The potential for green roofs in sustainable urban drainage systems

Urban environments tend to lack the capacity to absorb water from precipitation. This is due to vegetated surfaces being replaced by impermeable ones, such as concrete, bitumen or similar. As a result problems can occur, where a period of heavy rainfall coincides with sudden increases in surface water runoff. This in turn can lead to a city’s sewerage system becoming overloaded. Sustainable Urban Drainage Systems (SUDS), are recognized worldwide as a successful manner by which to mitigate this phenomenon. One of the principal components of SUDS are permeable areas in an urban setting, which have the ability to absorb and retain rainfall that would otherwise flow as surface runoff. To date there has been little research into what the effect of a massive increase in green roofs would have for cities in Ecuador. As a developing country, it is not uncommon for cities’ sewerage systems to suffer collapse when faced with sudden rainfall peak loads. It is suggested in this paper, that instead of looking to implement costly sewerage expansion programs, it would be more cost effective to implement city scale green roof systems. The paper sets out to quantify the theoretical effect of such an initiative.