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Columbia River (columbia + river)

Distribution by Scientific Domains

Life Sciences	55%

Terms modified by Columbia River

columbia river basin

Selected Abstracts

Interchannel hydraulic geometry and hydraulic efficiency of the anastomosing Columbia River, southeastern British Columbia, Canada

EARTH SURFACE PROCESSES AND LANDFORMS, Issue 8 2003
Kevin K. Tabata
Abstract The morphodynamics of the anastomosing channel system of upper Columbia River in southeastern British Columbia, Canada, is examined using an adaptation of conventional hydraulic geometry termed ,interchannel hydraulic geometry'. Interchannel hydraulic geometry has some of the characteristics of downstream hydraulic geometry but differs in that it describes the general bankfull channel form and hydraulics of primary and secondary channels in the anastomosing channel system. Interchannel hydraulic geometry generalizes these relationships and as such becomes a model of the geomorphology of channel division and combination. Interchannel hydraulic geometry of upper Columbia River, based on ,eld measurements of ,ow velocity and channel form at 16 test sections, is described well by simple power functions: wbf = 3·24Qbf0·64; dbf = 1·04Qbf0·19; vbf = 0·30Qbf0·17. These results, with other related measurements of ,ow resistance, imply that channel splitting leads to hydraulic inef,ciency (higher ,ow resistance) on the anastomosing Columbia River. Because these ,ndings differ from those reported in studies elsewhere, we conclude that hydraulic ef,ciency does not provide a general explanation for anabranching in river channels. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Changes in productivity and contaminants in bald eagles nesting along the lower Columbia River, USA

ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2005
Jeremy A. Buck
Abstract Previous studies documented poor productivity of bald eagles (Haliaeetus leucocephalus) in the lower Columbia River (LCR), USA, and elevated p,p,-dichlorodiphenyldichloroethylene (DDE), polychlorinated biphenyls (PCBs), dioxins, and furans in eagle eggs. From 1994 to 1995, we collected partially incubated eggs at 19 of 43 occupied territories along the LCR and compared productivity and egg contaminants to values obtained in the mid-1980s. We found higher productivity at new nesting sites along the river, yet productivity at 23 older breeding territories remained low and was not different (p = 0.713) between studies. Eggshell thickness at older territories had not improved (p = 0.404), and eggshells averaged 11% thinner than shells measured before dichlorodiphenyltrichloroethane use. Decreases in DDE (p = 0.022) and total PCBs (p = 0.0004) in eggs from older breeding areas occurred between study periods. Productivity was not correlated to contaminants, but DDE, PCBs, and dioxin-like chemicals exceeded estimated no-effect values. Some dioxin-like contaminants in eggs were correlated to nest location, with highest concentrations occurring toward the river's mouth where productivity was lowest. Although total productivity increased due to the success of new nesting pairs in the region, egg contaminants remain high enough to impair reproduction at older territories and, over time, may alter productivity of new pairs nesting near the river's mouth. [source]

UTILIZING INDUCED RECHARGE FOR REGIONAL AQUIFER MANAGEMENT,

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 2 2001
John S. Koreny
ABSTRACT: The deep aquifers of the Portland Basin are used as a regional water supply by at least six municipalities in Oregon and Washington. Maximum continuous use of the aquifers in 1998 was 13 mgd and peak emergency use was 55 mgd. Continuous use of the deep aquifers at a rate of 55 mgd has been proposed and inchoate water rights have been reserved for expansion of pumping to 121 mgd. A study was completed, using a calibrated ground water flow model, to evaluate the role of induced recharge from the Columbia River in mitigating aquifer drawdown from continuous-use and expanded pumping scenarios in the center and eastern areas of the basin. The absolute average residual was less than 3.6 feet for steady-state model calibrations, and less than 8.0 feet for transient calibration to a 42 mgd pumping event in 1987 with 170 feet of drawdown. Continuous use of the aquifers at a rate of 55 mgd is predicted to increase drawdown to 210 feet. Expansion of pumping to 121 mgd in the center basin is predicted to cause 400 feet of drawdown. However, expansion of pumping in the east basin is predicted to result in only 220 feet of drawdown because of induced recharge from the Columbia River. [source]

PACIFIC NORTHWEST REGIONAL ASSESSMIENT: THE IMPACTS OF CLIMATE VARIABILITY AND CLIMATE CHANGE ON THE WATER RESOURCES OF TEE COLUMBIA RWER BASIN,

JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 2 2000
Edward L. Miles
ABSTRACT: The Pacific Northwest (PNW) regional assessment is an integrated examination of the consequences of natural climate variability and projected future climate change for the natural and human systems of the region. The assessment currently focuses on four sectors: hydrology/water resources, forests and forestry, aquatic ecosystems, and coastal activities. The assessment begins by identifying and elucidating the natural patterns of climate vanability in the PNW on interannual to decadal timescales. The pathways through which these climate variations are manifested and the resultant impacts on the natural and human systems of the region are investigated. Knowledge of these pathways allows an analysis of the potential impacts of future climate change, as defined by IPCC climate change scenarios. In this paper, we examine the sensitivity, adaptability and vulnerability of hydrology and water resources to climate variability and change. We focus on the Columbia River Basin, which covers approximately 75 percent of the PNW and is the basis for the dominant water resources system of the PNW. The water resources system of the Columbia River is sensitive to climate variability, especially with respect to drought. Management inertia and the lack of a centralized authority coordinating all uses of the resource impede adaptability to drought and optimization of water distribution. Climate change projections suggest exacerbated conditions of conflict between users as a result of low summertime streamfiow conditions. An understanding of the patterns and consequences of regional climate variability is crucial to developing an adequate response to future changes in climate. [source]

Balancing the Need to Develop Coastal Areas with the Desire for an Ecologically Functioning Coastal Environment: Is Net Ecosystem Improvement Possible?

RESTORATION ECOLOGY, Issue 1 2005
R.M. Thom
Abstract The global human population is growing exponentially, close to a majority lives and works near the coast, and coastal commerce and development are critical to the economies of many nations. Hence, coastal areas will continue to be a major focus of development and economic activity. People desire the economic advantages provided by coastal development along with the fisheries and social commodities supported by estuarine and coastal ecosystems. Because of these facts, we view the challenge of balancing coastal development with enhancing nearshore marine and estuarine ecosystems (i.e., net ecosystem improvement) as the top priority for coastal researchers in this century. Our restoration research in Pacific Northwest estuaries and participation in nearshore project design and impact mitigation has largely dealt with these competing goals. To this end, we have applied conceptual models, comprehensive assessment methods, and principles of restoration ecology, conservation biology, and adaptive management to incorporate science into decisions about uses of estuarine systems. Case studies of Bainbridge Island and the Columbia River demonstrate the use of objective, defensible methods to prioritize tidally influenced shorelines and habitats (i.e., riparian forests, marshes, unvegetated flats, rocky shores, seagrass meadows, kelp forests) for preservation, conservation, and restoration. Case studies of Clinton, Washington, and Port Townsend, Washington, demonstrate the incorporation of an ecological perspective and technological solutions into design of overwater structures to minimize impacts on nearshore ecosystems. Adaptive management has allowed coastal development and restoration uncertainties to be better evaluated, with the information used to improve management decisions. Although unproven on a large scale, we think these kinds of methods can contribute to the net improvement of already degraded ecosystems. The ingredients include applied science to understand the issues, education, incentives, empirical data, cumulative impact analysis, and an effective adaptive management program. Because the option of net ecosystem improvement is often more costly than alternatives such as no net loss, commitment by the local or regional community to this approach is essential. [source]

Differences in the impacts of dams on the dynamics of salmon populations

ANIMAL CONSERVATION, Issue 4 2001
Phillip S. Levin
Modern concrete dams have devastated fish populations world-wide. However, dams vary greatly in how they are engineered and operated, and thus pose a range of threats to riverine fauna. Understanding the differences in the impacts of dams is critical for setting conservation priorities. We used a modified BACI (before-after-control-impact) sampling design as a means to quantify the effects of dams on spring/summer chinook salmon in two watersheds (Snake and Upper Columbia Rivers) of the Columbia River Basin, USA. The construction of four dams in the Columbia River Basin from 1966 to 1975 allowed us to test the hypothesis that the presence of these dams does not affect the abundance, survival and population growth of chinook salmon. In both the Snake and Upper Columbia Rivers, there was a significant decline from the period before dams were constructed (1959-65) to the period after dams were constructed (1980-90). In the Upper Columbia River, declines in productivity or population performance (measured as recruits per spawner or Ricker function residuals) were greater than in the control region. On the other hand, patterns of fish productivity in the Snake River were similar to those seen in the control region. The disparity between fates of Upper Columbia and Snake River populations points to the differences between regions in current efforts to reduce fish mortality associated with dams. Our analysis suggests that dams in the Upper Columbia River, but not Snake River, are a potential force preventing recovery of endangered salmon populations. [source]

Capture,Recapture Studies Using Radio Telemetry with Premature Radio-Tag Failure

BIOMETRICS, Issue 3 2005
Laura Cowen
Summary Radio tags, because of their high detectability, are often used in capture,recapture studies. A key assumption is that radio tags do not cease functioning during the study. Radio-tag failure before the end of a study can lead to underestimates of survival rates. We develop a model to incorporate secondary radio-tag failure data. This model was applied to chinook smolts (Oncorhynchus tshawytscha) on the Columbia River, Washington. Estimates of fish survival from this model were much larger than those from the standard Cormack,Jolly,Seber analysis. [source]