Reactivation of former watercourses to support urban stormwater management

In recent decades many urban water courses have been heavily modified by land gaining measures aiming at canalising, straightening and draining existing water systems. Additionally, urbanisation causes a higher degree of sealing which results in higher surface runoff during rainfall. Today, in many regions of the world climate change leads to an increase of heavy rain events causing severe flooding problems in settlement areas. To support related problem-solving, the presented work investigates the question of whether the reactivation of former water courses could make a positive contribution to urban stormwater management. Based on the case study of an Austrian municipal area the research work follows a two-target approach: First, the collection, digitalisation and verification of the former water courses in the investigated area based on historical maps and recent planning documents. Second, a GIS-based overlap of the verified (still existing but inactive) natural water courses with the current sewage and stormwater network to derive potential options for relieving the strain on the entire urban drainage system. Results show, that reactivation of former water courses can be an interesting and promising component of an integrated and thus an even more natural urban stormwater management approach.