See an example of the problem with colmation in the next slide.

Transcription

1 1. How is the hyporheic zone defined? a. based on age of the water in the pore spaces beneath the streambed b. defined as the volume beneath the streambed influenced by diurnal temperature changes c. based on some component of surface water contained in the pore water beneath the streambed The region of saturated sediments beneath and beside the active channel and that contain some proportion of surface water that was part of the flow in the surface channel and went back underground and can mix with groundwater California Dept. of Water Resources GW glossary 2. Why do water-supply managers have such a problem with colmation (clogging of the riverbed) when they extract river water by pumping groundwater? a. it reduces the volume of water they can extract from the river b. they get their feet stuck in the accumulated mud c. the muddy layer smells bad d. colmation causes river levels to drop below the water intakes. See an example of the problem with colmation in the next slide.

2 Sonoma County Water Agency, Russian River, CA Produce 300,000 m 3 /day Inflatable dam raises river stage 3 m Still can t get enough water because the riverbed is becoming clogged Russian River Inflatable dam 4-m diameter Ranney collector well 3. What has the biggest influence on local-scale hyporheic exchange? a. sediment anisotropy b. stream velocity c. stream depth d. bed topography All of these choices influence hyporheic exchange to some extent, but local-scale bed topography is by far the largest influence.

3 4. What is baseflow? a. constant flow in winter b. portion of stream flow that comes from groundwater or other delayed sources c. flow that occurs at the base of mountain d. high flow during or immediately after a storm 5. It is important to study baseflow because: a. baseflow maintains aquatic habitats during dry periods b. baseflow provides water supply during dry periods c. baseflow minimizes temperature extremes. d. all of the above

4 6. Automated baseflow separation method is: a. better than graphical methods because it gives more accurate values of baseflow. b. accurate because it represents the actual amount of groundwater input to streams. c. not better or worse than graphical method, but it gives objective and consistent results. d. worse than graphical method because it gives less accurate values of baseflow. discharge Q (m 3 s -1 ) 2 1 raw data 1st pass 2nd pass 3rd pass time 0 5/30 6/9 6/19 6/29 7/9 7. What is a seepage run? a. It is a running race to raise money so scientists can make seepage measurements. b. It is way to determine the net exchange between groundwater and stream water along segments of a stream. c. It is a series of seepage measurements along the shoreline of a lake. d. It is a method used to quantify the amount of water flowing into a reservoir. See an example in the next page.

5 8. Why is an automated seepage meter so useful? a. It allows us to sleep while it works at night. b. It is much better at measuring variability of seepage over time. c. We do not have to worry about problems with seepage bags. d. All of the above.

6 9. Which variable do we often have a difficult time obtaining? a. L, the distance from the well to the shoreline b. b, the depth of aquifer that exchanges with the lake c. m, the shoreline length associated with the monitoring well d. None of the above. It is all very easy. m L b 10. When stream temperature has diurnal (24-hour cycle) fluctuation, temperature in the streambed sediments also has diurnal fluctuation. Consider a streambed where groundwater is flowing upward. Compared to a streambed with no groundwater flow, does the streambed with upward flow have: a. higher amplitude of temperature fluctuation. b. about the same amplitude of temperature fluctuation. c. lower amplitude of temperature fluctuation.

7 11. Temperature is a useful indicator of groundwater seepage flux because: a. it is easy to measure. b. temperature sensors are generally much cheaper than other sensors. c. thermal properties of sediments have a smaller range of variability than hydraulic properties, resulting in smaller errors in calculation compared to hydraulic methods such as Darcy s law. d. all of the above.