Rivers: Key Terms, Concepts, and Landforms, Study notes of Physical Geography

Download Rivers: Key Terms, Concepts, and Landforms and more Study notes Physical Geography in PDF only on Docsity! KEY TERMS FOR RIVERS Vocabulary for Notes (use wherever there is a ______________________) Abrasion Drainage divide Saltation Aggradation Floodplain Sand sized Alluvium Greater Solution Base level Hydraulic force Terrace Bedload Interconnectedness Turbidity Clay sized Larger Watershed Climate Meandering Stream Cut bank Point bar RIVERS Objectives: To Successfully be Able to Explain: 1. The concept and importance of a watershed. 2. The processes of stream erosion, transportation, and deposition. 3. The origin and characteristics of river landforms. Misconceptions: 1. Only the Nile River flows north. 2. Stream velocity decreases as one approaches base level (ocean or lake). 3. Tornados will not strike between two rivers. 4. Groundwater flows in underground rivers 5. Rivers and groundwater are separate. 6. Excluding the oceans, there is more river water than groundwater. 7. Water from natural springs is safe to drink. 8. All rivers empty into lakes, seas, or oceans. Did you Know? 1. The Chicago River is colored green on St. Patrick’s Day? 2. The Chicago River’s flow was reversed in 1900 for sanitation reasons? 3. Along the Detroit River is one of the very few places where you look south into Canada from the lower 48 states. 4. A river horse is a hippopotamus, and that a river jack is an unpleasant-looking snake, the African puff adder 5. The Congo River is the longest river that flows generally westward? 6. The Missouri-Mississippi is the longest river flowing generally southward? 7. The Yangtze is the longest eastward flowing river? 8. The Nile is the world's longest northward flowing river? 9. Saudi Arabia has no natural rivers? A. Stream Erosion ___________________ grinding of the river bed due to particle friction. Solution: rock and sediment become dissolved within the water column. ________________________ the force or weight of the water striking the river bed results in erosion. Hydraulic force results in a type of plucking that can pry loose weak rock and sediment. B. Stream Transport (click on Fig. 10.14 - Modes of Sediment Transport (80.0K)) __________________ sediment in contact with the bed carried downstream by stream flow. __________________________ the downstream bouncing motion of sediment in which sediments are dislodged from the stream bed, suspended for a short distance, and then fall back to the stream bed. Sediment impact will often dislodge other sediments, beginning the process over again. Rolling: Rock or sediment that rotates across the surface of the river bed. At all times the body is in contact with the river bed. ______________________ dissolved sediment held within the water column. Suspension: visible sediment carried within the water column. Excessive amounts of suspended sediment results in increased water cloudiness or _____________________. Turbidity decreases light penetration, reduces photosynthesis, buries spawning beds, and allows contaminants to be transported on suspended sediment. C. Stream Deposition _________________________ the deposition of sediment by streams when the quantity of material carried by the stream is greater than the competence or ability of the stream to carry its current load of sediment. ____________________ any sediment deposited by streams. Discharge and Deposition: the ________________the discharge, the _____________ the ability to carry material through suspension and through bedload. When discharge declines, aggradation will occur. Discharge and Sediment Size: the ________________ the discharge the greater the ability or competence of the stream to carry _______________ sediment sizes. Boulders will be moved when discharge is greatest, only clay sized particles will be moved when discharge is low. Access the following video on a graded stream to better understand the graded stream concept. The relationship between flow, erosion, and deposition is depicted for a steep and gentle stream profile. The graded stream concept is also applied for a flood scenario. OBJECTIVE 3: The origin and characteristics of river landforms. (Images: http://www.uwsp.edu/geo/courses/geog391/toriv/images%5Clandform.gif) __________________ a plain next to a river and prone to flooding. Bluff: a steep, prominent slope originating from river erosion. _________________ a flat, narrow stretch of ground, often having a bluff face facing the river. Terraces often represent former floodplains that were left stranded at a higher position when the river down cut to a lower level. (Click on Figs. 10.27, 10.43, 10.45 - Flood Plain and Stream Terrace (140.0K)) Natural Levee: An elevated bank of alluvium bordering a river. The bank is deposited when the river leaves behind much of its load during flooding. ___________________________ a stream having a pattern of snake like turns. View this animation to view how an actual river has meandered over a half century. ______________________ the outer portion of a river meander, usually steep, which is continually undergoing erosion. _________________________ a gentle-sloped, wedge-shaped deposit of alluvium on the inner portion of a meander. Thalweg: The deepest portion of the stream’s channel produced by faster moving, erosive stream flow. In the space below, draw a meander and where to navigate a canoe Meander Neck: a narrow isthmus of land separating two adjacent meanders. Oxbow Lake Formation: A portion of a meander, now a lake, which has been cut off from the original river channel. Oxbow lakes became isolated from the original channel as a river cuts through a meander neck to shorten its course, blocking off the old channel. The new river channel then migrates away from the lake. Eventually, oxbow lakes silt up to form wetlands and finally meander scars. Based on this animation of oxbow lake formation, draw a two to four step diagram illustrating how oxbow lakes form. Return to Resources for Earth Science and Geography Instruction