Observations indicate that over the past several decades, geomorphic processes in the Arctic have been changing or intensifying. Coastal erosion, which currently supplies most of the sediment and carbon to the Arctic Ocean [Rachold et al., 2000], may have doubled since 1955 [Mars and Houseknecht, 2007]. Further inland, expansion of channel networks [Toniolo et al., 2009] and increased river bank erosion [Costard et al., 2007] have been attributed to warming. Lakes, ponds, and wetlands appear to be more dynamic, growing in some areas, shrinking in others, and changing distribution across lowland regions [e.g., Smith et al., 2005]. On the Arctic coastal plain, recent degradation of frozen ground previously stable for thousands of years suggests 10–30% of lowland and tundra landscapes may be affected by even modest warming [Jorgenson et al., 2006]. In headwater regions, hillslope soil erosion and landslides are increasing [e.g., Gooseff et al., 2009].

Decision-support tools (DSTs) are often produced from collaborations between technical experts and stakeholders to address environmental problems and inform decision making. Studies in the past two decades have provided key insights on the use of DSTs and the importance of bidirectional information flows among technical experts and stakeholders-a process that is variously referred to as co-production, participatory modeling, structured decision making, or simply stakeholder participation. Many of these studies have elicited foundational insights for the broad field of water resources management; however, questions remain on approaches for balancing co-production with uncertainty specifically for watershed modeling decision support tools. In this paper, we outline a simple conceptual model that focuses on the DST development process. Then, using watershed modeling case studies found in the literature, we discuss *

The Tanana River flows through interior Alaska, a region characterized by discontinuous permafrost. Studies link degrading permafrost to increased winter river discharge due to greater groundwater (GW) recharge increasing GW input to river baseflow. In winter, interior Alaskan rivers are exclusively fed by GW, which provides an external source of heat. In fact, some portions of rivers fed by GW maintain thin ice cover throughout the winter, or remain ice-free, despite very cold air temperatures. These ice conditions represent a significant danger to rural Alaskans who extensively use rivers for wintertime travel in this largely roadless area. A physically based, numeric model was developed to examine the consequences of permafrost degradation in explaining unfrozen river conditions in the winter. Results show that the ice melt was amplified by increased water column temperatures, flow velocities, air temperature, and snowfall. Abrupt changes in snowfall were illustrated to contribute to decreased ice thickness and more hazardous conditions for winter travelers. The model examines the physical mechanisms that underlie dangerous ice conditions in winter and early spring, and suggests that GW flow parameters need to be better characterized to model midwinter ice degradation in sub-arctic environments.

ABSTRACT. The integration of local knowledge and science represents an opportunity to enhance the understanding of interrelations among climate, hydrology, and socioeconomic systems while providing mutual benefits to scientists and rural communities. Insight from rural Alaskans helped to identify a social-ecological threshold used to model potential driftwood harvest from the Yukon River. Information from residents of Tanana, Alaska, was combined with scientific data to model driftwood harvest rates. Modeling results estimated that between 1980 and 2010, hydrologic factors alone were responsible for a 29% decrease in the annual wood harvest, which approximately balanced a 23% reduction in wood demand because of a decline in number of households. The community's installation of wood-fired boilers in 2007 created a threshold increase (76%) in wood demand that is not met by driftwood harvest. Modeling analyses of numerous climatic scenarios illustrated that increases in hydrologic variability would decrease the reliability of future driftwood harvest. Economic analyses demonstrated that increased climatic variability could have serious economic consequences for subsistence users while demanding more of their time. Lost time is important because it reduces their availability for performing other subsistence activities and learning to adapt to climate-related challenges. Our research may benefit communities by providing a tool that can be used to predict the timing and duration of driftwood runs. Information gathered from discussions with local stakeholders provided critical information for model development and thus provided a better understanding of regional social-ecological dynamics. Our research also illustrates the potential for regional-scale adaptations to limit the social-ecological impacts of environmental change, while providing economic opportunities and energy independence that reduce their vulnerability to variations in climate.

Wetland hydrologic connections to downstream waters influence stream water quality. However, no systematic approach for characterizing this connectivity exists. Here using physical principles, we categorized conterminous US freshwater wetlands into four hydrologic connectivity classes based on stream contact and flowpath depth to the nearest stream: riparian, non-riparian shallow, non-riparian mid-depth and non-riparian deep. These classes were heterogeneously distributed over the conterminous United States; for example, riparian dominated the south-eastern and Gulf coasts, while non-riparian deep dominated the Upper Midwest and High Plains. Analysis of a national stream dataset indicated acidification and organic matter brownification increased with connectivity. Eutrophication and sedimentation decreased with wetland area but did not respond to connectivity. This classification advances our mechanistic understanding of wetland influences on water quality nationally and could be applied globally.