Term | Definition |
Marine Waters | 96.5% of Earth's water; 1.351 billion km of global water supply |
Seawater | Average salinity: 35ppt (35 g/kg); varies slightly depending on pressure, temperature and location |
Frozen Occurences | Ice Caps
Ice Sheets
Polar Ice Caps
Glaciers
Permafrost
Snow & Sleet |
Frozen Waters | 1.74% of water on Earth is currently in the solid state, which accounts for 69.5% of all fresh water resources on Earth (freeing water pushes out any salt) |
Stored Water | The amount of water stored in the solid state has changed drastically over geologic time:
Pleistocene Glacial Maxima
Snowball Earth
Cretaceous epicontinental flooding |
Surficial Ice Deposits | Ice Caps, Ice Sheets, Polar Ice Caps and Glaciers |
Ice Caps | Cover an area <50,000km |
Ice Sheets | Cover an area >50,000km |
Polar Ice Caps | No size limitation, but must be located at very high latitudes |
Glaciers | Large, slow-moving mass of ice |
Permafrost | (Subsurface Ice Deposits) soil that remains below the freezing point for more than two years, where water remains in a solid state; persists in high latitude regions |
Surface Waters | Lakes, Soil, Marshes, Rivers, Plants, Animals; 0.01% of total water - available for use; 0.4% of fresh water sources |
Runoff | Overland Flow
Streams
Rivers
Lakes
Deltas |
Evaporation | Change from liquid to gas phase of water as a result of heating (sublimation: solid to gaseous phase) |
Transpiration | The evaporation of water via plants the exposed aerially (10% of atmospheric water vapor) |
Precipitation | The condensation of water vapor into a liquid (rain) or solid state (snow/hail) |
Water Residence Time | How long water stays in a certain reservoir or system |
Biospheric | 1 week |
Atmospheric | 1-5 weeks |
River | 2 weeks |
Streams | 1-10 years |
Lakes | 10 years |
Soil | 2 weeks |
Ice Caps/Glaciers | 1000 years |
Oceans/Seas | 4000 years |
Groundwater | 2 weeks-10,000 years |
Running Water | Water flows down gradient in response to gravity; water attempts to reach the lowest energy state possible |
Potential Energy | Of the water is related to the elevation at which the water occurs |
Kinetic Energy | Of the water is related to the motion of the water |
Sheet Flow | Water flows down gradient over flat gentle slopes; water flow forms a continuous film across land surface |
Channel Flow | Water flow is a confined to a linear trough-like depressions
Includes: Rills, Gullies, Brooks, Creeks, Streams, Rivers
Classification is based on size and is subjection |
Fluid Flow | Flow behavior depends on the amount of energy in the system; if the infiltration rate into the ground is exceeded by precipitation rate, then surface flow will occur |
Laminar Flow | Flow is constant in one direction; little or no mixing of fluid as it is transported down gradient; parallel line flow of path |
Turbulent Flow | Complex flow paths such that water can be moving in any direction at any instant in time, but as a whole fluid move down gradient; extensive mixing of fluid; Inter |
Turbulence | Created through the irregularities in the channel or bed and the velocity of the water |
Gradient | Slope of the channel bed as drop in elevation over a given distance; change in vertical distance/horizontal distance; generally steeper in upstream direction than in downstream direction; higher the gradient the greater the potential energy in the system |
Velocity | Speed at which fluid is moving; V= distance travelled/time required to travel; Varies across channel width and depth due to resistance (friction) b/w fluid walls/bed |
Velocity Increases | Due to fluid acceleration, channel shape/composition, and the joining of multiple channels, thus increasing total volume of fluid |
Discharge | Volume of fluid to be transported; D=V of fluid X the cross sectional area of the fluid in the channel; Increases down gradient as multiple channels converge |
Dissolved Load | Solution of rock and transport of ions |
Bed Load | (Solid load) Larger material is transported by traction and saltation |
Suspended Load | (Solid load) Small material "float" during transport |
Abrasion | (Solid load) Weathering occurs through the physical impact of solid load with the channel walls and floor |
Hydraulic Abrasion | (Solid load) Physical weathering due to friction between fluid and rock |
Overland Flow | Flow produced when the ground becomes saturated or when the rate of rainfall exceed infiltration rates |
Overland Flow Commonly Occurs: | Arid Regions, Urban areas, Deforested Regions |
Braided Channels | Intricate network of sand/gravel bars and channels |
Bars | Deposited primarily as bed-load; deposited during intense flow, but divide channel during normal flow |
Braided Channels Occur: | In regions where sediment supply exceeds transport capacity; Common in arid, semiarid and arctic regions |
Meandering Channels | Single channels that broadly curve along their flow path |
Cut Banks | Regions of faster water flow on outer edge of meanders where erosion dominates |
Point Bars | Regions of slower water flow on inner edge of meanders where deposition dominates |
Oxbow Lakes | Abandoned meanders that were cut off from main channel |
Floodplain Deposits | Sedimentation that occurs when the fluid capacity of the channel is exceed, primarily during floods |
Fluid | Velocity decreases as it exceeds channel capacity; spreads out and drops its solid load as velocity decreases |
Natural levees | Form at edge of channel where coarse grained sediments drop out as velocity decreases rapidly |
Deltas | Form as channels reach large bodies of water, primarily oceans; sediments are deposited as fluid velocity of decreases |
Progradation | Occurs as sediments build outward through distributary channels |
Delta Types: | Stream Dominated
Wave Dominated
Tide Dominated |
Alluvial Fans | Similar features to deltas that develop on land that primarily form in arid regions |
Alluvial Fan Channel Flow | Channelized flow in high gradient regions rapidly spreads out and decrease velocity as mountain slopes decrease |
Alluvial Fan Deposits | Deposits are usually loose and unstable because of limited vegetation |
Drainage Systems | Region of land over which surface waters drain to a central point during a precipitation event |
Drainage Basins | Divides (topographic highs) divide drainage basins; range in size from local regions to entire continents |
Drainage Patters | Dendritic
Rectangular
Trellis
Radial
Deranged |
Base Level | The lowest level to which any channel can erode; control the erosion and deposition by changing hydrologic gradient |
Ultimate Base level | Sea level; Ultimate base levels shifts with changes in sea level |
Basel Level Shifting | Can shift as:
Resistant beds are breached
Sedimentation occurs
Subsidence
Changes in ultimate base levels |
Graded Profiles | Develop as gradient is smoothed over time |
Sea Level Lowstand | Rivers cut down through the rock to reach the new, lower base level, creating incised valleys |
Sea Level Highstand | Rivers fill up the valleys with sediment and try to reach the new, higher base level, creating flat floodplains |
Base level rise and fall | Results in a complex sequence of sediments being deposited on the continental shelf and in fluvial systems |
Radial (Early) Stage | Downcutting occurs when the stream has excess energy. Deep, narrow, v-shaped valleys form |
Intermediate Stage | Lateral erosion widens valleys often with the assistance of mass wasting; Headward erosion extends valley length and often capture channels (stream piracy); valley broaden |
Aerial Flooding | When more water is supplied than can either run off or infiltrate into the ground in areas not connected to a stream channel;
Caused by:
Shallow water tables
Intense rain or snow melt
Impermeable Surfaces |
Riverine (channel) flooding | When more water is supplied than the river can hold; when a river overtakes its banks;
Caused by:
Excess rain upstream
Stream blockage downstream
Excess precipitation and intense runoff |
Flash floods | Rapid flooding of of low lying areas over less than 6 hours |
Controlling floods | Artificial impoundments are often constructed to prevent flooding:
Levees, Dams, Floodways, floodwalls, reforestation |
Advanced (Late) Stage | Meander streams develop with well-developed stream terraces |