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Summary - Water 1
1.1 Catchment characteristics
What is a catchment and why is this unit used?The area from which excess water flows towards that river.
Which landscape properties affect hydrology?1) size
How can the catchment boudary be delineated?1) Topographical water divide (follows the highest point in the landscape)
2) Groundwater devide (infiltrating water may hit an impermeable layer in the ground and be led in another direction
What is the 1st zone of a catchment?Zone 1 : Upper course / upstream area / production zone
- dense dendritic network of channels
- surface water and sediments are formed
What is the 2nd zone of a catchment?Zone 2 : Middle course / transport zone
- main channel which meanders throug the landscape
- surface water and sediments are transported
What is the 3d zone of a catchment?Zone 3 : Lower course / downstream area / deposition zone
- multiple braches as a result of the flat landscape
- low flow velocity causes sediment to settle
What is the topographic wetness indexDraining area : local slope
High is wet
Which hillslopes are the wettest?Concave converging slopes
Which hillslopes are the dryest?Convex diverging slopes.
What is porosity?The fraction of open spaces between the soil particles. Detirmines how much water is stored underground.
What is conductivity?A measure of how easy it is for water to flow betweeen soil particles. Determines how quickly water is transported.
What is an aquifer?A layer of permeable soil. Can store and transport water well.
What is a DEM?Gives the elevation for each pixel on a map.
What is a GIS?This spatial data can be used as input for computer models simulating the hydrological processes in different parts of the catchment en predict river discharge.
What is topology?Channel networks.
What is the formula for drainage density?Dd = Ltot : A
Dd = drainage density
Ltot = total length of the channels
A = certain area (m2)
What does an high drainage density indicate?A certain area contains many channels and the average distance from a location on land to the nearest channel is small. And there is water flowing on the ground (low conductivity, farming)
What is a dendritic pattern?Tree shaped channel network. Homogeneous geological fromations.
What is a radial pattern?Streams start from 1 central point and flow into all directions.
What is a trellis pattern?Large number of cahnnels that have the same direction on easch side of the river. Folds in the earths crust.
What is a parallel pattern?Occurs on steep slopes where the water flows downhill fast.
What are the rules of Strahler order numbering?- exterior links get order 1 (links between source and first junction)
- when links of the first order merge, add 1
- when links with different orders merge, it will continue as the highest
- the highest order is always found at the outlet and represents the Strrahles order of the catchment
Latest added flashcards
3rd: planktivorous fish
- scramble competition
-food web relations
- food web
2. Water management: reduce peak discharges to prevent weirs
3. Natural morphology
- re-meandering (restore natural profile)
- remove obstacles -> install fish ladders
- retention areas, inundation zones
-regulation of morphology (meanders weghalen etc)
- obstacles (weirs/stuwen)
-dams and reservoirs
shredders: predominantly upper reach and a little in middle reach
grazers: middle reach and a little in upper reach
collectors: predominantly lower reach
-collectors: filter/collect FPROM 0,5 mum-1 mm
-scrapers/grazers: eat periphyton
- more open:
- lower flow velocity
- high primary
-low flow velocity