Integral water management model for urban areas during extreme rainfall events. Case study: Purmerend, The Netherlands

Evelyn Aparicio Medrano, Martijn Siemerink, Ber Albers

Friday 3 july 2015

14:00 - 14:15h at Asia (level 0)

Themes: (T) Extreme events, natural variability and climate change, (ST) Flood resilient cities and infrastructures

Parallel session: 16C. Engineering - Industrial

Society is facing serious threats due to climate change. Climate change affects urban areas by increased air temperatures (Heat Urban Island Effect) and possibly by increasing the chances of heavy rainfall. In the case of extreme rainfalls, flooding assessment tools are important for decision makers. Moreover, accurate modeling tools could directly contribute to the resilience of cities and its existing infrastructure. In the present article we describe a methodology which combines 1 and 2 dimensional modeling. The surface runoff is considered in the 2 dimensional component. Here, we apply a newly developed numerical method (Stelling, 2012) for detailed 2 dimensional flooding simulations. The sewer system and surface channels are considered in the 1 dimensional component. Both components are interactively coupled. Another specific feature of the presented methodology is the innovative method for handling the inflow of rainfall into the sewer. In contrast to standard methods of lateral inflow on the 1 dimensional component for the distribution of rainfall our methodology applies spatially distributed rainfall on the 2 dimensional component. We apply this methodology to construct a model for the city of Purmerend, the Netherlands. The model results are satisfactorily compared with existing measurements of water levels in canals and information from pumping stations for the year 2013. Next, the model is applied to analyze the effects of extreme rainfall scenarios, e.g. a rainfall event with a return period of 200 years. The results of the presented model are used to highlight the focusing areas and structures to guarantee the resilience of Purmerend against extreme rainfall. Reference Stelling G.S., 2012. Quadtree flood simulations with subgrid digital elevation models. Water Management 165 (WM1):1329-1354.