GLG 112 NAU: Final Exam (Questions + Answers) Solved

What is climate? - Precipitation, temperature, and biometric pressure measurements averaged over a period of years Prevailing global winds travel in the same direction independent of latitude: T or F - False Monsoon rains occur in places where the wind direction shifts seasonally, pulling warm moist air from the ocean onto land: T or F - True Ellison Creek Flood - Heavy rain fell over the Highline Burn Scar, sending floodwater and debri into and down Ellison Creek, to the Cold Springs swimming hole How do urban areas influence the severity of a flood? - As cities expand, natural vegetation may be removed and replaced with concrete. This leads to an increase in surface runoff in a rain event because concrete surfaces are impermeable. What determines whether a flood will rise quickly or slowly? - Size of drainage basin, How much water per hour, Soil Saturation levels Why are some floods muddy (and have debris) while other floods are relatively clear? - How does climate influence flood severity? - - Rate of rain soak: some climates accommodate a lot of rain, others will quickly repel water - Soil saturation prior to storm: spongy/thick soils absorb water (oversaturation = flash flood); hydrophobic soils (flash flood common) All of the following determine the height & speed of a flood except? -Slope of the stream bed-Size of the area that is being flooded -Amount, duration, and timing of precipitation -Shape of the stream drainage network - The last time the stream flooded - The last time the stream flooded What is a dendritic drainage network? (sketch) - Drainage network whose interconnecting streams resemble the pattern of branches connecting to a deciduous tree What is a watershed? (sketch) - Area of land that drains to a particular stream, river or lake What is the largest watershed in the US? - Mississippi River What type of drainage network will have a slower flood? - Networks with many tributaries How do the number of tributaries in a drainage network affect the flood speed? - The more tributaries, the slower the flood will be (more room to store water). How does the size of the watershed affect flooding? - Large areas will have slower floods How does the amount of rain and its distribution affect flooding? - Small watersheds= Quick rise Large Watersheds= Slower rise How does stream shape and stream gradient affect flooding? - Streams with a steep gradient flood faster How is discharge calculated? - Stream or Flood Discharge=Volume of water per second Q=VAWhat is a hydrograph? - Graph showing the rate of discharge vs time How is the cross-sectional area of a stream related to stream discharge(when velocity is constant)? -If area increases, discharge increases -If area increases, discharge decreases -Discharge is not related to area -There is not enough information to answer - If area increases, discharge increases What happens to stream velocity when the area of a stream is narrowed, and discharge is constant? -Velocity of the water increases -Velocity of the water decreases -Velocity of the water remains constant -There is not enough information to answer - Velocity of the water increases (This is how rapids form in rivers) How does the size of watershed affect the height of a flood? -The smaller the watershed area, the higher the flood level(actual height of water) -The smaller the watershed area, the lower the flood level -Flood levels are the same regardless of watershed area - The smaller the watershed area, the higher the flood level(actual height of the water) What controls infiltration? - Precipitation, Base flow, soil characteristics, slope What controls runoff? - Precipitation? Slow Floods (hydrograph and explain) - Slow rise, like a hill