Reduce anthropogenic flow peaks

General description

Anthropogenic flow peaks are part of a modified flow regime and often occur due to hydropeaking. Read more about measures to modify hydropeaking on: http://wiki.reformrivers.eu/index.php/Modify_hydropeaking. Anthropogenic flow peaks can also result from surface runoff, especially in urban areas (urban runoff) (compare USGS). Effects of urban runoff:

• Drift of organisms due to flow peaks and,
• Decreased water quality because stormwater flows over land and potentially picks up pollutants.

stormwater retention basin built as open green pond in the Ruhr catchment, Germany (source: Bildarchiv Ruhrverband)

Applicability

The construction of stormwater retention basins is recommended to prevent direct urban runoff into streams. These facilities store surface runoff in events of heavy rain and prevent flooding. Stormwater retention basins can be understood as artificial lakes or ponds (open and green or concrete). Another way to buffer runoff is an underground storage system (e.g. tanks). Constrains could rise due to the area needed to build retention basins. If possible, open and near-natural systems should be favored (MKULNV NRW). A less technical approach to mitigate surface runoff is the use of open, vegetated space within a city (has to be involved in urban planning). Open areas (e.g. parks, green areas) can be expected to prevent urban runoffs by retaining rainwater (storage and evapotranspiration). It further increases infiltration to groundwater.

Expected effect of measure on (including literature citations):

• Decreased drift due to lower flow peaks,
• Increased chemical condition (less pollution) which has positive effects on stream biota.

Temporal and spatial response

Not available

Pressures that can be addressed by this measure

• Discharge diversions and returns
• Hydrological regime modification

Cost-efficiency

Not available

Case studies where this measure has been applied

• Thur
• Lower Traun

Useful references

• REFORM Wiki - Modify hydropeaking : http://wiki.reformrivers.eu/index.php/Modify_hydropeaking
• USGS - Runoff (surface water runoff) : http://water.usgs.gov/edu/runoff.html (accessed October 7th, 2015).
• MKULNV NRW (Ministerium für Klimaschutz, Umwelt, Landwirtschaft, Natur- und Verbraucherschutz des Landes Nordrhein-Westfalen): http://www.flussgebiete.nrw.de/index.php/Ma%C3%9Fnahmen/M1.0 (German)