Hydrodynamic modelling to assess the contribution of nature-based solutions for flood resilience at the delta city of Guayaquil, Ecuador.

Abstract:

Urban floods impact millions of lives and cause billions of dollars of economical losses worldwide every year. As human population shift from rural areas to cities, higher exposition occurs, specially at delta cities around the world. Human settlements along coastal areas and river deltas in developing countries face not only changing patterns in precipitation, but also the threat that high level of impermeabilization and sea level rise represents for lowland areas. Here, floods are managed trough important investments to expand the capacity of traditional stormwater drainage systems. Nature Based Solutions (NBS) in the urban environment, such as greener areas, blue infrastructure, among other well documented interventions are nowadays increasingly seen as complementary and multi-benefit solutions to enhance flood resilience in cities. Nevertheless, limited experience is currently available about the opportunities and challenges that this approach can have in major cities of low- and middle-income countries. A joint effort between local and foreign research institutions, supported by city authorities within the framework of international collaboration allowed the assessment of the opportunities that NBS in the urban environment can bring to the city of Guayaquil (coastal Ecuador) aiming to enhance flood resilience of the city. A city district was selected for the present study, due to its characteristics of high-level of impermeability, low elevation, and surrounded almost entirely by estuarine branches. A 1D-2D hydrodynamic model was built for the area in order to assess the flood extension, level and duration within the parish under historical events and further scenarios (i.e. sea level rise and heavy rain). A participatory process was adopted for the selection of NBS in the area, and their contribution to flood resilience latter assessed trough the model. The preliminary results show an improvement in flood resilience and liveability of the area.