This paper explores the impacts of reconfiguration and leaf morphology on the flow downstream of a flexible foliated plant. 3D acoustic Doppler velocimetry and particle image velocimetry were used to experimentally investigate the hydrodynamic interaction between a foliated plant and the flow, testing two plants with different leaves morphology under different bulk flow velocities. The model vegetation was representative of riparian vegetation species in terms of plants hydrodynamic behavior and leaf to stem area ratio. To explore the effects of the seasonal variability of vegetation on the flow structure, leafless conditions were tested. Reconfiguration resulted in a decrease of the frontal projected area of the plants up to the 80% relative to the undeformed value. Such changes in plant frontal area markedly affected the spatial distributions of mean velocity and turbulence intensities, altering the local exchanges of momentum. At increasing reconfiguration, the different plant morphology influenced the mean and turbulent wake width. The leafless stem exhibited a rigid behavior, with the flow in the wake being comparable to that downstream of a rigid cylinder. The study revealed that the flexibility-induced reconfiguration of plants can markedly affect the local distribution of flow properties in the wake, potentially affecting transport processes at the scale of the plant and its subparts.
This paper investigates the incipient motion of sediment particles under non-uniform flow in river and laboratory. In rivers, the non-uniform flow is often observed due to the presence of various bed forms. Threshold condition has been examined by using the Shields diagram based on the uniform flow assumption, however, this approach can be led to fallacious results for non-uniform flows where the effect of pressure gradient is significant due to bed forms. This study investigates the chronological order of incipient motion of the particles, the average threshold velocity (Ucr), and Shields parameter for non-uniform flows. River data collection with gravel is used for investigating the incipient motion of surface layer of river bed and the laboratory data collection is considered studying the incipient motion of sub-surface layer of river. Both river and laboratory data collections are conducted in the presence of bed forms. Results reveal that the Shields diagram underestimates the particle incipient motion under accelerating and decelerating flows for the both case of laboratory and river. In both weak and general motion in the laboratory, the values of the critical Shields parameter are located below the Shields diagram, showing no particle motion. Our analysis shows that the incipient motion in river is affected by the presence of bed forms, river width changes, and flow non-uniformity conditions. The results show that in the accelerating flow (the bed form exit with a negative slope), the incipient motion is greater than the decelerating flow (the bed form entrance with a positive slope).
editorky Stanislava Fedrová, Alice Jedličková., Obsahuje bibliografie a bibliografické odkazy, and Částečně polský a slovenský text, česká a anglická resumé
Longer term monitoring of soil water content at a catchment scale is a key to understanding its dynamics, which can assist stakeholders in decision making processes, such as land use change or irrigation programs. Soil water monitoring in agriculturally dominated catchments can help in developing soil water retention measurements, for assessment of land use change, or adaptation of specific land management systems to climate change. The present study was carried out in the Pannonian region (Upper-Balaton, Hungary) on Cambisols and Calcisols between 2015 and 2021. Soil water content (SWC) dynamics were investigated under different land use types (vineyard, grassland, and forest) at three depths (15, 40, and 70 cm). The meteorological data show a continuous decrease in cumulative precipitation over time during the study with an average of 26% decrease observed between 2016 and 2020, while average air temperatures were similar for all the studied years. Corresponding to the lower precipitation amounts, a clear decrease in the average SWC was observed at all the land use sites, with 13.4%, 37.7%, and 29.3% lower average SWC for the grassland, forest, and vineyard sites, respectively, from 2016 to 2020 (measured at the 15 cm depth of the soil). Significant differences in SWC were observed between the annual and seasonal numbers within a given land use (p < 0.05). The lowest average SWC was observed at the grassland (11.7%) and the highest at the vineyard (28.3%). The data showed an increasing average soil temperature, with an average 6.3% higher value in 2020 compared to 2016. The grassland showed the highest (11.3 °C) and the forest soil the lowest (9.7 °C) average soil temperatures during the monitoring period. The grassland had the highest number of days with the SWC below the wilting point, while the forest had the highest number of days with the SWC optimal for the plants.
Biocrust sustainability relies on dew and rain availability. A study of dew and rain resources in amplitude and frequency and their evolution is presented from year 2001 to 2020 in southern Africa (Namibia, Botswana, South Africa) where many biocrust sites have been identified. The evaluation of dew is made from a classical energy balance model using meteorological data collected in 18 stations, where are also collected rain data. One observes a strong correlation between the frequency of dew and rain and the corresponding amplitudes. There is a general tendency to see a decrease in dew yield and dew frequency with increasing distance from the oceans, located west, east and south, due to decreasing RH, with a relative minimum in the desert of Kalahari (Namibia). Rain amplitude and frequency decreases when going to west and north. Short-term dew/rain correlation shows that largest dew yields clearly occur during about three days after rainfall, particularly in the sites where humidity is less. The evolution in the period corresponds to a decrease of rain precipitations and frequency, chiefly after 2010, an effect which has been cyclic since now. The effect is more noticeable towards north. An increase of dew yield and frequency is observed, mainly in north and south-east. It results in an increase of the dew contribution with respect to rain, especially after 2010. As no drastic changes in the distribution of biomass of biocrusts have been reported in this period, it is likely that dew should compensate for the decrease in rain precipitation. Since the growth of biocrust is related to dew and rain amplitude and frequency, future evolution should be characterized by either the rain cycle or, due to global change, an acceleration of the present tendency, with more dew and less rainfalls.
Deposition of solid particles in the stormwater sewers reduces the discharging capacity, causing inundation. A sediment invert trap (SIT) is an option that can be installed at the bottom of the stormwater sewer drain to intercept the flowing solid particles. In the present study performance of rectangular SIT were analyzed experimentally and computationally. Variation of particle trapping efficiency of rectangular SIT fitted at the bottom of the open channel flume has been studied under the interpretation of invert trap depth, flow depth, particle size, particle shape, and slot width. To predict the flow field and trap efficiency of a rectangular invert trap, 2D-VOF-DPM-CFD modelling has been carried out using ANSYS Fluent 2020 R1 software. For velocity field determination, the volume of fluid (VOF) model was used along with realizable k-є turbulence model. To predict particle trap efficiency, stochastic discrete phase model (DPM) was utilized. From experimental study and CFD modeling, it has been found that the particle trap efficiency of rectangular invert trap varied with change in the depth of invert trap, sediment size, shape factor, depth of flow and slot width. Consideration of particle shape in terms of shape factor in the modeling of solid-phase through DPM validated the CFD predicted results with those obtained experimentally with mean absolute percent error (MAPE) of 2.68%, 3.99% and 6.6% for sewer solid size ranges SS1, SS2, and SS3 respectively at all flow depths for both slot widths considered in this study.
Detailed data on the long-term performance of bioretention cells (BC) for stormwater management are sparse. This research aimed at setting up and testing an infrastructure that will provide the data on hydrologic and chemical performance of BC. Two identical experimental BC’s were built. The monitoring methodology monitoring was developed and tested during a first growing season with the first BC supplied with natural rainfall, while the second BC was used for ponding experiments. Key layer of the BCs, a biofilter, was composed of sand, compost and topsoil. Both BCs are equipped with sensors monitoring the components of water balance and the water potential of the biofilter. High levels of total suspended solids were detected in the outflow. The runoff coefficient for the entire period of the growing season was 0.72 in the first BC and 0.86 in the second BC, while the peak outflow reduction for individual rainfall episodes ranged between 75% to 95% for the first BC and 19% to 30% for the second BC. Saturated hydraulic conductivity of the biofilter in the first BC decreased by two orders of magnitudes after the first year of operation. Retention curves of the biofilter changed due to material consolidation.
Below-average precipitation and above-average air temperature are important factors in the occurrence and intensity of drought. In the context of global climate change, air temperature increase, as a key climatological parameter, has to be considered when calculating the drought index. We introduce a new method of drought analysis, relying on standardized values of precipitation and mean air temperatures for a certain period. The standardized value is calculated by subtracting the average value for each period from each measured value and dividing the obtained value by the standard deviation of the sample. Next, the New Drought Index (NDI) is calculated by subtracting the standardized temperature value from the standardized precipitation value. NDI values were determined for the monthly and annual precipitation time series and mean monthly and annual air temperatures measured at the stations Split-Marjan and Zagreb-Grič between 1948 and 2020. The NDI indicates that the risk of drought has intensified significantly in recent decades, which may be related to the effect of global warming.
Objectives. The main aim of this study was to qualitatively explore the general population’s understanding of forgiveness with regard to its definition, factors, and effects. The special focus of the study was on comparing the views on forgiveness by two generations, young adults, and seniors. Participants and setting. Semi-structured interviews were done with 20 participants from two age groups: ten young adults aged 21 to 29 years (M = 23.4, SD = 2.79) and ten seniors aged 61 to 68 years (M = 64, SD = 2.47). Research questions. Research questions were focused on examining how laypersons conceptualize forgiveness; notably, how they view the factors and effects of forgiveness. It was also explored whether there are any specifics and differences in the views on forgiveness between young adults and seniors. Data analysis. The data obtained from semi-structured interviews were analyzed by Consensual Qualitative Research (Hill et al., 2005). Results. For most individuals in both generations, the basis of forgiveness was letting go of anger and pain. The most significant factor positively related to forgiveness was an apology and admitting the mistake. The most noteworthy negative factor was the depth of the hurt. Individuals perceive positive consequences of forgiveness, especially on their mental health and strengthening their relationships. It seems that young adults perceive forgiveness more as an interpersonal process, while seniors perceive it more as an internal process of an individual. Study limitations. The use of qualitative methodology and the sample size limit the generalization of the findings and comparing two samples at the level of statistical significance. Participants may have had various experiences dealing with hurt and forgiveness throughout their lives which could have influenced their views on forgiveness. Implications. Gaining a deeper understanding of how young adults and seniors understand forgiveness and its effects, what they perceive as helpful or blocking in their forgiving, can help counselors and therapists to improve their interventions aimed at promoting forgiveness., Ciele. Hlavným cieľom štúdie bola kvalitatívna analýza vnímania odpustenia u laickej populácie s ohľadom na jeho definíciu, faktory a dôsledky odpustenia. Vedľajším cieľom štúdie bolo porovnanie názorov na odpustenie u dvoch generácií, mladých dospelých a seniorov.Metóda. 20 participantov dvoch vekových skupín, desať mladých dospelých vo veku 21 až 29 rokov (M = 23,4, SD = 2,79) a desať seniorov vo veku 61 až 68 rokov (M = 64, SD = 2,47) absolvovali pološtrukturované rozhovory. Výskumné otázky. Výskumné otázky boli zamerané na vnímanie odpustenia u laickej po-pulácie; špecificky na vnímanie faktorov a dôsledkov odpustenia. Skúmané boli špecifiká a rozdiely v nazeraní na odpustenie u mladých dospelých a seniorov. Analýza dát. Dáta z pološtrukturovaných rozhovorov boli analyzované pomocou Konsenzuálneho kvalitatívneho výskumu (Hill et al., 2005). Výsledky. Pre väčšinu jednotlivcov oboch generácií bolo základom odpustenia pustenie hnevu a bolesti. Najdôležitejším faktorom pozitívne súvisiacim s odpustením bolo ospravedlnenie a priznanie chyby. Najvýznamnejším blokujúcim faktorom odpustenia bola hĺbka zranenia. Jednotlivci popisovali pozitívne dôsledky odpustenia, predovšetkých na ich psychické zdravie a posilnenie vzťahov. Zdá sa, že mladí dospelí vnímajú odpustenie viac ako interpersonálny proces, kým seniori ho vnímajú viac ako interný proces jednotlivca. Limitácie. Použitie kvalitatívnej metodológie a veľkosť výskumného súboru neumožňujú zovšeobecnenie výsledkov alebo porovnanie dvoch skupín na úrovni štatistickej signifikancie. Participanti mohli mať rôzne skúseností so zraneniami a odpustením v priebehu života, čo mohlo ovplyvniť ich postoje k odpusteniu. Implikácie. Získanie bližšieho porozumenia tomu, ako mladí dospelí a seniori koncipujú odpustenie, čo vnímajú ako nápomocné a rizikové v odpustení a ako popisujú jeho dôsledky, môže pomôcť poradcom a terapeutom k zlepšeniu intervencií zameraných na podporu odpustenia., Lucia Záhorcová, Božena Zelenáková., and Obsahuje bibliografické odkazy