-
Declining annual streamflow distributions in the Pacific Northwest United States, 1948–2006
-
Much of the discussion on climate change and water in the western United States centers on decreased snowpack and earlier spring runoff. Although increasing variability in annual flows has been noted, the nature of those changes is largely unexplored. We tested for trends in the distribution of annual runoff using quantile regression at 43 gages in the Pacific Northwest. Seventy-two percent of the stations showed significant (a = 0.10) declines in the 25th percentile annual flow, with half of the stations exceeding a 29% decline and a maximum decline of 47% between 1948 and 2006. Fewer stations showed statistically significant declines in either median or mean annual flow, and only five had a significant change in the 75th percentile, demonstrating that increases in variance result primarily from a trend of increasing dryness in dry years. The asymmetric trends in streamflow distributions have implications for water management and ecology well beyond those of shifted timing alone, affect both rain and snow-dominated watersheds, and contribute to earlier timing trends in high- elevation watersheds.
Located in
Resources
/
Climate Science Documents
-
Climate change effects on stream and river temperatures across the northwest U.S. from 1980–2009 and implications for salmonid fishes
-
Thermal regimes in rivers and streams are fundamentally important to aquatic ecosystems and are expected to change in response to climate forcing as the Earth’s temperature warms. Description and attribution of stream temperature changes are key to understanding how these ecosystems may be affected by climate change, but difficult given the rarity of long-term monitoring data. We assembled 18 temperature time-series from sites on regulated and unregulated streams in the northwest U.S. to describe historical trends from 1980–2009 and assess thermal consistency between these stream categories. Statistically significant temperature trends were detected across seven sites on unregulated streams during all seasons of the year, with a cooling trend apparent during the spring and warming trends during the summer, fall, and winter. The amount of warming more than compensated for spring cooling to cause a net temperature increase, and rates of warming were highest during the summer (raw trend = 0.17°C/decade; reconstructed trend = 0.22°C/decade). Air temperature was the dominant factor explaining long-term stream temperature trends (82–94% of trends) and inter-annual variability (48–86% of variability), except during the summer when discharge accounted for approximately half (52%) of the inter-annual variation in stream temperatures. Seasonal temperature trends at eleven sites on regulated streams were qualitatively similar to those at unregulated sites if two sites managed to reduce summer and fall temperatures were excluded from the analysis. However, these trends were never statistically significant due to greater variation among sites that resulted from local water management policies and effects of upstream reservoirs. Despite serious deficiencies in the stream temperature monitoring record, our results suggest many streams in the northwest U.S. are exhibiting a regionally coherent response to climate forcing. More extensive monitoring efforts are needed as are techniques for short-term sensitivity analysis and reconstructing historical temperature trends so that spatial and temporal patterns of warming can be better understood. Continuation of warming trends this century will increasingly stress important regional salmon and trout resources and hamper efforts to recover these species, so comprehensive vulnerability assessments are needed to provide strategic frameworks for prioritizing conservation efforts.
Located in
Resources
/
Climate Science Documents
-
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.
Located in
Resources
/
Climate Science Documents
-
Biophysical controls on organic carbon fluxes in fluvial networks.pdf
-
Metabolism of terrestrial organic carbon in freshwater ecosystems is responsible for a large amount of carbon dioxide outgassing to the atmosphere, in contradiction to the conventional wisdom that terrestrial organic carbon is recalcitrant and contributes little to the support of aquatic metabolism. Here, we combine recent findings from geophysics, microbial ecology and organic geochemistry to show geophysical opportunity and microbial capacity to enhance the net heterotrophy in streams, rivers and estuaries. We identify hydrological storage and retention zones that extend the residence time of organic carbon during downstream transport as geophysical opportunities for microorganisms to develop as attached biofilms or suspended aggregates, and to metabolize organic carbon for energy and growth. We consider fluvial networks as meta-ecosystems to include the acclimation of microbial communities in downstream ecosystems that enable them to exploit energy that escapes from upstream ecosystems, thereby increasing the overall energy utilization at the network level.
Located in
Resources
/
Climate Science Documents
-
Watershed Decision Tool Webinar Series (UPDATE)
-
The USFWS Southeast Region Office is sponsoring a webinar series on Watershed Decision Tools with the aim of promoting awareness of the many various watershed prioritization tools available to assist in planning conservation actions and fostering discussion about how each tool is or could be used, applicability and limitations, and possible future improvements and needs. We currently have 4 remaining webinars scheduled and hope to add more. We have switched to a new webex platform to enable recording and archiving of webinar presentations, so login details for the series has changed.
Located in
News & Events
/
Watershed Decision Tool Webinar Series (UPDATE)
-
Primary Influences on Water Temperature for Inland Streams
-
The COMET Program is pleased to announce the publication of the new lesson, "Primary Influences on Water Temperature for Inland Streams". The temperature of inland streams, rivers, and reservoirs affects aquatic wildlife, riparian vegetation, and infrastructure.
Located in
News & Events
-
FY2015 Brook Trout Conservation Funding Opportunity
-
The Eastern Brook Trout Joint Venture (EBTJV) is seeking project proposals focused on conserving the habitats needed to support healthy and productive wild Brook Trout populations.
Located in
News & Events
-
Kentucky partnership with Tennessee, Ohio and West Virginia will restore mussels in 180 miles of the Licking River
-
Imperiled species will benefit from a total of $5.6 million in grants for 16 projects in 12 states through the U.S. Fish and Wildlife Service’s competitive State Wildlife Grants program. The grants, which focus on large-scale conservation projects yielding measurable results, will be matched by more than $2.9 million in non-federal funds from states and their partners for projects that work to conserve and recover wildlife identified by states as Species of Greatest Conservation Need and their habitats.
Located in
News & Events
-
Canaan Valley Institute (CVI)
-
Canaan Valley Institute (CVI) is driven by a mission to ensure the Appalachian region has healthy streams — a critical economic engine for rural communities. CVI’s approach for clean and healthy rivers creates positive results environmentally AND economically.
Located in
LP Members
/
Organizations Search
-
Researchers map fishing resources to assist land managers, anglers
-
Anglers in North Carolina and Virginia who are looking for privacy at good fishing spots should head for the mountains, according to a Virginia Tech study of the capacity, quality, and demand of freshwater recreational fishing sites in the two states.
Located in
News & Events
