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Infiltration

Introduction

Processes at the ground layer:

  • F ---  infiltration
  • L ---   Lateral flow
  • Pe -- percolation
  • Ss -- subsurface flow

Infiltration (F) -- The process by which water arriving at the soil surface enters the soil.

  •  does not show up on the water balance equation but is an important intermediary process. 
  • In this course, we also call all processes related to water movement in the unsaturated zone infiltration
  • Water moves in the soil via capillary and gravitational forces through micropores and macropores

 

Four possibilities for water in the soil:

  • Held in the soil (if moisture is below field capacity (FC))
  • Evaporation back to the atmosphere
  • Percolation downwards to groundwater
  • Reaches a stream via subsurface flow (saturated zone)

 

  • Infiltration rate: rate at which water enters the soil from the surface; decreases as 0v increases
  • water input rate: rate at which water arrives at the surface
  • Infiltration capacity: maximum rate at which infiltration can occur
  • Cumulative infiltration: accumulated depth of water infiltrated over a given time period. Equal to the integral of infiltration rate over that period
  • Ponding: accumulation of water in the surface when w(t) is igher than f(t)
  • Depth of ponding: depth of water that is ponding

 

Fundamentals of infiltration