J. Hydrol. Hydromech., Vol. 67, No. 2, 2019, p. 113 - 120, doi: 10.2478/johh-2018-0039
Scientific Paper, English

Pavel Vlasák, Zdeněk Chára, Václav Matoušek, Jiří Konfršt, Mikoláš Kesely: Experimental investigation of fine-grained settling slurry flow behaviour in inclined pipe sections

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• For the safe and economical design and operation of freight pipelines it is necessary to know slurry flow behaviour in inclined pipe sections, which often form significant part of pipelines transporting solids. Fine-grained settling slurry was investigated on an experimental pipe loop of inner diameter D = 100 mm with the horizontal and inclined pipe sections for pipe slopes ranging from –45° to +45°. The slurry consisted of water and glass beads with a narrow particle size distribution and mean diameter d50 = 180 μm. The effect of pipe inclination, mean transport volumetric concentration, and slurry velocity on flow behaviour, pressure drops, deposition limit velocity, and concentration distribution was studied. The study revealed a stratified flow pattern of the studied slurry in inclined pipe sections. Frictional pressure drops in the ascending pipe were higher than that in the descending pipe, the difference decreased with increasing velocity and inclination. For inclination less than about 25° the effect of pipe inclinations on deposition limit velocity and local concentration distribution was not significant. For descending pipe section with inclinations over –25° no bed deposit was observed.
  
  KEY WORDS: Settling slurry; Effect of pipe inclination; Concentration distribution; Pressure drops; Deposition limit; Gamma-ray radiometry.
  
  Address:
  - Pavel Vlasák, Institute of Hydrodynamics of Czech Academy of Sciences, v. v. i., Pod Patankou 30/5, 160 00, Prague 6, Czech Republic. (Corresponding author. Tel.:+420 233109019 Fax.: +420 233324861 Email: vlasak@ih.cas.cz)
  - Zdeněk Chára, Institute of Hydrodynamics of Czech Academy of Sciences, v. v. i., Pod Patankou 30/5, 160 00, Prague 6, Czech Republic.
  - Václav Matoušek, Institute of Hydrodynamics of Czech Academy of Sciences, v. v. i., Pod Patankou 30/5, 160 00, Prague 6, Czech Republic.
  - Jiří Konfršt, Institute of Hydrodynamics of Czech Academy of Sciences, v. v. i., Pod Patankou 30/5, 160 00, Prague 6, Czech Republic.
  - Mikoláš Kesely, Institute of Hydrodynamics of Czech Academy of Sciences, v. v. i., Pod Patankou 30/5, 160 00, Prague 6, Czech Republic.

J. Hydrol. Hydromech., Vol. 67, No. 2, 2019, p. 121 - 128, doi: 10.2478/johh-2018-0040
Scientific Paper, English

Zuzana Allmanová, Mária Vlčková, Martin Jankovský, Matúš Jakubis, Michal Allman: Bank erosion of the Tŕstie stream: BANCS model predictions vs. real bank erosion

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• 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.
  
  KEY WORDS: BANCS model; Bank erosion; Prediction curves.
  
  Address:
  - Zuzana Allmanová, Department of Forest Harvesting, Logistics and Ameliorations, Faculty of Forestry, Technical University in Zvolen, T.G. Masaryka 24, 960 53 Zvolen, Slovakia.
  - Mária Vlčková, Department of Forest Harvesting, Logistics and Ameliorations, Faculty of Forestry, Technical University in Zvolen, T.G. Masaryka 24, 960 53 Zvolen, Slovakia.
  - Martin Jankovský, Department of Forestry Technology and Constructions, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 165 00 Prague 6 – Suchdol, Czechia. (Corresponding author. Tel.:+420 22438 3729 Fax.: Email: jankovskym@fld.czu.cz)
  - Matúš Jakubis, Department of Forest Harvesting, Logistics and Ameliorations, Faculty of Forestry, Technical University in Zvolen, T.G. Masaryka 24, 960 53 Zvolen, Slovakia.
  - Michal Allman, Department of Forest Harvesting, Logistics and Ameliorations, Faculty of Forestry, Technical University in Zvolen, T.G. Masaryka 24, 960 53 Zvolen, Slovakia.

J. Hydrol. Hydromech., Vol. 67, No. 2, 2019, p. 129 - 134, doi: 10.2478/johh-2018-0038
Scientific Paper, English

Elena Benito, Eufemia Varela, María Rodríguez-Alleres: Persistence of water repellency in coarse-textured soils under various types of forests in NW Spain

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• The primary purpose of this work was to assess the persistence of water repellency in the surface horizon of coarse-textured soils under natural Quercus robur ecosystems, and Pinus pinaster and Eucalyptus globulus plantations, in the northwest of the Iberian Peninsula. Water repellency was determined by applying the water drop penetration test (WDPT) to soil samples collected from variable depths (0–40 cm). Measurements were made on field-moist samples obtained at the end of the dry period and on samples dried at 25ºC in the air. All soils exhibited very high (severe to extreme) water repellency in the topmost soil layer (0–5 cm) but no significant differences among the three plant species studied. Extreme persistence was observed down to 20 cm in the soils under eucalyptus and down to 10 cm in those under pine. The soils under oak were those exhibiting the highest variability in water repellency and the greatest decrease in it with increasing depth (especially in relation to soils under eucalyptus). Water repellency exhibited significant positive correlation with the C content and C/N ratio of the soils. Soil water repellency was similar in the air-dried samples and field-moist samples.
  
  KEY WORDS: Soil water repellency; Forest soils; Soil organic carbon; Soil moisture; NW Spain.
  
  Address:
  - Elena Benito, Departamento de Biología Vegetal y Ciencia del Suelo, Universidad de Vigo, 36310 Vigo, Spain. (Corresponding author. Tel.:+34986812396 Fax.: Email: rueda@uvigo.es)
  - Eufemia Varela, Departamento de Biología Vegetal y Ciencia del Suelo, Universidad de Vigo, 36310 Vigo, Spain.
  - María Rodríguez-Alleres, Departamento de Biología Vegetal y Ciencia del Suelo, Universidad de Vigo, 36310 Vigo, Spain.

J. Hydrol. Hydromech., Vol. 67, No. 2, 2019, p. 135 - 142, doi: 10.2478/johh-2018-0041
Scientific Paper, English

Bahman Jabbarian Amiri, Junfeng Gao, Nicola Fohrer, Jan Adamowski: Regionalizing time of concentration using landscape structural patterns of catchments

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• There is an emerging challenge within water resources on how, and to what extent, borrowing concepts from landscape ecology might help re-define traditional concepts in hydrology in a more tangible manner. A stepwise regression model was adopted in this study to assess whether the time of concentration of catchments could be explained by five landscape structure-representing metrics for land use/land cover, soil and geological patches, using spatial data from 39 catchments. The models suggested that the times of concentration of the catchments could be predicted using the measures of four landscape structure-representing metrics, which include contiguity index (r2 = 0.46, p ≤0.05), fractal dimension index (r2 = 0.51, p ≤0.05), related circumscribing circle (r2 = 0.52, p ≤0.05), and shape index (r2 = 0.47, p ≤0.05). The models indicated that the regularity or irregularity in land use/land cover patch shape played a key role in affecting catchment hydrological response. Our findings revealed that regularity and irregularity in the shape of a given patch (e.g., urban and semi-urban, rangeland and agricultural patches) can affect patch functions in retarding and/or increasing flow accumulation at the catchment scale, which can, in turn, decrease or increase the times of concentration in the catchments.
  
  KEY WORDS: Landscape metrics; Time of concentration; Hydrologic Soil Group; Hydrologic response.
  
  Address:
  - Bahman Jabbarian Amiri, Department of Environmental Science, Faculty of Natural Resources, University of Tehran, Chamran Blvd., Karaj, Iran. Key Laboratory of Watershed Geographic Sciences, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, 73 East Beijing Road, Nanjing 210008, China. (Corresponding author. Tel.: Fax.: Email: Jabbarian@ut.ac.ir)
  - Junfeng Gao, Key Laboratory of Watershed Geographic Sciences, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, 73 East Beijing Road, Nanjing 210008, China.
  - Nicola Fohrer, Department of Hydrology and Water Resources, Institute for Nature Conservation and Resource Management, Christian Albrecht Universitaet zu Kiel, Olshausenstr. 75, 24098 Kiel, Germany.
  - Jan Adamowski, Department of Bioresource Engineering, Faculty of Agricultural and Environmental Sciences, McGill University, Ste-Anne-de-Bellevue, Québec H9X 3V9, Canada.

J. Hydrol. Hydromech., Vol. 67, No. 2, 2019, p. 143 - 153, doi: 10.2478/johh-2018-0043
Scientific Paper, English

Jaime G. Cuevas, José L. Arumí, José Dörner: Assessing methods for the estimation of response times of stream discharge: the role of rainfall duration

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• Lagtimes and times of concentration are frequently determined parameters in hydrological design and greatly aid in understanding natural watershed dynamics. In unmonitored catchments, they are usually calculated using empirical or semiempirical equations developed in other studies, without critically considering where those equations were obtained and what basic assumptions they entailed. In this study, we determined the lagtimes (LT) between the middle point of rainfall events and the discharge peaks in a watershed characterized by volcanic soils and swamp forests in southern Chile. Our results were compared with calculations from 24 equations found in the literature. The mean LT for 100 episodes was 20 hours (ranging between 0.6–58.5 hours). Most formulae that only included physiographic predictors severely underestimated the mean LT, while those including the rainfall intensity or stream velocity showed better agreement with the average value. The duration of the rainfall events related significantly and positively with LTs. Thus, we accounted for varying LTs within the same watershed by including the rainfall duration in the equations that showed the best results, consequently improving our predictions. Izzard and velocity methods are recommended, and we suggest that lagtimes and times of concentration must be locally determined with hyetograph-hydrograph analyses, in addition to explicitly considering precipitation patterns.
  
  KEY WORDS: Empirical equations; Lagtimes; Semiempirical equations; Streamflow; Times of concentration.
  
  Address:
  - Jaime G. Cuevas, Centro de Estudios Avanzados en Zonas Áridas (CEAZA), Av. Raúl Bitrán 1305, La Serena, Chile. Centro de Investigación en Suelos Volcánicos (CISVo), Universidad Austral de Chile, Valdivia, Chile. (Corresponding author. Tel.:+56 51 2204378 Fax.: Email: jxcuevas@ceaza.cl)
  - José L. Arumí, Facultad de Ingeniería Agrícola, Departamento de Recursos Hídricos, Centro CRHIAM, Universidad de Concepción, Chillán, Chile.
  - José Dörner, Centro de Investigación en Suelos Volcánicos (CISVo), Universidad Austral de Chile, Valdivia, Chile.

J. Hydrol. Hydromech., Vol. 67, No. 2, 2019, p. 154 - 162, doi: 10.2478/johh-2019-0001
Scientific Paper, English

Mahsa Jahadi, Hossein Afzalimehr, Paweł M. Rowinski: Flow structure within a vegetation patch in a gravel-bed river

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• Investigation of the interactions between submerged vegetation patch and flow structure is of crucial importance for river engineering. Most of hydraulic models have been presented for fully developed flows over uniform vegetation in the laboratory conditions; however, the mentioned interactions are complex in river flows where the flow is not developed along small patch. This reveals a gap between developed and non-developed flow along the vegetation patch. This study was conducted in a gravel-bed river in the central Iran. The results reveal that the flow structure in evolving flow (non-developed flow) along the patch resembles that in shallow mixing layer. Accordingly, a shallow mixing layer model and modified equations are combined to quantify evolving area along the patch. The evolving shallow mixing layer equations for the flow along a non-uniform vegetation patch reach a reasonable agreement with field data. However, the spreading coefficient of this model less than one was reported in literature, 0.06 and 0.12. In addition, the flow immediately downstream the vegetation patch behaves similar to a jet and is parameterized by two conventional models, conventional logarithmic law and mixing layer theory. These models present a reasonable agreement with the measured velocity profiles immediately downstream the patch.
  
  KEY WORDS: Submerged vegetation patch; Mixing layer; Spatially evolving flow; Gravel bed river.
  
  Address:
  - Mahsa Jahadi, Department of Water Engineering, Isfahan University of Technology, Isfahan Iran.
  - Hossein Afzalimehr, Department of Civil Engineering, Iran University of Science and Technology, Tehran Iran. (Corresponding author. Tel.: Fax.: Email: hafzali@iust.ac.ir)
  - Paweł M. Rowinski, Institute of Geophysics, Polish Academy of Sciences, Warszawa, Poland.

J. Hydrol. Hydromech., Vol. 67, No. 2, 2019, p. 163 - 170, doi: 10.2478/johh-2018-0042
Scientific Paper, English

Gašper Rak, Marko Hočevar, Franci Steinman: Water surface topology of supercritical junction flow

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• The complexity of flow conditions at junctions amplifies significantly with supercritical flow. It is a pronounced three-dimensional two-phased flow phenomenon, where standing waves with non-stationary water surface are formed. To analyse the hydrodynamic conditions at an asymmetric right-angled junction with incoming supercritical flows at Froude numbers between 2 and 12, an experimental approach was used. For a phenomenological determination of the relations between the integral parameters of incoming flows and the characteristics of standing waves at the junction area, water surface topographies for 168 scenarios at the junction were measured using non-intrusive measurement techniques. The new, phenomenologically derived equations allow for determination of location, height and extent of the main standing waves at the junction. Research results give important information on the processes and their magnitude for engineering applications.
  
  KEY WORDS: Junction; Hydraulic experimentation; Standing wave; Supercritical flow; Flow patterns.
  
  Address:
  - Gašper Rak, Chair of Fluid Mechanics, Faculty for Civil and Geodetic Engineering, University of Ljubljana, Jamova 2, 1000 Ljubljana, Slovenia. (Corresponding author. Tel.:+386 1 4254052 Fax.: Email: gasper.rak@fgg.uni-lj.si)
  - Marko Hočevar, Laboratory for Water Turbine Machinery, Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia.
  - Franci Steinman, Chair of Fluid Mechanics, Faculty for Civil and Geodetic Engineering, University of Ljubljana, Jamova 2, 1000 Ljubljana, Slovenia.

J. Hydrol. Hydromech., Vol. 67, No. 2, 2019, p. 171 - 178, doi: 10.2478/johh-2019-0002
Scientific Paper, English

Jun Wang, Yifan Wu, Jueyi Sui, Bryan Karney: Formation and movement of ice accumulation waves under ice cover – an experimental study

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• Ice jams in rivers often arise from the movement of frazil ice as cover-load under ice cover, a process which is conceptually similar to the movement of sediment as bed-load along a river bed. The formation and movement of an iceaccumulation wave is one facet of a larger class of cover-load movements. The movement of an ice-accumulation wave obviously plays a crucial role in the overall process of ice accumulation. In the present study, experiments under different flow and ice conditions help reveal the mechanics of formation and evolution of ice-accumulation waves. In particular, suitable criteria for formation of an ice-accumulation wave are investigated along with the resulting speed of wave propagation. The transport capacity of frazil ice under waved accumulation is modeled by comparing those of experiments collected in laboratories, and the resulting equation is shown to be in good agreement with measured experimental results.
  
  KEY WORDS: Cover-load; Experimental results; Frazil ice; Ice-accumulation wave; Ice jam; Ice transport capacity; Moving speed.
  
  Address:
  - Jun Wang, College of Civil Engineering, Hefei University of Technology, Hefei, China.
  - Yifan Wu, College of Civil Engineering, Hefei University of Technology, Hefei, China.
  - Jueyi Sui, Environmental Engineering Program, University of Northern British Columbia, Prince George, Canada. (Corresponding author. Tel.: Fax.: Email: jueyi.sui@unbc.ca)
  - Bryan Karney, Department of Civil Engineering, University of Toronto, Toronto, Canada.

J. Hydrol. Hydromech., Vol. 67, No. 2, 2019, p. 179 - 190, doi: 10.2478/johh-2018-0009
Scientific Paper, English

Fatemeh Afrasiabi, Habib Khodaverdiloo, Farrokh Asadzadeh, Martinus Th. van Genuchten: Comparison of alternative soil particle-size distribution models and their correlation with soil physical attributes

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• Complete descriptions of the particle-size distribution (PSD) curve should provide more information about various soil properties as opposed to only the textural composition (sand, silt and clay (SSC) fractions). We evaluated the performance of 19 models describing PSD data of soils using a range of efficiency criteria. While different criteria produced different rankings of the models, six of the 19 models consistently performed the best. Mean errors of the six models were found to depend on the particle diameter, with larger error percentages occurring in the smaller size range. Neither SSC nor the geometric mean diameter and its standard deviation correlated significantly with the saturated hydraulic conductivity (Kfs); however, the parameters of several PSD models showed significant correlation with Kfs. Porosity, mean weight diameter of the aggregates, and bulk density also showed significant correlations with PSD model parameters. Results of this study are promising for developing more accurate pedotransfer functions.
  
  KEY WORDS: Lake Urmia (Iran); Particle-size distribution models; Pedotransfer functions; Soil physical properties.
  
  Address:
  - Fatemeh Afrasiabi, Department of Soil Science, Urmia University, Urmia 57135-165, Iran.
  - Habib Khodaverdiloo, Department of Soil Science, Urmia University, Urmia 57135-165, Iran. (Corresponding author. Tel.: Fax.: Email: h.khodaverdiloo@urmia.ac.ir)
  - Farrokh Asadzadeh, Department of Soil Science, Urmia University, Urmia 57135-165, Iran.
  - Martinus Th. van Genuchten, Department of Earth Sciences, Utrecht University, Utrecht, Netherlands. Center for Environmental Studies, CEA, Sao Paulo State University, UNESP, Rio Claro, SP, Brazil.

J. Hydrol. Hydromech., Vol. 67, No. 2, 2019, p. 191 - 200, doi: 10.2478/johh-2018-0023
Scientific Paper, English

Vincenzo Alagna, Vincenzo Bagarello, Simone Di Prima, Fabio Guaitoli, Massimo Iovino, Saskia Keesstra, Artemi Cerda: Using Beerkan experiments to estimate hydraulic conductivity of a crusted loamy soil in a Mediterranean vineyard

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• In bare soils of semi-arid areas, surface crusting is a rather common phenomenon due to the impact of raindrops. Water infiltration measurements under ponding conditions are becoming largely applied techniques for an approximate characterization of crusted soils. In this study, the impact of crusting on soil hydraulic conductivity was assessed in a Mediterranean vineyard (western Sicily, Italy) under conventional tillage. The BEST (Beerkan Estimation of Soil Transfer parameters) algorithm was applied to the infiltration data to obtain the hydraulic conductivity of crusted and uncrusted soils. Soil hydraulic conductivity was found to vary during the year and also spatially (i.e., rows vs. interrows) due to crusting, tillage and vegetation cover. A 55 mm rainfall event resulted in a decrease of the saturated soil hydraulic conductivity, Ks, by a factor of 1.6 in the inter-row areas, due to the formation of a crusted layer at the surface. The same rainfall event did not determine a Ks reduction in the row areas (i.e., Ks decreased by a non-significant factor of 1.05) because the vegetation cover intercepted the raindrops and therefore prevented alteration of the soil surface. The developed ring insertion methodology on crusted soil, implying pre-moistening through the periphery of the sampled surface, together with the very small insertion depth of the ring (0.01 m), prevented visible fractures. Consequently, Beerkan tests carried out along and between the vine-rows and data analysis by the BEST algorithm allowed to assess crusting- dependent reductions in hydraulic conductivity with extemporaneous measurements alone. The reliability of the tested technique was also confirmed by the results of the numerical simulation of the infiltration process in a crusted soil. Testing the Beerkan infiltration run in other crusted soils and establishing comparisons with other experimental methodologies appear advisable to increase confidence on the reliability of the method that seems suitable for simple characterization of crusted soils.
  
  KEY WORDS: Hydraulic conductivity; Water infiltration measurements; Soil surface crust; Vineyard; BEST procedure.
  
  Address:
  - Vincenzo Alagna, Department of Agricultural, Food and Forest Sciences, University of Palermo, Viale delle Scienze, 90128 Palermo, Italy.
  - Vincenzo Bagarello, Department of Agricultural, Food and Forest Sciences, University of Palermo, Viale delle Scienze, 90128 Palermo, Italy.
  - Simone Di Prima, Agricultural Department, University of Sassari, Viale Italia, 39, 07100 Sassari, Italy. (Corresponding author. Tel.: Fax.: Email: sdiprima@uniss.it)
  - Fabio Guaitoli, Assessorato regionale dell’Agricoltura, dello Sviluppo Rurale e della Pesca Mediterranea, UO S5.05, Viale Regione Siciliana 2771, 90145 Palermo Italy.
  - Massimo Iovino, Department of Agricultural, Food and Forest Sciences, University of Palermo, Viale delle Scienze, 90128 Palermo, Italy.
  - Saskia Keesstra, Team Soil Water and Land Use, Wageningen Environmental Research, Wageningen UR, Droevendaalsesteeg 3, 6700 AA Wageningen, The Netherlands. Civil, Surveying and Environmental Engineering, The University of Newcastle, Callaghan 2308, Australia.
  - Artemi Cerda, Team Soil Water and Land Use, Wageningen Environmental Research, Wageningen UR, Droevendaalsesteeg 3, 6700 AA Wageningen, The Netherlands. Department of Geography, University of Valencia, Blasco Ibánez, 28, 46010 Valencia, Spain.