| A | B |
|---|
| Hydrosphere | The part of the earth system that contains the oceans, lakes and streams: underground water ; and snow and ice, including glaciers |
| Evaporation | The process by which a water changes from a liquid into a vapor |
| Transpiration | The process by which water taken up by the roots of plants passes directly into the atmosphere |
| Condensation | The process by which water changes from a vapor into a liquid or solid |
| Precipitation | The process by which water that has condensed in the atmosphere falls as rain, snow or hail on the land or ocean |
| Surface Runoff | Precipitation that drains off over the land or in stream channels |
| Infiltration | The process by which water works its way into the ground, passing through small openings and channels in the soil and other surface materials |
| Stream | A body of water that flows downslope along a clearly defined natural passageway, transporting particles and dissolved substances |
| Channel | The pasageway of a stream |
| River | A stream with a conciderable volume and a well-defined channel |
| streamflow | That part of surface runoff that travels in stream channels |
| Discharge | The amount of water passing by a point on a channels bank during a unit of time |
| Load | The material carried along by a stream |
| Erosion | The wearing away of bedrock and transport of loosened particles |
| Deposition | The laying down of sediment |
| Alluvium | Sediment that has been deposited by a stream in fairly recent times |
| Floodplain | The relatively flat valley floor adjacent to a stream channel, which inundated when the stream overflows its banks |
| Drainage Basin | The total area from which water flows into a stream |
| Divide | The topographic high that separates adjacent drainage basins |
| Lake | A water body that has an upper surface exposed to the atmosphere and has no appreciable gradient |
| Flood | An event in which a water body overflows its banks |
| Ground Water | Sub-surface water, that is, water contained in spaces within bedrock and regolith |
| Water Table | The top surface of the saturated zone |
| Porosity | The percentage of the total volume of the body of rock or regolith that consists of open spaces or pores |
| Permeability | A measure of how easily a solid allows fluids to pass through it |
| Percolation | The process by which ground water seeps downward under the influence of gravity |
| Recharge | Replenishment of ground water |
| Discharge | The process by which sub-surface water leaves the saturated zone and becomes surface water |
| Spring | A flow of gound water that emerges naturally at the ground surface |
| Cave | Underground open space |
| Aquifer | A bosy of water-saturated, porous and permeable rock or regolith |
