Spatial Combination Modeling Framework of Saturation-Excess and Infiltration-Excess Runoff for Semihumid Watersheds
Table 4
The optimized parameters of the spatial combination models.
Parameter meaning
SCM I
SCM II
Ratio of potential evapotranspiration to pan evaporation
0.65
0.65
Exponential parameter with a single parabolic curve, which represents the nonuniformity of the spatial distribution of the soil moisture storage capacity over the watershed
0.3
0.3
Coefficient of the deep layer that depends on the proportion of the basin area covered by vegetation with deep roots
0.08
0.08
Averaged soil moisture storage capacity (mm)
180
180
Averaged soil moisture storage capacity of the upper layer (mm)
20
20
Averaged soil moisture storage capacity of the lower layer (mm)
90
90
Percentage of impervious areas in the watershed
0.01
0.01
Areal mean free water capacity of the surface soil layer, which represents the maximum possible deficit of free water storage (mm)
35
34
Exponent of the free water capacity curve influencing the development of the saturated area
1.2
1.2
Outflow coefficients of the free water storage to groundwater relationships
0.35
0.35
Outflow coefficients of the free water storage to interflow relationships
0.35
0.35
Recession constants of the groundwater storage
0.998
0.998
Recession constants of the lower interflow storage
0.768
0.902
Recession constants in the lag and route method for routing through the channel system within each subbasin
0.038
0.026
Lag in time (h)
0
0
Coefficient representing the ratio of surface soil thickness to the vadose zone thickness
0.4
0.4
Steady-state infiltration capacity (mm⋅h−1)
1
1.2
Infiltration coefficient of the improved Horton equation
0.004
0.007
The maximum point infiltration capacity in the watershed (mm⋅h−1)
249
211
Exponent of the spatial infiltration capacity distribution curve
1.5
1.7
Recession constants of the interflow and groundwater storage
