Bigger Pipes or Greener Communities: “Projected changes in land use and climate have nearly equivalent effects on flooding,” says Chris Jensen

Note to Reader:

In November 2013, the 53rd Annual Conference of the Pacific Northwest International Section (PNWIS) of the Air and Waste Management was held in Victoria, British Columbia. The program included a session titled Environmental Protection in the Built Environment. This session highlighted innovative approaches to achieving environmental protection in the Built Environment; and encompassed non-point source pollution, cumulative effects, area-based management and local government planning.

Chris Jensen, a Policy Analyst with the Integrated Policy Branch (BC Ministry of Community, Sport and Cultural Development) spoke about his research into the benefits of green infrastructure in a changing climate.


Use of Low Impact Development to Mitigate Future Flooding

Low Impact Development (LID) has been identified as a potential solution for mitigating the projected flood impacts of climate change. To evaluate the feasibility of using LID as a climate change adaption strategy, a hydrological assessment was performed on the Bowker Creek Watershed, a 10km2  urbanized catchment located in Victoria BC.

The presentation by Chris Jensen showed how watershed hydrology may be affected by changes in climate, increases in impervious areas and by the introduction of green roofs, rain gardens and top soil amendments.

Techniques used for generating future storm events and identifying suitable LID sites were also discussed.  This research demonstrates the potential practical application and performance limits of the three LID treatments for the case study watershed. Findings indicate that within the study area and potentially, in similar rainfall-dominated, urbanized watersheds, LID can provide certain important functions for adapting to climate change.

Implication of Hydrologic Findings

“The effects that climate change may have on flood hazard is a concern for many local governments and citizens in British Columbia,” stated Chris Jensen. “Planning for future changes in precipitation is important, but it should not overshadow the significance that day-to-day development has on stream flows.”

Chris-Jensen_2012__120p“For example, in the Bowker Creek Watershed, modelling shows that projected changes in land use and climate have nearly equivalent effects on flooding. When both factors are combined, results shows that the flood extent will increase by approximately 50% for a 25 year rainfall event.”

“This finding is based on conventional land development. If low impact development practices are applied, then this risk is reduced. Local governments may not be able to change future storm events, but they can affect how land is developed and redeveloped.”

To Learn More:

To download a copy of the PowerPoint presentation, click on Bigger Pipes or Greener Communities: A Hydrologic Assessment of using Low Impact Development to Mitigate Future Flooding

To read a story posted previously on the Waterbucket website about the research by Chris Jensen, click here.