What is Water Retention?
Water retention is a term from water management: lakes, wetlands and also hydraulic structures such as ponds, terraces or ditches can hold back precipitation, store it temporarily, seep into the ground or distribute it in the landscape. Water can be used on the surface for longer, fed into the groundwater or made available to the plants.
Three basic principles
In English it is the three "s":
- slow
- spread
- sink
In German this means (precipitation) water through decentralized water retention in the landscape to:
- verlangsamen
- verteilen
- versickern
The aim is always to increase intermediate storage and infiltration while reducing surface runoff.
This will allow our watersheds, which presently cause a variety of problems as water runoff areas, to function as water retention areas again.
Effects of decentralized water retention
- Reduced Flood Risk: By retaining water in the landscape, it drains more slowly. Flood waves are dampened (Ryan et al., 2015).
- Drought prevention: By distributing and seeping away precipitation water in the landscape and by storing it in water bodies, vegetation and the soil, it is available longer in the next dry phase (e.g. for agriculture, natural areas)(Ryan et al., 2015).
- Groundwater recharge: Rainwater that collects in decentralized water retention structures can slowly seep away, is filtered through layers of soil, and can replenishe our groundwater.
- Healthier water bodies: Improved flow dynamics and reduced sediment inputs make our bodies of water healthier habitats for diverse flora and fauna(Ryan et al., 2010).
- Improved microclimate: Water evaporating through plants (evapotranspiration) cools the environment (UNEP Forsight, 2021). Water bodies buffer the cold in their surroundings.
More or more regular precipitation: On a larger scale, persistent water and living, transpiring vegetation can increase humidity and contribute to cloud formation. This moisture then falls back locally or regionally in the form of rain, fog or dew (restoration of the “little water cycle”)(UNEP Forseight, 2021; Ryan et al., 2010).
