Increase In Infiltration Rate Research Articles

Water Ponding Depths Affect Temporal Infiltration Rates in a Water‐Repellent Sand

Water‐repellent soils exhibit a positive water entry pressure head, hp The effects of imposing differing water pressure head values, by using differing water ponding depths, h0, on infiltration into water‐repellent soils was investigated. A sand, with particulate size between 0.05 and 2.0 mm, was treated with two concentrations of octadecylamine to create a sand with hp values of 8.4 and 3.5 cm. The hydraulic conductivity, K, of the water‐repellent sands increased with increasing values of h0 The K of the treated sand was equal to K of untreated sand when the ratio h0/hp was ≈3.1 for each treated sand. The infiltration rate increased with increased time for lower h0 values, but decreased with increased time for higher h0 values. The transition from increasing to decreasing infiltration rates with time occurred when h0/hp was approximately equal to 2.6. The infiltration rate behavior of an aqueous ethanol solution was consistent with theoretical relationships based on liquid surface tension. A positive hydraulic head was created at the interface of an overlying wettable and underlying water‐repellent layer that affected the infiltration rate consistent with the effects of h0 on a nonlayered water‐repellent sand. The following mechanism is proposed to explain the increase in infiltration rate with time. In water‐repellent materials, positive hydraulic heads can be created within the profile during infiltration, which can increase as the depth to the wetting front increases. The higher hydraulic head induces an increase in hydraulic conductivity, which contributes to increased infiltration rate. Alternatively, if the depth of ponded water is sufficient to cause a hydraulic conductivity equal to that of the wettable material, the infiltration rate behavior is the same as traditionally observed for wettable soils.

Effects of soil faunal activity and woody shrubs on water infiltration rates in a semi-arid fallow of Senegal

The effects of soil faunal activity on the physical properties of the soils of a 2-year-old fallow in the sahelian zone of Senegal were studied. Factors studied included the presence or absence of woody shrubs and the effect of protection of plots from grazing and removal of fuel wood. The experimental design included a control in which termite activity was excluded by treating the soil with the persistent insecticide dieldrin. In both the protected and unprotected area of the experiment, termite burrowing activity (as measured by the number of entrance holes per square-metre) and water infiltration rates were significantly (ca. 80%) lower in termite exclusion plots than in plots not treated with insecticide 2 years after initial treatment. In protected plots where termites were present, there was a significant increase in infiltration rates in the part where woody shrubs were removed. In unprotected plots, by contrast, the presence of shrubs significantly increased infiltration rates, whether or not termites were present. Burrowing activity of earthworms was greater in the protected than in the unprotected area, and in the unprotected area burrowing in dieldrin treated plots was significantly increased by almost 65%. Activity of ants appeared to be little affected by the different treatments. The results demonstrate that the presence of healthy soil faunal populations was important in the infiltration of water in fallow soils and that protection from grazing and human activity improves faunal activity and water infiltration.

The effect of ponding depth on infiltration in a crusted surface depression

Over the past few decades, the influence of surface sealing on infiltration has been the subject of numerous publications. However, very few of these experiments have considered the effect of spatial variability in seal hydraulic characteristics on infiltration. Field and laboratory observations have demonstrated that seal characteristics vary considerably within a range of a few cm, and the changes are often related to microtopography. The objective of this experiment was to investigate the influence on infiltration of a seal with varying hydraulic properties in a surface depression. Two soils of different aggregate stability were used in the experiment: Blosseville silt loam and Villamblain silty clay loam. Soil columns (23 cm diameter by 30 cm length) were packed with aggregates of <2.0 cm and a 6 cm depression was formed in the soil surface. A sedimentary crust was formed in the centre of the depression, and the sample was rained upon for 60 min at a rainfall intensity of 35 mm h −1. Subsequently, water outflow at the base of the column and pressure heads in the column were measured during two ponding periods corresponding to depths of 0.5 and 4.0 cm. Water outflow rates increased with ponding depth substantially more than could be attributed to the increases in ponding pressure head and submerged area for both soils. The experiment demonstrated that where seal hydraulic conductivity varies with microtopography, a significant increase in infiltration rate occurs as areas of greater hydraulic conductivity are submerged. The increases in ponded pressure head and submerged area are negligible compared to the influence of spatial variability in seal hydraulic conductivity.

Effects of an organic mat filter on artificial recharge with turbid water

Total recharge was 81% larger for a sandy basin with an organic mat filter than for the same basin with a clean, fully renovated surface, but without the mat. Surface impedance was larger for check areas without organic mat, while areas with the mat exhibited impedance increases to greater depths. Experimental results indicated a likely trade‐off between short‐term recharge enhancement and an eventual larger depth of renovation to offset deeper sediment penetration under the mat. A substantial decrease in hydraulic impedance and a corresponding increase in infiltration rate were measured between 90 and 400 hours and indicated that despite large sediment influx, soil hydraulic conductivity was larger under the organic mat than for the same basin positions on clean sands using clean water. The large decrease in impedance is attributed to microbial transformation of O2 to CO2 which increased water‐filled large porosity.

The temperature dependence of ponded infiltration under isothermal conditions

A simple temperature-sensitive modification to the Green and Ampt infiltration equation is described; this assumes that the temperature dependence of the hydraulic conductivity is reciprocally equal to the temperature dependence of the viscosity of liquid water, and that both the transmission zone saturation and the wetting front matric potential gradient are independent of temperature. This modified Green and Ampt equation is compared with ponded, isothermal infiltration experiments run on repacked columns of Olympic Sand and Aiken Loam at 5, 25, and 60°C. Experimental results showed increases in infiltration rates of at least 300% between 5 and 60°C for both soil materials, with subsequent increases in cumulative infiltration of even greater magnitudes for the loam. There is good agreement between measured and predicted initial infiltration rates at 25°C for both soil materials, yet at 60°C, the predicted results overestimate initial infiltration rates for the sand and underestimate initial rates for the loam. Measurements of the wetting depth vs. cumulative infiltration indicate that the transmission zone saturation increased with increasing temperature for both soil materials. In spite of this increased saturation with temperature, the final infiltration rates at both 25 and 60°C were predicted accurately using the modified Green and Ampt equation. This suggests that increased saturation occurred primarily in dead-end pore spaces, so that transmission zone hydraulic conductivities were unaffected by these temperature-induced changes in saturation. In conclusion, except for initial infiltration rates at 60°C, the measured influence of temperature on infiltration rates was fully accounted for by the temperature dependence of the viscosity of liquid water.

Infiltration Rate as Affected by an Alfalfa and No-till Cotton Cropping System

Previous studies measured a long-term increase in infiltration rate in a sandy loam soil with time when alfalfa (Medicago sativa L., cv. WL514) was grown. Cotton (Gossypium hirsutum L.) was direct-planted into alfalfa to determine if the high infiltration rates measured under alfalfa culture could be maintained in cotton under either a till or no-till system. Treatments were no-till or tillage to the 0.15-m depth just before the cotton was planted. Prior compaction levels created by harvest traffic applied to the alfalfa made the soil loose or compacted. Cotton was planted flat and irrigated as a basin. Infiltration rates measured 2 h after water was applied and averaged for the season were 101 (no-till, loose), 56 (till, loose), 82 (no-till, compacted), and 42 mm/h (till, compacted). All the infiltration rates were much higher than normally measured for cotton in these soils. Water flow in the 5-yr-old alfalfa was determined to be mainly through the soil macropore system. High infiltration rates measured in the no-till cotton were also probably the result of flow through the macropores.

Effects of Livestock Grazing on Infiltration Rates, Edwards Plateau of Texas

The influence of short duration grazing (SDG), moderate continuous grazing (MCG), heavy continuous grazing (HCG), and gmzingexcusionon iralonntesof -ig--and s asdominated communities was evaluated over a 20-month period on the Texas Agricultural Research Station, located near Sonora in the Edwards Plateau, Texas. A combination of cattle, sheep, and goats were used in each grazing treatment. Infiltration rates were consistently less in the midgrass (bunchgrass) than in the shortgrass (sodgrass) community. The HCG pasture was severely overgrazed and infiltration rates were reduced to about one-half those in the MCG pasture. The midgrasses in this pasture were destroyed after 26 months of overgrazing. Infiltration rates in the SDG pasture, stocked at double the recommended rate, decreased during the study period. Infiltration rates in the SDG pasture shortgrass community, near the end of the study, approached those in the HCG pasture. The greatest infiltration rates for both communities were maintained in the MCG pasture. Infiltration rates for the midgrass community remained relatively stable during the study when the general trend in the SDG and HCG pastures was toward reduced infiltration rates. The nongrazed pasture subsequent to the 1980 drought had a general increase in infiltration rates. Infiltration rates vary naturally in time and space because of normal variations in climate, vegetation, and intensity and duration of livestock use. Few studies have attempted to account for these natural variations. The literature is filled with examples of the adverse impact of heavy or abusive grazing on infiltration rates. Few research projects have studied seasonal or long-term impacts of grazing systems or proper grazing management on infiltration rates (Blackburn et al. 1982). Much interest has been generated by specialized grazing systems and their potentials. Short duration grazing and its potential economic benefits to the ranching industry have become extremely popular (Savory 1978). Little information is available, however, to support many of the claims concerning specialized grazing systems. Gifford and Hawkins (1978) found no published evidence to show that any single grazing system consistently or significantly increased plant and litter cover on watersheds. Other reviews (Van Pollen and Lacey 1979, Beck 1980) of the impacts of grazing support Gifford and Hawkins' conclusions. Most of the information on the impact of specialized grazing systems on infiltration rates come from studies conducted in the Rolling Plains and Edwards Plateau of Texas. The results of these studies indicate that infiltration rates of pastures grazed under a deferred-rotation system (4-3:12:4 mo)1 were similar to those of livestock exclosures and greater than high intensity, low frequency pastures (8-1:17:119 days) or moderate or heavy continuously grazed pastures (McGinty Authors are graduate research assistant and professor of watershed management, Range Science Department, Texas AM and professor of Range Science, Texas Agricultural Experiment Station, Sonora 76950. Published with approval of the Director, Texas Agricultural Experiment Station, as TA-I 8727. Manuscript received May 31, 1983. 'Nomenclature follows Kothmann 1974. et al. 1978, Wood and Blackburn 1981). Infiltration rates of pastures grazed under a high intensity, low frequency system were similar to moderate continuously grazed pastures (Wood and Blackburn 1981, Blackburn et al. 1982). Livestock grazing can alter infiltration rates of rangeland soils by removing protective plant cover and by trampling. Vegetation and mulch cover serve to protect the soil surface from raindrop impact and influence soil surface properties such as bulk density, organic matter content, and aggregation (Osborn 1954, Copeland 1963, Blackburn 1975, Meeuwig and Packer 1976, Blackburn et al. 1982). Reduced infiltration rates as a result of livestock grazing have been attributed to: ( loss of vegetation cover, (2) decreased mulch cover, (3) decreased amounts of vegetation standing crop and mulch, (4) increased bare ground, and (5) increased bulk density as a result of trampling (Alderfer and Robinson 1947, Knoll and Hopkins 1959, Reed and Peterson 1961, Branson et al. 1962, Copeland 1963, Dee et al. 1966, Rauzi and Hanson 1966, Smith 1967, Blackburn et al. 1982). Type of vegetation is important in determining infiltration rates (Blackburn 1975). Infiltration rates are consistently higher in bunchgrass-dominated areas than in sodgrass-dominated areas (Blackburn et al. 1980, Wood and Blackburn 1981). Livestock grazing has the greatest potential impact on bunchgrasses. Not only are bunchgrasses usually the better forage species but they are usually more sensitive to heavy grazing pressure than low-growing sodgrasses (Wood and Blackburn 1981). Objectives of this study were to determine: (1) infiltration rates of pasture soils under short duration grazing; moderate continuous grazing; and heavy continuous grazing; and grazing exclusion; and (2) the variables influencing infiltration.

Effect of orthostatic blood pressure changes upon capillary filtration-absorption rate in the human calf.

The effect of postural changes upon fluid filtration rate in the calf was studied in 3 healthy subjects placed in supine position. Volume changes in the calf were measured by a water plethysmograph. Relative changes in blood flow in subcutaneous tissue and anterior tibial muscle were measured by the local 133Xe washout technique. Lowering the calf from 5-25 cm caused a linear increase in filtration rate whereas blood flow in subcutaneous tissue of the segment studied and anterior tibial muscle remained constant. Based on this average CFC was about 0.0012 ml X min-1 X 100 g-1 X mmHg-1. Further lowering of the calf caused a decrease in blood flow in subcutaneous tissue and skeletal muscle by about 50% corresponding to an increase in total vascular resistance by about 100%. During these circumstances the increase in infiltration rate was reduced by about 33%. The resulted indicate that the local veno-anterior reflex responsible for the observed vasoconstriction in the tissue under study together with intrinsic vascular mechanisms reduces transcapillary fluid filtration in the lower position. The mechanism appears to be mainly due to a reduction of the increase in mean capillary pressure whereas CFC seems to remain almost constant.

Management of Nonleguminous Green Manures and Crop Residues to Improve the Infiltration Rate of an Irrigated Soil

AbstractThe effects of nonleguminous green manures and crop residues on the rate of infiltration were studied in field experiments on an irrigated soil.The increase in infiltration rate resulting from the green manure species was inversely related to their nitrogen concentration at the time of incorporation. The effect of the low nitrogen green manures persisted throughout the 28‐month trial period. Nitrogen fertilization of crop residue reduced infiltration rate in one experiment, but had no significant effect in another. Barley (Hordeum vulgare) crop residue and the resultant increase in infiltration rate were associated with an increase of 7 cwt of sugar produced/acre by the following crop of sugar beet (Beta vulgaris).

The Effect of surface head on infiltration rates based on the performance of ring infiltrometers and ponds

Studies with infiltrometers and small ponds indicate that the normal relatively low infiltration rates of certain soils may be increased by providing sufficient depth of water or surface head on the soil surface. Infiltration rates increased directly proportional to head motivating flow in infiltrometers and ponds on untreated soil under water‐spreading conditions. Hydraulic head loss and length of saturated soil column explain why greater increases in infiltration rates occurred with increases in surface head on untreated soil than on a soil rendered more permeable by treatment. Hydraulic head losses were obtained with infiltrometers equipped with manometers located 1 ½ 4 ½, and 7 ½ inches below the soil surface. The resistance of untreated soil to flow reduced the total head motivating flow to a negligible amount at a depth of 7 ½ inches below the soil surface. Where hydraulic head exists at the bottom end of an infiltrometer extending into the soil, the need for a “balanced buffer” rather than a “partial buffer” or an “excessive buffer” to prevent lateral flow is discussed. Piezometric heads in relatively pervious soil horizons below the soil surface within and outside of a pond are reported.