Study of bacterial transport and retention in soil is important for various environmental applications such as groundwater contamination and bioremediation of soil and water. The main objective of this research was to quantitatively assess bacterial transport and deposition under saturated conditions in calcareous soil. A series of leaching experiments was conducted on two undisturbed soil columns. Breakthrough curves of Pseudomonas fluorescens and Cl were measured. After the leaching experiment, spatial distribution of bacteria retention in the soil columns was determined. The HYDRUS-1D one- and two-site kinetic models were used to predict the transport and deposition of bacteria in soil. The results indicated that the two-site model fits the observed data better than one-site kinetic model. Bacteria interaction with the soil of kinetic site 1 revealed relatively fast attachment and slow detachment, whereas attachment to and detachment of bacteria from kinetic site 2 was fast. Fast attachment and slow detachment of site 1 can be attributed to soil calcium carbonate that has favorable attachment sites for bacteria. The detachment rate was less than 0.02 of the attachment rate, indicating irreversible attachment of bacteria. High reduction rate of bacteria was also attributed to soil calcium carbonate.
The problematics of creation and development of bank erosion, follow-up repairs of abrasion damaged banks and development of abrasion progress prognostic methods is often discussed. One of the contributions to this discussion is presentation of ''Modificated Methods of Abrasion Terminal Line Determination''. The prognosis of bank erosion advance is determined also in areas, where original condition of bank is unknown. This method was successfully verified during years 1998-2001 at Brno Reservoir on the Svratka River and can be used at other dam reservoirs as well. and O problematice vzniku a rozvoje břehové abraze, o návrzích následné sanace abrazí poškozených břehů a vývoji prognostických metod postupu abraze se v posledních letech diskutuje stále častěji. Jedním z příspěvků k této diskusi je i prezentace ''modifikované metody určení abrazní terminanty''. Jedná se zde o stanovení prognózy postupu břehové abraze, a to i v oblastech, ve kterých neznáme původní stav pobřeží. Tato metoda byla úspěšně ověřována v letech 1998-2001 na údolní nádrži Brno na řece Svratce a je široce použitelná i na jiných vodních dílech.
This paper focused on predicting the bank erosion through the Bank Assessment for Non-point source Consequences of sediment (BANCS) model on the Tŕstie water stream, located in the western Slovakia. In 2014, 18 experimental sections were established on the stream. These were assessed through the Bank Erosion Hazard Index (BEHI) and the Near Bank Stress (NBS) index. Based on the data we gathered, we constructed two erosion prediction curves. One was for BEHI categories low and moderate, and one for high, very high, and extreme BEHI. Erosion predicted through the model correlated strongly with the real annual bank erosion – for low and moderate BEHI, the R2 was 0.51, and for
high, very high and extreme BEHI, the R2 was 0.66. Our results confirmed that the bank erosion can be predicted with sufficient precision on said stream through the BANCS model.
In numerical models of fluid flow with particles moving close to solid boundaries, the Basset force is usually calculated for the particle motion between particle-boundary collisions. The present study shows that the history force must also be taken into account regarding particle collisions with boundaries or with other particles. For saltation - the main mode of bed load transport - it is shown using calculations that two parts of the history force due to both particle motion in the fluid and to particle-bed collisions are comparable and substantially compensate one another. The calculations and comparison of the Basset force with other forces acting on a sand particle saltating in water flow are carried out for the different values of the transport stage. The conditions under which the Basset force can be neglected in numerical models of saltation are studied. and V numerických modelech proudění tekutin s pevnými částicemi v blízkosti pevné stěny je Bassetova historická síla obvykle počítána pro pohyb částice mezi jejími jednotlivými kolisemi se dnem. Předložená studie ukazuje, že při výpočtu Bassetovy historické síly je nutné brát v úvahu kolisi částice s pevným dnem nebo s jinými částicemi. Pro saltaci, hlavní typ pohybu splavenin u dna koryta, je na základě použitých výpočtů ukázáno, že dvě části Bassetovy historické síly, tj. síly způsobené pohybem částice v tekutině a kolisí částice se dnem, jsou srovnatelné a mohou se vzájemně významně kompensovat. Výpočet Bassetovy historické síly a její srovnání s ostatními silami působícími na písčitou částici při jejím saltačním pohybu ve vodě je uskutečněn pro různé hodnoty tzv. transport stage (poměr aktuálního a kritického smykového napětí na dně). Zároveň byly studovány podmínky, za nichž může být Bassetova historická síla v numerických modelech zanedbána.
In this study the hydraulic and solute transport properties of an unsaturated soil were estimated simultaneously from a relatively simple small-scale laboratory column infiltration/outflow experiment. As governing equations we used the Richards equation for variably saturated flow and a physical non-equilibrium dual-porosity type formulation for solute transport. A Bayesian parameter estimation approach was used in which the unknown parameters were estimated with the Markov Chain Monte Carlo (MCMC) method through implementation of the Metropolis-Hastings algorithm. Sensitivity coefficients were examined in order to determine the most meaningful measurements for identifying the unknown hydraulic and transport parameters. Results obtained using the measured pressure head and solute concentration data collected during the unsaturated soil column experiment revealed the robustness of the proposed approach.