A Long Wey to Go

It is time to diverge from pure theory, and try to illustrate a few points with a case study.  In my last post, I talked about the River Wey (a tributary of the Thames) and how urbanised floodplains have exacerbated flooding along some parts of the river. I have been studying this river in some detail for the last 6 months, and it illustrates some of the points I have been talking about so far.

The UKCP09 climate projections are often used in thinking about the potential effects of climate change on water resources in the UK (Christierson, et al. 2012). These projections suggest a variety of changes, but the general pattern is an increase in evapotranspiration and the intensity of rainfall events. For the majority of its length, the Wey is bounded by ample natural floodplain, making any flooding slow moving and of a slow intensity – however the channel is more constrained in some urban areas and flooding can be faster moving and intense (EnvironmentAgency, 2010).

The Wey flooded considerably in some urban areas during late 2013/early 2014. Wang, et al., (2012) have suggested that the weather leading to recent flooding on the River Wey may be associated with a pattern of increasing storm intensity in the North Atlantic, consistent with patterns of climate change. Data suggests that the highest flows since the extreme floods of September 1968 (a 1 in 1000 year event) were recorded on the River Wey (Met Office and Centre for Ecology and Hydrology, 2014). This is a very large change in discharge and runoff, likely forced by climate change. At different points along the river, thousands of homes and businesses were affected by floodwater. 

If the rainfall event that caused these flows has been influenced by climate change, we need to act sooner rather than later, or this level of flooding could become a common occurrence. Things need to change on a number of scales; all the way through from local building on the River Wey’s floodplain to global emissions of greenhouse gases. Herein lies the problem – there are so many different actors involved, that just solving changes in discharge caused by climate change along a small catchment is very difficult.