Practice questions

Project Sediment and Habitat Dynamics

In the framework of the project Sediment and Habitat Dynamics, 12 questions from authorities and practice were answered.

1. Heterogeneity of sediments

Why does sediment heterogeneity matter at all? What degree of sediment heterogeneity is needed in order to re-establish important ecological processes at the river bottom? Answer

2. Sediment thickness

How does the thickness of the sediment layer affect ecological functioning? To what depth do fish and other aquatic organisms use the sediment? Answer

3. Improving spawning habitat for fish by local gravel additions

What is the ecological success of such measures in small streams? A mini-review of the scientific literature Answer

4. Designing gravel additions

What types of gravel additions in lowland rivers and alpine streams have been implemented so far and what lessons have been learned? Answer

5. Constructing and maintaining bedload traps in areas of particular ecological importance

What are the requirements in these important areas? How should trap maintenance look like in order to guarantee optimal conditions for aquatic communities? Answer

6. Reservoir flushing and ecological effects

What is the impact of water and sediment pulses on sediment transport and morphology in rivers? Answer

7. Bedload trap vs. river widening

What criteria should be used to decide between a bedload trap and a “deposition area”? Answer

8. Bedload management and river rehabilitation (1)

Should soil material that was excavated during river rehabilitation be deposited in the local river corridor/river bed? Answer

9. Bedload management and river rehabilitation (2)

How do fine sediments adversely affect morphodynamic processes and aquatic communities in rehabilitated rivers? Answer

10. Riparian vegetation connected by stepping stone areas

What are the ecological requirements for floodplain vegetation in “stepping stone areas”? Answer

11. Width of riparian area

How does a riparian area look like? What are the ecological and legal requirements regarding minimal and optimal width of riparian areas? Answer

12. Induced bank erosion

What types of artificial structures exist in order to deflect the current in rivers and what are their effects on the river banks? Answer