광주흥신소
Infiltration is a key process in hydrology, agricultural and civil engineering, irrigation design, and soil and water conservation. A lot of effort has been invested in understanding its physics and in developing quantitative predictors.
광주흥신소The most important factor controlling infiltration is the amount and characteristics (intensity, duration etc) of precipitation. It is also influenced by the soil properties, pre-saturation levels and landscape topography.
Water
Water infiltration is the downward entry of water into soil, usually measured at a rate of inches per hour. This process allows water to be temporarily stored in the soil and made available for root uptake, plant growth and soil organisms. Water infiltration is a critical part of the water cycle and it is necessary for the proper functioning of the natural environment and human society.
Infiltration practices increase water quality by reducing stormwater runoff volume, removing fine sediment and associated pollutants, and recharging groundwater aquifers. These practices are designed to reduce runoff in a drainage area by increasing soil porosity and infiltration capacity, while also protecting the underlying groundwater from erosion and contamination.
Water infiltration into buildings can be a significant problem and can cause structural damage. Short term solutions include finding and fixing the source of the leak and moisture, and repairing any damaged areas in order to prevent further damage. Long term solutions can include the use of vapor barriers and other moisture control measures to prevent further damage to the building.
Infiltration basins treat stormwater using processes involving soil infiltration, such as sorption, trapping, straining and bacterial degradation. Because the basins are located in highly permeable soils, they are able to filter out most of the dissolved contaminants (i.e., “passenger chemicals”) that are carried with the stormwater. However, clogging and compaction of the infiltration structures may reduce their effectiveness.
Soil
There is a need 광주흥신소 to evaluate soil infiltration depths and the total amount of water used by plants in a rainfall event. However, the measurement of VSWC is difficult due to the complexity of the soil moisture profile distribution and its change with time under natural conditions21,22. Thus, there is a need to develop a non-destructive method for estimating maximum infiltration depth and soil water supply in long term studies23,24.
Ring infiltrometers are commonly used for evaluating infiltration. These infiltrometers consist of a ring-shaped tube that can be inserted into the soil with a constant head that is maintained by either manual water addition or a Mariotte system25. However, water seepage around the infiltrometer can cause compaction and alter the measurement results.
After a rain, soil water redistributes under the influence of gravity and the capillary potential generated by soil matric suction and soil porosity. Infiltration capacity is high at the start of a rain when the soil is dry, but decreases rapidly as the wetting front moves down the profile and is impeded by swelling clays and other impeding structures in coarse layers (Fig. 3-2).
The changes in infiltration depth with time during three rainfall events on 20-30 June 2002 were investigated using two-curve methods to estimate soil infiltration depth and VSWC. The results showed that the two-curve method could be used to estimate infiltration depth and VSWC for each rainfall event. Infiltration was faster into a sandy soil than into a clay, but the differences were not consistent for each rainfall event. Moreover, the ability of the fungi to enmesh and expand the soil particles significantly altered infiltration dynamics. F. proliferatum decreased the SWR on WR-soil and increased it on W-soil, while T. harzianum improved infiltration on both types of soil.
Runoff
In hydrology, the term runoff refers to surface water that drains off a land area and is discharged into streams. It may be water that ponds on or infiltrates into the soil, as well as that which flows over the land surface and is carried by gravity toward a stream channel (surface runoff). The term also refers to interflow, which occurs when groundwater rises and enters a stream channel from a lower elevation. Runoff can carry pollutants and sand and silt that are washed from the land by rain or groundwater seepage.
Precipitation falls on the ground in the form of rain, snow, sleet, ice pellets, hail, or dew. Most of this precipitation sinks into the shallow layer near the soil surface, but if the amount of rainfall exceeds the infiltration capacity of the soil, surface runoff occurs. The infiltration capacity of a soil decreases with time during a storm, due to pore space saturation and decreased permeability resulting from swelling clays.
Most of the surface runoff is intercepted by buildings, roads, and other impervious surfaces, and then infiltrates into the ground. However, a significant percentage of the runoff is lost to evaporation and transpiration. This can contribute to a drop in soil moisture and lead to plant stress and damage. Infiltration into the soil replenishes some of this loss. Infiltrated water also may percolate into deeper soil layers, recharging groundwater aquifers.
Management
Infiltration tests are a valuable tool for site selection and stormwater facility design. It is important to perform the tests on the whole proposed development area and at different times of the year. This allows LID facilities to be located on sites with optimal soils and geology, which in turn will improve water quality and decrease the cost of the stormwater infrastructure.
The infiltration rate depends on many variables including the amount of water applied to the soil surface, pore size and hydraulic conductivity of the soil, the initial soil moisture content, the condition of the surface of the soil (i.e., clogging or compaction), and the changing conditions of the water as it moves deeper into the soil. As a general rule, the infiltration capacity declines rapidly for the first few hours of a rainfall event and then slowly decreases as previously infiltrated water fills the available storage spaces and reduces capillary forces that draw in additional water.
Once infiltration stops, any remaining water will either collect on the surface of the ground or become runoff. As the infiltration capacity of the soil decreases, runoff and sediment will accumulate over time, increasing the load on downstream drainage structures and affecting the ability of the soil to remove pollutants. This is a common issue with urban infiltration practices that recharge groundwater. In addition, dissolved contaminants in the stormwater may be carried into groundwater aquifers and potentially contaminate drinking water supplies.