Climate Change and Urban Hydrology: Research Needs in the Developed and Developing Worlds

Kim Irvine


Over the past year climate change issues have received media attention in Canada as the result of Environment Canada’s budget cuts that included atmospheric programs and Canada’s decision to withdraw from the Kyoto Protocol. Such actions represent the more contentious policy implementation elements of the climate change issue. While the majority of scientists agree that increasing anthropogenically-sourced greenhouse gases have contributed substantially to rising global temperature over the second half of the 20th century, there remain some skeptics in the scientific community and this uncertainty has been magnified in the public debate. Some of the reasons for this greater public uncertainty (including concepts of politicizing science, “balance as bias” in public media, lobbying, poorly constructed opinion polls, and the role of internet communications) are discussed briefly, but this paper takes the approach that the role of science from a policy perspective is to identify, assess, and explain a wide range of choices or scenarios. As Pielke (2004) aptly points out, science’s “….goal is to enhance freedom of choice”. This paper therefore takes the position that global warming and attendant changes in the precipitation regime have started and likely will intensify over the next century and explores these issues in relation to urban hydrology research needs for both the developed and developing worlds. Most research on climate change and water resources has focused on river flooding and drought at the watershed scale, irrigation demands, and impacts due to sea level rise. Assessment of urban drainage and sanitation infrastructure impacts and resiliency under climate change scenarios has received little attention. Urban hydrologic impacts are broadly defined in this paper and are discussed under seven categories: storm frequency and runoff; water use; water and sediment quality; health impacts; sea level rise; energy use/heat island effect; and greenhouse gas emissions. “Resiliency” refers to the ability of a system to respond and recover from disasters and includes attributes that allow the system to absorb impacts. Adaptation measures to improve urban hydrologic resiliency are explored, with a focus on low impact development technologies, water re-use, water conservation, so-called “smart growth” and green buildings. Examples are drawn from both the developed and developing world to illustrate these adapative approaches to climate change. Research needs in hydrologic science and engineering include: continued improvement of General Circulation Models (GCMs), particularly in the area of spatial downscaling; the need to further link GCM outputs and stormwater/sewer modeling efforts (for both water quantity and quality); reconsideration of IDF curves under nonstationary rainfall time series; and more extensive field verification (and modeling linkages) related to low impact development benefits. Scientists and engineers must increase their communication with politicians and policy-makers about the need to consider greater temperature and precipation variability in community planning and include full cost accounting of hydrologic services in these discussions. A more integrated approach to green community planning and management is required and the Singaporean model offers an interesting possibility. However, we also must recognize that a “one size fits all” solution to climate change resiliency is not possible. Exchanges regarding water resource management technologies between the developed and developing world are occuring, but must be culturally appropriate and adapted to the specific physical environment.

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