Difference Between Infiltration And Percolation

Infiltration and percolation are two related hydrological processes that affect soil moisture. Infiltration is the downward movement of water into the soil, while percolation is the upward or lateral movement of water through the soil. Water infiltration is determined by soil type, texture, porosity, slope, surface cover, and compaction. Percolation is affected by the same factors and the depth and duration of rainfall events.

What Is Infiltration?

Infiltration is the process by which water, either from precipitation or an external source such as a river, seeps into the soil. This water moves downward through pores and cracks in the soil until it reaches an impermeable layer. The infiltration rate depends on several factors, including the amount of rainfall, the land’s steepness, and the soil’s composition.

What Is Percolation?

Percolation is the downward movement of water through subsurface material caused by gravity. It describes the rate at which water travels through different layers of permeable soils, from a lower to an upper one. Unlike infiltration, it does not require precipitation or an external water source. When percolation occurs, the soil’s pores become filled with water, and gravity pulls the newly formed water downward until it reaches a non-permeable layer. The percolation rate depends on many factors, such as the type of soil, its texture, the slope of the land, and the presence of barriers like rocks or other materials.

Difference Between Infiltration And Percolation

  • Definition: Infiltration is the process of water entering the soil surface, while percolation is the downward movement of water through a saturated medium.
  • Process: Water infiltration occurs when rain, snowmelt, or irrigation water enters the ground and begins to seep into small cracks within the soil. The soils can absorb some of this water and hold it until it is used by plants or evaporates. Percolation, on the other hand, occurs when water saturates the soil and begins to move downward through the ground. This process continues until it reaches an impermeable layer of soil or rock which blocks the further flow.
  • Speed: Infiltration occurs much faster than percolation.
  • Movement: Water movement during infiltration is vertical, while the flow during percolation is horizontal.
  • Pressure Gradient: During infiltration, the pressure gradient drives water flows from higher to lower areas in the soil. On the other hand, during percolation, the pressure gradient does not play a role in the movement of water, and it is primarily driven by gravity instead.
  • Source: Infiltration occurs from surface water sources such as rain or snowmelt, while percolation can occur from subsurface sources such as groundwater or a lake.
  • Occurrence: Infiltrations occur when water, or other fluids, enter the ground through cracks and fissures in rocks. Percolation, however, is a slower process. It involves water slowly moving through soil and sediment particles, taking advantage of the space between them until it reaches an impermeable layer beneath the surface.
  • Measuring Instrument: Infiltration is measured with an infiltrometer, and percolation is measured using Lysimeter.
  • Practical Applications: In medicine, infiltration is used for minor surgical and dental procedures. Percolation is used in household use and coffee makers.
  • Symbol: The symbol of infiltration is f, while the symbol of percolation is P.

Factors That Affect Infiltration

  • Precipitation: Infiltration highly depends on rainfall in a given area. When more water is present, there is more potential for infiltration into the soil.
  • Soil characteristics: Soil characteristics play a crucial role in determining the infiltration and percolation of water. For instance, if the soil is sandy, it will have higher infiltration than clayey soils due to its larger pore spaces and lower cohesion among particles. The presence of rock fragments such as gravel or stones can also influence the infiltration rate. On the other hand, organic matter helps hold water and increases the infiltration rate.
  • Soil moisture content: Soil moisture content is an important factor in soil fertility, affecting water availability to crops or vegetation.
  • Organic materials in soils: Organic materials enhance infiltration and reduce runoff. They do this by increasing the porosity or how much space exists between soil particles. This increases the amount of water entering and flowing through the soil profile. In contrast, inorganic materials such as clay resist infiltration and increase runoff.


What happens during filtration?

Filtration passes the liquid through a porous material, such as sand or other media, to remove suspended solids. During filtration, the suspension is allowed to pass through the filter material and then collected on the surface or in the pores of the filter medium.

Is there a water filtration system that removes everything?

No, no single water filtration system can remove all contaminants from water. Different systems use different techniques to filter and purify water, such as infiltration, percolation, reverse osmosis, and distillation.


Difference between infiltration and Percolation - infographic
Difference between infiltration and Percolation – infographic

Infiltration and percolation are related hydrological processes that help regulate water flow differently. Infiltration is the process of rainwater or other types of water entering the soil, while percolation is the process of water from an overlying zone moving downward through the soil. Both of these processes are essential for providing sustainable water resources, as they provide a way to store water and slowly release it into aquifers and streams.

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