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 Al-Azhar University-Gaza
 Master Program of Water and Environmental 
Science
I.  Introduction
A. Diagram
“ the water table is a subdued replica of the surface topography”

A ground water basin is def...
Regional groundwater flow

- Simple flow nets provide basis for understanding regional groundwater
flow

- flow patterns a...
Natural basin yield - average rate of discharge from a hill slope 
or basin in the 
absence of anthropogenic disturbances
...
Effect of Basin aspect Ratio
-basin shape exerts influence over the groundwater flow pattern
- the basin aspect ratio (len...
- the depth of the basin will also affect the pattern of flow
- in deep basins vertical hydraulic gradient’s exist over a ...
-similarly local flow systems are superimposed on top of regional
flow systems

-independently these flow systems appear s...
-spring flows from local systems is more variable than regional

-intermediate flow systems have at least one local flow s...
Stagnation points
II. Groundwater Flow Patterns
II. Groundwater Flow Patterns
GW Divide
II. Groundwater Flow Patterns
Discharge Zone

Recharge Zone
GW Divide

Hinge Line

Discharge Zone
III. Piezometer Patterns
IV.

Effects of Topography
Toth systems of flow
local
intermediate
regional
IV.

Effects of Topography
IV.

Effects of Topography
V. Flow System Mapping
(recharge and discharge zones)
V. Flow System Mapping
A.

(recharge and discharge zones)
Topography
V. Flow System Mapping
A.
B.

(recharge and discharge zones)
Topography
Piezometer Trends
V. Flow System Mapping
A.
B.
C.

(recharge and discharge zones)
Topography
Piezometer Trends
Hydrochemical Trends
V. Flow System Mapping
A.
B.
C.
D.

(recharge and discharge zones)
Topography
Piezometer Trends
Hydrochemical Trends
Envir...
V. Flow System Mapping
A.
B.
C.
D.
E.

(recharge and discharge zones)
Topography
Piezometer Trends
Hydrochemical Trends
En...
Groundwater-Lake/Wetland interactions
-hydrologic regime of a Lake is strongly influenced by
the regional groundwater flow...
Groundwater that is “noncyclical”
- some groundwater by and large does not take part in flow
systems:
connate water: Water...
VI. Salt Water Encroachment
A. The problem
VI. Salt Water Encroachment
B. Possible Solutions
1. modification of pumping pattern
VI. Salt Water Encroachment
B. Possible Solutions
2. artificial recharge
3. pumping troughs
4. freshwater ridge (injection barrier)
5. subsurface barrier
VI. Salt Water Encroachment
B. Possible Solutions
1. modification of pumping pattern
2. artificial recharge
3. pumping tro...
Quantitative Interpretation of Regional Flow Systems (how much
recharge/discharge)

-using flow net construction we can ca...
Chapter 7 fetter regional groundwater flow
Chapter 7 fetter regional groundwater flow
Chapter 7 fetter regional groundwater flow
Chapter 7 fetter regional groundwater flow
Chapter 7 fetter regional groundwater flow
Chapter 7 fetter regional groundwater flow
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Chapter 7 fetter regional groundwater flow

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Chapter 7 fetter regional groundwater flow

  1. 1.  Al-Azhar University-Gaza  Master Program of Water and Environmental  Science
  2. 2. I.  Introduction A. Diagram “ the water table is a subdued replica of the surface topography” A ground water basin is defined volume of subsurface through  which ground water flows from areas where the water  table is recharged to location where ground water  discharge occurs.
  3. 3. Regional groundwater flow - Simple flow nets provide basis for understanding regional groundwater flow - flow patterns are dictated by the variation in the shape of the basin and water table, and spatial patterns of hydraulic conductivity Discharge area - water is crossing the water table upwards into unsaturated zone, land surface, or base of some surface water body
  4. 4. Natural basin yield - average rate of discharge from a hill slope  or basin in the  absence of anthropogenic disturbances - water table is usually at or near the surface at the discharge  area and are usually the  sites of lakes, marshes, etc. - the line separating recharge from discharge areas is called the  hinge line of (or midline
  5. 5. Effect of Basin aspect Ratio -basin shape exerts influence over the groundwater flow pattern - the basin aspect ratio (length to depth) is one measure of basin  shape -two basins of identical length but different depths will have  different natural basin yields - the deeper basin will have a higher yield because there is more  cross-sectional area to pass the water through
  6. 6. - the depth of the basin will also affect the pattern of flow - in deep basins vertical hydraulic gradient’s exist over a large  portion of the basin - and shallower basins flow is essentially horizontal over most of a  basin Effect of topography -Complex land-surface topography should produce complex  water-table topography
  7. 7. -similarly local flow systems are superimposed on top of regional flow systems -independently these flow systems appear similar but on different  scales -local vs. regional is subjective, but regional is usually considered  to recharge at a basin divide and discharge at a valley bottom -local flow system water has less of a residence time underground  and therefore less interaction with geology -local flow system water temperatures close to mean annual  surface, more active in hydrologic cycle
  8. 8. -spring flows from local systems is more variable than regional -intermediate flow systems have at least one local flow system between their  recharge and discharge areas -for shallow basins the regional system may exist but may be attenuation to as a  result of the dominant influence of local flow systems
  9. 9. Stagnation points
  10. 10. II. Groundwater Flow Patterns
  11. 11. II. Groundwater Flow Patterns GW Divide
  12. 12. II. Groundwater Flow Patterns Discharge Zone Recharge Zone GW Divide Hinge Line Discharge Zone
  13. 13. III. Piezometer Patterns
  14. 14. IV. Effects of Topography Toth systems of flow local intermediate regional
  15. 15. IV. Effects of Topography
  16. 16. IV. Effects of Topography
  17. 17. V. Flow System Mapping (recharge and discharge zones)
  18. 18. V. Flow System Mapping A. (recharge and discharge zones) Topography
  19. 19. V. Flow System Mapping A. B. (recharge and discharge zones) Topography Piezometer Trends
  20. 20. V. Flow System Mapping A. B. C. (recharge and discharge zones) Topography Piezometer Trends Hydrochemical Trends
  21. 21. V. Flow System Mapping A. B. C. D. (recharge and discharge zones) Topography Piezometer Trends Hydrochemical Trends Environmental Isotopes
  22. 22. V. Flow System Mapping A. B. C. D. E. (recharge and discharge zones) Topography Piezometer Trends Hydrochemical Trends Environmental Isotopes Soil, Vegetation and Land Surface Features
  23. 23. Groundwater-Lake/Wetland interactions -hydrologic regime of a Lake is strongly influenced by the regional groundwater flow system in which it sets - large permanent lakes almost always discharge areas for regional groundwater systems - small permanent lakes in upland portions of watersheds usually discharge areas for local or intermediate flow systems -where water table elevations are higher than Lake levels on all sides, recharge-lake only possible if high permeability at depth
  24. 24. Groundwater that is “noncyclical” - some groundwater by and large does not take part in flow systems: connate water: Water which was deposited, by geological means, simultaneously with the surrounding rock formations and held without flow. - This water usually occurs deep in the earth, and is high in mineral content due to long contact with rock. connate water and fossil water often get interchanged - some definitions have connate water as any water that is out of contact with the surface for a long time magmatic water: may contain water that was subducted previously and juvenile water
  25. 25. VI. Salt Water Encroachment A. The problem
  26. 26. VI. Salt Water Encroachment B. Possible Solutions 1. modification of pumping pattern
  27. 27. VI. Salt Water Encroachment B. Possible Solutions 2. artificial recharge
  28. 28. 3. pumping troughs
  29. 29. 4. freshwater ridge (injection barrier)
  30. 30. 5. subsurface barrier
  31. 31. VI. Salt Water Encroachment B. Possible Solutions 1. modification of pumping pattern 2. artificial recharge 3. pumping troughs 4. freshwater ridge (injection barrier) 5. subsurface barrier
  32. 32. Quantitative Interpretation of Regional Flow Systems (how much recharge/discharge) -using flow net construction we can calculate rates are recharge and discharge throughout the basin profile Recharge-discharge profiles -can be created above flow nets -also a good way of checking flow that construction since in steady state recharge must equal discharge - 3-D maps possible as well

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