Lectures 11-13 13 Hydrology & Fluvial Geomorphology Gauley River Images http://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!
Strange Ideas? Stream Water Came From the Earth Runoff >> Precipitation Not Strange in a Desert St. Catherine's Monastery at the base of Mount Sinai painting by David Roberts http://www.touregypt.net/card3.html 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) H 2 O Volumes: Liter (l) = Quart + Oceans 1,350,000 X 10 15 l Glaciers 26,000 X 10 15 l Ground-water 7,200 X 10 15 l Lakes 220 X 10 15 l Atmosphere 13 X 10 15 l Streams 1 X 10 15 l Biomass (Plants) 0.7 X 10 15 l Rates of H 2 0 Change - Approximate Ocean Evap 440 X 10 15 l/y Ocean Precip 404 X 10 15 l/y Ocean -> Cont (vapor) 36 X 10 15 l/y Continental Evap 70 X 10 15 l/y Continental Precip 106 X 10 15 l/y Cont -> Ocean Runoff 36 X 10 15 l/y only about 1/3 precip runs off continents Outgassing + Comets 0.0003 X 10 15 l/y new water
Outgassing: 0.0003 X 10 15 l/y How was outgassing determined? 1,380,000 X 10 15 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 Morgantown Petersburg Pickens Spruce Knob 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, WV photo by John Remo River Creek Run Fork Draft Stream Brook others Streams 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 2001 iplayoutside, Inc.
http://www.wvoutside.com/events/2000/10/1993.html Copyright 2001 iplayoutside, Inc. Subcritical Flow Rapids Supercritical Flow Debris Fan Subcritical Flow Upper Railroad Rapids, NRG: Subcritcial Flow 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.tryrivers.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 Low P High 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 - lift Low P High P Meandering Stream Flow
Meanders and Oxbow Lakes Oxbow Lakes Cut Off Neck Point Bar Meander Cut-Off: Oxbow Lake
Channel Sediments 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 Grained Steep: Coarse Bedload Shallow: Fine Bedload The Sea Immature Sediments Mature Sedime Facies 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 Channelled Scablands Washington (State)