Green gutter as a nature-based solution for a mitigation and adaptation strategy in urban environments

The goal of this article is to report an experimental study conducted to evaluate the efficiency of the "green gutter" as a prospective green wall to delay stormwater. The innovative pilot green gutter structure was formed by an unplanted prismatic vertical column of metal filled with mineral wool (height 4 m, width 0.6 m, depth 0.15 m). Along the structure elevation, eight moisture sensors divided in two lines of four were embedded within the filling material to assess saturation levels, and flow meters were installed in the inlet and outlet of the system. This system was tested with different flows and durations to simulate distinct rain events. The monitored parameters were peak flow reduction and peak flow delay. From the results, it could be verified that the performance of the system showed a consistent capacity to delay peak flows, on average within 15 min, but showed a limited capacity for peak flow reduction. Higher peak flow reductions ranging from 30% to 50% were obtained only for design rains of 10-min duration and 0.5- and 5-year return periods, respectively. By effectively delaying peak flow the green gutter was shown to be a promising solution to be used in stormwater strategies focused on creating time lags of peak flows among subwatersheds.