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Floodplain Management SESSION 2 Stream Systems on Dynamic Earth Geologic Framework Prepared By Donald R. Reichmuth, PhD. Geologic Framework Objectives: Define Floodplains Describe Stream System Functions Explain Tectonic Plates Explain Vertical Plate Motion Identify Tectonic Domains Summarize Glacial Behavior Compare Erosion Related Processes River Basin Definition A region or area bounded by a topographic divide that contributes water to a particular stream channel (corridor) or other water body. Floodplain Definition That portion of a Drainage Basin that is covered by Transported Sediment that was deposited in or near a stream channel. FUCTIONS OF RIVER SYSTEMS • Removes Erosional Debris – Most Important – Acts Over Long Periods • Removes Excess Water – Importance Secondary – Acts Sporadically Over Short Periods • Provides Fresh Water Supply – Necessary To Sustain Life • Transports Chemicals & Nutrients Geologic Framework • Tectonics • • • • Passive Margins Stable Platforms Active Margins Hot Spots • Glaciation • Alpine Glaciers • Continental Glaciers • Geomorphology • Surface Forming Processes – – – – Water Ice Gravity Wind Present Plate Boundaries BASIC TYPES OF PLATE INTERACTION Stream Systems on Dynamic Earth North America Structure – Craton • Shield • Stable Platform – Mobile Belts Tectonic Activity – Active Margin – Passive Margin Karst Topography Example • Solution Cavities In Limestone • Streams Have Subsurface Connections Cretaceous Inland Sea 100 Million Years Ago Vertical Plate Motion Causes: Tectonic/Earthquake Activity Erosion & Sediment Loading Glaciation Human Activities Uplift Example Himalayan Data Present Height --30,000 Ft (9,500 m) Tectonic Uplift Rate --More Than 1 cm/yr Erosion Rate --Now Equals Uplift Rate Sediment Yields Highest Known Worldwide Erosion Rates Oceanic-Continental Convergence Oceanic Crust Subducts Ocean Trench Forms Lighter Melted Material Rises Volcanoes Form Lithosphere Plunges Into Asthenosphere Effects Of Plate Locking Effects Of Erosion Man Induced Vertical Movement Ongoing Elevation Changes Active Margin Note: • Aleutian Trench • Canada – Strike-Slip Faulting • Mobile Belt Deposits • California – Strike-Slip Faulting Active Margin • Ocean-Continent Subduction • Strike Slip Faulting Hot Spot Locations Hawaiian Hotspot Passive Margin • Coastline Sinking – Drowned River Valleys – Numerous Nearshore Islands – Shoreline Migrating Landward Northern Hemispheric Glacial Areas 16,000 B.P. NOTE: Portions Of Alaska Are Ice Free Pleistocene Glaciation Note: • Alpine Glaciers • Continental Glaciers • Ice Marginal Rivers • Alaska Ice Free Area Glacial Impact Areas Preglacial Teays Basin Teays Basin Overrun By Ice Channel Buried Ohio River Forms Drains Basin Western Glacial Lakes 15,000 B.P. – Climate Much Wetter Than Present – Large Basins Had Internal Drainage Loess Wind Blown Silt From Glaciers Rock Flour Stream Banks Stand Vertical When Stable Glacial Rebound Contours In Meters Uplift Great Lakes Glacial Rebound Contours – Uplift per 100 Yrs. Sea Level Changes 16,000 Years BP -120 Meters Lower 6,000 Years BP – Reached Present Level Near Future – Expected To Rise Holocene Sea Level Changes Primarily Cause --Glacial Melting In The Northern Hemisphere Erosion In River Basins Controlling Factors: • Chemical vs. Mechanical Weathering – Temperature – Precipitation • Basin Gradient • Basin Soil/Bedrock Type • Tectonic Activity Chemical & Mechanical Weathering Erosion Processes Erosion Processes Mass Movements Class Handout CASE STUDIES • • • • • • • Columbia River Mississippi River Ohio River Potomac River Red River of the North Rio Grande River Santa Ana River Geologic Setting GEOLOGIC SETTING RIVER BASIN Tectonic Glacial Water Sediment Outlet Considerable Bedrock Control, Average Sediment Production Pacific Ocean, Glacial Flood Deposits Off Coast, Northern Shore Current Dominant COLUMBIA RIVER (INCLUDING ROCKY MTN. TRENCH, Active Margin, Subducting Plate, Alpine Glaciation, Lake Missoula Significant SnowSNAKE RIVER, WILLAMETTE Flood Basalts Shifted Channel Floods, Bonneville Flood pack, Dryer Summers RIVER, COLUMBIA RIVER BAR & LONG BEACH) MISSISSIPPI RIVER (INCLUDING MISSOURI RIVER & LOUISIANA DELTA) OHIO RIVER (INCLUDING TEAYS RIVER, MONONGAHELA RIVER & ALLEGHENY RIVER) Passive Margin, Stable Midcontinent Shelf, Coastal Zone Sinking Stable Mid-continent, Heads In Old Eroded Allegheny Mtns., Crosses Stable Mid-continent Sedimentary Shelf Major Glacial Meltwater Channel, Heavy Lowland Large Quantities Of Fine Strong Impact From Low Glacial Spring Runoff, Heavy Sediment And Dissolved Sea Level Rainfall At Times Solids Ice Marginal Channel Built From Pieces Of Numerous Drainages Passive Margin, Heads In Old Eroded Allegheny Mtns., Crosses Originally Graded To Low Glacial Into Sinking Sedimentary (INCLUDING CHESAPEAKE BAY & Sea level Coastal Shelf, Impacted By A DELMARA PENINSULA) Meteor POTOMAC RIVER RED RIVER OF THE NORTH (INCLUDING LAKE WINNIPEG & HUDSON BAY) RIO GRANDE RIVER (INCLUDING ELEPHANT BUTTE RESERVOIR, RIO PUERCO & PADRE ISLAND) Significant Spring Runoff, Above Average Precipitation Below Average Because Of Low Elevation And Good Vegetative Cover Flows Into Mississippi River, Can Have Flood Synchronization Problems Above Average Precipitation Below Average Because Of Low Elevation And Good Vegetative Cover Atlantic Ocean, Submerged River Valley, Northern Coastal Circulation. Rapid Spring Lowland Snowmelt Occasionally Mixed With Rain Fine Grained Derived From Old Glacial Lake Bed Hudson Bay That Has Uplifted Over 100 Meters Since The Last Glaciation Stable Mid-continent, Flows From Sedimentary Shelf OnTo Continental Craton Originates In Glacial Lake Agassiz, Flows North Against Glacially Induced Crustal Rebound Centered Near Hudson Bay, Stream Gradient Lowering Active Uplift At Head (Mtn. Building), Mouth Sinking At Passive Margin No Significant Glacial Impacts, Small Amount Of Alpine Glaciation At Head High Fine Sediment Area Arid, Gulf Of Mexico, Northeast Production Caused By Significantly Higher Coastal Circulation Occasional High Intensity Precipitation During Strongly Influences The Storms And Scant Glacial Periods Stability Of Padre Island Vegetative Cover No Significant Glacial Impacts Area Arid, High Fine Sediment Significantly Higher Production Caused By Precipitation During Occasional High Intensity Glacial Storms And Scant Periods,Water Vegetative Cover Imported Into Basin SANTA ANA RIVER (INCLUDING SAN BERNARDINO MTNS., PRADO WETLANDS, LOS ANGLES BASIN & HUNTINGTON BEACH) Gulf Of Mexico, Large Marine Fan-delta, Westward Coastal Circulation Active Margin, Strike-slip Faulting Very Active Pacific Ocean, Southern Coastal Circulation Influences Huntington Beach JURISDICTION & CONCERNS RIVER BASIN RECENT CONCERNS JURISDICTION COMMENTS Habitat Pollution Development Declining Salmon Populations Cominco Smelter (Canada) Numerous Large Dams, Hanford Nuclear Facility, Barge Traffic Conflict Developing Between Indian Nations & Newer Arrivals Levee Construction, Barge Traffic, Large Dams, Oil & Gas Drilling/Production Conflict Developing Between Upper River States (Especially Along The Missouri) & Lower River States Change In Vegetative Cover, Major Urban Growth In Valleys Original Teays River Partially Buried During Glaciation Expanding Urbanization, Shoreline Construction Demand For Domestic Water Supplies Becoming Critical Construction On The Floodplain, Levee Construction Near Towns Management Requires Cooperaton Between Canada & The U.S. COLUMBIA RIVER (INCLUDING ROCKY MTN. TRENCH, SNAKE RIVER, WILLAMETTE RIVER, COLUMBIA RIVER BAR & LONG BEACH) MISSISSIPPI RIVER (INCLUDING MISSOURI RIVER & LOUISIANA DELTA) OHIO RIVER (INCLUDING TEAYS RIVER, MONONGAHELA RIVER & ALLEGHENY RIVER) POTOMAC RIVER (INCLUDING CHESAPEAKE BAY & DELMARA PENINSULA) RED RIVER OF THE NORTH (INCLUDING LAKE WINNIPEG & HUDSON BAY) RIO GRANDE RIVER (INCLUDING ELEPHANT BUTTE RESERVOIR, RIO PUERCO & PADRE ISLAND) SANTA ANA RIVER Washington, Oregon, British Columbia & Indian Nations Midwestern States & Montana Pennsylvania, Ohio, West Virginia, Kentucky, Indiana & Illinois West Virginia, Virginia, Washington D.C. & Maryland Loss Of Channel Agricultural Chemicals Length, Disruption Of Entering River, Gulf Of Mexico Sediment Transport "Dead Zone" Impacted By Industrial Use Industrial Discharges, Acid Rain From Power Plant Emissions Industrial Discharges, Urban Bay Contains 160 Runoff, Salt Water Intrusion In Nonindigenous Species Groundwater North Dakota, Minnesota, & Manitoba Degraded By Agriculture Colorado, New Mexico, Texas, Chihuahua, Coahuila, Nuevo Leon & Tamaulipas Loss Of Fresh Water Access For Marine Species Dam Construction, Water Channel Heavily Dewatered Withdrawal For Agriculture, Particularly In Lower Reaches Sediment Filling Channel In Some Sections Requires Water Allocation Between The United States & Mexico Channel Concrete Lined, Total Loss Of Cover Sewer Outfalls Discharge Into Massive Urban Development In River, Salt Water Intrusion Lowlands, Construction On Steep Into Groundwater, Fires In Erosive Hillsides Upper Watershed Water Imported From The Colorado River California (INCLUDING SAN BERNARDINO MTNS., (Containing Cities & Counties Of PRADO WETLANDS, LOS ANGLES BASIN The Los Angles Basin) & HUNTINGTON BEACH) Agricultural Chemicals Entering River Slide Presentation Prepared By Geomax, P.C. Dr. Donald R. Reichmuth, President 1023 W. 30th Ave. Spokane, WA 99203-1324 Phone & FAX – 509-838-6390 E-mail – [email protected]
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