The experimental and educational rain gardens of the Agripolis Campus (north-east Italy): Preliminary results on hydrological and plant behavior

In most urbanized areas stormwater runoff, flowing on impervious surfaces, can increase the risk of floods and overload of drainage systems. Landscape designers may contribute to the mitigation of the problem by incorporating appropriate solutions in the design of green spaces. Rain gardens are green infrastructures that can contribute to more sustainable urban development. Since 2011, an experiment has been carried out at the University of Padova with the aim to assess the use of rain gardens for a sustainable management of the stormwater runoff. Two circular rain gardens with herbaceous perennials, differently sized and equipped with TDR soil moisture sensors, were designed and built to intercept equal amounts of runoff draining from a building roof with an area of 215 m2. The experiment consisted of testing the capacity of intercepting runoff caused by storm of different magnitude, in measuring the dynamics of water in the topsoil after the rainfall events and in evaluating the growth and aesthetic quality of the different plant species used. Input and output water volumes were measured and actual ET was estimated using WUCOLS Landscape Coefficient Methods. Results of the preliminary phase showed that both the rain gardens were able to satisfactorily manage the roof runoff, which was taken off the urban drainage system, with a good aesthetic result.