Despite the economic stimulus provided by many dams historically, the global experience with dam building warns that traditional approaches to water infrastructure development in a rapidly changing world carry severe risks of economic and environmental failure. First, large water projects are very capital-intensive and long-lived, costing billions of dollars to plan, build, and maintain. Yet, they are vulnerable to biased economic analyses 3 , cost overruns and construction delays, and changing environmental, economic and social conditions that can diminish projected benefits 4,5 . Under a variable and changing climate, large water infrastructure even risk becoming stranded assets 6 . Second, the principles of economic efficiency inherent in cost-benefit analysis dominate project design and performance assessment, and integrating social and environmental benefits and costs into a comprehensive economic evaluation presents significant challenges 7,8 .These costs can be substantial, as evidenced by human displacement 5,9 , local species extinctions 10 , and the loss of ecosystem services such as floodplain fisheries and other amenities 11,12 .As unanticipated economic, social and environmental costs accumulate with aging water infrastructure, society is investing in restoration projects to undo some of the long-term environmental degradation, including modifying flow releases from dams 13,14 and in some cases dam removal 15 . As the global impairment of aquatic ecosystem function becomes increasingly documented and articulated 16,17 , a broader conception of sustainable water resources management that formulates environmental health as a necessary ingredient for water security and the social wellbeing it supports is urgently needed [18][19][20] . Notably, new national directives are emerging to develop and manage river ecosystems in less environmentally harmful and more sustainable ways, including in the US 21 , Europe 22,23 , and Australia 24 . Towards a more sustainable water resources management paradigmHere we ask if a more sustainable water management philosophy can be forged to guide investment in, and design of, water infrastructure while avoiding adverse, sometimes irreversible, social and

Vegetation canopies intercept and redistribute precipitation in space. Although throughfall patterns are challenging to correlate with plant characteristics, many studies have shown that the spatial patterns persist through time. This persistence leads to wet and dry spots that can affect recharge, transpiration, and other nonlinear ecohydrologic and biogeochemical processes. A stochastic framework is used to determine the effect of throughfall variability on hydrologic fluxes. Throughfall variability increases and concentrates recharge, and the magnitude of the effect depends on the character of throughfall variability along with characteristics of climate, soil, and vegetation. This framework is also used to explore specific differences in summertime recharge between stands of deciduous trees (birch, maple, and oak) and eastern hemlock (Tsuga canadensis). Throughout the eastern United States, the invasive hemlock woolly adelgid poses a significant threat to hemlock forests, and replacement of hemlock forests by other species has the potential to alter hydrologic fluxes and other processes. Field investigations in 2009 and 2010 indicate that, relative to deciduous stands, hemlock canopies intercept more water and tend to produce dry rather than wet spots. Although deciduous stands produce more throughfall, model results indicate that differences in canopy interception are outweighed by large differences in peak transpiration rates, and predictions of summertime recharge are lower in deciduous forests than in hemlock. Copyright © 2011 John Wiley & Sons, Ltd.

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Hydroclimatic stationarity is increasingly questioned as a default assumption in flood risk management (FRM), but successor methods are not yet established. Some potential successors depend on estimates of future flood quantiles, but methods for estimating future design storms are subject to high levels of uncertainty. Here we apply a Nonstationary Decision Model (NDM) to flood risk planning within the decision scaling framework. The NDM combines a nonstationary probability distribution of annual peak flow with optimal selection of flood management alternatives using robustness measures. The NDM incorporates structural and nonstructural FRM interventions and valuation of flows supporting ecosystem services to calculate expected cost of a given FRM strategy. A search for the minimum‐cost strategy under incrementally varied representative scenarios extending across the plausible range of flood trend and value of the natural flow regime discovers candidate FRM strategies that are evaluated and compared through a decision scaling analysis (DSA). The DSA selects a management strategy that is optimal or close to optimal across the broadest range of scenarios or across the set of scenarios deemed most likely to occur according to estimates of future flood hazard. We illustrate the decision framework using a stylized example flood management decision based on the Iowa City flood management system, which has experienced recent unprecedented high flow episodes. The DSA indicates a preference for combining infrastructural and nonstructural adaptation measures to manage flood risk and makes clear that options‐based approaches cannot be assumed to be “no” or “low regret.”

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