Rapid transformations of the urban landscape to cope with infrastructure needs have adverse consequences on the aquatic environments from urban stormwater runoffflows and the associated pollutants washed into the rivers and lakes. The implementation of low impact design (LID) infrastructure is considered a better approach to conventional management and control of urban runoffbut has been slow, or non-existent, in many new urban cities. In addition to institutional, technological, social and economic barriers, risks and concern for contractual liabilities are identified as factors prohibiting uptake of low impact design. This article is based on findings from interviews; a survey and online questionnaire. The data obtained from the online survey was analyzed using non-parametric tests. First, the study showed risk as the most dominant factor inhibiting implementation of LID infrastructure. In addition, the results show a significant difference exists between professionals with LID implementation hands-on experience versus their counterparts with theoretical knowledge alone. Due to self-efficacy of professionals with practical experience, they are more inclined to favour and promote LID infrastructure, and hence possess better propensity for contractual liabilities risk taking. Summarily, the article proposes dissemination of relevant information among practitioners to improve LID knowledge apprehension and utilization. This will reduce perception of risk that will promote uptake. In addition, team collaboration with equitable contractual risk sharing for LID project planning and implementation is advocated.
Keywords: stormwater runoffs, LID, risks perceptions, hands-on experience, theoretical knowledge, decision making
Urban landscapes are constantly undergoing transformations from the development of shelters and other essential infrastructure to cope with rural-urban migration and increasing world population. These transformations are not without their environmental consequences. Of concern in this article is stormwater runofffrom impermeable surfaces such as roof tops, roads, and car parks, etc. Several studies have established the links between the collapse of healthy freshwater ecosystems in urban environments and stormwater runofffrom such impervious surfaces (Konrad & Booth, 2005; Ladson et al., 2006; Paul & Meyer, 2001). Altered hydrologic regimes and the pollutants associated with urban runoff(such as hydrocarbons, heavy metals, sediments and other emerging contaminants) causes severe damage to aquatic ecosystems.
Urban runoffdamage affects ecology functions, biological diversity, public health, recreation, economic activity, and general community well-being (Bannerman et al., 1993; Booth & Jackson, 1997; Haile et al., 1999). Evidence suggests that high concentration of Lead, Zinc, Cadmium and other toxic pollutants in stormwater cause damage to ecosystems. In particular, an industrial substance like Nonylphenol is said to act as an endocrine disrupter that suppresses the production of sperms in fish decreasing fish production (Al-Bareeq, 1995). Furthermore, excessive phosphorus and nitrogen levels in waterways are also found to stimulate the growth of plants and algae, which can reduce dissolved oxygen levels that could harm the entire aquatic ecosystem when their natural habitat become 'dead zone' for lack of oxygen. The presence of E. coli and fecal coliform bacteria that get washed to the rivers and lakes also make them unsafe for swimming, forcing beach closures.
While the impacts of urban runoffmay not easily be expressed in monetary value, damage to properties and loss of life has been reported across urban cities in recent times. In 2011, the Queensland flood was estimated to cost the Australian Government $5.0billion dollars for the reconstruction works and a reduction in the Australian gross domestic product of $30 billion dollars (Daley, 2011; White, 2011). …