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[en] For modelling complex hydrological problems, realistic models and accurate hydraulic properties are needed. A mechanistic model (HYDRUS-1D) and a compartment model are evaluated for simulating the water balance in a soil-vegetation-atmosphere system using time series of measured water content at several depths in two lysimeters in a podzol soil with Scots Pine vegetation. 10 calibration scenarios are used to investigate the impact of the model type and the number of horizons in the profile on the calibration accuracy. Main results are: (i) with a large number of soil layers, both models describe accurately the water contents at all depths, (II) the number of soil layers is the major factor that controls the quality of the calibration. The compartment model is as an abstracted model and the mechanistic model is our reference model. Drainage values are the considered output. Drainage values simulated by the abstracted model were close to those of the reference model when averaged over a sufficiently long period (about 9 months). This result suggests that drainage values obtained with an abstracted model are reliably when averaged over sufficiently long periods; the abstracted model needs less computational time without an important loss of accuracy.
[en] The spatial variation of the soil structure influences the water movement through its porous geometry, which could cause problems in the development of agricultural cultures and also accelerate processes of soil erosion. The gamma ray transmission method has established efficiency for the non-destructive measurement of moisture temporal and space evolution, and consequently in the determination of the hydraulic conductivity of the soil, K(θ). Columns of undisturbed soil (approximately 0.11 x 0.06 x 0.60 m) were removed from a trench in the Campus of Londrina State University. The used soil was classified like distrophic dark red soil (LRd). The indeformed soil columns were wrapped up with paraffin and gauze and were fixed on the table of measurement. The water vertical infiltration in the soil was accomplished by maintaining a water layer of approximately 0.01 m over an area of soil of 75 x 10-4 m2 . Layers of filter papers and foam controlled the flow of water in the soil surface. After the conclusion of the infiltration, began the process of redistribution of the water in the soil column, with the objective to determine the function K(θ) in relation to the depth in the column. The moisture profiles θ(z,t) are obtained using a radioactive source of 241Am (3.7 x 109 Bq; 0.0596 MeV), spectrometric electronic chain, a 2x2'' NaI(Tl) detector and a measurements table , which allows the sample to move vertically. The hydraulic conductivity function was determined, applying the Sisson model , at 10 levels in the soil column and the results exhibit an increase of K(θ) with depth. (author)
[en] Vertical joints and large pores existing uniquely in loess cause difference between loess and other homogenous soil media in water infiltration. Field test of water infiltration in loess aerated zone of and analysis with hydraulic theory of soil concludes that for the loess aerated zone of vertical joints existing in it makes little contribution to water infiltration under unsaturated condition, and large pores in the media would significantly retard water infiltration
[en] The investigations carried out as part of safety analyses show clearly that, in fractured compact rock, the properties of the fractures are of outstanding importance. This is because, in such rocks, practically all water flow occurs in the fractures and the water in the rock matrix is more or less stagnant. Radionuclides which could be released from the near-field of a repository would therefore be transported through a network of fractures. Since the transport properties of the fractures are important in assessing the long-term safety of a repository, their characterisation plays a significant role in the site investigation programme. This theme is also important in the objectives of the GTS. The possibilities of locating fracture zones are being investigated in the underground seismics and radar tests; the fracture system flow test, on the other hand, is more concerned with characterising the hydraulic properties of such fractures while the migration test concentrates on rock/radionuclide interaction. (author) 6 figs
[en] Anisotropy in unsaturated hydraulic conductivity is saturation-dependent. Accurate characterization of soil anisotropy is very important in simulating flow and contaminant (e.g., radioactive nuclides in Hanford) transport. A recently developed tensorial connectivity-tortuosity (TCT) concept describes the hydraulic conductivity tensor of the unsaturated anisotropic soils as the product of a scalar variable, the symmetric connectivity tortuosity tensor, and the hydraulic conductivity tensor at saturation. In this study, the TCT model is used to quantify soil anisotropy in unsaturated hydraulic conductivity. The TCT model can describe different types of soil anisotropy; e.g., the anisotropy coefficient, C, can be monotonically increase or decrease with saturation and can vary from greater than unity to less than unity and vice versa. Soil anisotropy is independent of soil water retention properties and can be characterized by the ratio of the saturated hydraulic conductivities and the difference of the tortuosity-connectivity coefficients in two directions. ln(C) is linearly proportional to ln(Se) with Se being the effective saturation. The log-linear relationship between C and Se allows the saturation-dependent anisotropy to be determined using linear regression with the measurements of the directional hydraulic conductivities at a minimum of two water content levels, of which one may be at full saturation. The model was tested using measurements of directional hydraulic conductivities
[en] Pakistan is situated in the most intensively colonized zone of the world. With the passage of time, farmer land holdings are decreasing due to the increasing population. To feed this increasing population the available lands had been cultivated intensively even using brackish water. The use of brackish water for this intensified cultivation is the chief cause of soil particle disintegration resulting in a poor structure. To address this problem a series of experiments were conducted using organic amendments [Farm Manure (FM), Poultry Manure (PM) and Molasses (MO)] maintaining soil water level at 75% of available water contents (AWC). The recommended dosage of mineral fertilizers was applied and maize hybrid Shahanshah was used as a test crop. Addition of farm manure as treatment resulted in better water-stable aggregation (40.68 and 39.91%), soil total organic carbon (12.64 and 12.09 g kg-1), saturated field hydraulic conductivity (27.85 and 27.04 mm h-1), infiltration rate (26.07 and 25.38 mm h-1), total porosity (0.49 and 0.48 m3 m-3). Similarly, plant agronomic parameters i.e. grain yield (9.47 and 9.21 Mg ha-1) and water use efficiency (11.13 and 10.83 kg mm-1 yr-1) were calculated highest in farm manure treatment plots that were significantly greater than control but were found statistically at par with other treatments. It was concluded that organic matter addition yields better soil structure that results in proper aeration, water retention, root penetration ultimately achieving yield goals along with saving up to 25% irrigation water as indicated from the correlation analysis. (author)
[en] The investigations have been carried out as transient injection tests with constant pressure and subsequent pressure fall-off tests. The tests have been performed in accordance with the tests used fin Sweden for site investigations. In total, 900 m of the 1001 m long borehole have been tested in 30 m long sections. The equipment used for the hydraulic tests was the umbilical hose system, developed within the Swedish KBS project. The umbilical hose equipment automatically operate each test during the entire test sequence. The different phases are: packer sealing (30 min), water injection (2 hours) and pressure fall-off (2 hours). In addition to the water-pressure and flowrate, the equipment is continuously measuring the barometric pressure, packer pressure, free groundwater level and different temperatures. Immediately after each test 13 different diagrams needed for the evaluation are plotted by a microcomputer, which also calculates a preliminary value of the hydraulic conductivity. The hydraulic conductivity of the bedrock in the vicinity of the borehole has primarily been determined by transient evaluation of the injection phase. Also the skin factor, effective borehole radius have been calculated. The evaluation of the water injection tests in the Lavia borehole give values of the hydraulic conductivity between 9.7x10-12 m/s and 2.7x10-7 m/s. From the highest value at test section 73-103 m, the hydraulic conductivity is decreasing to the measuring limit at c. 300 m. Then follows an interval with increasing hydraulic conductivity to a peak value of 3.2x10-8 m/s to again decrease to the measuring limit at c. 500 m. The interval from 493 m to 863 m is characterized by hydraulic conductivities near the measuring limit. At the lower part of the borehole the K-values again increase to a maximum value of 2.5x10-7 near the bottom of the borehole. The distribution of the piezometric pressure along the borehole indicates that the borehole is located in a recharge area
[en] A total of eight short duration injection tests were conducted on wells at the M-Area Western Sector In-Situ Chemical Oxidation (ISCO) test site. For each injection event, approximately 200 gallons of water were gravity drained into the well casing. Pressure response was monitored in the injection well and these data were used to estimate the injection capacity of each well. Nearby injection wells were used as observation wells and data from these wells were used to estimate local hydraulic conductivity.
[en] Tracer experiments supply thorough knowledge of the karst, facilitate confirmation or rejection of hydraulic connections between sinkholes and water emergences, and provide for the discovery of new connections. They are an ideal means of studying the vulnerability of the karst to pollutants. Tracer labelling also permits verification of the flow patterns of hydrokarstic structures and the performance of methodological and comparative studies concerning the behaviour of the karst between low flow and flood; important quantities of the tracer may remain in its auxiliary systems for a long period of time. Consequently, investigation of hydrokarstic structures should be performed through simultaneous or repeated labelling using different 'conservative' tracers. Multitracing experiments are employed to shorten the duration of research work by avoiding repeated trials and the necessity of performing investigations under analogue hydraulic conditions. 4 refs, 1 fig., 1 tab