How does water movethrough the drainage    basin system?
Elements of a drainage basin: Inputs Flow / Transfer Storage Output
Input:   major input - precipitation.   The type: rain or snow, hail, etc.   Factors affecting the amount of water in t...
Flow / transfer:   Interception   Throughfall   Stemflow   Overland flow   Infiltration   Percolation   Throughflow...
Interception   defined as the capture of    precipitation by the plant    canopy and return to the    atmosphere through ...
   leaf type – increase interception capacity if leaves &                twigs are dry    wind speed – the higher the wi...
   Throughfall:       the process of        precipitation        passing through the        plant canopy (Yellow        ...
   Stemflow:       is the process that directs        precipitation down plant        branches and stems (red        arr...
Infiltration   Some of the precipitation    seeps into the ground and    stored in aquifers   then it is transported to ...
Overland Flow    Rills - Water moving over ground in small channels    Sheetflow - Water moving over ground across the who...
Overland flow
Rills
Sheetflow
   A process where water enters the ground    vertically through pores   Factors affecting infiltration:       Intensit...
   the slow movement of water through compact layers of soil    and rocks   Factors affecting percolation:       Precip...
   Water transfers laterally in the aquifers   If the water table reaches the surface it means ground is    saturated.(a...
Channel flow   Water transfers to channel through 3    processes:     Surface run-off     Throughflow     Groundwater ...
   Rainfall   Vegetation and land use   Climate   Shape   Conditions in drainage basin   Size and shape of the river...
   Groundwater Storage   Interception Storage   Aeration Zone Storage   Depression Storage   Surface Storage
   Process of percolation produces groundwater    storage   Water collected above the impermeable layer   Or it may fil...
   Soil pores are mostly    filled with    microchannels so    water can move as    percolation and    throughflow   Bio...
   Water accumulates   all the soil pores are full    of water   Baseflow / groundwater    occurs   No biological acti...
   Zone between the    unsaturated and    saturated zones   Changing patterns of    precipitation and EVT    throughout ...
18                         Infiltration rate                    16                                            Rainwater wh...
How does water move through the drainage basin  lesson 3
How does water move through the drainage basin  lesson 3
How does water move through the drainage basin  lesson 3
How does water move through the drainage basin  lesson 3
How does water move through the drainage basin  lesson 3
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How does water move through the drainage basin lesson 3

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How does water move through the drainage basin lesson 3

  1. 1. How does water movethrough the drainage basin system?
  2. 2. Elements of a drainage basin: Inputs Flow / Transfer Storage Output
  3. 3. Input: major input - precipitation. The type: rain or snow, hail, etc. Factors affecting the amount of water in the system:  the intensity,  the duration and  Frequency of the precipitation
  4. 4. Flow / transfer: Interception Throughfall Stemflow Overland flow Infiltration Percolation Throughflow Groundwater flow / baseflow Channel flow
  5. 5. Interception defined as the capture of precipitation by the plant canopy and return to the atmosphere through evaporation or sublimation.* Interception loss: water which is retained by plant surfaces and which is later evaporated away & absorbed by plant
  6. 6.  leaf type – increase interception capacity if leaves & twigs are dry wind speed – the higher the wind speed the lower the interception capacity - the more frequent the storm events lesser the interception loss temperature, and the humidity of the atmosphere
  7. 7.  Throughfall:  the process of precipitation passing through the plant canopy (Yellow lines)  Factors affecting:  plant leaf and stem density,  type of the precipitation,  intensity of the precipitation,  and duration of the precipitation event.
  8. 8.  Stemflow:  is the process that directs precipitation down plant branches and stems (red arrows ).  this process causes the ground area around the plants stem to receive additional moisture.  The amount of stemflow is determined by  leaf shape and stem  branch architecture.  In general, deciduous trees have more stemflow than coniferous vegetation.
  9. 9. Infiltration Some of the precipitation seeps into the ground and stored in aquifers then it is transported to streams and lakes by subsurface flow. The amount of infiltration is influenced by:  the permeability and moisture content of the soil,  the presence of vegetation and  the volume and intensity of
  10. 10. Overland Flow Rills - Water moving over ground in small channels Sheetflow - Water moving over ground across the whole surface Hortonian Overland Flow: Saturated Overland Flow: infiltration excess overland  Long period of steady flow rain and water table reach the surface rainfall is greater than infiltration capacity  No additional water can E.g. If a soil surface can be infitrated so must infiltrate 30mm/hr but remain on surface precipitation is 40mm/hr, therefore 10mm will be overland flow  Common in the temperate Very common in the tropics
  11. 11. Overland flow
  12. 12. Rills
  13. 13. Sheetflow
  14. 14.  A process where water enters the ground vertically through pores Factors affecting infiltration:  Intensity & duration of the precipitation  Type of soil  Vegetation & Land cover  Slope of the land  Evapotranspiration  Soil saturation
  15. 15.  the slow movement of water through compact layers of soil and rocks Factors affecting percolation:  Precipitation  Relief – steeper the gradient the less water will be percolated  Flora & fauna – animal tunnels & burrow - root system of direct movement of water in the soil  Rock structure / composition  Porous rock – sandstone  Permeable rock - limestone
  16. 16.  Water transfers laterally in the aquifers If the water table reaches the surface it means ground is saturated.(a) infiltration to deep groundwater,(e) overland flow to (g)(g) temporary ponds(f) deep groundwater flow.
  17. 17. Channel flow Water transfers to channel through 3 processes:  Surface run-off  Throughflow  Groundwater flow /baseflow
  18. 18.  Rainfall Vegetation and land use Climate Shape Conditions in drainage basin Size and shape of the river basin Soil type and depth Bedrock
  19. 19.  Groundwater Storage Interception Storage Aeration Zone Storage Depression Storage Surface Storage
  20. 20.  Process of percolation produces groundwater storage Water collected above the impermeable layer Or it may fill all the pores spaces, creating a zone of saturation Above the impermeable layer, there are 3 zones:  An unsaturated zone  A saturated zone  An intermediate zone
  21. 21.  Soil pores are mostly filled with microchannels so water can move as percolation and throughflow Biological activity with plant roots, soil flora and fauna create microchannels
  22. 22.  Water accumulates all the soil pores are full of water Baseflow / groundwater occurs No biological activity
  23. 23.  Zone between the unsaturated and saturated zones Changing patterns of precipitation and EVT throughout the year gives a layer which is alternatively saturated and unsaturated Interflow occurs
  24. 24. 18 Infiltration rate 16 Rainwater which is not infiltrated will become 14 surface run-off / overlandInfiltration Rate flow 12 10 8 6 4 2 0 1 2 3 4 5 6 Hours from the start of rainfall
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