An emerging water crisis is on the horizon and is poised to converge with several other impending problems in the 21st century. Future uncertainties such as climate change, peak oil and peak water are shifting the international focus from a business as usual approach to an emphasis on sustainable and resilient strategies that better meet these challenges. Cities are being reimagined in new ways that take a multidisciplinary approach, decompartmentalising functions and exploring ways in which urban systems can share resources and operate more like natural organisms. This study tested the landscape design implications of wastewater wetlands in the urban environment and evaluated their contribution to environmental sustainability, urban resilience and social development. Black and grey water streams were the central focus of this study and two types of wastewater wetlands, tidal flow (staged planning) and horizontal subsurface flow wetlands were tested through design investigations in the earthquake-affected city of Christchurch, New Zealand. These investigations found that the large area requirements of wastewater wetlands can be mitigated through landscape designs that enhance a matrix of open spaces and corridors in the city.
Wastewater wetlands when combined with other urban and rural services such as food production, energy generation and irrigation can aid in making communities more resilient. Landscape theory suggests that the design of wastewater wetlands must meet cultural thresholds of beauty and that the inclusion of waste and ecologies in creatively designed landscapes can deepen our emotional connection to nature and ourselves.
The increase in urban population has required cities to rethink their strategies for minimising greenhouse gas impacts and adapting to climate change. While urban design and planning policy have been guided by principles such as walkability (to reduce the dependence on cars) and green infrastructure (to enhance the quality of open spaces to support conservation and human values), there have been conflicting views on what spatial strategies will best prepare cities for a challenging future. Researchers supporting compact cities based upon public Transit Oriented Development have claimed that walkability, higher density and mixed-uses make cities more sustainable (Owen, 2009) and that, while green spaces in cities are necessary, they are dull in comparison with shopfronts and street vendors (Speck, 2012, p 250). Other researchers claim that green infrastructure is fundamental to improving urban sustainability and attracting public space users with improved urban comfort, consequently encouraging walkability (Pitman and Ely, 2013). Landscape architects tend to assume that ‘the greener the better’; however, the efficiency of urban greenery in relation to urban comfort and urbanity depends on its density, distribution and the services provided. Green infrastructure can take many forms (from urban forests to street trees) and provide varied services (amended microclimate, aesthetics, ecology and so forth). In this paper, we evaluate the relevance of current policy in Christchurch regarding both best practice in green infrastructure and urban comfort (Tavares, 2015). We focus on the Christchurch Blueprint for rebuilding the central city, and critically examine the post-earthquake paths the city is following regarding its green and grey infrastructures and the resulting urban environment. We discuss the performance and appropriateness of the current Blueprint in post-earthquake Christchurch, particularly as it relates to the challenges that climate change is creating for cities worldwide.
