Hydrology Exam - Minnesota Water Stewards

1. What is hydrology?*
- The study of waves or wave motions
- The science of the properties, distribution, and circulation of the waters of the Earth
- An area or ridge of land that separates waters flowing to different rivers, basins, or seas
- All of the above
2. Why do we study hydrology?*
- Because water shapes the land
- Because water influences where we live
- Because flowing water picks up and conveys all kinds of stuff
- Because it’s the only water we’ll ever have
- All of the above
3. What are the primary processes of the hydrologic (water) cycle?*
- CO2, Photosynthesis, Resiration, O2
- Rain, snow, fog, sleet
- Condensation, precipitation, infiltration, runoff, and evaporation
- All of the above
4. What is a watershed?*
- Something that releases water into an environment
- An area of land that drains to a water resource
- An event or period marking a turning point in a course of action or state of affairs
- All of the above
5. What does a hyetagraph illustrate?*
- An event hyetograph shows the distribution of precipitation over time
- The distribution of water over an area of land
- A graph of the movement of water over time
- All of the above
6. What period of time does a hyetagraph represent?*
- 1 minute
- Exactly 24 hours
- Any period of time within a 24-hour window you select to focus on
7. What three things are important to know about a rainfall event*
- Depth, Duration, Intensity
- Cloud cover, temperature, depth
- Area, ground cover, impermeable surfaces
- All of the above
8. What is a 100-year rain event?*
- A rain fall that happens every 100 years
- An event that has a 1% chance of occurring in any year
- An event that has a 100% chance of happening in 100 years
The formula for calculating runoff is: Area x Rainfall Depth = Volume

To calculate runoff, you will need to convert rainfall depth to cubic feet, then convert cubic feet to gallons

Area x Rainfall depth x (convert rainfall to cubic feet) 1 ft/12” = cubic feet
Convert cubic feet to gallons (1 cf = 7.5 gallons)
9. Calculate the runoff of the property in the image above, in a 1” rainfall*
- 167 gallons
- 12,500 gallons
- 1250 gallons
- none of the above
10. Calculate the runoff of the property in the same image in a 3.5” rainfall*
- 4375 gallons
- 52,500 gallons
- 583 gallons
- none of the above
11. What is a hydrologic soil group?*
- A group of soil types that infiltrate water
- A classification of soil based on the particle size
- A mixed soil type that is attracted to water
- None of the above
12. What factor (besides soil type) has the most significant impact on infiltration rates of soils?*
- Color
- Compaction
- Biota
- All of the above
13. How does the slope of land influence how water moves across the landscape?*
- The greater the slope, the faster water moves.
- The greater the slope, the slower the water moves.
- Increase in slope = increase in infiltration rates
- None of the above
14. Urban stormwater systems have directly connected impervious surfaces into one large area that drains to stormwater pipes. What is the most important consequence of these systems?*
- Stormwater soaks into the ground faster.
- Stormwater is polluted
- Stormwater runs off faster, and has little chance to soak into the ground.
- All of the above
15. Of all the factors that influence how water moves across the landscape- Soil Type and Porosity, Soil Compaction, Slope, Directly Connected Impervious Surface- which one is most important in urban areas?*
- Soil type and porosity
- Soil Compaction
- Slope
- Directly Connected Impervious Surface
16. What does a hydrograph illustrate?*
- The movement of water during and after precipitation
- An area of water depth
- The time it takes water to infiltrate
- All of the above
17. How does urban development in a subwatershed affect the curve of a hydrograph?*
- Base flow is reduced and peak flow spikes later than normal
- Base flow increases and peak flow is smaller
- Base flow is reduced, and peak flow spikes earlier and higher in the rain event
- None of the above
18. If you wanted to reduce the impacts of urbanization on our lakes, streams, and wetlands, what changes to the developed landscape would you recommend?*
- Increase impervious surfaces
- Increase capacity of storm sewers
- Disconnect impervious surfaces, increase surface areas to infiltrate water
- All of the above