Dr.  Mirka  Mobilia
University of Salerno (UNISA),  Italy

Title: The use of satellite images to detect suitability for green roof conversion in a municipality in Southern Italy interested by a rapid land use change

Abstract:

The most direct impact of the rapid population growth is the demand for new buildings, which causes the overdevelopment of urban areas all over the world. The uncontrolled soil sealing leads to increasingly severe and frequent urban flooding events. The low impact developments (LID) strategies consist of a number of practices, which mimic the site’s predevelopment hydrologic functions so as to mitigate the hazardous hydrological events. Among these, the green roofs (GR) are better able to minimize, detain and retain the extra-runoff. In this context, the use of satellite images allows to identify the potential of existing buildings for green roof retrofitting. Sustainability for green roof retrofit mainly depends on four criteria that are roof slope, number of stories, orientation of the roof, number of site boundaries. The aim of the present work is to test the effectiveness of GRs at city scale in reducing the hydraulic load on urban drainage system so as to avoid urban flooding events. The case study is Preturo municipality in Southern Italy. The site has been selected as part of Sarno river basin, a catchment that during the last two decades has been interested by damaging flash floods. The analysis of land use change within the studied watershed has been carried out using SAR images from ERS-1 and COSMO-SkyMed sensors. It has allowed to highlight that the increase in the occurrence of extreme events matches with the expansion of urban area in the same period, reason why the application of LID technologies could lead to great hydrological benefits. Indeed, the coherence estimation of SAR imagery, has detected a build-up area ranging from about 7% to about 12% between 1995 and 2016. An in-depth analysis has been performed moving from basin to city scale with the aim to test the ability of GRs in mitigation the urban flooding. High-resolution satellite images available in Google Earth have been used to evaluate the suitability for green roof retrofit in Preturo municipality. According to building attributes for GR retrofit, it has been possible to identify the existing roofs suitable for hosting a vegetated cover. The percentage of green roof conversion is about of 7% resulting in a low attenuation of flooding volume. This finding suggests coupling the GR technology to other LID practices in order to improve the stormwater reduction.

Biography:

Ing. Mirka Mobilia earned a Bachelor's degree in Environmental Engineering at University of Salerno, Italy in 2011. In 2014 she earned Master's degree in Environmental Engineering, at University of Salerno. In November 2014, she started a Ph.D. course in “Risk and sustainability in civil, environmental and construction engineering”, at the University of Salerno (UNISA). She is currently a Research Fellow at the department of civil engineering (UNISA). Her research interest is about the sustainable stormwater management for urban drainage systems, with a particular focus on urban greening.