cars to cities for bicycles. This increases the requirements to avoid slippery roads for increasing the stability of these vehicles. In addition, the proposed rain gardens with shrubs can perform safe protective functions by extinguishing the kinetic energy of bouncing cars during a road accident.