Search results for "infiltration"
showing 10 items of 291 documents
Unsaturated Soil Hydraulic Properties
2016
In the first part of this chapter, the tension infiltrometer (TI) technique is illustrated. After having described apparatus and instruments as well as the operative procedures in the field, the solutions based on the Wooding’s equation for steady-state flow are presented. Specific focus is given to the multi-potential approaches that allow determination of unsaturated soil hydraulic conductivity, K 0, corresponding to a sequence of pressure head values, h 0, imposed on the soil surface. The analytical model proposed by Haverkamp et al. (1994) to describe three-dimensional transient infiltration from a circular source is introduced and a single-test approach is presented that allows estimat…
Modeling belowground water table fluctuations in the Everglades
2010
[1] Humid lands, such as riparian zones, peatlands, and unsubmerged wetlands, are considered among the most biologically diverse of all ecosystems, providing a bountiful habitat for a large number of plant and animal species. In such ecosystems, the water table dynamics play a key role in major ecohydrological processes. The aim of the present study is to test with field data a recent analytical model for the estimation of the long-term probability distribution of the belowground water table position in groundwater-dependent environments. This model accounts for stochastic rainfall and processes such as infiltration, root water uptake, water flow from/to an external water body, and capillar…
An assessment of the BEST procedure to estimate the soil water retention curve: A comparison with the evaporation method
2018
The Beerkan Estimation of Soil Transfer parameters (BEST) procedure is an attractive, easy, robust, and inexpensive way for a complete soil hydraulic characterization but testing the ability of this procedure to estimate the water retention curve is necessary as relatively little information is available in the literature. In this investigation the soil water retention curve was predicted for four differently textured soils by applying three existing BEST algorithms (i.e., slope, intercept and steady) and the results compared with those measured by the standard Wind evaporation method. A sensitivity analysis of the infiltration constants, beta and gamma, was also carried out and their impac…
Application of minidisk infiltrometer to estimate soil water repellency
2016
Soil water repellency (SWR) reduces affinity of soils to water resulting in detrimental implication for plants growth as well as for hydrological processes. During the last decades, it has become clear that SWR is much more widespread than formerly thought, having been reported for a wide variety of soils, land uses and climatic conditions. The repellency index (RI), based on soil-water to soil-ethanol sorptivity ratio, was proposed to characterize subcritical SWR that is the situation where a low degree of repellency impedes infiltration but does not prevent it. The minidisk infiltrometer allows adequate field assessment of RI inherently scaled to account for soil physical properties other…
Saturated Soil Hydraulic Conductivity
2016
This chapter deals primarily with field measurement of saturated soil hydraulic conductivity, K fs . Well or borehole permeameter techniques, specifically developed for subsurface soil measurements above the water table, are initially illustrated. Particular attention is paid to establishment of steady flow under constant head in an uncased borehole, widely developed both theoretically and experimentally in the last 30 years. Situations involving cased boreholes, transient flow, or falling head processes are then described. These variants have received a renewed interest in the last few years. New data analysis procedures have been proposed and this circumstance allows us to obtain subsurfa…
Seasonal changes of the infiltration rates in a Mediterranean scrubland on limestone
1997
To investigate the seasonal changes of infiltration rates, measurements by means of simulated rainfall experiments and cylinder infiltrometer were done in a small E–W oriented watershed in Southeast Spain. Data were collected during both the wet seasons (autumn, winter and spring) and the dry season (summer). Infiltration rates were very high in summer, when direct surface runoff is very low. During the wet seasons, the infiltration rates were lower due to the increase in soil moisture. Measurements by means of both ponding as well as simulated rainfall are suitable to study the infiltration process. The former needs more replications, due to the small observation area encompassed for each …
EVALUATION OF THE EFFECTS OF CONTI- NUOUS PREPERITONEAL WOUND INFILTRATION ON POSTOPERATIVE RESPIRATORY PERFORMANCE IN PATIENTS WHO UNDERWENT MAJOR A…
2013
Aim. According to the recent literature, continuous pre-perito- neal wound infiltration with local anaesthetics (CPWI) is an effective analgesic therapy in patients who undergo major abdominal surgery 1. Although it is not inferior to other com- monly used techniques in postoperative analgesia, many studies report conflictive results about its efficacy compared to them 2. The aim of our study was to evaluate the effects of CPWI on the postoperative respiratory performance in patients after major abdominal surgery. Materials and methods. From June 2011 to July 2012, a total of 14 patients have been evaluated. All patients were treated using the protocol generally used in our Department for t…
Source shape and data analysis procedure effects on hydraulic conductivity of a sandy-loam soil determined by ponding infiltration runs
2017
Performing ponding infiltration runs with non-circular sources could represent a good means to sample completely an area of interest. Regardless of the shape of the source, predicting the expected reliability of the collected data by infiltrometers should facilitate soil hydraulic characterisation and also allow a more conscious use of the field data. The influence of the shape of the infiltration source (i.e., circular or square) and the analysis procedure of the steady-state infiltration data on the saturated hydraulic conductivity, Ks, of a sandy-loam soil was tested in this investigation. Circular and square surfaces sampled with the pressure infiltrometer (PI) yielded similar estimates…
Discussion of "Hydraulic Model of Transition of Transient to Steady Flows in the Vadose Zone" by Yaguo Zhang, Tonglu Li, Wei Shen, and Yu Wang
2020
The authors wrote an interesting article dealing with a simple hydraulic model to illustrate the transition mechanism of transient to steady flows in the vadose zone. The soil behavior is described by a set of nine vertically aligned cylinders, each opened at the top and with a small outlet at the bottom. The water level dynamic of each cylinder, associated with an intermittent constant rainfall applied to the top cylinder, C0, was analyzed and numerical simulations were performed. The only objective of this discussion is to show that results similar to those proposed by the authors could be obtained by using the recently introduced Richards equation analytical solution, under gravity-drive…
On the use of geophysical methods to characterize heterogeneities of quaternary alluvial deposits. Application to stormwater infiltration.
2007
Colloque avec actes et comité de lecture. International.; International audience; Stormwater infiltration basins are generally built on geological formations with large values of hydraulic conductivity. Such is the case for quaternary alluvial formations, among which are glaciofluvial deposits. Two geophysical investigation methods, namely ground-penetrating radar and electrical tomography, were tested on an infiltration basin built on a glaciofluvial deposit. Geophysical profiles were calibrated on a trench wall dug in the glaciofluvial formation. A sedimentological study coupled to geophysical measurements behind the trench wall highlights the three-dimensional architecture of the deposit…