scholarly journals The effects of cumulative forest disturbance on streamflow in a large watershed in the central interior of British Columbia, Canada

2012 ◽  
Vol 16 (7) ◽  
pp. 2021-2034 ◽  
Author(s):  
M. Zhang ◽  
X. Wei
Keyword(s):  
British Columbia ◽  
Large Scale ◽  
Forest Disturbance ◽  
Climatic Variability ◽  
Natural Disturbance ◽  
Low Flow ◽  
Mean Flow ◽  
Salvage Logging ◽  
Positive Effects ◽  
Creek Watershed

Abstract. The Baker Creek watershed (1570 km2), situated in the central interior of British Columbia, Canada, has been severely disturbed by both logging and natural disturbance, particularly by a recent large-scale mountain pine beetle (MPB) infestation (up to 2009, 70.2% of the watershed area had been attacked by MPB) and subsequent salvage logging. The concept of equivalent clear-cut area (ECA) was used to indicate the magnitude of forest disturbance, with consideration of hydrological recovery following various types of disturbance (wildfire, logging and MPB infestation), cumulated over space and time in the watershed. The cumulative ECA peaked at 62.2% in 2009. A combined approach of statistical analysis (i.e. time series analysis) and graphic method (modified double mass curve) was employed to evaluate the impacts of forest disturbance on hydrology. Our results showed that severe forest disturbance significantly increased annual mean flow. The average increment in annual mean flow caused by forest disturbance was 48.4 mm yr−1, while the average decrease in annual mean flow caused by climatic variability during the same disturbance period was 35.5 mm yr−1. The opposite changes in directions and magnitudes clearly suggest an offsetting effect between forest disturbance and climatic variability, with the absolute influential strength of forest disturbance (57.7%) overriding that from climate variability (42.3%). Forest disturbance also produced significant positive effects on low flow and dry season (fall and winter) mean flow. Implications of our findings for future forest and water resources management are discussed in the context of long-term watershed sustainability.

scholarly journals The cumulative effects of forest disturbance on streamflow in a large watershed in the central interior of British Columbia, Canada

2012 ◽  
Vol 9 (3) ◽  
pp. 2855-2895 ◽  
Author(s):  
M. Zhang ◽  
X. Wei
Keyword(s):  
British Columbia ◽  
Large Scale ◽  
Mountain Pine Beetle ◽  
Forest Disturbance ◽  
Climatic Variability ◽  
Natural Disturbance ◽  
Low Flow ◽  
Mean Flow ◽  
Salvage Logging ◽  
Creek Watershed

Abstract. The Baker Creek watershed (1570 km2) situated in the central interior of British Columbia, Canada has been severely disturbed by both human-being logging and natural disturbance, particularly by a recent large-scale mountain pine beetle (MPB) infestation (up to 2009, 70.2% of the watershed area was attacked by MPB) and subsequent salvage logging. The concept of equivalent clear-cut area (ECA) was used to indicate the magnitude of forest disturbance with consideration of hydrological recovery following various types of disturbances (wildfire, logging and MPB infestation) cumulated over space and time in the studied watershed. The cumulative ECA was up to 62.2% in 2009. A combined approach of statistical analysis (time series analysis) with modified double mass curve was employed to evaluate the impacts of forest disturbance on hydrology. Our results showed that severe forest disturbance significantly increased annual mean flow. The average increment in annual mean flow caused by forest disturbance was 48.4 mm yr−1, while the average decrease in annual mean flow caused by climatic variability during the same disturbance period was −35.5 mm yr−1. The opposite change directions and magnitudes clearly suggest offsetting effect between forest disturbance and climatic variability, with the absolute influential strength of forest disturbance (57.7%) overriding that from climate variability (42.3%). Forest disturbances also produced significant positive effect on low flow and dry season (fall and winter) mean flow. Implications of our findings for future forest and water resources management are discussed in the context of long-term watershed sustainability.

scholarly journals The Cumulative Effects of Forest Disturbance and Climate Variability on Streamflow in the Deadman River Watershed

Forests ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 196 ◽  
Author(s):  
Krysta Giles-Hansen ◽  
Qiang Li ◽  
Xiaohua Wei
Keyword(s):  
Climate Variability ◽  
Forest Cover ◽  
Forest Disturbance ◽  
Climatic Variability ◽  
High Flow ◽  
The Body ◽  
Cumulative Effects ◽  
Low Flow ◽  
Mean Flow ◽  
River Watershed

Climatic variability and cumulative forest cover change are the two dominant factors affecting hydrological variability in forested watersheds. Separating the relative effects of each factor on streamflow is gaining increasing attention. This study adds to the body of literature by quantifying the relative contributions of those two drivers to the changes in annual mean flow, low flow, and high flow in a large forested snow dominated watershed, the Deadman River watershed (878 km2) in the Southern Interior of British Columbia, Canada. Over the study period of 1962 to 2012, the cumulative effects of forest disturbance significantly affected the annual mean streamflow. The effects became statistically significant in 1989 at the cumulative forest disturbance level of 12.4% of the watershed area. The modified double mass curve and sensitivity-based methods consistently revealed that forest disturbance and climate variability both increased annual mean streamflow during the disturbance period (1989–2012), with an average increment of 14 mm and 6 mm, respectively. The paired-year approach was used to further investigate the relative contributions to low and high flows. Our analysis showed that low and high flow increased significantly by 19% and 58%, respectively over the disturbance period (p < 0.05). We conclude that forest disturbance and climate variability have significantly increased annual mean flow, low flow and high flow over the last 50 years in a cumulative and additive manner in the Deadman River watershed.

Salvage harvesting – past lessons and future issues

2006 ◽  
Vol 82 (1) ◽  
pp. 48-53 ◽  
Author(s):  
David Lindenmayer
Keyword(s):  
Environmental Impacts ◽  
Large Scale ◽  
Natural Disturbance ◽  
Forest Planning ◽  
Salvage Logging ◽  
Eastern Australia ◽  
Wide Range ◽  
Natural Resource Managers ◽  
Salvage Harvesting

The increasing prevalence and/or increasing intensity of large-scale natural disturbance events in forests means that post-disturbance salvage logging is becoming more widespread. Salvage logging can have a wide range of environmental impacts, but some of these are not well known or not well understood by policy makers and natural resource managers. Some of these impacts are briefly summarized in this paper. Improved long-term forest planning needs to be embraced that takes into account the not only the environmental but also the social and environmental impacts of salvage harvesting. Past mistakes and future opportunities associated with salvage harvesting are illustrated by a case study from the Lower Cotter Catchment in south-eastern Australia. Key words: salvage harvesting, natural disturbance, environmental impacts, ecologically sustainable forestry, forest planning, long-term forest sustainability

Boreal forest disturbance and streamflow response, northeastern Ontario

2000 ◽  
Vol 57 (S2) ◽  
pp. 5-18 ◽  
Author(s):  
J M Buttle ◽  
R A Metcalfe
Keyword(s):  
Boreal Forest ◽  
Large Scale ◽  
Forest Disturbance ◽  
Landsat Imagery ◽  
Climatic Variability ◽  
Temporal Trends ◽  
Small Degree ◽  
Hydrologic Impacts ◽  
Streamflow Response ◽  
Canadian Boreal Forest

The effects of forest disturbance on streamflow from small (<10 km2) basins have been well documented; however, implications of such disturbance for streamflow from relatively large rivers in the Canadian boreal forest are unclear. Landsat imagery was used to determine changes in the type, amount, and location of forest disturbance in northeastern Ontario between 1985 and 1990. These were compared with streamflow responses from medium- and large-scale basins in the region. Harvesting dominated forest disturbance, and total disturbance as of 1990 ranged from 25% of basin area in the northwest part of the region to 5% in the southeast. There was limited streamflow response to land cover changes, with no definitive changes in water year runoff or peak flow magnitude and timing. This likely reflects the ability of relatively large basins to buffer the hydrologic impacts of the small degree of recent forest disturbance, combined with the influence of climatic variability on temporal trends in basin streamflow. However, disturbance was associated with increases in moderate and low flows from medium and large basins, respectively, which occurred largely during summer months.

scholarly journals The 6 August 2010 Mount Meager rock slide-debris flow, Coast Mountains, British Columbia: characteristics, dynamics, and implications for hazard and risk assessment

2012 ◽  
Vol 12 (5) ◽  
pp. 1277-1294 ◽  
Author(s):  
R. H. Guthrie ◽  
P. Friele ◽  
K. Allstadt ◽  
N. Roberts ◽  
S. G. Evans ◽  
...  
Keyword(s):  
British Columbia ◽  
Debris Flow ◽  
Large Scale ◽  
Rock Avalanche ◽  
Volcanic Complex ◽  
Rock Slide ◽  
Night Time ◽  
Coast Mountains ◽  
Creek Watershed ◽  
The Impact

Abstract. A large rock avalanche occurred at 03:27:30 PDT, 6 August 2010, in the Mount Meager Volcanic Complex southwest British Columbia. The landslide initiated as a rock slide in Pleistocene rhyodacitic volcanic rock with the collapse of the secondary peak of Mount Meager. The detached rock mass impacted the volcano's weathered and saturated flanks, creating a visible seismic signature on nearby seismographs. Undrained loading of the sloping flank caused the immediate and extremely rapid evacuation of the entire flank with a strong horizontal force, as the rock slide transformed into a debris flow. The disintegrating mass travelled down Capricorn Creek at an average velocity of 64 m s−1, exhibiting dramatic super-elevation in bends to the intersection of Meager Creek, 7.8 km from the source. At Meager Creek the debris impacted the south side of Meager valley, causing a runup of 270 m above the valley floor and the deflection of the landslide debris both upstream (for 3.7 km) and downstream into the Lillooet River valley (for 4.9 km), where it blocked the Lillooet River river for a couple of hours, approximately 10 km from the landslide source. Deposition at the Capricorn–Meager confluence also dammed Meager Creek for about 19 h creating a lake 1.5 km long. The overtopping of the dam and the predicted outburst flood was the basis for a night time evacuation of 1500 residents in the town of Pemberton, 65 km downstream. High-resolution GeoEye satellite imagery obtained on 16 October 2010 was used to create a post-event digital elevation model. Comparing pre- and post-event topography we estimate the volume of the initial displaced mass from the flank of Mount Meager to be 48.5 × 106 m3, the height of the path (H) to be 2183 m and the total length of the path (L) to be 12.7 km. This yields H/L = 0.172 and a fahrböschung (travel angle) of 9.75°. The movement was recorded on seismographs in British Columbia and Washington State with the initial impact, the debris flow travelling through bends in Capricorn Creek, and the impact with Meager Creek are all evident on a number of seismograms. The landslide had a seismic trace equivalent to a M = 2.6 earthquake. Velocities and dynamics of the movement were simulated using DAN-W. The 2010 event is the third major landslide in the Capricorn Creek watershed since 1998 and the fifth large-scale mass flow in the Meager Creek watershed since 1930. No lives were lost in the event, but despite its relatively remote location direct costs of the 2010 landslide are estimated to be in the order of $10 M CAD.

Forest disturbance effects on snow and water yield in interior British Columbia

2014 ◽  
Vol 46 (4) ◽  
pp. 521-532 ◽  
Author(s):  
Rita Winkler ◽  
Dave Spittlehouse ◽  
Sarah Boon ◽  
Barbara Zimonick
Keyword(s):  
Mountain Pine Beetle ◽  
Snow Water Equivalent ◽  
Forest Disturbance ◽  
Natural Disturbance ◽  
High Elevation ◽  
Snow Accumulation ◽  
Water Yield ◽  
Hydrologic Response ◽  
Salvage Logging ◽  
Snow Water

Long-term studies at Mayson Lake (ML) and Upper Penticton Creek (UPC) in British Columbia's southern interior quantify snow-dominated hydrologic response to natural disturbances and logging. Following natural disturbance at ML, changes in snow accumulation related directly to mountain pine beetle attack were measurable by the fifth year following attack, when canopy transmittance had increased 24% due to needlefall. In year 1, April 1 snow water equivalent (SWE) was 48% higher in the clearcut than in the pine forest. This difference was reduced to 23% by year 8. A 3-year lag in snow response was also observed in a nearby burned stand where SWE was on average 27 and 59% higher in the clearcut than in the burn and forest, respectively. At UPC, April 1 SWE averaged 12% more and 12% less in a low and high elevation clearcut than forest, respectively, and snow disappeared ∼10 days earlier in both clearcuts. Partially as a result of snowmelt synchronization from higher with lower elevations after 50% of the treatment watersheds had been clearcut, April water yield increased and June to July yield decreased. Research results improve evaluation of hydrologic response to forest disturbance, including retention of beetle-killed stands versus salvage logging.

scholarly journals Spatio-temporal associations of albacore CPUEs in the Northeastern Pacific with regional SST and climate environmental variables

2014 ◽  
Vol 71 (7) ◽  
pp. 1717-1727 ◽  
Author(s):  
A. Jason Phillips ◽  
Lorenzo Ciannelli ◽  
Richard D. Brodeur ◽  
William G. Pearcy ◽  
John Childers
Keyword(s):  
North Pacific ◽  
Large Scale ◽  
Environmental Variability ◽  
Southern Oscillation ◽  
Spatial Dynamics ◽  
Catch Per Unit Effort ◽  
Variable Effect ◽  
Positive Effects ◽  
The North ◽  
Additive Mixed Models

Abstract This study investigated the spatial distribution of juvenile North Pacific albacore (Thunnus alalunga) in relation to local environmental variability [i.e. sea surface temperature (SST)], and two large-scale indices of climate variability, [the Pacific Decadal Oscillation (PDO) and the Multivariate El Niño/Southern Oscillation Index (MEI)]. Changes in local and climate variables were correlated with 48 years of albacore troll catch per unit effort (CPUE) in 1° latitude/longitude cells, using threshold Generalized Additive Mixed Models (tGAMMs). Model terms were included to account for non-stationary and spatially variable effects of the intervening covariates on albacore CPUE. Results indicate that SST had a positive and spatially variable effect on albacore CPUE, with increasingly positive effects to the North, while PDO had an overall negative effect. Although albacore CPUE increased with SST both before and after a threshold year of 1986, such effect geographically shifted north after 1986. This is the first study to demonstrate the non-stationary spatial dynamics of albacore tuna, linked with a major shift of the North Pacific. Results imply that if ocean temperatures continue to increase, US west coast fisher communities reliant on commercial albacore fisheries are likely to be negatively affected in the southern areas but positively affected in the northern areas, where current albacore landings are highest.

scholarly journals Instability wave models for the near-field fluctuations of turbulent jets

2011 ◽  
Vol 689 ◽  
pp. 97-128 ◽  
Author(s):  
K. Gudmundsson ◽  
Tim Colonius
Keyword(s):  
Flow Field ◽  
Large Scale ◽  
Microphone Array ◽  
Near Field ◽  
Turbulent Jets ◽  
Instability Wave ◽  
Mean Flow ◽  
Velocity Fluctuations ◽  
The Mean ◽  
Scale Structures

AbstractPrevious work has shown that aspects of the evolution of large-scale structures, particularly in forced and transitional mixing layers and jets, can be described by linear and nonlinear stability theories. However, questions persist as to the choice of the basic (steady) flow field to perturb, and the extent to which disturbances in natural (unforced), initially turbulent jets may be modelled with the theory. For unforced jets, identification is made difficult by the lack of a phase reference that would permit a portion of the signal associated with the instability wave to be isolated from other, uncorrelated fluctuations. In this paper, we investigate the extent to which pressure and velocity fluctuations in subsonic, turbulent round jets can be described aslinearperturbations to the mean flow field. The disturbances are expanded about the experimentally measured jet mean flow field, and evolved using linear parabolized stability equations (PSE) that account, in an approximate way, for the weakly non-parallel jet mean flow field. We utilize data from an extensive microphone array that measures pressure fluctuations just outside the jet shear layer to show that, up to an unknown initial disturbance spectrum, the phase, wavelength, and amplitude envelope of convecting wavepackets agree well with PSE solutions at frequencies and azimuthal wavenumbers that can be accurately measured with the array. We next apply the proper orthogonal decomposition to near-field velocity fluctuations measured with particle image velocimetry, and show that the structure of the most energetic modes is also similar to eigenfunctions from the linear theory. Importantly, the amplitudes of the modes inferred from the velocity fluctuations are in reasonable agreement with those identified from the microphone array. The results therefore suggest that, to predict, with reasonable accuracy, the evolution of the largest-scale structures that comprise the most energetic portion of the turbulent spectrum of natural jets, nonlinear effects need only be indirectly accounted for by considering perturbations to the mean turbulent flow field, while neglecting any non-zero frequency disturbance interactions.

Study of the Standard k-ε Model for Tip Leakage Flow in an Axial Compressor Rotor

2016 ◽  
Vol 33 (4) ◽  
Author(s):  
Yanfei Gao ◽  
Yangwei Liu ◽  
Luyang Zhong ◽  
Jiexuan Hou ◽  
Lipeng Lu
Keyword(s):  
Flow Field ◽  
Large Scale ◽  
Turbulent Viscosity ◽  
Axial Compressor ◽  
Leakage Flow ◽  
Reynolds Stresses ◽  
Mean Flow ◽  
Tip Leakage Flow ◽  
Tip Leakage ◽  
Compressor Rotor

AbstractThe standard k-ε model (SKE) and the Reynolds stress model (RSM) are employed to predict the tip leakage flow (TLF) in a low-speed large-scale axial compressor rotor. Then, a new research method is adopted to “freeze” the turbulent kinetic energy and dissipation rate of the flow field derived from the RSM, and obtain the turbulent viscosity using the Boussinesq hypothesis. The Reynolds stresses and mean flow field computed on the basis of the frozen viscosity are compared with the results of the SKE and the RSM. The flow field in the tip region based on the frozen viscosity is more similar to the results of the RSM than those of the SKE, although certain differences can be observed. This finding indicates that the non-equilibrium turbulence transport nature plays an important role in predicting the TLF, as well as the turbulence anisotropy.

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