Fluvial Geomorphology
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Explain How Rivers Adjust to a Change in Base Level with Reference to Examples You Have Studied (2013 Q1C)
Isostasy | A1 Sample answer Explain how rivers adjust to a change in base level with reference to examples you have studied (2013 Q1C) Isostatic uplift is when land rises above sea level because of tectonic activity. This is usually due to a large weight being removed from the land e.g. when an ice cap melts. Eustatic changes are when the sea level drops. This is due to water being locked away somewhere e.g., in a glacier. When it melts, the sea level rises again. The River Nore in Kilkenny has experienced a change in base level. This can be seen since there are knickpoints along it, roughly 150-200m above sea level. A knickpoint can be seen when the sea level drops and a river rejuvenates because the river starts vertically eroding once more. Rejuvenation is the term used to describe a river that starts eroding like a youthful river even when it is in its old age stage. A knickpoint is a spot where the newly eroded river profile meets the old river profile. Sometimes you will find a waterfall here. River terraces are also found where rejuvenation has occurred. This is when a river forms a new floodplain that is lower down than the last. The remnants of the old floodplain are left as steps and are called terraces. If there are terraces on both sides of the river, they are called paired terraces. Terraces can be formed multiple times if the river rejuvenates more than once, appearing as a series of steps down to the river. -
Late Holocene Sea Level Rise in Southwest Florida: Implications for Estuarine Management and Coastal Evolution
LATE HOLOCENE SEA LEVEL RISE IN SOUTHWEST FLORIDA: IMPLICATIONS FOR ESTUARINE MANAGEMENT AND COASTAL EVOLUTION Dana Derickson, Figure 2 FACULTY Lily Lowery, University of the South Mike Savarese, Florida Gulf Coast University Stephanie Obley, Flroida Gulf Coast University Leonre Tedesco, Indiana University and Purdue Monica Roth, SUNYOneonta University at Indianapolis Ramon Lopez, Vassar College Carol Mankiewcz, Beloit College Lora Shrake, TA, Indiana University and Purdue University at Indianapolis VISITING and PARTNER SCIENTISTS Gary Lytton, Michael Shirley, Judy Haner, STUDENTS Leslie Breland, Dave Liccardi, Chuck Margo Burton, Whitman College McKenna, Steve Theberge, Pat O’Donnell, Heather Stoffel, Melissa Hennig, and Renee Dana Derickson, Trinity University Wilson, Rookery Bay NERR Leda Jackson, Indiana University and Purdue Joe Kakareka, Aswani Volety, and Win University at Indianapolis Everham, Florida Gulf Coast University Chris Kitchen, Whitman College Beth A. Palmer, Consortium Coordinator Nicholas Levsen, Beloit College Emily Lindland, Florida Gulf Coast University LATE HOLOCENE SEA LEVEL RISE IN SOUTHWEST FLORIDA: IMPLICATIONS FOR ESTUARINE MANAGEMENT AND COASTAL EVOLUTION MICHAEL SAVARESE, Florida Gulf Coast University LENORE P. TEDESCO, Indiana/Purdue University at Indianapolis CAROL MANKIEWICZ, Beloit College LORA SHRAKE, TA, Indiana/Purdue University at Indianapolis PROJECT OVERVIEW complicating environmental management are the needs of many federally and state-listed Southwest Florida encompasses one of the endangered species, including the Florida fastest growing regions in the United States. panther and West Indian manatee. Watershed The two southwestern coastal counties, Collier management must also consider these issues and Lee Counties, commonly make it among of environmental health and conservation. the 5 fastest growing population centers on nation- and statewide censuses. -
2019 Li, Z., Wu, X., and Gao, P.*, Experimental Study on the Process of Neck Cutoff
Geomorphology 327 (2019) 215–229 Contents lists available at ScienceDirect Geomorphology journal homepage: www.elsevier.com/locate/geomorph Experimental study on the process of neck cutoff and channel adjustment in a highly sinuous meander under constant discharges Zhiwei Li a,b, Xinyu Wu a,PengGaoc,⁎ a School of Hydraulic Engineering, Changsha University of Science & Technology, Changsha 410114, China b Key Laboratory of Water-Sediment Sciences and Water Disaster Prevention of Hunan Province, Changsha 410114, China c Department of Geography, Syracuse University, Syracuse, NY 13244, USA article info abstract Article history: Neck cutoff is an essential process limiting evolution of meandering rivers, in particular, the highly sinuous ones. Received 29 July 2018 Yet this process is extremely difficult to replicate in laboratory flumes. Here we reproduced this process in a Received in revised form 1 November 2018 laboratory flume by reducing at the 1/2500 scale the current planform of the Qigongling Bend (centerline length Accepted 1 November 2018 13 km, channel width 1.2 km, and neck width 0.55 km) in the middle Yangtze River with geometric similarity. In Available online 07 November 2018 five runs with different constant input discharges, hydraulic parameters (water depth, surface velocity, and slope), bank line changes, and riverbed topography were measured by flow meter and point gauges; and bank Keywords: fl Meandering channel line migration and a neck cutoff process were captured by six overhead cameras mounted atop the ume. By Neck cutoff -
Rivers and Base Level—Cool Stuff Earth Science Essentials by Russ Colson
Stories of Other Worlds—How to Build a Landscape Rivers and Base Level—Cool Stuff Earth Science Essentials by Russ Colson The River—The state boundary that moves. The migration of rivers has a long and complex history in human politics and war. The problem arises because rivers were commonly used to mark boundaries of adjacent political entities. When the rivers inevitably migrated, as mature streams are wont to do, disagreements arose about who owned the new land formed on the inside bend of the meanders. It seems like a simple solution would be to keep the boundaries fixed, whether the river migrates or not. That way, the land controlled by a particular political entity is not changed by the vagaries of erosion and deposition. However, suppose that the river is an important defensive barrier against attack? Clearly, in that case the border needs to be maintained along the river. Or, what if the river is important for commerce and transportation? Again, keeping the border along the river makes sense, regardless of the gain or loss of land. In his 1715 (edition) book Of the Rights of War and Peace, Hugo Grotius took the view that many rivers are defensive boundaries and ...the river, by gradually altering its course, does also alter the borders of the territory; and whatsoever the river casts up to the opposite side, shall be under his jurisdiction, to whom the augmentation is made Although geologists treat the various processes of river migration (such as erosion, deposition, meander cut offs, etc) as part of a single process, courts have often ruled that they are quite different. -
Preprint 06-041
SME Annual Meeting Mar. 27-Mar.29, 2006, St. Louis, MO Preprint 06-041 A MEANDER CUTOFF INTO A GRAVEL EXTRACTION POND, CLACKAMAS RIVER, OREGON P. J. Wampler, Grand Valley State Univ., Allendale, MI E. F. Schnitzer, Dept. of Geology and Mineral Industries, Albany, OR D. Cramer, Portland General Electric, Estacada, OR C. Lidstone, Lidstone and Assoc(s)., Fort Collins, CO Abstract Introduction The River Island mining site is located at approximately river mile The River Island site provides a unique opportunity to examine (RM) 15 on the Clackamas River, a large gravel-bed river in northwest the physical changes to a river channel resulting from avulsion into a Oregon. During major flooding in February 1996, rapid channel gravel extraction pond. Data from before and after the meander cutoff change occurred. The natural process of meander cutoff, slowed for allow evaluation of changes to river geometry, sediment transport, several years by dike construction, was accelerated by erosion into temperature, habitat, and channel form. gravel extraction ponds on the inside of a meander bend during the An avulsion is defined as a lateral migration or cutoff of a river. It flood. involves the diversion of water from the primary channel into a new In a matter of hours, the river cut off a meander and began flowing channel that is either created during the event or reoccupied. through a series of gravel pits located on the inside of the meander Avulsions may be rapid or take many years to complete (Slingerland bend. The cutoff resulted in a reduction in reach length of and Smith, 2004). -
Classifying Rivers - Three Stages of River Development
Classifying Rivers - Three Stages of River Development River Characteristics - Sediment Transport - River Velocity - Terminology The illustrations below represent the 3 general classifications into which rivers are placed according to specific characteristics. These categories are: Youthful, Mature and Old Age. A Rejuvenated River, one with a gradient that is raised by the earth's movement, can be an old age river that returns to a Youthful State, and which repeats the cycle of stages once again. A brief overview of each stage of river development begins after the images. A list of pertinent vocabulary appears at the bottom of this document. You may wish to consult it so that you will be aware of terminology used in the descriptive text that follows. Characteristics found in the 3 Stages of River Development: L. Immoor 2006 Geoteach.com 1 Youthful River: Perhaps the most dynamic of all rivers is a Youthful River. Rafters seeking an exciting ride will surely gravitate towards a young river for their recreational thrills. Characteristically youthful rivers are found at higher elevations, in mountainous areas, where the slope of the land is steeper. Water that flows over such a landscape will flow very fast. Youthful rivers can be a tributary of a larger and older river, hundreds of miles away and, in fact, they may be close to the headwaters (the beginning) of that larger river. Upon observation of a Youthful River, here is what one might see: 1. The river flowing down a steep gradient (slope). 2. The channel is deeper than it is wide and V-shaped due to downcutting rather than lateral (side-to-side) erosion. -
C. Natural Stream Processes
Natural Stream Processes Guide No. 03 Streams in their natural state are dy- agency officials, and others to start a recycle nutrients from natural pollution namic ecosystems that perform many thoughtful inquiry into the true source sources, such as leaf fall, to purifying beneficial functions. Natural streams of local stream management problems. the water. The natural stream tends and their flood plains convey water The material contained in this guide to maintain itself through the flushing and sediment, temporarily store excess makes evident that the source of many flows of annual floods that clear the flood water, filter and entrap sediment stream problems is in the watershed, channel of accumulated sediments, and pollutants in overbank areas, far from the main stream channel. debris, and encroaching vegetation. recharge and discharge groundwater, Landowners, local officials, and oth- Extreme floods may severely disrupt naturally purify instream flows, and ers concerned with streams need to the stream on occasion, but the natural provide supportive habitat for diverse work together across property lines balance of the stream ecosystem is plant and animal species. The stream and jurisdictional boundaries to find restored rapidly when it is in a state of corridors wherein these beneficial func- suitable solutions to stream problems dynamic equilibrium. tions occur give definition to the land and to implement practices to protect, and offer “riverscapes” with aesthetic restore and maintain healthy stream qualities that are attractive to people. ecosystems. CHANNEL FORMING Human activities that impact stream AND RECONDITIONING ecosystems can and often do cause STREAMS ARE problems by impairing stream functions PROCESSES and beneficial uses of the resource. -
A Groundwater Sapping in Stream Piracy
Darryll T. Pederson, Department of energy to the system as increased logic settings, such as in a delta, stream Geosciences, University of Nebraska, recharge causes groundwater levels to piracy is a cyclic event. The final act of Lincoln, NE 68588-0340, USA rise, accelerating stream piracy. stream piracy is likely a rapid event that should be reflected as such in the geo- INTRODUCTION logic record. Understanding the mecha- The term stream piracy brings to mind nisms for stream piracy can lead to bet- ABSTRACT an action of forcible taking, leaving the ter understanding of the geologic record. Stream piracy describes a water-diver- helpless and plundered river poorer for Recognition that stream piracy has sion event during which water from one the experience—a takeoff on stories of occurred in the past is commonly based stream is captured by another stream the pirates of old. In an ironic sense, on observations such as barbed tribu- with a lower base level. Its past occur- two schools of thought are claiming vil- taries, dry valleys, beheaded streams, rence is recognized by unusual patterns lain status. Lane (1899) thought the term and elbows of capture. A marked of drainage, changes in accumulating too violent and sudden, and he used change of composition of accumulating sediment, and cyclic patterns of sediment “stream capture” to describe a ground- sediment in deltas, sedimentary basins, deposition. Stream piracy has been re- water-sapping–driven event, which he terraces, and/or biotic distributions also ported on all time and size scales, but its envisioned to be less dramatic and to be may signify upstream piracy (Bishop, mechanisms are controversial. -
Sediment-Triggered Meander Deformation in the Amazon Basin
Sediment-triggered meander deformation in the Amazon Basin Joshua Ahmed, José A. Constantine & Thomas Dunne 1 Jose A. Constantine, Thomas Dunne, Carl Legleiter & Eli D. Lazarus Sediment and long-term channel and floodplain evolution across the Amazon Basin 2 Meandering rivers & their importance 3 Controls on meander migration • Curvature • Discharge • Floodplain composition • Vegetation • Sediment? 4 Alluvial sediment • The substrate transported through our river systems • The substrate that builds numerous bedforms, the bedforms that create habitats, the same material that creates the floodplains on which we build and extract our resources. Yet there is supposedly no real connection between this and channel morphodynamics? 5 6 7 Study site: Amazon Basin 8 9 What we did • methods 10 Results 11 Results 12 Results 13 Results 14 Results 15 Proposed mechanisms 16 Summary • Rivers with high sediment supplies migrate more and generate more cutoffs • Greater populations of oxbow lakes (created by cutoffs) mean larger voids in the floodplain • Greater numbers of voids mean more potential sediment accommodation space (to be occupied by fines) • DAMS – connectivity • Rich diversity of habitats 17 36,139 ha Dam, Maderia Finer and Olexy, 2015, New dams on the Maderia River 18 For further information 19 For more information Ahmed et al. In prep i.e., coming soon… to a journal near you 20 References • Constantine, J. A. and T. Dunne (2008). "Meander cutoff and the controls on the production of oxbow lakes." Geology 36(1): 23-26. • Dietrich, W. E., et al. (1979). "Flow and Sediment Transport in a Sand Bedded Meander." The Journal of Geology 87(3): 305-315. -
Drainage Basin Morphology in the Central Coast Range of Oregon
AN ABSTRACT OF THE THESIS OF WENDY ADAMS NIEM for the degree of MASTER OF SCIENCE in GEOGRAPHY presented on July 21, 1976 Title: DRAINAGE BASIN MORPHOLOGY IN THE CENTRAL COAST RANGE OF OREGON Abstract approved: Redacted for privacy Dr. James F. Lahey / The four major streams of the central Coast Range of Oregon are: the westward-flowing Siletz and Yaquina Rivers and the eastward-flowing Luckiamute and Marys Rivers. These fifth- and sixth-order streams conform to the laws of drain- age composition of R. E. Horton. The drainage densities and texture ratios calculated for these streams indicate coarse to medium texture compa- rable to basins in the Carboniferous sandstones of the Appalachian Plateau in Pennsylvania. Little variation in the values of these parameters occurs between basins on igneous rook and basins on sedimentary rock. The length of overland flow ranges from approximately i mile to i mile. Two thousand eight hundred twenty-five to 6,140 square feet are necessary to support one foot of channel in the central Coast Range. Maximum elevation in the area is 4,097 feet at Marys Peak which is the highest point in the Oregon Coast Range. The average elevation of summits in the thesis area is ap- proximately 1500 feet. The calculated relief ratios for the Siletz, Yaquina, Marys, and Luckiamute Rivers are compara- ble to relief ratios of streams on the Gulf and Atlantic coastal plains and on the Appalachian Piedmont. Coast Range streams respond quickly to increased rain- fall, and runoff is rapid. The Siletz has the largest an- nual discharge and the highest sustained discharge during the dry summer months. -
Physical Landscapes of the UK 1. Where Are the UK's Main Upland
Lesson 1: Physical Landscapes of the UK 1. Where are the UK’s main upland areas? North and west 2. Where are the majority of the UK’s cities? Lowland areas on the UK’s main rivers 3. Listen to the following descriptions and name the physical landscapes: a) ‘Part of the Highlands. Home to Ben Nevis, the highest mountain in the UK. Steep, rocky and sparsely populated.’ Grampian mountains b) ‘A National Park located in the north-west of England that is very popular with tourists. This is due to the glaciated environment that has formed spectacular scenery that includes many bodies of water.’ Lake District c) ‘A National Park located in northern Wales. It was designated a national park due to its spectacular glaciated scenery with steep mountains and valleys.’ Snowdonia d) ‘An area on the north-east coast that is eroding rapidly due to the underlying soft boulder clay. The eroded material has been transported in a southerly direction to form Spurn Head.’ Holderness Coast e) ‘An area on the south-western coast that stands proud within the landscape. The alternate bands of hard and soft rock has led to the formation of headlands and bays and associated landforms.’ Dorset coast f) ‘Flat low-lying marshy area on the eastern side of the UK near Norfolk. A lot of this area has been drained for farming.’ The Fens g) ‘A wide lower valley with flood plain upon which Glasgow is situated.’ River Clyde (9 marks) Lesson 2: The Long profile of a river 1. What is the long profile of a river? The gradient of a river as it journeys from its source to its mouth 2. -
Modification of Meander Migration by Bank Failures
JournalofGeophysicalResearch: EarthSurface RESEARCH ARTICLE Modification of meander migration by bank failures 10.1002/2013JF002952 D. Motta1, E. J. Langendoen2,J.D.Abad3, and M. H. García1 Key Points: 1Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA, • Cantilever failure impacts migration 2National Sedimentation Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Oxford, Mississippi, through horizontal/vertical floodplain 3 material heterogeneity USA, Department of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, USA • Planar failure in low-cohesion floodplain materials can affect meander evolution Abstract Meander migration and planform evolution depend on the resistance to erosion of the • Stratigraphy of the floodplain floodplain materials. To date, research to quantify meandering river adjustment has largely focused on materials can significantly affect meander evolution resistance to erosion properties that vary horizontally. This paper evaluates the combined effect of horizontal and vertical floodplain material heterogeneity on meander migration by simulating fluvial Correspondence to: erosion and cantilever and planar bank mass failure processes responsible for bank retreat. The impact of D. Motta, stream bank failures on meander migration is conceptualized in our RVR Meander model through a bank [email protected] armoring factor associated with the dynamics of slump blocks produced by cantilever and planar failures. Simulation periods smaller than the time to cutoff are considered, such that all planform complexity is Citation: caused by bank erosion processes and floodplain heterogeneity and not by cutoff dynamics. Cantilever Motta, D., E. J. Langendoen, J. D. Abad, failure continuously affects meander migration, because it is primarily controlled by the fluvial erosion at and M.