Water infiltration

Because many pesticides are appHed to the soil surface, the transport of pesticide during water infiltration is important. Water infiltration is characterized by high initial infiltration rates which decrease rapidly to a nearly constant rate. Dry soils have greater rates of infiltration than wet soils during the initial appHcation of water. Thus, perfluridone movement after appHcation of 3.8 cm of water was considerably greater in soil at a water content of <1% of field capacity than at 50% of field capacity (62). Fluometuron moved deeper into the soil in response to greater rainfall intensity or after rainfall onto a dry rather than a moist soil (63). 

Soil conditioners are materials that measurably improve the physical characteristics of the soil as a plant growth medium. Typical uses include erosion control, prevention of surface sealing, and improvement of water infiltration and drainage. Many natural materials such as peat and gypsum are used alone or in combination with synthetics for soil conditioning. This article is concerned with synthetic soil conditioners, many of which are introduced as polymeric systems similar to the gels and foams formed in situ by chemical grouts. 

Overland water flow appHes shear forces to sod surfaces. When shear forces exceed the stress required to overcome cohesive forces between sod particles, the particles are detached and suspended in the flow. Suspended particles are carried into surface sod with infiltrating water where they block pores and initiate seal formation (47). Thus, erosion results in reduced water infiltration as well as loss of sod from the field and consequent downstream water pollution. If erosion is controlled, good water infiltration is maintained. 

The use of clay has been the favored method of reducing or ehmi-nating the percolation of leachate (see Fig. 25-74 and Table 25-73). Membrane liners are used most often today but require care so that they will not be damaged during the filling operations. Equally important in controlhng the movement of leachate is the ehmination of surface-water infiltration, which is the major contributor to the total volume of leachate. With the use of an impermeable clay layer, mem-... 

Storm water infiltration or runoff wbicb could transport hazardous substances... 

Sicker-taok, m. percolating tank, -wasser, n. ground water infiltrated water, percolating water. 

For a given set of conditions (lithology, climate, slope, etc.), there is presumably an optimum soil thickness that maximizes the rate of bedrock weathering (Fig. 9-3) (Carson and Kirkby, 1972 Stallard, 1985). For less than optimum soil thicknesses, there is insufficient pore volume in the soil to accept all the water supplied by precipitation and downhill flow. Excess water runs off and does not interact with the subsurface soil and bedrock. In contrast, water infiltrates and circulates slowly through thick soils (especially where forested If profile thicknesses greatly... 

Surface water control is necessary to minimize contamination of surface waters, to prevent surface water infiltration, and to prevent off-site transport of surface waters that have been contaminated. Control of run-on and runoff will accomplish the following ... 

A higher than expected gain or loss of fuel in a tank may be caused by water infiltration or leakage of fuel through the tank wall. 

Payer80 states that the UNSAT-H model was developed to assess the water dynamics of arid sites and, in particular, estimate recharge fluxes for scenarios pertinent to waste disposal facilities. It addresses soil-water infiltration, redistribution, evaporation, plant transpiration, deep drainage, and soil heat flow as one-dimensional processes. The UNSAT-H model simulates water flow using the Richards equation, water vapor diffusion using Fick s law, and sensible heat flow using the Fourier equation. 

Rate of infiltration is measured by a small flexible bag. As water infiltrates from the inner ring into the soil, the flexible bag is gradually compressed as water leaves it to enter the ring. To determine how much flow has taken place, the flexible bag is disconnected, dried off, and weighed. Then it can either be refilled or replaced with a fresh bag. 

The SWCR system is built on top of the FMC. The purpose of the SWCR system is to prevent infiltration of surface water into the landfill by containing and systematically removing any liquid that collects within it. Actual design levels of surface water infiltration into the drainage layer can be calculated using the water balance equation or the HELP model.36 37... 

Even though only a small proportion of the non-harvested biomass returned to soil ends up in soil humus, SOC is needed to improve water infiltration rates and reduce erosion. SOC contents can be increased by adding more non-harvested biomass to soil or by slowing the mineralization rate of fresh biomass. 

In addition to the physical effects previously described, animals can change the soil s biological and chemical reactions. For instance, animal paths become devoid of plants and compacted, thereby changing water infiltration and percolation and oxidation-reduction reactions, particularly when there is continual use of the paths [1-4]. 

Kessler, A. and Rubin, H., 1987, Relationships between Water Infiltration and Oil Spill Migration in Sandy Soils Journal of Hydrology, Vol. 91, pp. 187-204. 

This work describes the application to soil of compounds of a previous study (11) which dealt primarily with organic synthesis and physical properties of reaction products of pure fatty acids with BETA. In this study derivatives were prepared from various industrial fatty materials. In addition, water infiltration studies on sand, sandy soil, and clay soils were carried out on the previously prepared and new compounds. Finally, an investigation was initiated to determine the biological effects of one water-repelling chemical, the partially hydrogenated tallow-fatty acid-DETA reaction product, on seed germination and plant growth. 

The industrial fatty acid-DETA derivatives were evaluated for application to soil. Water infiltrated soil coated with the BETA derivative of tallow more rapidly than the controls. This was due to the high unsaturation content and also in part to the glycerine retained in the product as discussed below. We were unable to find a solvent system which would readily separate the glycerine, formed from the triglyceride, from the BETA reaction product. If the glycerine were removed, the infiltration rates for the tallow-DETA derivative should be identical with the rates obtained for tallow fatty acid-DETA reaction product. 

Water infiltration tests were conducted on soils treated with the BETA derivatives of tall oil fatty acids,... 

MO-5 acids, and isostearic acid, all of which melted below 45°. Water infiltrated sandy soil treated with these compounds within 4 hr and through clay containing soil within 8 hr, confirming their hydrophilic nature. The blending of these diamides into the tallow derivatives in order to lower melting points and enhance solubility causes... 

Groundwater may contain dissolved gases as a result of exposure to the surface environment prior water infiltration, contact with the subsurface gaseous phase, and gas produced biologically below the water table. The most important dissolved gas in groundwater is CO. ... 

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