Torben Dam

Stormwater management challenges as revealed through a design experiment with professional landscape architects

Despite a number of potential benefits, using the urban landscape for managing stormwater runoff is spreading rather slowly. As urban planners and landscape architects are considered key protagonists of this trend, the objective of the study was to identify the challenges they confront when asked to retrofit an urban landscape for the management of stormwater runoff. Monitoring a two-week design experiment involving six teams of professional landscape architects identified 11 challenges, including sizing of elements, estimating costs, understanding water dynamics, aspects of biodiversity promotion, and dealing with land administrations and ownership issues. Measures to address the challenges are discussed. It should be noted that all six teams approached the stormwater management challenge in an energetic and focused way, applying their technical, personal and site-specific knowledge, and delivered innovative, flexible and coherent solutions. This emphasizes that the design process constitutes a strong and unique problem solving tool.

Surface sedimentation at permeable pavement systems: implications for planning and design

Abstract Newly installed permeable pavement (PP) systems provide high surface infiltration capacity, but the accumulation of sediments causes a decrease in capacity over time, eventually leading to surface clogging. With the aim of investigating local sedimentation processes and the importance of restorative cleaning (RC), nine recently built PP systems were tested for their infiltration capacity with and without restorative cleaning (RC) over an interval of 12–14.5 months. The results were related to each site’s unique history of sedimentation. RC significantly improved permeability, but when revisited after approximately one year, the permeability of cleaned surfaces was not significantly better for the RC spots than from their uncleaned neighbouring areas. Relating permeability to the contextual issues revealed that PP perimeter, adjacent bare soil and mismanagement strongly affected the sedimentation process. At two of the sites, sedimentation processes were so advanced that surface permeability was below the level of service (five-year design storm).