Surface water and groundwater flow

Global water budget

Surface water flow

Forces on fluids

Bernoulli equation


Flow in channels

RH=wh/(2h+w): Hydraulic radius
k=1 m1/3s-1
S: slope
n: roughness coefficient

Measuring flow in natural channels


Conceptual model of groundwater flow

  • the flow of water through a porous medium (Fig 6.1)
  • water flows tortuous paths
  • geometry of channels is very complex
  • frictionles flow is totally meaningless!
  • conceptual model of flow through a porous medium is flow through a bundle of very small (capillary) tubes of different diameters (Fig 6.2)
  • the flow (Q) through a horizontal tube can be described as: Q = -p*D4/(128*m)*dp/dx (Poiseuille's law)

  • => size of the capillary tubes is important!

    Darcy's law


  • Freeze, R.A. and Cherry, J.A. (1979) Groundwater. Prentice Hall, 604p.
  • Hornberger, G.M., Raffensberger, J.P., Wiberg, P.L., and Eshleman, K.N. (1998) Elements of physical hydrology. Johns Hopkins University Press,  Baltimore, 302p.
  • see also BC 3025 Hydrology class