Groundwater Hydraulics: Ground Water – Conceptual Model and Zones in Groundwater

Doorsteptutor material for competitive exams is prepared by world's top subject experts: get questions, notes, tests, video lectures and more- for all subjects of your exam.

Ground Water – Conceptual Model

  • Soil water system
  • Cup with ice and juice
  • 97 % is oceans
  • 3 % is freshwater – 2.14 % in ice caps
  • Of the remaining, 98 % as groundwater – fresh – 0.61 % & only 2 % in lakes

Zones in Groundwater

  • Unsaturated or vadose zone – 3 system
  • Saturated – 2 system
  • Unsaturated zone includes soil water zone, intermediate zone and capillary fringe
  • Most terrestrial plants extract water from the vadose zone. Plants wilt when soils become too dry because the forces holding the water in the soil are too great to allow the plants access to the water
  • the capillary fringe is a saturated zone above the water table where water is affected by capillary forces.
  • The uppermost belt, or belt of soil water, is that part of the lithosphere immediately below the surface, from which water is discharged into the atmosphere in perceptible quantities by the action of plants or by soil evaporation.

Unsaturated System

Separate air, water and solid

Unsaturated System
  • Porosity (volume of void/total volume) typically 0.4
  • Volumetric water content volume wetness is defined as the volume of water per bulk volume of soil sample
  • So, varies from
  • Saturation ratio
  • Varies from
  • Dry bulk density that is typically 1.6gm/cm3
  • Soil particle density that is typically 2.66gm/cm3
  • In saturated soil, there is only 2 phases
  • Cubic packing of uniform sphere of equal diameter yield porosity of 47 - 65 % regardless of particle size (same porosity – so same amount of water)
  • Porosity of heterogenous material will be less – as small size particles will block pores
  • Porosity is not a function of grain size in idealized state.