Iškritus krituliams ant žemės paviršiaus, dalis jų susigeria į gruntą, o kita dalis nuolydžio kryptimi teka link žemiausių reljefo vietų. Susigėrimo intensyvumas priklauso nuo grunto laidumo. Sunkiuose gruntuose vandens susigeria ir patenka į gilesnius grunto sluoksnius gana sunkiai dėl mažo grunto laidumo. Intensyviausiai vanduo nuo žemės paviršiaus teka drenažo tranšėjomis ir šalia jų. Šios vandens tekėjimo sąlygos tranšėjose susidaro pakitus grunto struktūrai, jas užverčiant. Laikui bėgant, drenažo tranšėjoje atsiradę plyšiai užnešami smulkiomis grunto dalelėmis. Tai įtakoja grunto vandens laidumo savybių prastėjimą. Norint pagerinti vandens nutekėjimą iš viršutinio dirvožemio sluoksnio, padėtų natūralios gamtoje sutinkamos medžiagos, įterptos skersai virš vamzdinio drenažo. Drenažo tranšėjų užpylimui naudojant poringas medžiagas, dalis atitekėjusio vandens akumuliuotųsi naujai įrengtose skersinėse drenažo tranšėjose. Tokios technologijos taikymas leistų padidinti sausinimo efektyvumą nekeičiant jau paklotų drenažo vamzdžių. Modeliuojant skersinių drenažo tranšėjų tankio įtaką vandens lygiui tarpdrenyje, nustatyta, kad papildomas jų įrengimas turi įtakos gruntinio vandens lygiams tarpdrenyje tik esant atstumui iki 30 m. Esant didesniam atstumui, jų poveikis gruntinio vandens lygio nuslūgimui tampa nežymus, siekia vos 1-2%. Didžiausią įtaką gruntinio vandens slūgimui tarpdrenyje turėjo skersinės drenažo tranšėjos įrengiamos 20 m tarpais, kai drenažo tranšėjos užpildo... [toliau žr. visą tekstą] / After rainfall, part of it is absorbed by the ground whereas the rest part flows upon the direction of the inclination towards the lowest points on the relief. Intensity of absorption depends on conductivity of the ground. In the hard ground water is absorbed and enters the deeper layers of the ground with difficulty due to low conductivity of the ground. Water flows most intensely through drainage trenches and next to them. These conditions of water flow in trenches form when the ground structure alters and overloads them. The time passing by, cracks, having occurred in the drainage trench, are filled with small ground particles. It influences deterioration of ground water conductivity qualities. In order to improve water runoff from the upper soil layer, natural substances found in nature, if inserted across, above the drain, could help. Using porous substances in order to cover drainage trenches, part of the water would accumulate in newly equipped cross-section drain trenches. Applying such a technology would allow increasing the efficiency of drainage without changing the already laid drainage pipes. Modeling the influence of cross-section drainage trench density on ground water level between drains, it was determined that additional installation could affect ground water level between the cross-section drains trench, the distance being up to 30 meters. When the distance is larger, its impact on the ground water level recession becomes insignificant and reaches only 1-2%... [to full text]

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In the past decade, the grouting industry has made significant technological advancements in real-time monitoring of flow rate and pressure of pumped grout, stable grout mix design, and with grout curtain concepts dealing with placement and orientation. While these practices have resulted in improved construction practices in the grouting industry, current design guidelines for grout curtains are still predominately based on qualitative measures such as engineering judgment and experience or are based on proprietary methods. This research focused on the development of quantitative guidelines to evaluate the effectiveness of a grout curtain in porous media using piezometric and hydraulic flow data. In this study, a laboratory-scale physical seepage model was developed to aid in the understanding and development methodology to evaluate the effectiveness of a grout curtain. A new performance parameter was developed based on a normalization scheme that utilized the area of the grout curtain and the area of the improved media. The normalization scheme combined with model-based Lugeon values that correspond to pore pressure and flow rate measurements at different soil unit weights and grout curtain spacings, produced a mathematical equation that can be used to quantify the effectiveness of a grout curtain. This study found a relationship that takes into account soil unit weight, grout curtain spacing and a new performance parameter that can be used to help predict the effectiveness of a grout curtain.

Linkages between the controls on depressional storage and catchment streamflow response were examined in a wetland dominated basin in the Canadian Prairie Pothole region through a combination of field monitoring and modelling. Snowmelt, surface storage, water table elevation, atmospheric fluxes, and streamflow were monitored during spring snowmelt and summer in a 1 km2 sub-catchment containing a semi-permanent pond complex connected via an intermittent stream. Snow accumulation in the basin in spring of the 2013 study year was the largest in the 24-year record. Rainfall totals in 2013 were close to the long term average, though June was an anomalously wet month. The water budget of the pond complex indicates that there was a significant subsurface contribution to surface storage, in contrast to previous studies in this region. Following snowmelt, subsurface connectivity occurred between uplands and the stream network due to activation of the effective transmission zone in areas where the water table was located near the ground surface, allowing significant lateral movement of water into the stream network. Modelling results suggest there was significant infiltration into upland soils during the study period and that upland ponds are an important consideration for accurately simulating catchment discharge. The flux of groundwater to the wetland complex during periods of subsurface connectivity was also important for maintaining and re-establishing surface connectivity and streamflow. As the observed period of surface and subsurface hydrological connectivity was one of the longest on record in the catchment due to very wet conditions, the results of this study denote observations of the wet extremes of the hydrological regime important for proper understanding, modelling, and prediction of streamflow in the region.

In this study, a two phase investigation of the hydraulic conductivity parameters of silty soils was performed. In the first phase, double-ring infiltrometer tests were used to measure infiltration rates in-situ at two sites in the Piedmont physiographic province of Georgia. The efficacy of predicting saturated hydraulic conductivity for Piedmont soils via published soil surveys from the National Resource Conservation Service and pedotransfer functions was then investigated. Work focused on the development of a consistent test methodology for soils (sandy, to silts and clays) in the Piedmont, and the final test method utilized being the constant head test, using a double-ring infiltrometer with Mariotte tubes to maintain the head. In the second phase of the investigation, laboratory based measurements of the saturated hydraulic conductivity of binary mixtures of fine sand and nonplastic silt were performed to investigate the effects of particle mixtures on hydraulic conductivity. The materials used were ASTM 100/200 sand and Sil-Co-Sil 40 non-plastic silt, chosen based on the ratio of the mean particle diameters. Significant effort was invested in the development and comparison of methodologies to produce uniform specimens of the binary mixtures for hydraulic conductivity testing, with the final being modified dry tubing. Two fixed densities were used to investigate the effects of particle packing on the hydraulic conductivity of binary mixtures, with critical fines contents chosen to ensure the finer particles primarily filled the pore volume of the coarse particles. Incremental fines contents, by mass, up to this theoretical fines content were tested. The measured saturated hydraulic conductivity was evaluated in terms of fines content, global and intergranular void ratio, and confining stress. Models for predicting extreme void ratios and saturated hydraulic conductivity of binary mixtures were also investigated.

Natural Attenuation can be an effective cleanup option for remediation of Groundwater contamination by BTEX. One of the important aspects of the methodology that has been recognized recently is that mass removal rates, the most important parameters used to determine effectiveness of the methodology, is controlled by groundwater flow regime, which to a large extent controlled by aquifer heterogeneity. Considering this recognition, the primary objective of this research is to quantitatively describe the relationship between natural attenuation rates of BTEX and aquifer heterogeneity using numerical solution techniques. To represent different levels of aquifer heterogeneity, hydraulic conductivity distributions are simulated using Turning Bands Algorithm, changing statistical parameters Coefficient of Variation (CV) and correlation length (h). Visual MODFLOW is used to model the transport of BTEX contamination, at different hydraulic conductivity fields. Degradation rates are calculated by Buscheck&amp / Alcantar and Conservative Tracer Methods. The results show that, for a given h, as CV increases, the plume slows down and stays longer at the domain, so areal extent of plume decreases. For anisotropic field, plumes are more dispersed along x and y-direction, and areal extents of the plumes are greater. During MNA feasibility studies, for the aquifer heterogeneity level of CV and h smaller than 100 % and 10 m, respectively, a minimum recommended biodegradation rate constant of 0.02 d-1 can be used, whereas for the aquifer heterogeneity level of CV and h greater than 100 % and 10 m, respectively, using a minimum biodegradation rate constant of 0.06 d-1 can be recommended.

Acacia holosericea A. Cunn. Ex G. Don (Velvet Leaf Wattle, Family Mimosaceae) is indigenous to Australia and holds promise as a novel cut foliage crop due to its silvery green silky phyllodes. Insufficient water uptake, possibly due to low stem hydraulic conductivity (Kh), is potentially responsible for early wilting and desiccation of phyllodes and limiting vase life. This study aimed to characterize the anatomy of stem xylem conduits and determine cation (K+ and Ca2+) mediated stem Kh. Differential localization of Ca2+ in xylem vessels and the effects of KCl and CaCl2 salts as cation contributors in vase solutions were also evaluated for their effects on cut foliage longevity. Anatomical characteristics of stem xylem conduits were studied using light, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Tracheids and vessels with simple perforation plates were the principal water conducting cells. SEM and TEM revealed bordered vestured intervessel pits in xylem conduits. Vestures were branched and coralloid-like structures. Xylem conduit lengths were assessed by ink perfusion. The majority of conduits (89%) were short (1 to 5 cm), and only ~ 2% were long (15 to 16 cm). Mean conduit diameter was 77 ± 0.9 µm, with 29% of conduits in the range 70 to 80 µm. Effects of S-carvone (0, 0.318, and 0.636 mM), a monoterpene inhibitor of wound-healing enzyme inhibitor found in caraway (Carum carvi) and dill (Anethum graveoleus) seeds, on several native Australian, non-proteaceous cut flower and foliage species including A. holosericea (Mimosaceae), Baeckea frutescens (Myrtaceae), Chamelaucium uncinatum cv. ‘Mullering Brook’ (Myrtaceae), and the non-native Chrysanthemum sp. cv. ‘Dark Splendid Reagan’ (Asteraceae) were examined. As comparator treatments regular recutting of stem ends and use of standard tap water (STW: 0.7 mM CaCl2, 1.5 mM NaHCO3, and 0.05 mM CuSO4 in vases) were tested. S-Carvone treatments significantly (P≤0.05) extended the vase life of B. frutescens and C. uncinatum, constituting the first report of positive S-carvone effects on the vase life of Myrtaceous species. S-Carvone at 0.318 and 0.636 mM did not have antibacterial effects against Bacillus cereus (the main vase solution microbe) either in vitro or in the vase solution. Regular recutting of stem ends consistently improved all vase life parameters [viz. relative fresh weight (RFW), solution uptake, and vase life] in the three native species examined. STW had a positive effect on RFW and solution uptake only for A. holosericea cut foliage. Effects of di- and monovalent cations (Ca2+ as CaCl2 and K+ as KCl) on stem Kh of cut stem segments were studied. Abundance of Ca2+ on pit membranes versus xylem lumen wall surfaces was investigated using a novel low vacuum (LV) SEM plus energy dispersive X-ray (EDX) microanalysis technique. Both salts (0.1, 1, 10, and 100 mM KCl or CaCl2) did not significantly increase stem Kh compared to the corresponding deionised (DI) water controls (experiment 1). Highest increase in Kh was with KCl and CaCl2 at 10 and 1 mM, respectively. Increases in Kh with 100 mM KCl and CaCl2 were significant over DI water (experiment 2) for long (10 and 20 cm) and short (2 and 5 cm) stem segments, respectively. Increases in Kh of 1.2- and 2.4-fold for 100 mM KCl over DI water were found with increasing stem length from 2 to 20 cm. Kh decreased as stem segment length increased from 5 to 20 cm. However, contrasting results were found with 100 mM CaCl2, where ΔKh was larger in shorter (2 cm) than longer (20 cm) segments. To prevent dislocation of ions and distortion damage to the specimens, stem pieces were first LV freeze-dried, and then carbon-coated, viewed under SEM, and analysed for elemental composition and distribution by EDX. However, the method could not identify specific calcium peaks in xylem vessels perhaps because background signals were too high, and tissue topography interfered with signal detection. Effects of KCl and CaCl2 on vase life were also tested. RFW, solution uptake, and vase life were higher with 10 mM KCl and CaCl2 in the vase solution than with 0, 1, and 100 mM. STW had a significant (P≤0.05) positive effect on RFW and solution uptake rate when tested against deionised water, 10 mM KCl and 10 mM CaCl2. Different combinations of 0.05 mM CuSO4, 10 mM CaCl2, and 10 mM KCl were also tested as vase solutions. A significant positive effect on RFW and vase life was obtained with CuSO4 alone, CaCl2 alone, and CuSO4 plus KCl. Only CuSO4 and CaCl2 gave a significant positive effect on solution uptake rate. None of the eight treatments tested showed a consistent effect on stomatal conductance or stem Kh. Overall, the research revealed that tracheids and vessels with simple perforation plates and bordered vestured intervessel pits are the principal water conducting cells in A. holosericea. LV-SEM-EDX technique was unable to assess the spatial distribution of Ca2+ on xylem vessels, but this was the first attempt to apply this technique. Also, this is the first report on the extension of vase life of B. frutescens and C. uncinatum (Myrtaceous species) using S-carvone. In vase solutions, 0.05 mM CuSO4, 10 mM KCl plus 0.05 mM CuSO4 and 10 mM CaCl2 should have positive influences on the water balance of A. holosericea cut foliage stems.

Thesis (M. En.)--Miami University, Institute of Environmental Sciences, 2006. / Title from first page of PDF document. Includes bibliographical references (p. 33-35).