Water Sensitive Urban Design

The traditional conventional approach to managing storm water has proven counterproductive and as one that mainly addresses the management of risk to life and property rather than the constructive use of resources to optimise environmental benefits, thereby mitigating risk to ensure a win win for the natural and built environments. This deficiency has become glaringly apparent and resulted in a slow paradigm shift within the built environment professions away from pure risk mitigation toward sustainable development where natural systems and processes are considered a resource to be used and enhanced rather than considered purely from the perspective of risk management.

The strategy is to consider all aspects of the urban water cycle holistically and to focus on Sustainable Urban Drainage Systems (SUDS) as part of this natural cycle with the intention of reducing the negative impacts of peak flows while carefully managing water quality and quantity with the intended spin off of enhancing amenity and biodiversity. Practical and affordable alternatives to storm water management need to be considered

It is vital to have an insight to local conditions in order to ensure guidelines are appropriate and specifically geared to address the unique local opportunities and constraints. South African guidelines have been developed as a best practice manual that highlights opportunities for successful implementation of SUDS principles rather than being a prescriptive tool. It is geared towards the design, implementation and maintenance aspects of the SUDS interventions. Complementary to this, an economic model was developed to enable professionals to analyse alternative approaches with their associated costs.

Sustainable Urban Drainage Systems approach is an interdisciplinary one rather than simply employing an engineered perspective due to the fact that natural systems are considered in the approach and design solution. This brings about complexity but with it many more benefits.

Design criteria, methods and tools provide professionals with considerations for storm attenuation by storm water experts. Storm water may be managed through a loose tiered classification that mainly implies storm water risk management, namely:

1. Control at source - storm water is controlled as close to the origin as possible.

2. Local controls - storm water is accommodated and managed in identified public and community spaces such as parks and road reserves.

3. Regional controls - storm water management is ameliorated through large scale interventions on municipal property.

References

Armitage, N. et al., 2013. Alternative Technology for Stormwater Management: The South African Guidelines for Sustainable Drainage Systems. TT 558/13 ed. Cape Town: Water Research Commission.

Image source: Internet