Geomorphology
, glossary of words
Drainage systems in south africa
- Surface run-off: water flowing downslope over the ground
- Groundwater: water found underground
- Saturated zone: part of the crust where all air spaces are filled with groundwater
- Water table: upper limit of the saturated zone
- Aerated zone: part of the crust above the water table where there are open air spaces
- Drainage basin: areas drained by a river system or stream network
- Direct runoff: water flowing over Earth in river channels
- Indirect runoff: water feeding into rivers by either surface runoff or base flow
- Base flow: water feeding river valleys from underground
- Source: the start of a river
- Mouth: the end of a river
- Tributary: a smaller river joining the main river
- Confluence: the point where two rivers join
- River system: the network of all tributaries that join to form one main river that flows into the sea
- Catchment area: the area that feeds water into a river system
- Watershed: the high ground around a draining basin that separates one drainage basin from another
- Permanent rivers: rivers that flow all year because the river bed is deeper than the water table all year
- Periodic rivers: rivers that only flow during the rainy season when the rainy season water table is
higher
- Episodic rivers: rivers that hardly ever flow because they are in low rainfall areas and the water table is
always below the river bed
- Exotic rivers: rivers found in low rainfall areas but flow all year because they are fed by tributaries in
high rainfall areas
- Perennial river: a river that flows all year round
- Non-perennial river: a river which does not flow all the time
- Drainage pattern: the pattern of a river system when seen on a map
- Stream pattern: another name for drainage pattern
- Dendritic drainage pattern: tributaries join at less than 90 degrees so the pattern looks like branches
of a tree
- Trellis drainage pattern: parallel main streams with short tributaries joining at 90 degrees
- Rectangular drainage pattern: main streams and tributaries take 90 degree bends
- Radial drainage pattern: rivers drain outwards, away from a high point such as a mountain peak
- Centripetal drainage pattern: rivers drain towards a central low point
- Deranged drainage pattern: no specific pattern
- Parallel drainage pattern: tributaries are mostly parallel to each other of the main stream
- Stream order: a number given to a segment of a river to indicate the interconnectedness of the
tributaries in a river system
- First order stream: source tributaries that do not have any streams flowing into them
- Second order stream: segment of a river after two first order streams gave joined together
- Third order stream: two second order streams join to form a third order stream
- Laminar flow: river flowing smoothly with no vertical mixing
- Turbulent flow: river water flowing with much vertical movement
, glossary of words
Drainage systems in south africa
- Surface run-off: water flowing downslope over the ground
- Groundwater: water found underground
- Saturated zone: part of the crust where all air spaces are filled with groundwater
- Water table: upper limit of the saturated zone
- Aerated zone: part of the crust above the water table where there are open air spaces
- Drainage basin: areas drained by a river system or stream network
- Direct runoff: water flowing over Earth in river channels
- Indirect runoff: water feeding into rivers by either surface runoff or base flow
- Base flow: water feeding river valleys from underground
- Source: the start of a river
- Mouth: the end of a river
- Tributary: a smaller river joining the main river
- Confluence: the point where two rivers join
- River system: the network of all tributaries that join to form one main river that flows into the sea
- Catchment area: the area that feeds water into a river system
- Watershed: the high ground around a draining basin that separates one drainage basin from another
- Permanent rivers: rivers that flow all year because the river bed is deeper than the water table all year
- Periodic rivers: rivers that only flow during the rainy season when the rainy season water table is
higher
- Episodic rivers: rivers that hardly ever flow because they are in low rainfall areas and the water table is
always below the river bed
- Exotic rivers: rivers found in low rainfall areas but flow all year because they are fed by tributaries in
high rainfall areas
- Perennial river: a river that flows all year round
- Non-perennial river: a river which does not flow all the time
- Drainage pattern: the pattern of a river system when seen on a map
- Stream pattern: another name for drainage pattern
- Dendritic drainage pattern: tributaries join at less than 90 degrees so the pattern looks like branches
of a tree
- Trellis drainage pattern: parallel main streams with short tributaries joining at 90 degrees
- Rectangular drainage pattern: main streams and tributaries take 90 degree bends
- Radial drainage pattern: rivers drain outwards, away from a high point such as a mountain peak
- Centripetal drainage pattern: rivers drain towards a central low point
- Deranged drainage pattern: no specific pattern
- Parallel drainage pattern: tributaries are mostly parallel to each other of the main stream
- Stream order: a number given to a segment of a river to indicate the interconnectedness of the
tributaries in a river system
- First order stream: source tributaries that do not have any streams flowing into them
- Second order stream: segment of a river after two first order streams gave joined together
- Third order stream: two second order streams join to form a third order stream
- Laminar flow: river flowing smoothly with no vertical mixing
- Turbulent flow: river water flowing with much vertical movement
