Simulation of the August 1979 sudden discharge of glacier-dammed Flood Lake, British Columbia

1984 ◽  
Vol 21 (4) ◽  
pp. 502-504 ◽  
Author(s):  
Garry K. C. Clarke ◽  
David A. Waldron
Keyword(s):  
British Columbia ◽  
Computer Model ◽  
Discharge Rate ◽  
Peak Discharge ◽  
Maximum Discharge ◽  
Flood Magnitude ◽  
Gauging Station

In August 1979 a glacier outburst from Flood Lake, British Columbia, released 150 × 106 m3 of water. The resulting flood was routed through the Stikine River and yielded a maximum discharge rate of 1200 m3 s−1 at a gauging station 90 km downstream from the glacier dam. We have used a computer model to simulate this outburst in order to test the usefulness of the model as a predictor of flood magnitude. The predicted peak discharge is 2160 m3 s−1 at the outlet tunnel of the ice dam and 1700 m3 s−1 at the gauging station.

scholarly journals Long-period variability in ice-dammed glacier outburst floods due to evolving catchment geometry

2021 ◽  
Author(s):  
Amy J. Jenson ◽  
Jason M. Amundson ◽  
Jonathan Kingslake ◽  
Eran Hood
Keyword(s):  
Peak Discharge ◽  
Water Volume ◽  
Flood Hazards ◽  
Outburst Flood ◽  
Ice Shelf ◽  
Outburst Floods ◽  
Flood Magnitude ◽  
Hydrological System ◽  
Basin Geometry ◽  
Glacier Flow

Abstract. We combine a glacier outburst flood model with a glacier flow model to investigate decadal to centennial variations in outburst floods originating from ice-dammed marginal basins. Marginal basins form due to retreat and detachment of tributary glaciers, a process that often results in remnant ice being left behind. The remnant ice, which can act like an ice shelf or break apart into a pack of icebergs, limits the basin storage capacity but also exerts pressure on the underlying water and promotes drainage. We find that during glacier retreat there is a strong, nearly linear relationship between flood water volume and peak discharge for individual basins, despite large changes in glacier and remnant ice volumes that are expected to impact flood hydrographs. Consequently, peak discharge increases over time as long as there is remnant ice remaining in a basin, the peak discharge begins to decrease once a basin becomes ice free, and similar size outburst floods can occur for very different glacier volumes. We also find that the temporal variability in outburst flood magnitude depends on how the floods initiate. Basins that connect to the subglacial hydrological system only after reaching flotation yield greater long-term variability in outburst floods than basins that are continuously connected to the subglacial hydrological system (and therefore release floods that initiate before reaching flotation). Our results highlight the importance of improving our understanding of both changes in basin geometry and outburst flood initiation mechanisms in order to better assess outburst flood hazards and impacts on landscape and ecosystem evolution.

Jökulhlaups and sediment transport in Watson River, Kangerlussuaq, West Greenland

2012 ◽  
Vol 44 (1) ◽  
pp. 58-67 ◽  
Author(s):  
A. B. Mikkelsen ◽  
B. Hasholt ◽  
N. T. Knudsen ◽  
M. H. Nielsen
Keyword(s):  
Sediment Transport ◽  
High Discharge ◽  
West Greenland ◽  
Northern Margin ◽  
Maximum Discharge ◽  
Annual Discharge ◽  
Gauging Station ◽  
Observation Period ◽  
Englacial Drainage

For 3 years, during a 4-year observation period (2007–2010), jökulhlaups were observed from a lake at the northern margin of Russells Gletscher. At a gauging station located on a bedrock sill near the outlet of Watson River into Sdr Strømfjord, discharge and sediment transport was monitored during the jökulhlaups. The stage rose up to 5.3 m and a maximum discharge of 1,430 m3 s−1 was recorded. The jökulhlaups were very different, indicating varying influences of weather and englacial drainage conditions. Although the jökulhlaups caused high discharge and sediment transport rates, their share of the annual discharge and sediment transport were less than 2%.

Professor Mathews, outburst floods, and other glaciological disasters

1986 ◽  
Vol 23 (6) ◽  
pp. 859-868 ◽  
Author(s):  
Garry K. C. Clarke
Keyword(s):  
British Columbia ◽  
Physical Model ◽  
Mining Operation ◽  
Glacial Lake ◽  
Outburst Flood ◽  
Transportation Corridor ◽  
Outburst Floods ◽  
Flood Magnitude ◽  
Unusual Problem

Misfortunes befalling the Granduc mining operation near Stewart, British Columbia, stimulated Professor Mathews' influential scientific contributions on subglacial hydrology. A series of violent floods from glacier-dammed Summit Lake menaced the transportation corridor between the Granduc ore concentrator and a tidewater dock at Hyder, Alaska. This unusual problem motivated the research of Mathews and later of Gilbert, who together laid the foundation for a greater understanding of the physics of outburst floods. The physical model that evolved from their research can be used to predict outburst flood magnitude and to cast light on the hydrology of ancient floods such as those from glacial Lake Missoula.

scholarly journals Estimates of Peak Discharge from the Drainage of Ice-Dammed Ape Lake, British Columbia, Canada

1989 ◽  
Vol 35 (121) ◽  
pp. 349-354 ◽  
Author(s):  
Joseph R. Desloges ◽  
David P. Jones ◽  
Karl E. Ricker
Keyword(s):  
British Columbia ◽  
Flood Plain ◽  
Peak Discharge ◽  
Outburst Flood ◽  
Flood Peak ◽  
Lake Volume ◽  
Outburst Floods ◽  
Direct Measurements ◽  
Instantaneous Discharge ◽  
Method Yield

AbstractThe first known occurrence of outburst flooding at Ape Lake, British Columbia, was in October 1984 following the formation of a subglacial tunnel in an ice dam created by Fyles Glacier. Following tunnel closure, the lake refilled in 150 d and then a second outburst flood occurred in August 1986. During both events, 55% of the Apc Lake volume or 46 × 106m3was released in less than 24 h into the 50 km long, ungauged Noeick River, producing an average discharge of 540 m3s−1. Channel and flood-plain erosion, damage to access roads, bridges, a logging camp, and an airstrip were related to the peak or maximum instantaneous discharge. In the absence of direct measurements, and to facilitate planning for future flood events, several independent methods were employed to estimate peak discharge. A modified version of the Clague-Mathews formula and the slope-area method yield consistent estimates which approach 1600 m3s−1near the ice-dam outlet. Attenuation of the flood peak in Noeick River is as high as 25% in the upper 12 km due to channel and flood-plain storage. Results using Clarke’s (1982) physical-based model suggest lower discharges and may be related to the irregular morphology of Ape Lake. Since Fyles Glacier is in continuous retreat, drainage around the margin of the ice dam which began in the summer of 1987 is expected to continue and no further outburst floods are anticipated.

Mobilising fine sediment in a highly regulated upland snowmelt river using hydrological scaled experimental floods

2017 ◽  
Vol 68 (1) ◽  
pp. 146 ◽  
Author(s):  
Daniel Coleman ◽  
Simon Williams
Keyword(s):  
Discharge Rate ◽  
Total Suspended Solid ◽  
Environmental Water ◽  
Suspended Solid ◽  
Fine Sediment ◽  
Peak Discharge ◽  
Water Diversion ◽  
Large Reservoir ◽  
Fine Sediments ◽  
Habitat Recovery

Significant water diversion, flow variability, and the lack of high flow events can result in altered channel surfaces and morphology through the accumulation of fine sediments within the riverbed. Mitigation of this issue using environmental water often involves single large annual flushing floods as peak discharge is often regarded as the critical hydrological metric for river habitat recovery. We assess the performance of a hydrological scaled flow strategy of five intra-annual experimental floods to mobilise fine sediment below a large reservoir in the Snowy River, Australia. Suspended sediment was measured using a high frequency sampling regime; before, during and post-flood along a longitudinal gradient of 2.2, 24 and 92km. Substantial sediment loads and high peak total suspended solid (TSS) concentrations were produced by the five experimental floods. The first (61.7m3s–1) and fourth (largest at 148.5m3s–1) experimental floods were by far the most effective, producing more than 70% of the total sediment load at each site. The effectiveness of each experimental flood was related to the peak discharge rate, time since flood, and the magnitude increase from the previous event. This study illustrates how a hydrological scaled flood regime can produce effective fine sediment mobilisation within the channel of a highly regulated lotic system.

A case study of flow characteristics of permeable pavements by time and space model

2014 ◽  
Vol 41 (7) ◽  
pp. 660-666 ◽  
Author(s):  
Wuguang Lin ◽  
SungWoo Ryu ◽  
Yoon-Ho Cho
Keyword(s):  
Urban Areas ◽  
Discharge Rate ◽  
Flow Characteristics ◽  
Infiltration Rate ◽  
Peak Discharge ◽  
Rainfall Simulation ◽  
Circulation System ◽  
Permeable Pavement ◽  
Permeable Pavements ◽  
Water Circulation System

Permeable pavement is widely used to improve the water circulation system in urban areas. The advantages of using permeable pavement are the storage of rainwater, reduction of runoff, out-flow delay, and reduction of peak discharge. The outflow characteristics of different types of permeable pavements are explained by runoff coefficients, which define the relationship between runoff and infiltration rate. This study presents a model of cumulative outflow with respect to time explaining the discharge characteristics of permeable pavement. The model can be used to explain storage capacity, delay time, peak discharge rate, and outflow of pavement structure by accumulating total discharge at the surface and subsurface relative to time. For further verification of the model, a rainfall simulation experiment was performed in the field. Based on the data analysis through the developed model, the advantages of different permeable pavements can be characterized.

scholarly journals An efficacy of Zobe dam for hydroelectricity generation in Katsina State, Nigeria

2021 ◽  
Vol 39 (4) ◽  
pp. 1232-1236
Author(s):  
I. Nuhu ◽  
H. Abdulsalam
Keyword(s):  
Discharge Rate ◽  
Sustainable Energy ◽  
Minimum Cost ◽  
Economic Transformation ◽  
Peak Discharge ◽  
System Operation ◽  
Cost Implication ◽  
Feasibility Assessment ◽  
Operation And Maintenance ◽  
Generation Capacity

The quest for other alternative and sustainable energy prompted the feasibility assessment of Zobe dam meant for irrigation to  produce electricity; In this write-up the scheme is designed to operate with two turbines; turbine T1 to operate all year round to take account of the irrigation need downstream, The second turbine T2 will operate on a spill discharge, and to be available for four months with a generation capacity of 0.969 MW. T1 is expected to discharge 55,500,000m3 within six months to cater for irrigation need with an average discharge rate of 3.6m3 /s. it was found that, the dam has the potential to generate a minimum 0.671MW all year round and a maximum of 1.5MW of power during Peak discharge period. The scheme was designed with minimum modification of the existing infrastructure at site which translate to minimum cost implication in construction, system operation and maintenance. Keywords: Economic transformation, Energy, hydropower, Irrigation farming, Zobe dam,

scholarly journals Estimates of Peak Discharge from the Drainage of Ice-Dammed Ape Lake, British Columbia, Canada

1989 ◽  
Vol 35 (121) ◽  
pp. 349-354 ◽  
Author(s):  
Joseph R. Desloges ◽  
David P. Jones ◽  
Karl E. Ricker
Keyword(s):  
British Columbia ◽  
Flood Plain ◽  
Peak Discharge ◽  
Outburst Flood ◽  
Flood Peak ◽  
Lake Volume ◽  
Outburst Floods ◽  
Direct Measurements ◽  
Instantaneous Discharge ◽  
Method Yield

AbstractThe first known occurrence of outburst flooding at Ape Lake, British Columbia, was in October 1984 following the formation of a subglacial tunnel in an ice dam created by Fyles Glacier. Following tunnel closure, the lake refilled in 150 d and then a second outburst flood occurred in August 1986. During both events, 55% of the Apc Lake volume or 46 × 106 m3 was released in less than 24 h into the 50 km long, ungauged Noeick River, producing an average discharge of 540 m3 s−1. Channel and flood-plain erosion, damage to access roads, bridges, a logging camp, and an airstrip were related to the peak or maximum instantaneous discharge. In the absence of direct measurements, and to facilitate planning for future flood events, several independent methods were employed to estimate peak discharge. A modified version of the Clague-Mathews formula and the slope-area method yield consistent estimates which approach 1600 m3 s−1 near the ice-dam outlet. Attenuation of the flood peak in Noeick River is as high as 25% in the upper 12 km due to channel and flood-plain storage. Results using Clarke’s (1982) physical-based model suggest lower discharges and may be related to the irregular morphology of Ape Lake. Since Fyles Glacier is in continuous retreat, drainage around the margin of the ice dam which began in the summer of 1987 is expected to continue and no further outburst floods are anticipated.

scholarly journals Glacier Outburst Floods From “Hazard Lake”, Yukon Territory, and the Problem of Flood Magnitude Prediction

1982 ◽  
Vol 28 (98) ◽  
pp. 3-21 ◽  
Author(s):  
Garry K. C. Clarke
Keyword(s):  
Yukon Territory ◽  
Peak Discharge ◽  
Dominant Factor ◽  
Tunnel Enlargement ◽  
Dimensionless Numbers ◽  
Flood Magnitude ◽  
Lake Temperature ◽  
Simplifying Assumptions ◽  
Reservoir Geometry ◽  
Manning Roughness

AbstractIn August 1978 “Hazard Lake” released 19.62 × 106m3of water through a subglacial tunnel beneath Steele Glacier, Yukon Territory, Canada. The discharge during the outburst flood was measured by recording lake level changes with time, and a peak discharge of approximately 640 m3s–1was estimated from the data. We have attempted to model the 1978 flood from “Hazard Lake” using an adaptation of Nye’s (1976) theoretical model for jökulhlaups from Grimsvötn. Our aim has been to calibrate the Nye model as a first step toward using it as a peak discharge estimator for other glacier–dammed basins. The agreement between our measured and simulated hydrographs is good, and we find that creep closure, though included in our analysis, appears to play an insignificant role in limiting the discharge of “Hazard Lake”. Release of thermal energy from the relatively warm lake water is the dominant factor contributing to tunnel enlargement.The Manning roughness of outlet channels from glacier–dammed lakes is not known aprioriand must either be assumed or estimated after the fact from the flood hydrograph. For “Hazard Lake” our fit implies Manning roughness in the rangen′ = 0.105 m–1⁄3s, consistent with Nye’s estimate ofn′ = 0.12 ml⁄3s for the 1972 Grimsvötn flood and our estimate ofn′ = 0.12 m1/3s for the 1967 Summit Lake flood. If the Manning roughness for flood conduits can be shown to lie within a narrow range, this would constrain one of the least certain variables of the Nye model.By making several simplifying assumptions, we have succeeded in reducing our adapted version of Nye’s model to a simple mathematical description involving dimensionless numbers characterizing reservoir geometry and the relative magnitudes of creep closure and tunnel enlargement by melting. In this simplified form, the influence of lake temperature, reservoir geometry, and creep closure on the character of flood hydrographs can be conveniently studied.

Influence of amplitude cancellation on the simulated surface electromyogram

2005 ◽  
Vol 98 (1) ◽  
pp. 120-131 ◽  
Author(s):  
Kevin G. Keenan ◽  
Dario Farina ◽  
Katrina S. Maluf ◽  
Roberto Merletti ◽  
Roger M. Enoka
Keyword(s):  
Motor Unit ◽  
Subcutaneous Tissue ◽  
Discharge Rate ◽  
Signal Amplitude ◽  
Peak Discharge ◽  
Experimental Conditions ◽  
Surface Electromyogram ◽  
Emg Amplitude ◽  
Emg Signal ◽  
Simulated Surface

The purpose of the study was to quantify the influence of selected motor unit properties and patterns of activity on amplitude cancellation in the simulated surface electromyogram (EMG). The study involved computer simulations of a motor unit population with physiologically defined recruitment and rate coding characteristics that activated muscle fibers whose potentials were recorded on the skin over the muscle. Amplitude cancellation was quantified as the percent difference in signal amplitude when motor unit potentials were summed before and after rectification. The simulations involved varying the level of activation for the motor unit population, the recording configuration, the upper limit of motor unit recruitment, peak discharge rates, the amount of motor unit synchronization, muscle fiber length, the thickness of the subcutaneous tissue, and the motor unit properties that change with advancing age. The results confirmed a previous experimental report (Day SJ and Hulliger M, J Neurophysiol 86: 2144–2158, 2001) that amplitude cancellation in the surface EMG can reach 62% at maximal activation. A decrease in the range of amplitudes of the motor unit potentials, as can occur during fatiguing contractions, increased amplitude cancellation up to ∼85%. Differences in the amount of amplitude cancellation were observed across all simulated conditions, and resulted in substantial changes in the absolute magnitude of the EMG signal. The most profound factors influencing amplitude cancellation were the number of active motor units and the duration of the action potentials. The effects of amplitude cancellation were minimal (<5%) when the EMG amplitude was normalized to maximal values, with the exception of variations in peak discharge rate and recruitment range, which resulted in differences up to 17% in the normalized EMG signal across conditions. These results indicate the amount of amplitude cancellation that can occur in various experimental conditions and its influence on absolute and relative measures of EMG amplitude.

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