Interactions between water, ice and sediment during spring … · 2019-06-11 · Interactions between water, ice and sediment during spring breakup at the mouth of the Mackenzie River,

Interactions between water, ice and sediment during spring breakup at the mouth of the Mackenzie River, Northwest Territories

Steven M. Solomon1, Donald L. Forbes1, Maxime Belanger2, Dustin Whalen1, Philip

Marsh3

1Geological Survey of Canada, 2University of Alberta, 3Environment Canada

Acknowledgements

Program for Energy Research and Development (PERD)Northern Energy Development MCPolar Continental Shelf ProjectAurora Research InstituteMGMEnergy, Shell Canada, Chevron Canada – logistic support and dataPartners and contractors: University of Calgary, University of Alberta, C-CORE, Aquatics Environmental, Tumichiat OutfittersSatellite imagery- ESA, CSA, University of Alaska – GINACanadian Helicopter Corporation

Issues and Objective

Onshore gas production will lead to offshore exploration and exploitation of known offshore discoveries (pipelines)Assessment of risk to pipelines, navigation channels and infrastructure due to nearshore geohazards

Ice-seabed interaction – scours, shallow subsea permafrostMagnitude, extent and mechanisms of nearshore erosion and deposition

Objective: Document river-mouth processes and river-ocean interactions during spring break-up.

Study Area

Winter-Spring Oceanographic Environment

Freeze-up in mid-late October with formation of landfast and bottom-fast ice.Continuous discharge throughout winterDevelopment of “Lake Herlinveaux” – fresh water ponded behind stamuki(MacDonald and Carmack)Punctuated quiescence beneath winter ice - winter surgesEarly-mid-May: increased river discharge prior to sea ice melt

Suspended sediment concentrations up to 4 g/lSPM load enters fresh water basinSediment may be flocculated (Droppo et al 1998)

Lake Herlinveaux Mackenzie at Arctic Red

River 1974-1983After Hill et al 2001

Fluvial sediment delivery modes

Hyperpycnal flowsRequire > 40 g/l if receiving water is salty, but < 1 g/l if fresh (e.g.Mulderand Syvitski, 1995)Spring freshet TSS > 1g/l) plus ice constrained!

Homopycnal

Hypopycnal

Boggs, S. 1995 Principles of Sedimentology and Stratigraphy, 2nd edition, Prentice Hall

Hyperpycnal

Methods

Synthetic Aperture Radar (SAR) for mapping bottomfast iceMODIS imagery to monitor progression of breakup in near-real timeTime lapse camera – flood elevation and timingWater level gauges – on-ice water levelsHelicopter overflights and on-ice observationsSidescan sonar and depth sounding – strudel scour mapping

Setting the stage: Winter Bottomfast Ice Development

Ice Elevations

( -5.1 to -4.8( -5.4 to -5.1( -5.5 to -5.4( -5.6 to -5.5( -5.8 to -5.6( -6.8 to -5.8

Bottomfast ice controls on overflow and drainage

End of Winter

Early breakup

Mid-breakup

BFI influence on water flow and channel incision

19962005

Nearshore BFI conditions prior to breakup

Spring breakup 2008

May 7, 18, 20, 22, 23, 24, 25, 30, June 4, 7, 11

Discharge and Overflow Timing

Overflow Initiation Overflow Max peak WL Inuvik

07- may-08 21-23- May-08 31- May-08

04-May-07 19-May-07 01-Jun-07

14-May-06 23-May-06 29-May-06

08-May-05 16-May-05 25-May-05

26-May-04 30-May-04 03-Jun-04

08-May-03 17-May-03 04-Jun-03

4-Jun-07

Overflow precedes peak WL by several days to 2 weeks

1-3 Jun-08

Peak WL Outer delta

Overflow – sediment concentration

Overflow waters – variable sediment concentrations

Peak freshet concentration: Lesack data 2007 – peak loads exiting delta in Aug Suspended Sediment 2008

0.0

200.0

400.0

600.0

800.0

1000.0

1200.0

22-Apr-08 12-May-08 1-Jun-08 21-Jun-08 11-Jul-08 31-Jul-08 20-Aug-08 9-Sep-08

Mackenzie at Arc tic Red Middle Channel at Langley (OD) East Channel (OD)

0.0200.0400.0600.0800.0

1000.01200.01400.01600.01800.02000.0

5/3 5/8 5/13 5/18 5/23 5/28 6/2 6/7 6/12 6/17 6/22

Mackenzie at Arctic Red Middle Channel (MD) East Channel (MD)Middle Channel at Langley (OD) Reindeer Channel (OD) Napoiak Channel (OD)West Channel (OD) East Channel (OD) Arctic Red RiverPeel River Peel Channel (MD)

Initiation of Breakup Rising limb of the spring freshet

Increased discharge from southern drainage basinsInitiation of overflow, backwater effectsIncreased current velocity in ice-constrained channels?

May 7, 2008May 18, 2008May 22, 2008

Local backwater effects?

Coastal well-site K30 looking north

May 21 Backwater flooding

June 3 Freshet Peak

May 18

May 31

Overflow water levels over ice

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

26-Apr 03-May 10-May 17-May 24-May 31-May 07-Jun 14-Jun

BH4depth_corr Strudel_depth_corr Tuk_WL_24hMA

Overflow and upwelling May 21-22, 2008

Strudel Drainage

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kilometres

10

Strudel Scours

Summary and Conclusions

Upwelling, overflow and strudel drainageenergetic but short-lived processes precede peak discharge by several days to two weekslocations are controlled by the distribution of BFI

Backwater flooding and overflow are indicators of ice-constraints at distributary mouths

Timing of overflow drainage indicates removal of constraints prior to peak discharge Flow perturbations at constraints are unknown

Strudel scour is extensivelocations appear to be predictableInfill may occur within a single season

Future: What is happening to the dirt?Erosion at ice-constrained channel mouths Behaviour of suspended materials in plumePhysical modelling of strudel drainage