CH Ecosystem Restoration 2 — Questions and Answers
Question 1: Which hydrological indicator is most commonly used to assess progress in wetland restoration projects?
- Groundwater table elevation relative to soil surface (Correct answer)
- Total dissolved solids concentration
- Turbidity measured in NTU
- pH of surface water
Correct answer: Groundwater table elevation relative to soil surface
Groundwater table elevation relative to the soil surface directly reflects hydrologic reconnection, the primary goal of most wetland restorations.
Question 2: In stream restoration, what does the term 'bankfull discharge' represent?
- The 100-year flood flow
- The flow that fills the channel to the top of the banks and controls channel morphology (Correct answer)
- Average annual streamflow
- The flow needed to mobilize bed material
Correct answer: The flow that fills the channel to the top of the banks and controls channel morphology
Bankfull discharge is the channel-forming flow that fills the stream to its banks and is the dominant control on channel shape and size.
Question 3: A hydrographer notices that a restored reach has a sinuosity ratio of 1.05. What does this indicate?
- The channel is highly meandering
- The channel is nearly straight, suggesting possible under-restoration (Correct answer)
- The channel is in a braided pattern
- Sinuosity ratio cannot be used for restored reaches
Correct answer: The channel is nearly straight, suggesting possible under-restoration
A sinuosity ratio near 1.0 indicates an almost straight channel; reference reaches for the same valley slope typically have higher sinuosity.
Question 4: Which method best estimates pre-disturbance channel geometry when designing a stream restoration?
- Current downstream cross-sections in the same watershed
- Aerial photograph analysis of reference reaches with similar drainage area and slope (Correct answer)
- Manning's equation applied to design discharge only
- LiDAR-derived flood-plain elevation alone
Correct answer: Aerial photograph analysis of reference reaches with similar drainage area and slope
Reference reach analysis using aerial photos of unimpacted streams with comparable drainage area and slope provides the most reliable pre-disturbance geometry estimate.
Question 5: What is the primary purpose of installing large woody debris (LWD) in a restoration project?
- To reduce channel gradient by raising bed elevation
- To create habitat complexity, pool formation, and sediment storage (Correct answer)
- To prevent bank erosion by armoring the channel bed
- To increase mean flow velocity
Correct answer: To create habitat complexity, pool formation, and sediment storage
LWD creates hydraulic diversity, pool-riffle sequences, and sediment storage that improve aquatic habitat complexity.
Question 6: During post-restoration monitoring, a rapid increase in bed aggradation upstream of a constructed riffle is observed. What is the most likely cause?
- Increased baseflow from groundwater contributions
- Excessive sediment supply from an unaddressed upland source (Correct answer)
- Downstream channel incision pulling sediment away
- Riparian vegetation shading reducing algal growth
Correct answer: Excessive sediment supply from an unaddressed upland source
Aggradation upstream of a grade control structure indicates sediment supply exceeds transport capacity, often from unaddressed upland erosion sources.
Question 7: Which ecological concept guides the selection of target conditions in ecosystem restoration?
- Succession theory only
- Historical range of variability (HRV) combined with reference ecosystem analysis (Correct answer)
- Maximum species richness at any cost
- Climax community theory applied rigidly
Correct answer: Historical range of variability (HRV) combined with reference ecosystem analysis
Historical range of variability combined with reference ecosystem analysis defines realistic, achievable target conditions that account for natural variation.
CH Ecosystem Restoration 2
Which hydrological indicator is most commonly used to assess progress in wetland restoration projects?