| Term | Definition |
| Surface runoff | Water flowing over the land. |
| Throughfall | Water dripping from one leaf to another. |
| Stemflow | Water running down a plant stem or tree trunk. |
| Throughflow | Water moving slowly downhill through soil. |
| Infiltration | Water soaking into the soil. |
| Percolation | Water seeping down through soil into the water table. |
| Groundwater flow | Water flowing slowly below the water table through permeable rock. |
| Baseflow | Groundwater flow that feeds into rivers through river banks and river beds. |
| Interflow | Water flowing downhill through permeable rock. |
| Channel flow | Water flowing through a river or stream. |