EARTH121 Lecture Notes - Lecture 16: Phreatic, Surface Tension, Capillary Fringe
25 Aug 2016
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Document Summary
Volume of water that can enter the ground water system is impacted by interception: vegetation stops water from percolating, slope, composition. Coarse grain: spaces in between water can penetrate easily. Fine grained: poor infiltration (sediment packed together so water cannot flush through) Soil moisture (held together by molecular attraction: saturated (phreatic zone) Surface tension holds water between the individual grains. The volume of fluid that sediment/rock can contain is dependent on its porosity (space between grain: uniform grains (shape/size) = greater space, cement reduces porosity if found in great quantity. Open spaces under the surface need to be connected: permeability. Porosity and water content generally decrease with increasing deth: due to structural deformation (metamorphism) reduces pore space. Needs to be well sorted, poorly cemented. Types of aquifer: depends on layers above or below, unconfined aquifer. Permeable surface on top and impermeable surface below: confined aquifer. Upper and lower layers are impermeable (water is trapped: recharge area and water pressure.
