Geomorphic controls on regional base flow

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Geomorphic controls on regional base flow

• Marco Marani
• Elfatih Eltahir
• Andrea Rinaldo

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Study Summary

• Recharge
• Geomorphic and topographic influences
• Groundwater response

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Background Summary

• Signatures
• Geomorphic variance
• Nonlinearity in groundwater rating curves

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On the asymmetric response of aquifer water level
to floods and droughts in IllinoisEltahir and
Yeh1999

• Floods and droughts in Illinois from 1983-1994
• Variables flux of atmospheric water vapor,
  precipitation, soil, moisture content,
  groundwater level, river flow
• Aquifers respond differently

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Seasonal Cycles
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Time series of normalized anomalies
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Physical basis of the nonlinear groundwater
rating curve

• qgKhr2DL
• qg base flow discharge
• K hydraulic conductivity
• hr average elevation
• of aquifer
• D drainage density
• L channel length

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Theoretical-Groundwater Rating Curves

• Water head fluctuations
• Aquifer thickness 100-102 m
• Planar 103-106 m
• Groundwater curve generated by steady states

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Aquifer water level and drainage density

• Usual definitionDdL/A
• Depends on geomorphic controls
• Topographically concave sites

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Aquifer transmissivity

• TKbL2/t
• Effects of geomorphic controls
• Geomorphic heterogeneity and vertical variability

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Basic Continuity Equation

• r net recharge
• T reference regional transmissivity

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Components
Assumption of NO FLOW Seepage Face
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GW surface with topography
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Saturation with recharge (r)
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Robustness of model
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Variance
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Variance and Stream flow
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Topographical influences
Vertical length Energy Gradient
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Topography compared to GW
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Density
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Conclusion

• Groundwater is important for base flow
• Topography can be used to mimic groundwater
  conditions to estimate base flow
• Variance plays a role, but its topography that
  has the controlling factors
• With this study, can decrease the use of
  groundwater models

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No questions?

• GREAT!