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Geography Chapter 14
Term | Definition |
---|---|
Fluvial | Stream related processes; from the Latin 'fluvius' meaning 'river' |
Erosion | Denudation by wind, water, or ice, which dislodges, dissolves, or removes surface material |
Deposition | The process whereby weathered, wasted, and transported sediments are laid down by gravity, wind, water, and ice |
Drainage Basin | The basic spatial geomorphic unit of a river system; marked by ridges and highlands that form divides |
Sheetflow | Surface water that moves downslope in a thin film as overland flow |
Drainage Pattern - | A distinctive geometric arrangement of streams in a region, determined by slope, differing rock resistance to weathering and erosion, climatic and hydrologic variability, and structural controls of the landscape |
- Dendritic | A tree-like pattern created from an area of similar rock structure; numerous short tributaries converge on one main channel |
- Rectangular | Formed by a faulted and jointed landscape which directs stream courses at right angles |
- Trellis | Formed in areas of nearly parallel mountains where alternating larger ones at right angles |
- Parallel | Associated with steep, newly uplifted slopes with uniform surfaces |
- Radial | Formed where streams flow off a central peak or dome such as a volcanic mountain |
- Annular | Created by dome structures with concentric patterns of rock strata, more and less resistant rock types |
- Deranged | Formed in areas affected by continental glaciation such as the Canadian Shield; no clear pattern is evident |
Discharge | The measured volume of flow in a river that passes by a given cross section of the stream in a given unit of time; expressed in cubic metres per second |
Hydraulic Action | The erosive work accomplished by the turbulence of water |
Abrasion | A type of erosion that breaks up rock particles and wears away bedrock, accomplished by the rolling and grinding of particles carried in a stream |
Sediment Transport | The movement of solid particles (sediment), typically by the action of gravity or the movement of a fluid in which the sediment is entrained |
Dissolved Load | Materials carried in chemical solution in a stream, derived from minerals such as limestone and dolorite |
Suspended Load | Fine particles held in suspension in a stream |
Bed Load | Coarse materials (too large for suspension) that are dragged along the bed of a stream by traction |
Saltation | The transport of fine sediment by bouncing along the stream bed in asymmetrical paths |
Solution | Dissolved sediment particles |
Traction | A type of sediment transport that drags coarser materials along the bed of a stream |
Degradation | The process occurring when sediment is eroded along a stream |
Aggradation | The general building of a land surface because of deposition of material; opposite of degradation |
Gradient | The drop in elevation from a stream's headwaters to its mouth, ideally forming a concave shape |
Meander (meandering stream) | The sinuous, curving pattern common to graded streams |
Undercut Bank | A bank that has experienced erosion on the lower half |
Oxbow Lake | A lake that was formerly part of the channel of a meandering stream; isolated when the stream eroded the outer bank |
Point Bar | In a stream, the inner portion of a meander, where sediment fill is redeposited |
Braided Stream | A stream carrying a high sediment load that becomes a maze of interconnected channels |
Floodplain | A flat, low-lying fluvial landform composed of alluvium along a stream or river channel, created by and subject to recurrent flooding |
Alluvial Terraces | Level areas composed of alluvium that appear as topographic steps above a stream, produced by erosion |
Delta | A depositional plain formed where a river enters a lake or an ocean |
Estuary | The point at which the mouth of a river enters the sea, where freshwater and seawater are mixed |
Natural Levee | A long, low ridge that forms on both sides of a stream in a developed floodplain |
Artificial Levee (Dike) | Human-built earthen embankments along river channels |
Flood | A high water level that overflows the natural river bank along any portion of a stream |