(LECTURE 4) INFILTRATION Flashcards
basic concept
-Infiltration
-Percolation
-Infiltration rate
-Hydraulic conductivity
-Permeability
-Cumulative infiltration
the process by which water on the ground surface enters the soil.
Infiltration
movement of water through the soil profile going to groundwater.
Percolation
infiltration per unit time; expressed in volume per unit time per unit area or depth per unit time
Infiltration rate
velocity of flow caused by a unit gradient; flow through soils in any direction
Hydraulic conductivity
used interchangeably with hydraulic conductivity
Permeability
The summation of the depth of water absorbed by a soil in a specified elapsed time in reference to the time of initial water application.
Cumulative infiltration
SOIL HORIZONS/ LAYERS
-humus
-topsoil (A horizon)
-subsoil (B soil)
-weathered rock fragments (C horizon)
-bedrock (D horizon)
IMPORTANCE OF SOIL INFILTRATION
-Groundwater Recharge
-Reducing Runoff
-Supporting Ecosystems
-Water conservation
-Reduced soil erosion by runoff
-Irrigation (manner of application)
Infiltration is a primary method for replenishing groundwater supplies, which are crucial for drinking water, irrigation, and industrial use
Groundwater Recharge
By allowing water to enter the soil, infiltration reduces surface runoff, which can help prevent flooding and erosion.
Reducing Runoff
Infiltration helps maintain soil moisture levels, supporting plant growth and sustaining ecosystems
Supporting Ecosystems
FACTORS AFFECTING INFILTRATION
-Soil
-Soil characteristics / compaction
-Soil’s degree of saturation
-Precipitation
-Land cover
-Base Flow
-Slope of the land
-Use of soil additives
soil texture, soil structure; the larger the pore size and the greater the continuity of the pores, the greater is the infiltration rate
Soil
formation of a thin compact layer on the surface as a result of severe breakdown of soil structure caused by the beating action of raindrops and flow of water over the surface
surface sealing or puddling of soil
The clay surfaced soils are compacted even by the impact of rain drops which reduce infiltration.
Soil characteristics / compaction
Clay has low and slow infiltration compared to sand and gravely soil.
Soil characteristics / compaction
he more saturated the loose Earth material are, the less infiltration.
Soil’s degree of saturation
typically refers to the collection of standing water at the ground surface due to the presence of an impermeable layer within the soil.
Ponding
The amount, intensity, and duration of precipitation significantly impact infiltration. Heavy, short-duration rainfall can lead to more runoff, while light, long-duration rainfall allows more water to infiltrate.
Precipitation
Vegetation and land use affect infiltration. Vegetated areas typically have higher infiltration rates due to root systems creating pathways for water.
Land cover
More vegetation, slower infiltration
Land cover
a portion of the stream flow that is not runoff; it is water from the ground, flowing into the channel over a long time and with a certain delay.
Base Flow
lateral movement of water.
Base Flow
Rivers near city has low baseflow because of impervious surface.
Base Flow
Steeper slopes tend to have higher runoff and lower infiltration rates compared to flat areas.
Slope of the land
chemicals that improve the soil structure hence increase infiltration; other chemicals cause soil particles to swell and to become hydrophilic hence reduce infiltration
Use of soil additives
INFILTRATION PROCESS
Surface Entry
Movement Through Soil
Recharge of Groundwater
Water first enters the soil at the surface, influenced by gravity and capillary forces.
Surface Entry
Water moves vertically and horizontally through soil layers, filling pore spaces and cracks.
Movement Through Soil
Some infiltrated water reaches deeper soil layers and recharges groundwater aquifers.
Recharge of Groundwater
involves direct measurement of water applied and water flowing from the field
Direct measurement
