A friend of mine sent me an interesting paper from a February issue of Science titled, "Stationarity Is Dead: Whither Water Management?" by Milly, P. et. al (2008) (subscription-only). It deals with the assumption of stationarity, or the "idea that natural systems fluctuate within an unchanging envelope of variability." In other words, natural occurrences, like stream flow or flood peaks, change within static extremes that can be estimated using some probability density gleaned from observation records.
Policy decisions regarding water management (i.e. water infrastructure, channel modification, and drainage works) have been impeded by this assumption because anthropogenic forces, such as land-use changes and climate change have added additional variability to the dynamics of the water cycle. Modeling efforts have historically assumed that these variability are small enough to assume stationarity, leading to ever less accurate results.
To address this issue, the paper states that stationarity must be replaced by non-probabilistic models that incorporate operations research and welfare economics. Yet, while this is a normal "scientific" response to a problem, is it enough?
It is assumed that better models produce better results, but it ultimately comes down to how those results are used. The paper hints at this by stating, "a stable institutional platform for climate-information delivery may help." It can be argued that many of the issues facing the US could be better modeled - and they can and it will help - but what of what happens after? If stationarity is a baseline assumption that is impeding researchers and water management experts, what is impeding emergency managers and policy makers?
What other complimentary efforts should be implemented along with better models? Are scientists suited to expand outside of producing results, into utilizing (policy making, for instance) those results? Does science have other avenues to create more sound, rational policy decisions?
Image: 2008 Iowa floods, picture taken from BBC website.
Tuesday, July 29, 2008