Table 1 Calculation methods and reference values of the indices in the ITO3dE model.
Dimension | Index | Calculation method | Reference value | Source of reference value | Direction of index |
|---|---|---|---|---|---|
Input dimension (A1) | I1 | Chemical fertilizer use intensity per unit of farmland area | 250 kg ha | Building indicators of national ecological town/ county/ city/ province | Positive |
I2 | Pesticide use intensity per unit of farmland area | 2.5 kg ha | Internationally recognized secure usage level | Positive | |
I3 | Calculating the livestock pollution load ratio, the deficiency ratio of environmentally protective facilities for large-scale breeding, and the ratio of large-scale breeding to small-scale breeding by the Nemerrow index23 environmental quality comprehensive evaluation method | Positive | |||
Translate dimension (A2) | I4 | Simplified calculation method of R value, proposed by Zhou et al.58 | 100 J cm ha h | Provisional regulations of ecological function zoning | Positive |
I5 | Calculating the index by a 7 × 7 window through ArcGIS neighborhood statistics | 50 | Provisional regulations of ecological function zoning | Positive | |
I6 | Calculating the K values (soil erodibility) of various land use types based on previous related research and the second overall soil examination results of Chongqing59 | Grading standard in provisional regulations of ecological function zoning | Positive | ||
I7 | Calculating the index according to the grading standard of soil erodibility classification by combining with farmland data and slope data | Field slope of 15° | Grading standard of soil erodibility classification | Positive | |
I8 | Calculating the index by the spatial distance analysis function in GIS, based on the data of three-level above rivers and lakes in the study area | 1500 m | Existing literature and document 60 | Negative | |
Output dimension (A3) | I9 | Calculating the index by computing pollution indices of COD, NH3-N, and TP, using the Nemerow index | Positive | ||
I10 | The ratio of overall runoff generation modulus to regional runoff generation modulus in the study area | 61.95 | Long-term average value during 2005–2015 in Chongqing | Negative | |
I11 | Calculating the index according to the lake and reservoir density and the river density according to the ecological environment status evaluation61 | 0.025 km^2 km^-2 and 0.404 km km^-2 are the reference values of the lake and reservoir density and the river density respectively | Long-term average value during 2005–2015 in Chongqing | Negative | |
I12 | Proportion of paddy field area in farmland area | 0.3339 | Long-term average value during 2005–2015 in Chongqing | Negative | |
