Mobile flood protection systems on mountain rivers in dense urban condition

Abstract

Significant climate change has been, leading to heavy rainfall and flood flow rate increasing the last twenty years. At the same time, natural factors, such as sediment accumulation and bottom elevations, channel clogging, and anthropogenic factors: intensive floodplain construction leads to floodplain narrowing and increased flood levels. European cities have been increasingly used mobile flood protection systems as one of the elements of flood protection. The peculiarity of the mountain rivers flood in Ukraine is their short duration: 3-5 days and a significant rate of water uplift, which requires a rapid and simple installation of temporary barriers. The aim of the review is to determine the optimal mobile structures for flood protection of urban areas in conditions of intense mountain floods. The existing mobile systems and the experience of their use in the EU countries were analyzed. The cost of mobile systems significantly exceeds the cost of embankment and has no economic benefits if there is enough area for embankment construction. But in dense urban conditions, the use of mobile flood protection systems become an economically viable alternative to permanent protective structures, because they do not require additional permanent space and do not block access to the river. Flood area mapping with precise identification of the protected area should be developed and automated information and measurement system for early forecasting and notification of the relevant authorities about the floods threat should be implemented, because barriers erection is required time of average 1 hour per 100m, excluding delivery time from the storage area. The installation of mobile systems requires the involvement of human resources, which must have periodically train. The equipment must be delivered quickly to the destination, which requires the involvement of transportation equipment and additional storage area for materials. So, the main requirements for mobile flood systems: light weight, simplicity and speed of installation, its reliability, storage areas and periodic training. The systems with a pre-installed foundation of segment-type, flip walls, segment walls with high foundation and mobile tubes were analyzed. The segment walls with pre-installed foundation (underground or in the form of a parapet) satisfy all above-stated requirements in dense urban condition.