Parameters and scoring functions for the Rapid Urban Site Index (RUSI) model. Precipitation = PPT; growing degree days = GDD; exposure = EXP; traffic = TRA; infrastructure = INF; surface = SUR; texture = TEX; structure = STR; penetration = PEN; A-horizon = HOR; estimated rooting area = ERA; wet aggregate stability = WAS; soil organic matter = SOM; electrical conductivity = EC; sand = S; sandy clay = SC; silt = SI; sandy loam = SL; clay = C; loam = L; clay loam = CL; loamy sand = LS; sandy clay loam = SCL; silty clay = SIC; silt loam = SIL; silty clay loam = SICL; coarse fragment (>2 mm in diameter) = CF; massive = M; single-grained = SG; platy = PL; angular blocky = ABK; subangular blocky = SBK; granular = GR.
| RUSI | Units | 0 | 1 | 2 | 3 |
|---|---|---|---|---|---|
| PPTa | mm yr−1 | < 500 | 500 to 750 | 751 to 1,000 | > 1,000 |
| GDD | d | < 1,000 | 1,001 to 2,500 | 2,501 to 4,000 | > 4,000 |
| EXP | # | 0 | 1 to 2 | 3 to 4 | 5 |
| TRA | n/a | > 4 lanes | 2 to 4; no parking | 2 to 4; parking | < 2 lanes |
| INF | m | < 1 | 1 to 5 | 6 to 10 | > 10 |
| SUR | n/a | nonpermeable or bare | patchy vegetation | thick vegetation | organic mulch |
| TEX | n/a | no soil; CF > 75% | S, SI, C; CF = 50% to 75% | LS, SCL, SICL, CL, SC, SIC; CF = 25% to 49% | SL, SIL, L; CF < 25% |
| STR | n/a | M, SG, PL | ABK | SBK | GR |
| PEN | cm | < 5 | 5 to 20 | 20 with max effort | 20 with min effort |
| HOR | cm | < 1 | 1 to 5 | 6 to 15 | > 15 |
| ERAb | m2 | < 5 | 5 to 25 | 26 to 50 | > 50 |
| WAS | % | no aggregates | < 50% post soak | < 50% post swirl | > 50% post swirl |
| SOM | IL SOM chart | gray | chip 1 | chip 2 to 3 | chip 4 to 5 |
| EC | μS cm−1 | < 50 or > 3,000 | 50 to 100 or 2,001 to 3,000 | 101 to 300 or 1,001 to 2,000 | 301 to 1,000 |
| pH | n/a | < 4 or > 9 | 4 to 4.9 or 8.1 to 9 | 5 to 5.9 or 6.6 to 8 | 6 to 6.5 |