Green gutter as a Nature-based Solution for mitigation and adaptation strategy in urban environments.

The goal of this paper is to conduct an experimental study to evaluate the efficiency of an innovative green infrastructure named green gutter made of mineral wool as a prospective green wall to delay stormwater. The pilot is formed by an unplanted prismatic vertical column of metal filled with mineral wool with 4 meters in height, width 0,6 m, and depth 0,15 m. Along its elevation, 8 moisture sensors divided in 2 lines of 4 are embedded within the filling material to assess saturation levels, flow meters are installed in the inlet and outlet of the system. The 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 noted that the system's performance shows a consistent capacity to delay peak flows, on average in 15 min, but 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 period, respectively. By effectively delaying peak flow the green gutter showed to be a promising solution to be used in stormwater strategies, focused on creating time lags of peak flows among subwatersheds.