It is predicted that by the year 2050, about 68% of the world’s population will be living in cities.  In Israel, which is now in the midst of accelerating urbanization, there are several major challenges.  As we build upwards within a city, the population density increases within a given area, requiring an expansion of the water supply infrastructure as well as the wastewater and stormwater removal infrastructure.  As we build in areas that were previously open spaces, the impervious surface area of the city increases, which leads to larger peak flow rates and increased loads on the city’s drainage system.  Climate change in our region requires city planners to prepare for extreme scenarios, such as flooding or long periods of drought.  In addition, the urban stormwater runoff that flows over the city’s streets and other surfaces picks up a range of pollutants (heavy metals, oils, petrol, phosphates and nitrates, organic and in-organic materials and compounds, including disease-causing bacteria).  This polluted runoff is removed from the city and eventually flows into the rivers and the sea.  Furthermore, the “urban heat island” effect, in which trapped heat results in increased temperatures within the city, affects the comfort of the city’s residents, and may be a health risk for sensitive populations such as babies and the elderly.

A water sensitive city attempts to address all of these challenges, by providing a variety of clean and safe water sources, and by creating resilience to potential extreme weather events. A water sensitive city seeks to improve and increase the biodiversity of its ecosystems by creating microclimates to mitigate the rising temperatures in the city.