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Beavers profoundly alter streams by building dams. Beaver dams change how water, sediment, nutrients and energy flow through stream corridors enhancing both habitat diversity and landscape connectivity. Humans are captivated by learning from nature and trying to mimic it, especially in human-degraded environments. There is considerable eagerness for using beaver dam analogues (BDAs), also called simulated beaver structures, as low-tech, low cost solutions for restoring the functioning of degraded streams where beavers are not present and cannot survive. The use of BDAs in stream enhancement projects, especially in the western United States, is outpacing the research, leading to questions about whether BDAs do, in fact, yield similar ecosystem-scale effects as natural beaver dams. We review the different names used for BDAs, discuss the many ways these structures can be built and how different types function, and how they compare to real beaver dams. We conclude the talk by exploring what we can expect from various types of BDAs in the short and long term and whether these structures can lead to stream and riparian zone restoration that can facilitate the return of beavers.

Mountain lakes are distinctive water bodies that not only serve as a crucial water resource for the inhabitants of the upland regions but also as an important destination for millions of tourists who are attracted by their beauty. Mountain lakes are fragile water bodies that are experiencing changes in their hydrological processes owing to global warming. Understanding the consequences is important as it can help identify whether climate change causes degradations in lake hydrological functioning. The interactions of hydrological processes in mountain lakes with external drivers are usually hard to explain explicitly owing to their complexity. To deal with that problem, scholars develop conceptual frameworks. The focus was on the Canadian Rocky Mountains where 5155 lakes were identified using GIS. To identify factors influencing lake hydrological function and their sensitivity to changing climate, a literature review was undertaken. Identified in the literature review were 13 natural drivers that reflected climate change impacts to lake hydrological functioning and 38 additional sub-factors that characterize the drivers. Using these factors, a conceptual framework for mountain lake hydrological functioning was developed. The major limitation to thorough testing of the conceptual framework was a small number of observations for lakes in the research area. Nevertheless, the conceptual framework is flexible and should be tested across many mountainous regions worldwide. Overall, the conducted research stresses the problem of limited hydrological understanding of lakes in the Canadian Rockies and presents a useful framework of the complex interactions of natural drivers and intra-lake processes under rising temperatures.

Beaver ponds are surface-water features that are transient through space and time. Such qualities complicate the inclusion of beaver ponds in local and regional water balances, and in hydrological models, as reliable estimates of surface-water storage are difficult to acquire without time- and labour-intensive topographic surveys. A simpler approach to overcome this challenge is needed, given the abundance of the beaver ponds in North America, Eurasia, and southern South America. We investigated whether simple morphometric characteristics derived from readily available aerial imagery or quickly measured field attributes of beaver ponds can be used to approximate surface-water storage among the range of environmental settings in which beaver ponds are found. Studied were a total of 40 beaver ponds from four different sites in North and South America. The simplified volume–area–depth (V–A–h) approach, originally developed for prairie potholes, was tested. With only two measurements of pond depth and corresponding surface area, this method estimated surface-water storage in beaver ponds within 5 % on average. Beaver pond morphometry was characterized by a median basin coefficient of 0.91, and dam length and pond surface area were strongly correlated with beaver pond storage capacity, regardless of geographic setting. These attributes provide a means for coarsely estimating surface-water storage capacity in beaver ponds. Overall, this research demonstrates that reliable estimates of surface-water storage in beaver ponds only requires simple measurements derived from aerial imagery and/or brief visits to the field. Future research efforts should be directed at incorporating these simple methods into both broader beaver-related tools and catchment-scale hydrological models.

Beaver ponds are surface water features that are transient through space and time. Such qualities complicate the inclusion of beaver ponds in local and regional water balances, and in hydrological models, as reliable estimates of surface water storage are difficult to acquire without time and labour intensive topographic surveys. A simpler approach to overcome this challenge is needed, given the abundance of the beaver ponds in North America, Eurasia and southern South America. We investigated whether simple morphometric characteristics derived from readily available aerial imagery or quickly measured field attributes of beaver ponds can be used to approximate surface water storage among the range of environmental settings in which beaver ponds are found. Studied were a total of 40 beaver ponds from four different sites in North and South America. The Simplified V-A-h approach, originally developed for prairie potholes, was tested. With only two measurements of pond depth and corresponding surface area, this method estimated surface water storage in beaver ponds within 5 % on average. Beaver pond morphometry was characterized by a median basin coefficient of 0.91, and dam length and pond surface area were strongly correlated with beaver pond storage capacity, regardless of geographic setting. These attributes provide a means for coarsely estimating surface water storage capacity in beaver ponds. Overall, this research demonstrates that reliable estimates of surface water storage in beaver ponds only requires simple measurements derived from aerial imagery and/or brief visits to the field. Future research efforts should be directed at incorporating these simple methods into both broader beaver-related tools and catchment scale hydrological models.

Soil moisture and ground thaw state are both indicative of a hillslope's ability to transfer water. In cold regions, in particular, it is widely known that the depth of the active layer and wetness of surface soils are important for runoff generation, but the diversity of interactions between ground thaw and surface soil moisture themselves has not be studied. To fill this knowledge gap, detailed shallow soil moisture and thaw depth surveys were conducted along systematic grids from April to July of 2008 at the Baker Creek Basin, Northwest Territories. Multiple hillslopes were studied to determine how the interactions differed along a spectrum of topological, typological and topographic situations across the landscape. Overall results did not show a simple link between soil moisture and ground thaw as was expected. Instead, correlation was a function of wetness. The drier the site was, the more random the interaction between soil moisture and ground thaw. This indicates that interactive soil moisture and thaw depth behaviour on hillslopes in cold regions changes with location and cannot necessarily be lumped together in hydrological models. To explore further why these differences arise, a companion paper (Part 2: Influences of water and energy fluxes) will examine how the hydrological and energy fluxes influenced the found spatiotemporal patterns.

The companion paper (Guan et al., 2010) demonstrated variable interactions and correlations between shallow soil moisture and ground thaw in soil filled areas along a wetness spectrum in a subarctic Canadian Precambrian Shield landscape. From wetter to drier, these included a wetland, peatland and soil filled valley. Herein, water and energy fluxes were examined for these same subarctic study sites to discern the key controlling processes on the found patterns. Results showed the key control in variable soil moisture and frost table interactions among the sites was the presence of surface water. At the peatland and wetland sites, accumulated water in depressions and flow paths maintained soil moisture for a longer duration than at the hummock tops. These wet areas were often locations of deepest thaw depth due to the transfer of latent heat accompanying lateral surface runoff. Although the peatland and wetland sites had large inundation extent, modified Péclet numbers indicated the relative influence of external and internal hydrological processes at each site were different. Continuous inflow from an upstream lake into the wetland site caused advective and conductive thermal energies to be of equal importance to conductive ground thaw. The absence of continuous surface flow at the peatland and valley sites led to dominance of conductive thermal energy over advective energy for ground thaw. The results suggest that the modified Péclet number could be a very useful parameter to differentiate landscape components in modeling frost table heterogeneity. The calculated water and energy fluxes, and the modified Péclet number provide quantitative explanations for the shallow soil moisture-ground thaw patterns by linking them with hydrological processes and hillslope storage capacity.