Interactions class

1. Getting and understanding watershed flux data

2. Influence of Large Woody Debris (LWD) on rivers

3. Influence of Hillslope materials and processes on rivers

4. Influence of the Atmosphere on rivers, 1927 flood example

Sediment Transport Through RiversBedload -- material moving along the bed, shear forces exerted by water sufficient to move clasts -- rarely measured (at % level)

Suspended Load -- material kept in the water column by turbulence and lift forces (easy to measure in grab samples)

Bedload usually <<< than suspended load and ignored

Dissolved Load -- material in solution (easy to measure in grab samples)

Dissolved load varies, usually < than suspended load

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Sampling for suspended load…….1

Mass Loadings and Erosion Rate Estimation

Integrate suspended load over all flows (mass/time)

Integrate bedload load over all flows (mass/time)

Integrate dissolved load over all flows (mass/time)

+

+

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Dissolvedload varies over time

and discharge

Calcium, Rio Puerco

0

100

200

300

400

500

600

700

10/4/58 3/26/64 9/16/69 3/9/75 8/29/80 2/19/86 8/12/91 2/1/97

Date

Ca (ppm or mg/kg)

Rio Puerco 1960-1990

y = -0.2709x + 1707.5

R2 = 0.0120

2000

4000

6000

8000

10000

0 500 1000 1500 2000 2500 3000

Dissolved Load (mg/kg)

Discharge (cfs)

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USGS Water Quality Data on lineDissolved and Suspended Load

http://nwis.waterdata.usgs.gov/nwis/qwdata?site_no=04282815&agency_cd=USGS&begin_date=&end_date=&format=html_table&inventory_output=0&rdb_inventory_output=file&date_format=YYYY-MM-DD&rdb_compression=file&qw_sample_wide=0&submitted_form=brief_list

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Data Manipulation1. Data supplied in mg/l (1/1000 g per 1000 g) or ppm2. Need to sum all constituents (Ca, Na, Mg, Cl, C03)3. Need to know daily flow (in liters). How many liters/m3?4. Multiply concentration by flow

Ca Na Mg Flow

15 mg/l 8 mg/l 3 mg/l 4 mg/l 0.1 m3/s

m3 = 100 cm* 100 cm* 100 cm = 106 cm3 =103 liters

100 l/s* 60s/min*60min/hr*24hr/day*15mg/l*0.000001kg/mg=

129.6 kg/day dissolved load

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TO GET YEARLY LOADIntegration over all flows is a non

trivial problem!Need Rating Curves (suspended, dissolved, bedload)

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Hysteresis loop

Suspended Load

Note Scatter

Other Approaches…Reservoir trapping (may miss dissolved)

Nahal Yael, Negev Desert

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SEDIMENT YIELD = what comes out

SEDIMENT GENERATION = Material generated

by erosion

= or ≠TimescaleSteady stateHuman impactEpisodic disturbance

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QuickTime™ and aTIFF (Uncompressed) decompressor

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QuickTime™ and aTIFF (Uncompressed) decompressor

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Trimblegram

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Importance of Vegetation

Bank Stabilization, effective soil cohesion

Source, Large Woody Debris

2

Queets River, Olympic Penninusla, Washington

Large Woody Debris

2

2

Queets -- Meander Jam

2

Most rivers have been

de-snagged

Montgomery et al., 2003

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Putget Lowland

2

Reach Scale Effects 2

In-Channel Effects 2

Valley Bottom Effects - Wood adds Complexity

Flo

od

pla

in E

leva

tio

n (

m) Nisqually River w/wood

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Effects Felt Downstream

2

• Briaded Rivers– Weak banks– High sediment load– Flashy

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Influence of Hillslope Materials and Processes on Channels

3

Example: Chris Brummer, Squire Creek, North Cascades, Slide into Channel

Slides are frequent in mountain environments

Toe of Slide - QT VR3

Sediment and Woody Debris Supply - pulsed delivery

3

Stepping of Channel Profile

Damming of ephemeral lakes by slides

Outlet, overtopping dam

3

Help set channel roughnessboulders may be delivered by older slides….or underlying

bedrock or till

3

Here, stratigraphic evidence this is not the first slide…

Recent Slide Debris

Older Slide Debris

3

• Antecedence --Rainfall during the month of October averaged about 150 percent of normal across the state. In northern and central sections, some stations received 200-300 percent of normal.

1927 Flood4

Major Channel Change and Realignment - Proctor

4

Major damage at constrictions, e.g., bridges

• Isohyet map

4

Winooski-Burlington response

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Cause of the 1927 Flood

Mositure-laden air was forced to rise as it encountered the Green Mountains, resulting in torrential downpours. Rainfall in Northfield totaled 1.65 inches from 4:00 am to 11:00 am on the 3rd, with 4.24 inches falling from 11:00 am to 8:00 pm. The total from late evening of the 2nd to late morning on the 4th was 8.71 inches.

4

Wednesday Lab

• Meet in classroom

• Move to the field, Bolton

• Cooler weather, be prepared.

• Wear sturdy shoes please