Fluvial Geomorphology Flashcards
Definition of a watershed
forms an imaginary dividing line between 2 drainage basins.
Drainage basin boundary
this forms the catchment area of the basin
Confluence
the point where 2 or more streams meet along the course of a river
Source
the origin of a river, in the catchment area
Interfluve
the area between two tributaries, which are about to form a confluence point.
Hydrological cycle
Runoff and infiltration -> evaporation -> precipitation
Permanent rivers
- receive water all year
- water table always lies above the river bed
Periodic rivers
- have a base flow that only contributes during the rainy season
- Below wet water table, on the dry water table
Episodic rivers
- never supplied with groundwater
- only flows after a heavy downpour, causing flash floods
- base flow above wet and dry water table
Exotic rivers
- rise in high rainfall areas, but flow mostly through dry regions
- groundwater does not contribute
- base flow above wet and dry water table
Laminar flow
when the river bed is very level and even, velocity is low, water moves in thin layers
- Flows in sheets
- No eddies
- Smoothness reduces friction and thus turbulence
- Usually a gentle gradient
Turbulent flow
When the velocity of the river increases or if the river bed is uneven, a more irregular, whirling flow results
- Water forms eddies and bubbles
- Seethes down the slope
- Friction causes turbulence
- Gradient is steeper and erosion takes place
Types of river loads
Solution load = minerals and dissolved substances
Suspension load = fine insoluble particles in suspension
Bed load = heavier particles bounce along bed, called saltation
Bed load = heaviest pebbles and boulders, rolled and shoved down stream - traction
Factors affecting flow hydrograph
- Size of the basin
- Shape of the basin
- Relief
- Underlying rock and soil
- Climatic features
- Vegetation cover
- Human impact
Transverse vs Longitudinal profile
T = shows shape
L = side view
