02. Flow regulations
Flushing flows are peaks of flow released from reservoirs to imitate elements of the natural flow regime downstream in order to aid recovery of their associated HYMO and ecological processes. Flushing flows maintain stream channel composition by removing accumulated fine sediment and organic debris, mobilizing and sorting bed material and restricting riparian vegetation encroachment. Flushing flows are necessary to maintain ecological integrity, especially increasing the availability and quality of fish spawning habitat and the production of benthic macroinvertebrates.
In contrast, the common practice of reservoir flushing to get rid of accumulated fine sediments has detrimental effects on the habitats and aquatic communities downstream of the dam. Depending on the sediment transport within the system, reservoir flushing for cleaning is a rather rare event occurring once every 10-20 years.
Effect/Impact on (including literature citations)
- HYMO (general and specified per HYMO element)
- physico - chemical parameters
- Biota (general and specified per Biological quality elements)
Case studies where this pressure is present
- No related measures were found.
Possible restoration, rehabilitation and mitigation measures
- Prevent sediment accumulation in reservoirs
- Improve continuity of sediment transport
- Trap sediments
- Reduce undesired sediment input
- Reduce erosion
- Manage dams for sediment flow
- Modify hydropeaking