AND FLOODS STREAMS
1) What does the term "stream" mean to a geologist? Anything in the runoff category 2) Know how the mouth, head, and base level of a stream are spatially related to the stream's longitudinal profile. Head is at the top of the stream and the mouth is at its lowest altitude Base level is the altitude of the bottom of the stream
3) Know what will happen if a portion of the land a stream runs through should rise above, or fall below the longitudinal profile. If it rises above, the stream will cut down into the land If the land subsides, the stream will deposit material to get back to profile 4) Besides vertical movement of the land, why else might a stream have to adjust to a new longitudinal profile? A change in base level
5) Know the difference between a young, middle aged, and old aged stream.
6) Be able to identify the following on a diagram: flood plain, cut bank, point bar, oxbow lake, meander scar, yazoo stream/tributary, terrace, and levee. Floodplain plain that will flood Cutbank outside of band of river cutting into feature Point Bar Inside of bend depositing Meander Scar Dry oxbow lake, horse shoe shape Yazoo Stream Small stream in floodplain Levee Mounds of sediment adjacent to channel Oxbow Lake Horseshoe shaped lake Terraces Flat areas above main flood plain
7) Know the definitions of a watershed (drainage basin) and a drainage divide. Watershed Area of land in which all the water that falls in it leaves from one plain Divide Highlands that separate one drainage basin from another 8) Know the difference between stream capacity and stream competence. Know what happens to a stream if its sediment load is greater than its capacity. Stream Capacity discharge Total of sediment the stream is transporting Stream Competence Largest particle being moved by the stream If sediment load is greater than capacity, makes a braided stream and dries up 9) What is the name of the sediment feature created by a mountain stream that discharges onto a relatively flat plain? Alluvial Fan 10) What is the name of the sediment feature created by a stream discharging into a larger body of water? Delta 11) Know the definition of, and how to calculate, stream discharge. Stream Discharge Volume per unit time of water. Q=WDV Q=Discharge, cfs W=Width, ft D=Avg Depth V=Avg Velocity
Manning Equation: V=(1.49/n)R^2/3S^1/2 n=manning coefficient A/P=R 12) Know what a hydrograph is. Know what is plotted on the x-axis and what is plotted on the y-axis. Hydrograph: discharge vs. time y-axis x-axis
13) Know the definition of stream stage, and what a graph relating stage to discharge is called. Stream Stage height of the stream Rating Curve Relates stage to discharge 14) Know what is meant by flood probability and flood recurrence interval. Understand the statistical nature of these two things. Flood recurrence interval Average time elapsed between floods of a given size/magnitude Flood probability Probability of flow being equaled or exceeded in any one year. 15) Know how a change in any of the other parameters of the hydrologic cycle can affect flooding (by increasing or decreasing stream runoff). P=R+ET+I Lower evapotransportation (Increase runoff) Infiltration down (Increase runoff) Deforestation (Increase runoff) 16) What was the name of the lake that emptied to create the channeled scablands and when did it empty? Lake Missoula, About 17000 years ago