Modelling Soil Water Retention for Weed Seed Germination Sensitivity to Water Potential
Table 2
Average fitted parameter and AIC values for the soil water retention models across hillslopes.
Hillslope position
Average parameter values (SE)
AICg
derivation
Model
c
d
e
f
(cm3/cm3)
(MPa)
(dimensionless)
Summit
0.379
Absent
CA
0.000 (—)
−0.0022 (0.0006)
—
3.29 (0.34)
—
−27.6
Measured
BC
0.065 (—)
−0.0042 (0.0006)
—
0.60 (0.05)
—
−28.5
VG5
0.065 (—)
—
−0.0042 (0.0006)
11.14 (0.04)
0.054 (0.005)
−26.5
VG4
0.065 (—)
—
−0.0053 (0.0010)
1.65 (0.07)
—
−28.1
TA
0.065 (—)
—
−0.0115 (0.0035)
—
—
−11.1
RU
0.065 (—)
−0.0011 (<.0001)
—
16.66 (5.07)
—
−13.5
Modified
BC
0.064 (0.011)
−0.0042 (0.0008)
—
0.69 (0.16)
—
−30.1
VG5
0.064 (0.008)
—
−0.0042 (<.0001)
11.83 (<.01)
0.059 (0.006)
−28.1
VG4
0.066 (0.011)
—
−0.0053 (0.0012)
1.79 (0.20)
—
−29.4
TA
0.088 (0.005)
—
−0.0055 (0.0007)
—
—
−24.1
RU
0.087 (0.005)
−0.0011 (<.0001)
—
5.43 (1.40)
—
−24.5
Estimated
BC
0.051 (0.015)
−0.0037 (0.0007)
—
0.51 (0.10)
—
−29.4
VG5
0.051 (0.011)
—
−0.0037 (<.0001)
11.05 (<.01)
0.046 (0.004)
−27.4
VG4
0.055 (0.015)
—
−0.0048 (0.0012)
1.58 (0.13)
—
−28.5
TA
0.106 (0.014)
—
−0.0070 (0.0019)
—
—
−15.6
RU
0.098 (0.015)
−0.0011 (<.0001)
—
9.93 (4.11)
—
−16.8
Backslope
0.391
Absent
CA
0.000 (—)
−0.0023 (0.0004)
—
3.61 (0.23)
—
−32.1
Measured
BC
0.073 (—)
−0.0040 (0.0006)
—
0.54 (0.04)
—
−28.8
VG5
0.073 (—)
—
−0.0040 (0.0006)
21.21 (0.05)
0.025 (0.002)
−26.8
VG4
0.073 (—)
—
−0.0053 (0.0009)
1.59 (0.06)
—
−29.4
TA
0.073 (—)
—
−0.0140 (0.0008)
—
—
−10.2
RU
0.073 (—)
−0.0011 (<.0001)
—
20.87 (6.05)
—
−12.8
Modified
BC
0.061 (0.014)
−0.0034 (0.0006)
—
0.51 (0.10)
—
−33.6
VG5
0.061 (0.010)
—
−0.0034 (<.0001)
9.68 (<.01)
0.052 (0.005)
−31.6
VG4
0.066 (0.009)
—
−0.0044 (<.0001)
1.58 (0.06)
—
−32.9
TA
0.102 (0.006)
—
−0.0055 (0.0009)
—
—
−21.9
RU
0.100 (0.007)
−0.0011 (<.0001)
—
5.57 (1.94)
—
−22.5
Estimated
BC
0.042 (0.015)
−0.0032 (0.0005)
—
0.39 (0.06)
—
−33.3
VG5
0.042 (0.011)
—
−0.0032 (<.0001)
9.38 (<.01)
0.042 (0.003)
−31.3
VG4
0.049 (0.011)
—
−0.0042 (<.0001)
1.45 (0.03)
—
−32.3
TA
0.120 (0.018)
—
−0.0078 (0.0031)
—
—
−13.6
RU
0.108 (0.019)
−0.0011 (<.0001)
—
13.00 (5.66)
—
−15.4
Toeslope
0.417
Absent
CA
0.000 (—)
−0.0014 (0.0003)
—
5.63 (0.30)
—
−34.5
Measured
BC
0.120 (—)
−0.0030 (0.0009)
—
0.41 (0.06)
—
−23.3
VG5
0.120 (—)
—
−0.0030 (0.0009)
19.63 (0.33)
0.021 (0.003)
−21.3
VG4
0.120 (—)
—
−0.0039 (0.0013)
1.44 (0.07)
—
−24.0
TA
0.120 (—)
—
−0.0177 (0.0057)
—
—
−8.1
RU
0.120 (—)
−0.0011 (<.0001)
—
29.02 (10.26)
—
−10.5
Modified
BC
0.000 (—)
−0.0014 (0.0003)
—
0.18 (0.01)
—
−32.5
VG5
0.000 (—)
—
−0.0014 (<.0001)
14.34 (0.24)
0.012 (<.001)
−30.5
VG4
0.000 (—)
—
−0.0016 (<.0001)
1.18 (<.01)
—
−32.8
TA
0.149 (0.005)
—
−0.0039 (0.0008)
—
—
−23.4
RU
0.149 (0.005)
−0.0011 (<.0001)
—
2.35 (1.23)
—
−23.4
Estimated
BC
0.000 (—)
−0.0014 (0.0003)
—
0.18 (0.01)
—
−32.5
VG5
0.000 (—)
—
−0.0014 (<.0001)
14.45 (1.64)
0.012 (0.001)
−30.5
VG4
0.000 (—)
—
−0.0016 (<.0001)
1.18 (<.01)
—
−32.8
TA
0.182 (0.020)
—
−0.0065 (0.0019)
—
—
−11.3
RU
0.162 (0.028)
−0.0011 (<.0001)
—
15.39 (10.95)
—
−12.4
a is measured saturation water content.
b is residual water content.
c is the air entry matric suction (, and of the CA, BC, and RU models, resp.).
d is the capillary pressure at the inflection point on the water retention curve (, , and of the VG5, VG4, and TA models, resp.).
e is a dimensionless parameter (, and of the CA, BC, VG5, VG4, and RU models, resp.).
f is a dimensionless parameter ( of the VG5 model).
gA lower value of Akaike Information Criterion (AIC) indicates a better model fit.