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41 Cards in this Set
- Front
- Back
Hydrologic Cycle
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The undending cycle of water constantly moving from the oceans, to the atmosphere, to the solid earth, and to the biosphere
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Infiltration
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occurs when the precipitation of water returns to the land. It is the portion that soaks into the ground
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runoff
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When the amount of precipitation exceeds the capacity for infiltration, the surplus water flows over the land surface into water bodies thorugh a process called runoff.
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Transpiration
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the situation in which some of the water that infiltrates the ground is absorbed by plants which release the water into the atmosphere
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Sheet flow
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runoff begins to flow in broad, unconfined, thin sheets.
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What determines runoff amount
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infiltration capacity of the soil
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Determinants of infiltration capacity
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1.Intensity and duration of rainfall
2.Prior wetted condition of the soil 3.Soil texture 4.Slope of the land 5.Nature of vegatative cover |
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Rills
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The tiny channels deveeloped by currents of sheet flow which carry water to a stream
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Stream
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"a general term to denote the flow of water within any natural channel. Thus, a small creek and a large river are both streams".
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Gradient
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The slope of a stream chanel expressed as the vertical drop of a stream over a specified distance is gradient
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Discharge
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The discharge of a stream is the volume of water flowing in the stream. Usually measured in cubic meters per second.
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Discharge is equal to
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The stream's cross-sectional area X its velocity
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Head or Headwaters
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"the vertical distance between the recharge and the discharge points of a water table. Also the source area of beginning or of a valley".
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Mouth
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"the point downstream where a river empties into another body of water"
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Ultimate base level
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Sea level
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Local or temporary base level
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can be resistant layers of rocks or main streams
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Base Level
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The lower limit to how deep a stream can erode. Lowering base level will cause a stream to gain energy and erode. Any change in abse level will cause a corresponding readjustment of stream activities
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Meanders
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The bends and turns that streams in a broad flat floored valled that is nea ra base level typically follow. If base level changes, the stream channel will change to balance again, resultingin incised meanders
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Erosion
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"the incorporation and transportation of material by a mobile agent, such as water, wind or ice".
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Capacity
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The maximum load it can carry. Directly related to its discharge, the greater the volume of water flowing in a stream, the greater its capacity for hauling sediment.
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Competence
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Measures the maximum size of particles the stream is capable of transporting. Velocity gets cubed.
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Sorting
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Stream transport provides a mechanism by which solid particles of various sizes are seperated, this process is called ____, and explains why particles of a same size are deposited together. It is important because each particle size has a critical settling velocity.
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Alluvium
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The material deposited by a stream is called alluvium, the general term for any stream deposited sediment. Several features can be produced as the stream deposits certain sediments
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Bars
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Channel deposits composed of sand and gravel
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Point bars
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deposits in the inside of a meander. Debris that is acquired by a stream at the cut bacnk movesdownstream withthe coarser material generally being deposited as point bars in zones of decreased velocity on the inseides of the meanders. In this situation, the meanders migrate laterally by eroding the outside of the bends and depositing on the inside.
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Deltas
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exists in oceans or basins
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Natural Levees
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Form parallel to the stream channel. Area behind natural levees may contain back swamps or yazoo tributaries
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well sorted
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a deposit of sediment consisting of one sediment size
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poorly sorted
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a deposit of sediment consisting in more than one size
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Braided
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streams are termed this way when they consist so f a complex network of converging and diverging channels that thread their way among numerous islands or gravel bars and have an intwoven appearance.
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How does a "Braided" characteristic become produced
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These form when a large proportion of the stream's load consists of coarse material (sand and gravel) and the stream has a highly variable discharge. This bank material is readily erodible, so these types of channels are wide and shallow.
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Floodplain
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A flat, broader valley floor covered with alluvium is termed this way. It is appropriately done so because when a river overflows its bank during a flood stage, it iunudates the floodplain
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Natural Levees- Production
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These are built by successive floods over many years. The elevated landforms composed of alluvium that parallel some streams and act to confine their water, except during a flood stage.
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Backswamps
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a pooorly drained area on a flood plain, resulting when natural levees are present.
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Yazoo Tributaries
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A trubutary that flows parallel to the main stream beacause a natural levee is present
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Delta (Detailed)
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When a stream enters the relatively still waters of an ocean or a lake its velocity drops abruptly and the resulting depositts form a delta. "An accumulation of sediment formed where a stream enters a lake or ocean" **A deposit that forms where a river meets a lake or an ocean
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Distributaries
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A section of a stream that leaves the main flow
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Cut Bank
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The outside zone of the meander which is very active
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Drainage Basin
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The land area that contributes water to a river system
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Divide
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The drainage basin of one stream is seperated by another by this imaginary line. These line sizes vary, in scale from a ridge seperating two small gullies on a hillside to a continental diveide that splits whole continents into enormous drainage basins
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Flood
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"the overflow of a stream channel that occurs when discharge exceeds the chanel's capactiy. This is the most common geologic and destructive hazard".
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