Calibrating and verifying 2-D and 3-D vadose zone flow and transport models requires detailed information on water and solute redistribution. Among the different water flow and mass transfer determination methods, staining tracers have the best spatial resolution allowing visualization and quantification of fluid flow including preferential flow paths. Staining techniques have been used successfully for several decades; however, the hydrological community is still searching for an “ideal” vadose zone tracer regarding flow path visualization. To date, most research using staining dyes is carried out with Brilliant Blue FCF. Fluorescent dyes such as Uranine, however, have significant advantages over nonfluorescents which makes them a promising alternative. This paper presents the first analysis of key properties any fluorescent substance must possess to qualify as a staining fluorescent tracer in vadose zone hydrological applications. First, we summarize the main physico-chemical properties of Uranine and evaluate its staining tracer potential with conventional suitability indicators and visibility testing in a soil profile. Based on numerical analysis using the theory of fluorescence, we show that a low molar absorption coefficient is a crucial parameter to quantify concentration accurately. In addition, excitation of a tracer on wavelengths different from the maximum excitation wavelength can extend the linear range of the concentration-fluorescence relationship significantly. Finally, we develop criteria for evaluating the suitability of any potential fluorescent soil staining compound for soil hydrological applications: 1) high quantum yield, 2) low molar absorption coefficient, 3) fluorescence independent of temperature, 4) low photodecomposition rates, and 5) fluorescence stable across a wide range of pH values.
The proposed method to estimate water supply of spring wheat crop is based on the ratio of the water amount extracted by plants under actual conditions of growth (transpiration) to cover needs for maximum (potential) yield (potential transpiration). Estimates of spatial, inter- and intra-annual water supply variability of the spring wheat crop in basic agricultural zones are given. Dependence of the spring wheat yield on water supply is presented. and Navrhnutá metóda určenia zásobovania porastu jarnej pšenice vodou je založená na určení pomeru množstva vody odobratého koreňmi rastlín (transpirácia) k potenciálnej transpirácii, ktorá je podmienkou maximálnej (potenciálnej) úrody. Práca obsahuje údaje o priestorovej, ročnej a medziročnej variabilite transpirácie jarnej pšenice v základných poľnohospodárskych oblastiach, ako aj závislosť úrod jarnej pšenice na zásobovaní porastu vodou (transpirácii).
I consider and reject a specific criticism advanced by Korsgaard against virtue ethics and epistemology when these are conceived with the help of what she calls the image of the “Good Dog.” I consider what virtue ethics and epistemology would look like if the Good Dog picture of virtues were largely correct. I argue that attention to the features that make Korsgaard undermine the usefulness of virtues when conceived along the lines of the Good Dog picture reveals the opposite of what she claims. On the Good Dog picture, virtue ethics and epistemology are seen as more promising approaches to rationality than Korsgaard’s own advocacy of reflection.
The runoff coefficient (RC) is widely used despite requiring to know the effective contributing area, which cannot be known a priori. In a previous work, we defined runoff length (RL), which is difficult to measure. This work aimed to define the minimum RL (mRL), a quantitative and easy proxy of RL, for use in a pilot study on biocrusts in the Tabernas Desert, Spain. We show that RC decreases according to a hyperbola when the contributing area increases, the independent variable being the length of the effective contributing area and its coefficient involving the effects of rainfall and surface features and antecedent conditions. We defined the mRL as the length of the effective contributing area making RC = 1, which is calculated regardless of the area. We studied mRL from three biocrust types and 1411 events clustered in seven categories. The mRL increased with rain volume and intensity, catchment area and slope, whereas plant cover and biocrust succession (with one exception) had a negative effect. Depending on the plot, mRL reached up 3.3–4.0 m on cyanobacterial biocrust, 2.2–7.5 m on the most widespread lichens, and 1.0–1.5 m on late-successional lichens. We discuss the relationships of mRL with other runoff-related parameters.
The age of the surfactant solution influences substantially effectiveness of drag reduction in a turbulent flow in tubes. In this paper are shown effects of both the surfactant concentration and the ratio of the surfactant to the compound containing counter ion, and their role in degradation rate at aging. and Stárnutí roztoku surfaktantu (povrchově aktivní látka) má velký vliv na účinnost snížení tření při turbulentním proudění vody v trubce. Byl zkoumán význam jak koncentrace surfaktantu, tak jeho poměru ke složce obsahující protiiont právě s ohledem na stárnutí roztoku.
A vital topic regarding the optimum and economical design of rigid boundary open channels such as sewers and drainage systems is determining the movement of sediment particles. In this study, the incipient motion of sediment is estimated using three datasets from literature, including a wide range of hydraulic parameters. Because existing equations do not consider the effect of sediment bed thickness on incipient motion estimation, this parameter is applied in this study along with the multilayer perceptron (MLP), a hybrid method based on decision trees (DT) (MLP-DT), to estimate incipient motion. According to a comparison with the observed experimental outcome, the proposed method performs well (MARE = 0.048, RMSE = 0.134, SI = 0.06, BIAS = -0.036). The performance of MLP and MLP-DT is compared with that of existing regression-based equations, and significantly higher performance over existing models is observed. Finally, an explicit expression for practical engineering is also provided.
The aim of this study is to detect changes in flow regime of rivers in Poland. On the basis of daily discharges recorded in 1951–2010 at 159 gauging stations located on 94 rivers regularities in the variability of the river flow characteristics in the multi-year period and in the annual cycle were identified and also their spatial uniformity was examined. In order to identify changes in the characteristics of river regime, similarities of empirical distribution functions of the 5-day sets (pentads) of discharges were analyzed and the percent shares of similar and dissimilar distributions of the 5-day discharge frequencies in the successive 20-year sub-periods were compared with the average values of discharges recorded in 1951–2010. Three alternative methods of river classification were employed and in the classification procedure use was made of the Ward’s hierarchical clustering method. This resulted in identification of groups of rivers different in terms of the degree of transformation of their hydrological regimes in the multi-year and annual patterns.
Winter season temperatures are becoming warmer. However, the transformation of the ice regime on the Vistula River in Toruń has also been affected by river engineering. In particular, the construction and operation of the Włocławek Dam had a significant impact on ice processes. The article presents the results of an analysis determining the contribution of natural and anthropogenic factors to the duration of ice phenomena and ice cover on the Vistula River in the city of Toruń. Compared to the end of the nineteenth century, there has been a reduction in the duration of ice phenomena from 88 to 53 days and of ice cover from 40 to 7 days (in the period of 1882-2011). The article compares the duration of ice cover and winter temperature in three different periods: before the completion of river engineering works (1882-1907); for the controlled river (1908-1969), and for the controlled river with the Włocławek Dam upstream of Toruń (1970-2011). The results showed a significant role of these anthropogenic factors in the changes of the ice cover duration on the Vistula River in Toruń.
Paper deals with sediments settled in the Elbe reservoir Les Království (King´s Forest) between 1914 and 2005. This reservoir is laid on upper Elbe closing the mountain watershed of Krkonoše (Giant Mountains) with the source of the river. To this profile, watershed can be taken as mountain and foothill area. The sediments, before approximately 1950, were non-polluted by heavy metals and specific organic matter because of the undisturbed natural environment. After that time, the conditions of sedimentation became worse. With the industrial boom and ploughing of the grazing land away there, the amount of sediments settled in the reservoir increased much times and high pollution appeared. To this point, the badly treated sewage waters and washing outs of the soil with pesticides and herbicides from the new high-sloped cropland contributed for many years. With this, the amount of sediments increased up to 21 % of the total volume of the reservoir, i.e., approximately, to 2 mil. m3 . It was decided in 1984 that the sediments have to be removed from reservoir. Up to this time, the quality of sediments was followed in the surface layers only and this quality was applied to all layers of sediments. Thus the wrong idea appeared that all sediments are polluted. On the contrary, the authors suppose that the old layers are not polluted and, in the case of cleaning of the reservoir, these need not be stored in a protected dump. Differentiating the sediments to polluted and non-polluted would bring a considerable increase in economy of cleaning. Thus the authors looked for a method to distinguish the sediment components one another. Among others, the method of the radar search of sediments appeared to be promising enough to describe the sediment layers from the actual bottom down to the original bedrock. To this aim, a new radar antenna working in two regimes was applied. In shallow parts of the reservoir, it was towed in cross profiles on water surface while in the deep ones it was moved along the bottom escorted by a diver. Using this, we were able to distinguish 5 components of sediment (i.e. the non-consolidated and cohesive sediment, the sandy loam, sandy silt and the gravel), to fix their positions and to estimate, in accordance to their apparent grain distribution, if they could be polluted or not. Moreover the mathematical method just presented here was worked out to compute volumes of different sediment components directly from radar signals. This method enables to compute the sediment volumes in relatively straight parts of the valley and the meandering ones., Thus the authors have presented a method enabling the estimate of component volumes on one side and to fix their positions to take samples for quality analyses on the other side., and Příspěvek se zabývá sedimenty usazenými v labské nádrži Les Království v období od r. 1914 do současnosti. Nádrž byla vybudovaná na horním Labi a prakticky uzavírá horskou a podhorskou část povodí, v němž je i pramen Labe. Sedimenty usazené v nádrži řekněme do r. 1950 nevykazují znečistění ani těžkými kovy, ani specifickými organickými látkami. Potom se však podmínky sedimentace zhoršily. S tehdejší extensivní industrializací a rozšířením rostlinné výroby i na svažité pozemky dřívějších luk a pastvin došlo k masivnímu zvýšení množství sedimentů přinesených do nádrže a podstatně se zhoršila jejich kvalita díky špatně čištěným odpadním vodám a intenzivnímu užívání chemie s pesticidy a herbicidy na nových velmi svažitých polích. Do r. 1984 stoupl pak objem sedimentů na cca 21 % objemu nádrže, tj. na téměř 2 mil. m3 . Až donedávna se uskutečňovaly kvalitativní analýzy pouze v povrchových vrstvách sedimentů a tak vznikl chybný názor, že celý objem sedimentů je silně znečistěný. Naproti tomu autoři předpokládají, že sedimenty usazené před r. 1950 nejsou znečistěné a nemusí být uloženy na zajištěné skládky. Rozlišení sedimentů na znečištěné a neznečištěné povede k velkým úsporám při čistění nádrže. K tomu cíli autoři hledali vhodnou metodu. Byla zvolena geofyzikální metoda radarového průzkumu dna, která může rozlišit jednotlivé složky sedimentů od jejich současné úrovně až po skalní podklad. K tomu byla použita radarová anténa pracující ve dvou režimech, a to tažením po hladině v malých hloubkách nádrže a tažením po dně za doprovodu potápěče ve větších hloubkách. Touto metodou jsme rozlišili 5 složek sedimentů (tj. nezpevněný sediment, kohesivní sediment, písčité hlíny, písčité bahno a štěrk), zjistili polohu vrstev a následně podle jejich granulometrie mohli odhadnout, jestli mohou obsahovat význačné znečištění. Tyto výsledky byly porovnány se všemi dosažitelnými kvalitativními analýzami a s jejich využitím jsme mohli rozlišit, které vrstvy je při čistění nádrže nutno uložit na zajištěnou skládku a které je možno využít jako výplňový materiál při zemních pracích. Tímto rozlišením je možno ušetřit značné náklady při čistění nádrže.
The process of sedimentation and subsequent gravity compression of kaolin and water suspensions was investigated experimentally. 45 batch tests were carried out and the time dependence of the height of the suspension column was measured. The one-dimensional equations of Darcian mechanics of two-phase porous media are applied to formulate the studied process mathematically. A very natural assumption makes it possible to find a solution of the forward problem for a starting period of the process. Analysis of the theoretical function and the experimental data gives hydraulic conductivity as a function of the suspension concentration. The obtained results are presented and discussed.