Lectures 11Lectures 11--1313Hydrology & Hydrology &

Fluvial Fluvial GeomorphologyGeomorphology

Gauley River Imageshttp://www.youtube.com/watch?v=EulmUyeGtz4&feature=related

Ancients' (= Biblical) Model of Water (Hydrologic) Cycle

• Stream Water Came From the Earth.• Stream Runoff >> Precipitation.

• 1700s Idea: Streams Carve Valleys in Which They Flow !

http://www.touregypt.net/card3.html

St. Catherine's Monastery at the base of Mount Sinai painting by David Roberts

Strange Ideas?

Stream Water Came From the Earth

Runoff >> Precipitation

Not Strange in a Desert

Problem: How Does Salt Ocean Water Become Fresh Spring Water?

• This MODEL Makes Sense in a Desert,

• Where Streams Are Fed by Springs and Runoff From Far-Away Mountains

Modern Concept of the Water Cycle

Modern Concept of the Water Cycle (Figure 10.1)

H2O Volumes: Liter (l) = Quart +

• Oceans 1,350,000 X 1015 l• Glaciers 26,000 X 1015 l• Ground-water 7,200 X 1015 l • Lakes 220 X 1015 l• Atmosphere 13 X 1015 l• Streams 1 X 1015 l • Biomass (Plants) 0.7 X 1015 l

Rates of H20 Change - ApproximateOcean Evap 440 X 1015 l/yOcean Precip 404 X 1015 l/y Ocean -> Cont (vapor) 36 X 1015 l/yContinental Evap 70 X 1015 l/y Continental Precip 106 X 1015 l/y Cont -> Ocean Runoff 36 X 1015 l/y

only about 1/3 precip runs off continents

Outgassing + Comets 0.0003 X 1015 l/y“new” water

Outgassing:0.0003 X 1015 l/y

How was outgassingdetermined?

1,380,000 X 1015 liters (volume of oceans)

divided by 4,600,000,000 years (age of the earth)

New Hypothesis: Comet Origin for Water

Comet Hale-Bopp February 16, 1997 Observer: Stephane Potvin, St-luc Dorchester, Quebec

http://www.jpl.nasa.gov/comet/images97026.html

Runoff: Water in Streams

Comes From: Direct Precipitation in Stream

Surface (Overland) Runoff Spring Discharge ...

What Happens to Precipitation?

• Runoff (direct) = RO• Infiltration ⇒ Ground-Water Recharge ⇒

Spring Discharge ⇒ Runoff (RO)• Evaporation & Transpiration = ET• Precip - ET = RO ...

Drainage Basin Water Budgets:

Precip - ET = RO

Desert (AZ) 3" - 3 = 0”

Rain Forest 400" - 50" = 350"

Orographic Effect on Precipitation

Orographic Effect on Precipitation

Orographic Effect on Precipitation

Orographic Effect on Precipitation

Orographic Effect on Precipitation

Orographic Effect on Precipitation

Orographic Effect on Precipitation

Orographic Effect on Precipitation

Pickens Spruce Knob

Petersburg

Morgantown

Drainage Basin Water Budgets

Precip - ET = RO Morgantown 40” 25” 15” Pickens 65 25 40 Spruce Knob 50 20 30 Petersburg 32 25 7

Stream Geomorphology

Sandstone Falls, New River, WVphoto by John Remo

Streams• River• Creek• Run• Fork• Draft• Stream• Brook• others

Main Stem (= Trunk Stream)

• Tributaries flow into Main Stem

• Distributaries channels split flow from main stem (rare in WV)

Stream Classes Based on Frequency of Flow

• Perennial• Intermittent• Ephemeral

Kite Stream, Victoria Valley, Antarctica

Stream Order

• First - Stream with no tributaries, smallest drainage we can recognize

• Second - Confluence of two First order stream

• Third, 4th, 5th, etc.• Mississippi River - ca. 12th Order

4th Order Drainage Basin

Drainage Divide

Turbulent Flow

• Mixing Between Layers

Flow in Stream is Turbulent

• Tranquil Flow - Subcritical Flow– eddies, rollers, vortices

• Shooting Flow - Supercritical Flow– whitewater, standing waves, wave

trains

Turbulent Flow

• Tranquil = Subcritical Flow

Flatwater = Subcritical Flow -New River Gorge (= NRG)

Debris Fan Constricts New River

Causing Rapids

Bridge Day 2000

Copyright 2001iPlayOutside, Inc.

Debris FanRapids

http:// ww

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Copyr ight 2001 iPlayO

utside, Inc.

Rapids

SubcriticalFlow

SubcriticalFlow

SupercriticalSupercriticalFlowFlow

Upper Railroad Rapids, NRG: SubcritcialFlow Transforms into Supercritcal Flow

Supercritical Flow - Standing Wave, NRG

Supercritical Flow - Standing Wave, Pillow Rock, Gauley River

Wave Train - NRG

Whitewater Images

• http://geology.csun.edu/jeff/esci.html• http://www.try-

rivers.com/gauley_river.html• http://www.nps.gov/neri/photo.htm

2009 Lecture• The Floods lecture was given on 26 Feb, because it was

the anniversary of the most deadly WV flood: the 1972 Buffalo Creek Flood that killed 125 in Logan County.

http://www.wvgazette.com/static/series/buffalocreek/bridge.JPG

Sediment Transport (Load)

• Dissolved Load – Ions in Solution

• Suspended Load – Clay, Silt, Sand - Kept in Water by

Turbulence • Bed Load

– Sand, Gravel - Moved by Traction Sliding, Rolling, Saltating

Sediment Transport

Which is difficult for streams to erode, but easy to transport?

(A) clay, (B) silt, (C) sand, or (D) boulders.

Sediment Transport

Which is difficult for streams to erode and transport?

(A) clay, (B) silt, (C) sand, or (D) boulders.

Sediment Transport

Which material is most easily transported, once eroded?

(A) clay, (B) silt, (C) fine sand, or (D) coarse sand.

Sediment Transport

Boulder Transported in Nov 1985 Flood, Cheat Narrows

Bed Load

• Bernoulli Principle - lift

Airplane Wing

Bernoulli Principle

Low P

High P

Bernoulli Principle & Lift

High P

Low P

Bed Load

• Bernoulli Principle - lift

Cobble

Channel Bed

Bed Load

• Bernoulli Principle - lift

Hign V, Low P

Low V, High P

Bed Load

• Bernoulli Principle - lift

Hign V, Low P

Low V, High P

Bed Load

• Bernoulli Principle - liftLow P

High P

Meandering Stream Flow

Meanders and Oxbow Lakes

Oxbow Lakes

Point Bar

Neck

Cut Off

Meander Cut-Off: Oxbow Lake

ChannelSediments

What might you expect to occur after a stream is straightened (channelized)?

(A) the stream erodes its bed to create a shallower channel, (B) the stream will erode its banks and construct point bars, re-creating a channel similar to its original channel, (C) the stream will shift from a third order stream to second order, or (D) base level will fall until the stream incises its bed, leaving a terrace or similar feature.

Straight Channel (Meandering Thalweg)

Meandering Channel

Braided Channel

Straight Channel = Rare, Most are Man-made or in Rock Gorges

Meandering Channel Bedload Energy > “Work”

Braided Channel Bedload Energy < “Work”

Stream Equilibrium• Balance of Energy & Work• Discharge (Water Volume / Time ) +

Channel Slope Provides Energy

• Work of a Stream?–Transporting Water–Transporting Sediment

• Especially Bedload– Ecological Template – Not in GEOL 101

Stream Adjusts to Sediment Under-Supply

• Deep Channel• Lengthen Channel - Meander Growth• Bank Erosion - Meander Growth

Stream Adjustments to Sediment Over-Supply

• Straighten Channel• Gravel or Sand Bars Clog Channel• Braided Channel Pattern

Glacier Fed Braided Stream, Denali National Park, Alaska

J.S. Kite Photo

Sediment Supply Boosters

• Steep Slopes – Commonly after Uplift of Mountains

• Easily Eroded Parent Material• Sparse Vegetation• Cold Climates• Glaciers

What might happen to a graded stream that has its sediment supply cut off by the construction of dams upstream?

(A) the stream would build up (aggrade) its channel and floodplain, (B) the stream would erode (degrade) its channel and floodplain, (C) nothing, once a stream is in grade it never changes, or (D) the channel will begin to braid.

Over-Supply of Sediment Can Cause Terraces

Over-Supply Builds Up Floodplain

Later

Stream Cuts Down Through Deposits When Supply is Reduced

Ohio River Terraces

• http://www.emporia.edu/S/www/earthsci/student/forge/ohio.htm

Stream Profile• Slope & Energy Decrease as Bedload

Becomes Finer GrainedSteep: Coarse

BedloadShallow: Fine

Bedload

The “Sea”

Immature SedimentsImmature Sediments

Mature SedimeMature Sedime

FaciesFacies

Maturity

Base Level• Lowest Point to which Stream Can Erode• Ultimate Base Level vs. Local Base Level

Sea Level= Base Level

Stream Adjustments to Lower Base Level

• Incision to Adjust Profile

Stream Adjustments to Higher Base Level

• Deposition to Adjust Profile

What would happen to stream whose base level drops by 100 meters.

(A) the stream will deposits sediment, raising its channel.(B) the stream will not change its profile. (C) the stream will meander and braid. or (D) the stream will erode its bed.

A rise in base level for a stream will produce:

(A) erosion, (B) deposition, (C) no change, or (D) a graded stream.

Base Levels

New River: 2nd Oldest River in the World?

photo by John Remo

New River: 2nd Oldest River in the World?

Spokane Flood

• ChannelledScablands

• Washington (State)