9 - Arctic rivers

Note by samflint93, updated more than 1 year ago
Created by samflint93 almost 7 years ago


University finals GEOG3004 (9 - A&A Rivers) Note on 9 - Arctic rivers, created by samflint93 on 11/06/2013.

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Due to rivers p

Due to rivers partially freezing up seasonally, the hydrograph's tend to peak very high for a short amount of time sometimes releasing upto 75% of flow in days.In continuous permafrost river tend to be entirely fed by surface runoff, whereas in discontinuous permafrost the river tends to be fed by a mix of surface run off and groundwater through talik'sRunoff season can be split into: 1] break-up, 2] snowmelt period, 3] late summer and 4] freeze-back.

Sediment in periglacial fluvial systems: Sources include weathering and mass wasting Transportation occurs via solution, suspension and bed load transport. Fluvio-thermal erosion:Occurs in periglacial environments concurrently with mechanical erosion which contributes to the massive sediment supply. Other consequences of thermal erosion are bank collapse (increased sediment availability) and lateral stream migration.

Modelling run off into the arctic sea from the US:A2 climate scenario: increased annual average temperature of between 5.2 and 6.8 degrees.snowmelt advances more rapidly with no discernible change in timing of the peak flow, but due to disappearance of a large proportion of snow cover discharge is reduced in June.Increases in annual freshwater flux to the Barents sea are between 25 and 40%.Conclusion is that the annual hydrographs and still strongly dominated by snowmelt.

Measuring the size of thaw bulbs underneath arctic rivers:Permafrost underlying artic rivers is melted during the thaw, Bradford et al. discovered that stream depth increased with thaw bulb thickness although they were unable to determine the cause of the pattern.Other factors that could influence the depth of thaw are : permeability of hyporheic zone (on the river bed where there is a mix of river water and groundwater), flow rate, solar heat, depth.

Groundwater flow through sorted nets.Earth Hummocks were foud to control the flow of groundwater from uplands to wetlands, the centre of frost mounds exhibited low flow due to fines. The flow was much higher in inter-hummock channels.High fines content reduces the hydraulic conductivity, which affects the nutrient content of the soil and therefore the vegetation cover.

French 2007

Koster et al. 2005

Bradford et al. 2005

Hodgson & Young 2001

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6 - Ice Wedges
Supplementary reading L2
8 -  Thermokarst
11 - Frost Shattering
Lecture 3 extra
French Ch. 5
13 - debris transfer
Lecture 1 - Introduction
12 - Pingo's & Palsas
Frost heaving/hillslope processes
7b - Soils and patterning