Fraser River Basin Research Articles

A Dynamical Climate Model–Driven Hydrologic Prediction System for the Fraser River, Canada

Abstract Recent improvements in forecast skill of the climate system by dynamical climate models could lead to improvements in seasonal streamflow predictions. This study evaluates the hydrologic prediction skill of a dynamical climate model–driven hydrologic prediction system (CM-HPS), based on an ensemble of statistically downscaled outputs from the Canadian Seasonal to Interannual Prediction System (CanSIPS). For comparison, historical and future climate traces–driven ensemble streamflow prediction (ESP) was employed. The Variable Infiltration Capacity model (VIC) hydrologic model setup for the Fraser River basin, British Columbia, Canada, was used as a test bed for the two systems. In both cases, results revealed limited precipitation prediction skill. For streamflow prediction, the ESP approach has very limited or no correlation skill beyond the months influenced by initial hydrologic conditions, while the CM-HPS has moderately better correlation skill, attributable to the enhanced temperature prediction skill that results from CanSIPS’s ability to predict El Niño–Southern Oscillation (ENSO) and its teleconnections. The root-mean-square error, bias, and categorical skills for the two methods are mostly similar. Hydrologic modeling uncertainty also affects the prediction skill, and in some cases prediction skill is constrained by hydrologic model skill. Overall, the CM-HPS shows potential for seasonal streamflow prediction, and further enhancements in climate models could potentially to lead to more skillful hydrologic predictions.

Impacts of variability and trends in runoff and water temperature on salmon migration in the Fraser River Basin, Canada

The 1911–2010 variability in monthly runoff and the effect of 1995–2005 summer water temperatures in a highly productive salmon system, the Fraser River Basin (FRB) of British Columbia, Canada are explored. Hydrometric data from 141 FRB gauges provide variations in monthly runoff including their extremes and months of occurrences, as well as trends in their variability. Stream temperatures and their relationships to runoff are also assessed. There is a gradual increase of monthly runoff ranges from the central plateau of the FRB towards higher altitudes with maxima in glacier-fed alpine streams. Maximum and minimum monthly runoff across the FRB typically occur during May–June and February, respectively. There is a tendency towards greater FRB variability in July runoff. Water temperatures show high variability in the unregulated North and South Thompson rivers and low variability in the regulated Nechako River. FRB low flows are associated with higher water temperatures, while high flows are associated with cooler ones, both of which may have a negative impact on salmon.Editor Z.W. Kundzewicz; Associate editor S. Yue

Dynamically Downscaled High-Resolution Hydroclimate Projections for Western Canada

Abstract Accurate identification of the impact of global warming on water resources in major river systems represents a significant challenge to the understanding of climate change on the regional scale. Here, dynamically downscaled climate projections for western Canada are presented, and impacts on hydrological variables in two major river basins, the Fraser and Athabasca, are discussed. These regions are both challenging because of the complexity of the topography and important because of the economic activity occurring within them. To obtain robust projections of future conditions, and to adequately characterize the impact of natural variability, a small initial condition ensemble of independently downscaled climate projections is employed. The Community Earth System Model, version 1 (CESM1), is used to generate the ensemble, which consists of four members. Downscaling is performed using the Weather Research and Forecasting Model, version 3.4.1 (WRF V3.4.1), in a nested configuration with two domains at 30- and 10-km resolution, respectively. The entire ensemble was integrated for a historical validation period and for a mid-twenty-first-century projection period [assuming representative concentration pathway 8.5 (RCP8.5) for the future trajectory of greenhouse gases]. The projections herein are characterized by an increase in winter precipitation for the mid-twenty-first-century period, whereas net precipitation in summer is projected to decrease, due to increased evapotranspiration. In the Fraser River basin, a shift to more liquid precipitation and earlier snowmelt will likely reduce the seasonal variability of runoff, in particular the spring freshet. In the Athabasca River basin, winter precipitation and snowmelt may increase somewhat, but increasing evapotranspiration may lead to reduced streamflow in late summer.

On the Changing Contribution of Snow to the Hydrology of the Fraser River Basin, Canada

Abstract This paper presents an application of the Variable Infiltration Capacity (VIC) model to the Fraser River basin (FRB) of British Columbia (BC), Canada, over the latter half of the twentieth century. The Fraser River is the longest waterway in BC and supports the world’s most abundant Pacific Ocean salmon populations. Previous modeling and observational studies have demonstrated that the FRB is a snow-dominated system, but with climate change, it may evolve to a pluvial regime. Thus, the goal of this study is to evaluate the changing contribution of snow to the hydrology of the FRB over the latter half of the twentieth century. To this end, a 0.25° atmospheric forcing dataset is used to drive the VIC model from 1949 to 2006 (water years) at a daily time step over a domain covering the entire FRB. A model evaluation is first conducted over 11 major subwatersheds of the FRB to quantitatively assess the spatial variations of snow water equivalent (SWE) and runoff (R). The ratio of the spatially averaged maximum SWE to R (RSR) is used to quantify the contribution of snow to the runoff in the 11 subwatersheds of interest. From 1949 to 2006, RSR exhibits a significant decline in 9 of the 11 subwatersheds (with p < 0.05 according to the Mann–Kendall test statistics). To determine the sensitivity of RSR, the air temperature and precipitation in the forcing dataset are then perturbed. The ratio RSR decreases more significantly, especially during the 1990s and 2000s, when air temperatures have warmed considerably compared to the 1950s. On the other hand, increasing precipitation by a multiplicative factor of 1.1 causes RSR to decrease. As the climate continues to warm, ecological processes and human usage of natural resources in the FRB may be substantially affected by its transition from a snow to a hybrid (nival/pluvial) and even a rain-dominated system.

Exploring cyclic dominance of sockeye salmon with a predator–prey model

We explain in an intuitive and detailed way a predator–prey model that generates cyclic dominance in Fraser River sockeye salmon. In contrast with usual predator–prey models, this model includes four distinct prey lines and thus a combination of continuous and discrete dynamics, reflecting the particular freshwater and marine life cycle features of sockeye salmon (Oncorhynchus nerka) populations. The predator–prey interaction causing the oscillations takes place in the rearing lakes, rather than in the ocean. The values of most parameters of this model can be estimated from empirical data that are available for the large salmon-rearing lakes in the Fraser River basin. The mechanism that produces the oscillations in this model is compared with other mechanisms that can generate population oscillations, and we argue that predator–prey dynamics is the most likely mechanism to produce the observed patterns. We explain why the period of the oscillation is exactly 4 years, and we explore how the dynamical pattern is affected by changes in external conditions or by management decisions.

Net Snowpack Accumulation and Ablation Characteristics in the Inland Temperate Rainforest of the Upper Fraser River Basin, Canada

This study examines the net snow accumulation and ablation characteristics and trends in the Inland Temperate Rainforest (ITR) of the Upper Fraser River Basin, British Columbia (BC), Canada. It intends to establish whether elevation and/or air temperature play(s) a dominant role in hydrological year peak snow water equivalent (SWE) and whether regional patterns emerge in the interannual variability in peak accumulation. To that end, SWE and air temperature data from seven snow pillow sites in the Upper Fraser River Basin at elevations ranging from 1118 to 1847 m above sea level are analyzed to infer snowpack characteristics and trends for hydrological years 1969–2012, with 2005–2012 being the actual period of data overlap. Average peak SWE ranges from 391.3 mm at Barkerville, BC on 16 April to 924.4 mm at Hedrick Lake, BC on 27 April. Snow cover duration lasts 206–258 days, with snow onset dates from mid-October to early November and snow off dates from late May to early July. Statistically-significant (p ≤ 0.05) cross correlations exist between peak SWE at nearly all sites, indicating regional coherence in seasonal synoptic activity across the study area. However, the lack of relationships between peak SWE and elevation as well as air temperature parameters indicate that mesoscale to local processes lead to distinct snow accumulation and ablation patterns at each site. Four sites with the longest records exhibit no trend in peak SWE values between 1990 and 2012. Changes to snowpack regimes may pose a threat to the productivity and immense biodiversity supported by the ancient western red cedar and hemlock stands growing in the wet toe slopes of the ITR. Thus, it is imperative that continued monitoring of snowpack conditions remains a top priority in the Upper Fraser River Basin, allowing for a better understanding of ecosystem changes in a warming climate.

Tracing river chemistry in space and time: Dissolved inorganic constituents of the Fraser River, Canada

The Fraser River basin in southwestern Canada bears unique geologic and climatic features which make it an ideal setting for investigating the origins, transformations and delivery to the coast of dissolved riverine loads under relatively pristine conditions. We present results from sampling campaigns over three years which demonstrate the lithologic and hydrologic controls on fluxes and isotope compositions of major dissolved inorganic runoff constituents (dissolved nutrients, major and trace elements, 87Sr/86Sr, δD). A time series record near the Fraser mouth allows us to generate new estimates of discharge-weighted concentrations and fluxes, and an overall chemical weathering rate of 32tkm−2y−1. The seasonal variations in dissolved inorganic species are driven by changes in hydrology, which vary in timing across the basin. The time series record of dissolved 87Sr/86Sr is of particular interest, as a consistent shift between higher (“more radiogenic”) values during spring and summer and less radiogenic values in fall and winter demonstrates the seasonal variability in source contributions throughout the basin. This seasonal shift is also quite large (0.709–0.714), with a discharge-weighted annual average of 0.7120 (2s.d.=0.0003). We present a mixing model which predicts the seasonal evolution of dissolved 87Sr/86Sr based on tributary compositions and water discharge. This model highlights the importance of chemical weathering fluxes from the old sedimentary bedrock of headwater drainage regions, despite their relatively small contribution to the total water flux.

Differences in the Potential Hydrologic Impact of Climate Change to the Athabasca and Fraser River Basins of Canada with and without Considering Shifts in Vegetation Patterns Induced by Climate Change

AbstractThe research objectives are to estimate differences between the potential impact of climatic change to the Athabasca River basin (ARB) and Fraser River basin (FRB) of Canada with and without considering shifts in vegetation patterns induced by climate change and how much the difference will depend on vegetation types and climate. The hydrologic effects of vegetation shifts on ARB and FRB were estimated by applying the Mapped Atmosphere–Plant–Soil System (MAPSS) simulated results based on the Intergovernmental Panel on Climate Change’s First and Second Assessment Report general circulation model (GCM) scenarios to the modified Interaction Soil–Biosphere–Atmosphere (MISBA) scheme. According to MAPSS, vegetation shifts in mountainous regions of FRB are expected to be dominated by conifer/broadleaf competition, while in ARB, climate projections of MAPSS predicted a southern expansion of the boreal forest. Because of differences in sublimation, there is a tendency for more snow to accumulate in open grassland than forests. Furthermore, changes to simulated mean annual maximum snowpack, runoff, and basin area covered by grassland are positively correlated to each other. Generally, a 4% increase in snow water equivalent (SWE) results in a 1% increase in mean annual runoff. These relationships hold true in both basins over a wide range of GCM-projected climate conditions and vegetation responses, suggesting that most changes in mean annual flow can be attributed to changes in SWE. Because of the different modeling approaches between MAPSS and MISBA, it seems that the treatment of these processes in vegetation and hydrologic models should be similar before conclusions can be drawn from various stand-alone simulations. Ideally, a land surface scheme should be coupled with a vegetation model in future studies.

Capacity for Watershed Cumulative Effects Assessment and Management: Lessons from the Lower Fraser River Basin, Canada

This study examines the capacity to support the cumulative effects assessment and management for watersheds. The research is set in the Lower Fraser River Basin, a densely populated sub-watershed in British Columbia's lower mainland. Eight requirements or requisites for the watershed cumulative effects assessment and management are applied to evaluate current capacity for implementation in the Lower Fraser, and to identify the areas in need of capacity development. Results show that advancing watershed cumulative effects assessment and management requires not only good science but also leadership in the coordination of monitoring programs, and in ensuring the appropriate incentives and penalties for engagement and nonengagement. The lack of leadership in this regard is the result of existing governance structures arranged around the political boundaries, which have produced over time multiple agencies and jurisdictional fragmentation. Notwithstanding this, we argue that the watershed is the most appropriate scale for assessing and managing the cumulative effects to complex ecosystems.

Retreat pattern of the Cordilleran Ice Sheet in central British Columbia at the end of the last glaciation reconstructed from glacial meltwater landforms

The Cordilleran Ice Sheet (CIS) covered much of the mountainous northwestern part of North America at least several times during the Pleistocene. The pattern and timing of its growth and decay are, however, poorly understood. Here, we present a reconstruction of the pattern of ice‐sheet retreat in central British Columbia at the end of the last glaciation based on a palaeoglaciological interpretation of ice‐marginal meltwater channels, eskers and deltas mapped from satellite imagery and digital elevation models. A consistent spatial pattern of high‐elevation (1600–2400 m a.s.l.), ice‐marginal meltwater channels is evident across central British Columbia. These landforms indicate the presence of ice domes over the Skeena Mountains and the central Coast Mountains early during deglaciation. Ice sourced in the Coast Mountains remained dominant over the southern and east‐central parts of the Interior Plateau during deglaciation. Our reconstruction shows a successive westward retreat of the ice margin from the western foot of the Rocky Mountains, accompanied by the formation and rapid evolution of a glacial lake in the upper Fraser River basin. The final stage of deglaciation is characterized by the frontal retreat of ice lobes through the valleys of the Skeena and Omineca Mountains and by the formation of large esker systems in the most prominent topographic lows of the Interior Plateau. We conclude that the CIS underwent a large‐scale reconfiguration early during deglaciation and was subsequently diminished by thinning and complex frontal retreat towards the Coast Mountains.

Modelling spatial and temporal variability of hydrologic impacts of climate change in the Fraser River basin, British Columbia, Canada

AbstractThis paper presents a modelling study on the spatial and temporal variability of climate‐induced hydrologic changes in the Fraser River basin, British Columbia, Canada. This large basin presents a unique modelling case due to its physiographic heterogeneity and the potentially large implications of changes to its hydrologic regime. The macro‐scale Variable Infiltration Capacity (VIC) hydrologic model was employed to simulate 30‐year baseline (1970s) and future (2050s) hydrologic regimes based on climate forcings derived from eight global climate models (GCMs) runs under three emissions scenarios (B1, A1B and A2). Bias Corrected Spatial Disaggregation was used to statistically downscale GCM outputs to the resolution of the VIC model (1/16°). The modelled future scenarios for the 11 sub‐basins and three regions (eastern mountains, central plateau and coastal mountains) of the FRB exhibit spatially varied responses, such as, shifts from snow‐dominant to hybrid regime in the eastern and coastal mountains and hybrid to rain‐dominant regime in the central plateau region. The analysis of temporal changes illustrated considerable uncertainties in the projections obtained from an ensemble of GCMs and emission scenarios. However, direction of changes obtained from the GCM ensembles and emissions scenarios are consistent amongst one another. The most significant temporal changes could include earlier onsets of snowmelt‐driven peak discharge, increased winter and spring runoff and decreased summer runoff. The projected winter runoff increases and summer decreases are more pronounced in the central plateau region. The results also revealed increases in the total annual discharge and decreases in the 30‐year mean of the peak annual discharge. Such climate‐induced changes could have implications for water resources management in the region. The spatially and temporally varied hydro‐climatic projections and their range of projections can be used for local‐scale adaptation in this important water resource system for British Columbia. Copyright © 2012 John Wiley & Sons, Ltd.

A century of hydrological variability and trends in the Fraser River Basin

This study examines the 1911–2010 variability and trends in annual streamflow at 139 sites across the Fraser River Basin (FRB) of British Columbia (BC), Canada. The Fraser River is the largest Canadian waterway flowing to the Pacific Ocean and is one of the world’s greatest salmon rivers. Our analyses reveal high runoff rates and low interannual variability in alpine and coastal rivers, and low runoff rates and high interannual variability in most streams in BC’s interior. The interannual variability in streamflow is also low in rivers such as the Adams, Chilko, Quesnel and Stuart where the principal salmon runs of the Fraser River occur. A trend analysis shows a spatially coherent signal with increasing interannual variability in streamflow across the FRB in recent decades, most notably in spring and summer. The upward trend in the coefficient of variation in annual runoff coincides with a period of near-normal annual runoff for the Fraser River at Hope. The interannual variability in streamflow is greater in regulated rather than natural systems; however, it is unclear whether it is predominantly flow regulation that leads to these observed differences. Environmental changes such as rising air temperatures, more frequent polarity changes in large-scale climate teleconnections such as El Niño-Southern Oscillation and Pacific Decadal Oscillation, and retreating glaciers may be contributing to the greater range in annual runoff fluctuations across the FRB. This has implications for ecological processes throughout the basin, for example affecting migrating and spawning salmon, a keystone species vital to First Nations communities as well as to commercial and recreational fisheries. To exemplify this linkage between variable flows and biological responses, the unusual FRB runoff anomalies observed in 2010 are discussed in the context of that year’s sockeye salmon run. As the climate continues to warm, greater variability in annual streamflow, and hence in hydrological extremes, may influence ecological processes and human usage throughout the FRB in the 21st century.

Bioassessment of stream ecosystems enduring a decade of simulated degradation: lessons for the real world

The effects on benthic macroinvertebrate communities of simulated degradation of streams enabled evaluation of the effects of starting condition, type of degradation, and biota descriptor on the type 1 and type 2 error rates of bioassessment. Benthic macroinvertebrate communities from five reference streams in the Fraser River basin (British Columbia, Canada) were used as the starting conditions of replicated simulations of the effects of suspended sediments in three temporal patterns (none, one-time severe, constant moderate). The dynamics of the simulated stream communities and the type 1 and type 2 errors associated with bioassessments, as described by (i) taxon richness, (ii) EPT (Ephemeroptera, Plecoptera, Trichoptera) richness, (iii) proportion of EPT individuals in the community, (iv) difference in composition from the median reference community (MCDist), (v) Simpson’s diversity, and (vi) Simpson’s equitability, depended on the combination of starting condition, simpact treatment, and the biota descriptor. To reduce type 1 and type 2 errors in bioassessments using the reference condition approach, bioassessment programs should include (i) matching of test and expected reference communities and refinement of the definition of reference condition and (ii) several biota descriptors that include measures of richness, tolerance, and community composition.

Streamflow response to climatic variability in a complex mountainous environment: Fraser River Basin, British Columbia, Canada

AbstractWithin an area where the regional climate variability signal is apparent, local factors including location, topography and land characteristics affect hydrological response to the signal. Mountainous areas, such as the Western Cordillera in North America, are expected to possess such local effects. The Fraser River Basin in British Columbia, Canada, contains stations with 40 years of precipitation and discharge records from stations widely distributed across the 217 000 km2 basin. Correlation coefficients were calculated to relate winter precipitation, spring and summer high flow to several climate indices: Pacific Decadal Oscillation (PDO), Pacific‐North American (PNA) and Southern Oscillation Index (SOI). Analyses confirmed that the level of correlation changes during the snowmelt period and does vary locally within the Basin. Correlation of discharge with the indices also changes along the Fraser River, being strengthened or weakened by the influence of its tributaries. These results caution that in hydrologic investigations, (1) even where the region as a whole manifests a strong teleconnection signal, deviation in signal strength within a medium‐sized basin causes local variations in streamflow response to the regional climatic forcing, and (2) the level of correlation attained by streamflow at a basin outlet does not necessarily apply to its tributary sub‐basins. Copyright © 2011 John Wiley & Sons, Ltd.

Geographical and host distribution patterns of Parvicapsula minibicornis (Myxozoa) small subunit ribosomal RNA genetic types

Parvicapsula minibicornis is a myxozoan parasite implicated in mortalities of both juvenile and pre-spawning adult salmon in the Pacific Northwest of North America. Disease severity and presentation varies between salmon species and geographical localities. To better characterize population structure of the parasite, we sought genetic markers in the P. minibicornis ribosomal RNA gene. We compared samples from California with the type specimen from British Columbia, identified sequence variations, and then sequenced 197 samples from fish, river water and the parasite's polychaete worm host. Although DNA sequences of the parasite were >98·9% similar, there was enough variation to define 15 genotypes. All genotypes were detected in fish samples, although not in all species. A single genotype only was found in sockeye and pink salmon in the Fraser River Basin, but was not detected in sockeye from the adjacent Columbia River Basin. All coho salmon, irrespective of river basin, were infected with a unique mix of 2 genotypes. These data indicated that the P. minibicornis population exhibited strong signals of structuring by both geography and salmonid host species. Particular genotypes may correlate with disease differences seen in salmon populations in the Pacific Northwest.

Relationships between habitat characteristics and breeding population densities in sockeye salmon (Oncorhynchus nerka)

We examine the importance of stream habitat characteristics in governing variation in spawning densities of sockeye salmon ( Oncorhynchus nerka ) across 32 streams in the Fraser River Basin, British Columbia, Canada. We used mixed-effects models to examine four competing hypotheses for the influence of abiotic stream characteristics acting on either adult salmon or embryo mortality. All models that received support using Akaike’s information criterion included stream characteristics that are associated with cover. These included the percent area of pools, percentage of the banks that were undercut, and large woody debris (in that order). These results suggest the importance of stream characteristics, which reduce risk of predation on adults, in determining spawning sockeye salmon densities. Thus, identification of a small number of physical characteristics of streams provides insight into ecological processes that determine population densities. This information can be used to quantify habitat quality, which can guide habitat prioritization for conservation.

A three-species model explaining cyclic dominance of Pacific salmon

The four-year oscillations of the number of spawning sockeye salmon ( Oncorhynchus nerka) that return to their native stream within the Fraser River basin in Canada are a striking example of population oscillations. The period of the oscillation corresponds to the dominant generation time of these fish. Various—not fully convincing—explanations for these oscillations have been proposed, including stochastic influences, depensatory fishing, or genetic effects. Here, we show that the oscillations can be explained as an attractor of the population dynamics, resulting from a strong resonance near a Neimark Sacker bifurcation. This explains not only the long-term persistence of these oscillations, but also reproduces correctly the empirical sequence of salmon abundance within one period of the oscillations. Furthermore, it explains the observation that these oscillations occur only in sockeye stocks originating from large oligotrophic lakes, and that they are usually not observed in salmon species that have a longer generation time.

Differences and sensitivities in potential hydrologic impact of climate change to regional-scale Athabasca and Fraser River basins of the leeward and windward sides of the Canadian Rocky Mountains respectively

Sensitivities to the potential impact of Climate Change on the water resources of the Athabasca River Basin (ARB) and Fraser River Basin (FRB) were investigated. The Special Report on Emissions Scenarios (SRES) of IPCC projected by seven general circulation models (GCM), namely, Japan’s CCSRNIES, Canada’s CGCM2, Australia’s CSIROMk2b, Germany’s ECHAM4, the USA’s GFDLR30, the UK’s HadCM3, and the USA’s NCARPCM, driven under four SRES climate scenarios (A1FI, A2, B1, and B2) over three 30-year time periods (2010–2039, 2040–2069, 2070–2100) were used in these studies. The change fields over these three 30-year time periods are assessed with respect to the 1961–1990, 30-year climate normal and based on the 1961–1990 European Community Mid-Weather Forecast (ECMWF) re-analysis data (ERA-40), which were adjusted with respect to the higher resolution GEM forecast archive of Environment Canada, and used to drive the Modified ISBA (MISBA) of Kerkhoven and Gan (Adv Water Resour 29(6):808–826, 2006). In the ARB, the shortened snowfall season and increased sublimation together lead to a decline in the spring snowpack, and mean annual flows are expected to decline with the runoff coefficient dropping by about 8% per °C rise in temperature. Although the wettest scenarios predict mild increases in annual runoff in the first half of the century, all GCM and emission combinations predict large declines by the end of the twenty-first century with an average change in the annual runoff, mean maximum annual flow and mean minimum annual flow of −21%, −4.4%, and −41%, respectively. The climate scenarios in the FRB present a less clear picture of streamflows in the twenty-first century. All 18 GCM projections suggest mean annual flows in the FRB should change by ±10% with eight projections suggesting increases and 10 projecting decreases in the mean annual flow. This stark contrast with the ARB results is due to the FRB’s much milder climate. Therefore under SRES scenarios, much of the FRB is projected to become warmer than 0°C for most of the calendar year, resulting in a decline in FRB’s characteristic snow fed annual hydrograph response, which also results in a large decline in the average maximum flow rate. Generalized equations relating mean annual runoff, mean annual minimum flows, and mean annual maximum flows to changes in rainfall, snowfall, winter temperature, and summer temperature show that flow rates in both basins are more sensitive to changes in winter than summer temperature.

Unconditional uncertainties of historical and simulated river flows subjected to climate change

► Observed and simulated river flows exhibit similar multifractal behavior. ► Multifractal characteristics have significant implications for uncertainty estimates. ► Climate Change can alter the multifractal character of river flows. ► Uncertainty due to multifractal variation is on the order of +/- 50%. ► Uncertainty due to emissions scenarios and GCM selection is on the order of +/- 20%. The objective of this study was to estimate the unconditional sample uncertainty of observed streamflows and streamflows simulated from a hydrologic model (MISBA) for the Fraser River Basin (FRB) and the Athabasca River Basin (ARB) of Canada under historic conditions and under future conditions simulated by General Circulation Models (GCMs). For each basin, the multifractal properties of 54 simulated hydrographs based on the predictions of seven GCMs and four climate scenarios over three 30-year periods of the 21st century were evaluated and used to generate extended artificial time series by the randomized generalized multifractal cascade model. Uncertainty estimates derived from this multifractal approach were compared with classical statistics, Hurst exponent, and autocorrelation methods. The multifractal approach resulted in greater departures from statistical independence, higher skewness, and a wider range of flows over a 30-year time scale than the other methods. Under climate change, the multifractal strength of streamflows of FRB increased with temperature as the snow fed character of the basin weakened, but in the colder ARB, a decrease in multifractal strength resulted under rising temperatures because of declined snow packs. The estimated unconditional sample uncertainty was compared with uncertainty associated with model and emissions scenario selection. Among four major sources of uncertainty, uncertainty associated with two different hydrologic models (MISBA and SAC-SMA) and global emission patterns in the 21st century were relatively small (20% or less) even though for the latter, the range of SRES climate scenarios may not be representative of future economy and the seven GCMs may not accurately represent actual physical processes. The uncertainties associated with multifractal variation were the largest, on the order of ±50%.

Comparison of Institutional Arrangements for River Basin Management in Eight Basins

This study represents an effort toward understanding conditions that affect successful or unsuccessful efforts to devolve water resource management to the river basin level and secure active stakeholder involvement. A theoretical framework is used to identify potentially important variables related to the likelihood of success. Using a comparative case-study approach, the study examined river basins where organizations have been developed at the basin scale and where organizations perform management functions such as planning, allocation, and pricing of water supplies, flood prevention and response, and water quality monitoring and improvement. This paper compares the alternative approaches to basin governance and management adopted in the following river basins: the Alto-Tiete and Jaguaribe River Basins, Brazil; the Brantas River Basin, East Java, Indonesia; the Fraser River Basin, British Columbia, Canada; the Guadalquivir Basin, Spain; the Murray-Darling River Basin, Australia; the Tarcoles River Basin, Costa Rica; and the Warta River Basin, Poland. The analysis focuses on how management has been organized and pursued in each case in light of its specific geographical, historical, and organizational contexts and the evolution of institutional arrangements. The cases are also compared and assessed for their observed degrees of success in achieving improved stakeholder participation and integrated water resources management.