Retention Potential of the Regional Water Balance
Favourable conditions for the quality of water retention services are met when ...
- high (surface-near) median water levels prevail and with that the requirement of higher humidity through evaporation and cooling
- the peatland is hydrogeolocically benefitting from surrounding mineral substrates characterized by low infitration rates in the catchment area (Edom 2001)
- the peatland is hydrogeolocically benefitting from water retaining organo-mineral gyttja at its basis
Determination of Parameters
- Water Height: The higher the water level, the larger the water-filled pore volume of a peatland and the larger the available water storage capacity during drier periods. Compared to mineral soils, peat soils (Schlichting et al. 1995) have a much larger pore volume (approx. 90 %) and, for this reason, the highest water storage potentials.
- Peatlands with underlying, water-retaining gyttjas are better protected against loss from seepage than peatlands without underlying gyttjas. Gyttjas have much lower kf-values (coefficient of permeability) than sands and gravel (Waniek 2014).
- Geology of catchment area: The water retention potential is to a major extent dependent on the permeability of substrates. If the catchment area is dominated by silty and clayey substrates (ground moraine, basin clay, and others), seepage is relatively small. If, however, sandy and gravelly substrates prevail, they promote seepage from the peatland into the mineral subsoil and into the catchment area (Rowinsky 1995), as the water permeability (kf-values) of sand and gravel (> 100 cm/d) is significantly higher than that of silt and clay (< 100 m/s as a rule).
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