Fourteen parameters for hydrology and sediment simulation (Table 1) were calibrated utilizing root mean squared error (RMSE) and relative error as objective functions, respectively. The calibrated model provided good monthly runoff and sediment load predictions for the entire simulation period of 6 years from 1990 to 1995 with Nash–Sutcliffe efficiency coefficients of 0.60 and 0.58 and coefficient of determination of 0.83 and 0.79, respectively. The parameters are described and calibrated values shown in Table 1.
Parameters of HYSTAR and their calibrated values
Process . | Parameter . | Description . | Feature . | Range . | Calibrated value . |
---|---|---|---|---|---|
Direct runoff | CNF | Curve number scale factor | Spatial scale factor | 0.5–1.5 | 1.094 |
MNO | Manning's roughness coefficient scale factor for overland areas | Spatial scale factor | 0.5–1.5 | 1.054 | |
MNC | Manning's roughness coefficient scale factor for channel | Spatial scale factor | 0.5–1.5 | 1.171 | |
THA | Threshold area that defines initiation points of channel networks | Unit: ha | 1–100 | 17.91 | |
Soil moisture | GCL | Coefficient L of the van Genuchten equation | – | 0.25–0.75 | 0.662 |
GCM | Coefficient M of the van Genuchten equation | – | 0.25–0.75 | 0.325 | |
BCC | Basal crop coefficient scale factor | Spatial scale factor | 0.5–1.5 | 0.512 | |
EFS | Effective fraction of soil surface covered by vegetation scale factor | Spatial scale factor | 0.5–1.5 | 1.187 | |
RZD | Root zone depth scale factor | Spatial scale factor | 0.1–2.0 | 0.339 | |
SAR | Soil anisotropy ratio | – | 0.1–2.0 | 0.164 | |
Sediment transport | CSO | Critical Shields parameter for overland flow | – | 0.1–10.0 | 0.744 |
CSC | Critical Shields parameter for channel flow | – | 0.035–2.0 | 0.057 | |
SDR | Soil detachability ratio scale factor | Spatial scale factor | 0.1–2.0 | 0.891 | |
SCR | Soil cohesion ratio scale factor | Spatial scale factor | 0.1–2.0 | 1.066 |
Process . | Parameter . | Description . | Feature . | Range . | Calibrated value . |
---|---|---|---|---|---|
Direct runoff | CNF | Curve number scale factor | Spatial scale factor | 0.5–1.5 | 1.094 |
MNO | Manning's roughness coefficient scale factor for overland areas | Spatial scale factor | 0.5–1.5 | 1.054 | |
MNC | Manning's roughness coefficient scale factor for channel | Spatial scale factor | 0.5–1.5 | 1.171 | |
THA | Threshold area that defines initiation points of channel networks | Unit: ha | 1–100 | 17.91 | |
Soil moisture | GCL | Coefficient L of the van Genuchten equation | – | 0.25–0.75 | 0.662 |
GCM | Coefficient M of the van Genuchten equation | – | 0.25–0.75 | 0.325 | |
BCC | Basal crop coefficient scale factor | Spatial scale factor | 0.5–1.5 | 0.512 | |
EFS | Effective fraction of soil surface covered by vegetation scale factor | Spatial scale factor | 0.5–1.5 | 1.187 | |
RZD | Root zone depth scale factor | Spatial scale factor | 0.1–2.0 | 0.339 | |
SAR | Soil anisotropy ratio | – | 0.1–2.0 | 0.164 | |
Sediment transport | CSO | Critical Shields parameter for overland flow | – | 0.1–10.0 | 0.744 |
CSC | Critical Shields parameter for channel flow | – | 0.035–2.0 | 0.057 | |
SDR | Soil detachability ratio scale factor | Spatial scale factor | 0.1–2.0 | 0.891 | |
SCR | Soil cohesion ratio scale factor | Spatial scale factor | 0.1–2.0 | 1.066 |