Research Article
Assessment of the Impacts of Land Use Changes on Nonpoint Source Pollution Inputs Upstream of the Three Gorges Reservoir
Table 3
List of sensitive parameters calibrated and ranges and values of major parameters used.
| Name | Description | Range | Optimum value | Sensitivity | Min | Max |
| SDNCO1 | Denitrification threshold water content | 0.908 | 0.987 | 0.974 | 0 | PPERCO2 | Phosphorus percolation coefficient (10 m3/Mg) | 14.578 | 14.770 | 14.674 | 0.02 | RSDCO3rs | Coefficient for mineralization of the residue fresh organic nutrients | 0.052 | 0.086 | 0.070 | 0.14 | PHOSKD4 | Phosphorus soil partitioning coefficient | 128.810 | 133.328 | 131.069 | 0.17 | BC45 | Local rate constant for organic phosphorus mineralization at 20°PHC (day−1) | 0.267 | 0.283 | 0.277 | 0.21 | ERORGP6 | Phosphorus enrichment ratio | 1.913 | 1.929 | 1.928 | 0.23 | BC17 | Rate constant for biological oxidation of ammonia nitrogen at 20°C (day−1) | 0.116 | 0.128 | 0.121 | 0.23 | GWSOLP8 | Concentration of soluble phosphorus in groundwater contribution to streamflow from subbasin (ppm). | 0.134 | 0.152 | 0.152 | 0.24 | USLE_K9 | Soil erodibility factor (0.013 metric ton m2 hr/(m3-metric ton cm)) | 5.752 | 6.963 | 6.600 | 0.25 | CMN10 | Rate coefficient for mineralization of the humus active organic nutrients | 0.001 | 0.001 | 0.001 | 0.26 | SHALLST11 | Initial depth of water in the shallow aquifer (mm H2O) | 2.773 | 2.992 | 2.989 | 0.42 | USLE_C12 | Minimum value for the cover and management factor | 0.028 | 0.036 | 0.032 | 0.67 | GW_DELAY13 | Delay time for aquifer recharge (days) | 1.584 | 1.670 | 1.608 | 0.71 | SPEXP14 | Exponent in sediment transport equation | 1.270 | 1.270 | 1.270 | 0.81 | ERORGN15 | Organic nitrogen enrichment ratio | 1.926 | 1.930 | 0.154 | 0.9 | REVAPMN16 | Threshold water level in shallow aquifer for revap or percolation to deep aquifer (mm H2O) | 282.438 | 291.261 | 286.850 | 0.94 | NPERCO17 | Nitrate percolation coefficient | 0.583 | 0.609 | 0.596 | 0.95 | CH_K18 | Effective hydraulic conductivity in main channel alluvium | 54.074 | 55.028 | 54.551 | 0.98 |
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aSuperscripts of each parameter are their corresponding orders from the sensitivity analysis.
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