Deployment of Green roof top as a Nature Based Solution in Dublin, Ireland

In the recent past, severe flooding have caused major natural disasters leading to severe damage to public property, infrastructure and human life. The threat of flooding can be attributed to rapid growth in population, uncontrolled urban expansion, global warming and climate change. It has been reported that more than 100,000 people were killed and over 1.4 billion people were affected worldwide due to flooding over the past ten years. The main contributing factors of flooding that affect death or injury to people include flood depth, velocity of flood flow and the degree to which people are exposed to flood in the region. A significant increase in rate of flooding occurred due to decrease in vegetation cover and increase in the imperviousness at urban areas, leading to decrease in the efficiency of urban drainage system that increase proneness of flooding. This study identifies an innovative approach to flood control by deployment of a Nature based solution (NBS). NBS is relatively new approach to tackle flooding and is a solution framed with an inspiration and support from nature. This research focuses on addressing the following three questions: which NBS to deploy, how to identify the ideal site for deployment of the selected NBS, and how to quantify the effectiveness of the deployed NBS in terms of flood control/reduction? As a part of the EU Horizon 2020’s OPERANDUM project, the case study is being conducted at Dublin as the Open Air Laboratory Ireland. The NBS implementation study has been initiated along with the partnership of Dublin City Council. Preliminarily, city planning rules and land development guidelines were reviewed from Dublin and green roof was selected as the potential NBS. Subsequently, rainfall-runoff based hydrological modelling was performed to assess the potential flood hazard areas and to identify an effective location for implementation of NBS. For this purpose, the hydrological model was simulated with and without the presence of NBS at different potential locations and the site exhibiting highest flood control was selected to be the optimal location. The selected location is close to the Dublin Port and adjacent to River Liffey, which is the main river in Dublin. In order to show the effectiveness of the green roof NBS, real world data has been collected before and after implementation of the NBS to assess its effectiveness in real world framework.