Evaluation of synergetic opportunities between Nature Base Solutions and sewer networks and processes.

Abstract

Since 2007 more than half of the world population is concentrated in urban areas. Not surprisingly, managing urban areas is one of the most important development challenges of the 21st century (UN DESA, 2014). The high urban growth, the imperviousness of urban centres, and the changes of meteorological patterns, has been giving rise to situations in which urban drainage systems are absent or insufficient to provide the expected performance for which they were initially designed.

The desired integrated management of different utilities is often not possible (due to different management agendas and financing sources). This issue is aggravated by the location of these infrastructures, mostly underground, subject to an aggressive environment, being pathologies difficult to detect.

Understanding of the systems? behaviour is complex given limited knowledge of nature and characteristics of the infrastructure and, sometimes even the location is uncertain. Consequently, the implementation of effective operation procedures and the design of effective corrective measures is a challenge.

Runoff has an intermittent nature, with high peak flows, that transport particles and pollutants from roads and other surfaces, including heavy metals and micro organic compounds (Ramisio and Vieira, 2012). Due to a diffuse origin, intermittent nature, and presence of non-biodegradable pollutants, urban runoff represents a big challenge, affecting the processes in sewers and in WWTP.

Nature Base Solutions (NBS) can be effective for flow control and retention of pollutants, including heavy metals. Therefore, the inclusion of NBS throughout the catchments could represent an opportunity to address the above-mentioned problems with the benefit of promoting the liveability of cities, the quality of life, and enabling sewer systems to evolve from being passive to active adaptive units that can respond differently depending on the given situation (Kerkez et al., 2016).