Topic 6: Analyzing possible contributions of re-activated former watercourses towards a more sustainable transformation of industrialized riverine landscapes in urban areas

Introduction/background

In the past decades/centuries urban water courses have been heavily modified (redirected, straightened, culverted) for purposes of gaining land, flood protection and public hygiene. Today, due to climate change cities face new challenges like urban heat island effects, droughts, and pluvial flooding caused by extreme stormwater events. To cope with these challenges the application of nature-based solutions (NBS) and blue-green infrastructure (BGI) is considered an appropriate measure. Consequently, related installations become more and more widespread. However, this incorporates two practical problems: (1) BGI requires space which is rather limited in existing urban structures, and (2) green assets (e. g. trees) often require irrigation, at least during peak summer. Today, the latter mainly relies on valuable drinking water resources.

Main objective/research question/hypothesis

In this context the question arises, whether a re-activation of former water courses could provide a possible contribution to solving the mentioned constraints in the urban context. Decoupled but still existing water courses in the form of open channels might be re-activated for intermediate stormwater storage to cut overland peak runoff. Furthermore, those remains might also serve for human recreation and as habitats for urban flora and fauna. In terms of culverted (non-polluted) water courses a daylighting could provide new structures, again serving as urban recreational area and/or living space. Finally, in regard to former water courses integrated into urban sewer systems, a decoupling could activate a new water source in urban areas. The use for non-human purposes (irrigation, street cleaning, etc.) could help to spare drinking water resources.

Approach/methods and time frame (Sites, areas, region of investigation)

The work primarily addresses the following research aspects: (1) method development for identification of former water courses in urban areas [year 1]. (2) Definition of possibilities for integrating remaining water course structures/assets and water resources into urban water management concepts (e. g. pluvial flood protection, water reuse for irrigation of urban green), and description of related chances and barriers [year 1]. (3) Case study investigations in the upper Danube basin addressing the pre-defined integration possibilities and development of local concepts for watercourse re-activation considering technical, environmental, social and organizational (governance) aspects [year 2]. (4) Generalizations of theoretical and practical findings and development of a procedure (guiding document) for the re-activation of former urban water courses to support sustainable urban water management [year 3].