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Berlin Environmental Atlas

01.06 Soil-Scientific Characteristic Values (Edition 2009)

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01.06.10 Water Permeability (kf)


Description

Water permeability (saturated water conductivity, kf value) indicates the permeability of soils. It depends on the soil type and storage density of the soil. Loose soils with high sand contents therefore have a considerably higher permeability than do clay-rich soils consisting of till. Water permeability is important for the evaluation of storage wetness, filtration qualities, erosion vulnerability and drainage effectiveness of soils. The speed of water permeability is given in m/s or in cm/d. The data on speed of water movement apply only to completely water-saturated soil, in which all pore spaces are filled with water. As a rule, terrestrial soils display non-saturated water conditions, with only a portion of the pores filled with water; at such non-saturated conditions, water movement is considerably slower. In addition, a large portion of the available water is taken up by the plants and is not available for flow. Since measurement of non-saturated water conductivity (ku) is very expensive and complicated, so that no accessible data are available in the Soil-Scientific Mapping Directive (1994), the attested values for saturated water conductivity are used in scientific practice as a rough measure.

The influence of the coarse soil was not taken into account.

Methodology

The kf value for the main soil types of the topsoil and the subsoil according to Table 1 was taken. The kf value for the topsoil and subsoil is the average of the topsoil kf and the subsoil kf. The kf values listed in the Table depending on soil type are based on an effective storage density of Ld3, which corresponds to the average for Berlin soils.

Table 1: Water Permeability in Water-Saturated Soil (kf value)
Type of soil kf value
[cm/d]
fHn 30
fS 106
fSms 169
gSfs 130
Hn 30
Hu 30
Ls2 20
Ls3 7
Ls4 14
Lt2 9
Lt3 10
Lts 6
Lu 18
mS 427
mSfs 221
mSgs 281
Sl2 49
Sl3 33
Sl4 21
 
Type of soil kf value
[cm/d]
Slu 11
Ss 229
St2 79
St3 17
Su2 88
Su3 32
Su4 24
Tl 3
Tt 2
Tu2 5
Tu3 28
Tu4 28
Uls 14
Us 10
Ut2 7
Ut3 8
Ut4 9
Uu 7
   
Table 1: Water Permeability in Water-Saturated Soil (kf value) by Soil Type at the Mean Effective Retention Density of Ld3, Supplemented by Medium-Decomposed Peat (Z 3) at Medium Substance Volume (SV 3); from the Soil-Scientific Mapping Directive (1994)

For representation on the map, the results of water permeability have been categorized in six stages, from very low to extremely high (1 -6), as shown in Table 2.

Table 2: Classification of Water Permeability in Water-Saturated Soil
kf value
[cm/d]
Stage Designation
0 - <1 1 very low
1 - <10 2 low
10 - <40 3 medium
40 - <100 4 high
100 - <300 5 very high
≥300 6 extremely high
Table 2: Classification of Water Permeability in Water-Saturated Soil
(Soil-Scientific Mapping Directive 1994)

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