| 不透水层面积分分级 | 温度/℃ |
| ≤10% | 33.01108 |
| 11%~20% | 34.41853 |
| 21%~30% | 36.58246 |
| 31%~40% | 36.69606 |
| 41%~50% | 39.08632 |
| 51%~60% | 41.0614 |
| 61%~70% | 41.26859 |
| 71%~80% | 45.9986 |
| 81%~90% | 46.76027 |
| >90% | 48.16331 |