J. Hydrol. Hydromech., Vol. 65, No. 4, 2017, p. 325 - 332, doi: 10.1515/johh-2017-0021
Scientific Paper, English

Ireneusz Laks, Krzysztof Szoszkiewicz, Tomasz Kałuża: Analysis of in situ water velocity distributions in the lowland river floodplain covered by grassland and reed marsh habitats - a case study of the bypass channel of Warta River (Western Poland)

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• The analysis of in situ measurements of velocity distribution in the floodplain of the lowland river has been carried out. The survey area was located on a bypass channel of the Warta River (West of Poland) which is filled with water only in case of flood waves. The floodplain is covered by grassland and reed marsh habitats. The velocity measurements were performed with an acoustic Doppler current profiler (ADCP) in a cross-section with a bed reinforced with concrete slabs. The measured velocities have reflected the differentiated impact of various vegetation types on the loss of water flow energy. The statistical analyses have proven a relationship between the local velocities and the type of plant communities.
  
  KEY WORDS: Floodplain vegetation; Flow resistance; In situ measurements; Velocity distribution.
  
  Address:
  - Ireneusz Laks, Institute of Construction and Geoengineering, Faculty of Environmental Engineering and Land Management, Poznan University of Life Sciences, Poland. (Corresponding author. Tel.: Fax.: Email: ilaks@up.poznan.pl)
  - Krzysztof Szoszkiewicz, Department of Ecology and Environmental Protection, Faculty of Environmental Engineering and Land Management, Poznan University of Life Sciences, Poland.
  - Tomasz Kałuża, Department of Hydraulic and Sanitary Engineering, Faculty of Environmental Engineering and Land Management, Poznan University of Life Sciences, Poland.

J. Hydrol. Hydromech., Vol. 65, No. 4, 2017, p. 333 - 342, doi: 10.1515/johh-2017-0048
Scientific Paper, English

Zbyšek Šustek, Jaroslav Vido, Jana Škvareninová, Jaroslav Škvarenina, Peter Šurda: Drought impact on ground beetle assemblages (Coleoptera, Carabidae) in Norway spruce forests with different management after windstorm damage – a case study from Tatra Mts. (Slovakia)

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• After the windstorm of November 2004, the ground beetle assemblages (Coleoptera, Carabidae) differentiated after the windstorm into four groups reflecting degree of damaging and forestry management (intact stand, fallen timber in situ, extracted timber, fire). The stand with fallen timber reduced abundances of original species. Removal of timber eliminated sensitive forest species and favored tolerant species, whereas the fire allowed invasions of field species. Later, the assemblages on burned sites converged to those in the unburned sites. Their restoration has a sigmoid-like course. Independently on the above differentiation and course assemblage succession, episodes of severe drought resulted with a 1–2-years delay in sudden decline of number of individuals and species. Their numbers were restoring after longer humid periods. Because these extremes occur with a considerable regularity, the observed extremes of fluctuations of number of species and individuals represent the variability limits of the Carabid assemblages in such conditions. The Standardized Precipitation Evapotranspiration Index was shown, using the cross-correlation of SPEI and number of individuals and species of Carabids, as a suitable means to explain and predict such changes for the period of 1–2 years.
  
  KEY WORDS: Drought; Ground beetle; Windstorm; Forest management; Norway spruce.
  
  Address:
  - Zbyšek Šustek, Institute of Zoology of Slovak Academy of Sciences, Dúbravská cesta 9, SK–845 06 Bratislava, Slovakia. (Corresponding author. Tel.:+421 2 59 30 26 17 Fax.: Email: zbysek.sustek@savba.sk)
  - Jaroslav Vido, Department of Natural Environment, Faculty of Forestry, Technical University in Zvolen, T. G. Masaryka 24, SK–960 53 Zvolen, Slovakia.
  - Jana Škvareninová, Department of Applied Ecology, Faculty of Ecology and Environmental Sciences, Technical University in Zvolen, T.G. Masaryka 24, SK–960 53 Zvolen, Slovakia.
  - Jaroslav Škvarenina, Department of Natural Environment, Faculty of Forestry, Technical University in Zvolen, T. G. Masaryka 24, SK–960 53 Zvolen, Slovakia.
  - Peter Šurda, Institute of Hydrology SAS, Dúbravská cesta 9, 841 04 Bratislava, Slovakia.

J. Hydrol. Hydromech., Vol. 65, No. 4, 2017, p. 343 - 346, doi: 10.1515/johh-2017-0035
Scientific Paper, English

Víctor Manuel Salas Aguilar, Víctor Reyes Gómez, Fernando Paz Pellat: An alternative approach in hydrograph decomposition and separation of the baseflow

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• The identification of the moment when direct flow ends and baseflow begins is one of the biggest challenges of hydrological cycle modeling. The objectives of this research were: to characterize the recession curves (RC) and to separate the components of the hydrograph in a compact model. The RC were extracted from time series in three subwatersheds in Mexico. An expo-linear model was adapted and fitted to the master recession curves to find the transition point of the hydrograph and separate the baseflow. The model discriminated the RC in two decreasing ratios: one linear associated to the direct flow, and one exponential linked to the baseflow. The transition point between these two flows was obtained analytically by equaling both ratios. The derivation of a model parameter allowed to find the maximum points in the hydrometric time series, which were the criterion to separate the baseflow. The application of this model is recommended in the analysis of RC with different magnitudes from the flexibility and attachment to the fundaments of exhaustion of a reservoir.
  
  KEY WORDS: Recession curve; Groundwater discharge; Expo-linear model; Reservoir.
  
  Address:
  - Víctor Manuel Salas Aguilar, Posgrado en Hidrociencias, COLPOS, Carretera México-Texcoco Km. 36.5 Montecillo, Texcoco 56230, Estado de México, México. (Corresponding author. Tel.:(52) 01 55 5804 5900 Ext. 1154 Fax.: Email: vsalasaguilar@gmail.com)
  - Víctor Reyes Gómez, Instituto Nacional de Ecología. Miguel de Cervantes 120, Complejo Industrial Chihuahua 31109, Chihuahua, México.
  - Fernando Paz Pellat, Posgrado en Hidrociencias, COLPOS, Carretera México-Texcoco Km. 36.5 Montecillo, Texcoco 56230, Estado de México, México.

J. Hydrol. Hydromech., Vol. 65, No. 4, 2017, p. 347 - 358, doi: 10.1515/johh-2017-0018
Scientific Paper, English

Maria M. Cárdenas Gaudry, Dieter Gutknecht, Juraj Parajka, Rui A.P. Perdigao, Günter Blöschl: Seasonality of runoff and precipitation regimes along transects in Peru and Austria

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• The aim of this study is to understand the seasonalities of runoff and precipitation and their controls along two transects in Peru and one transect in Austria. The analysis is based on daily precipitation data at 111 and 61 stations in Peru and Austria, respectively, and daily discharge data at 51 and 110 stations. The maximum Pardé coefficient is used to quantify the strength of the seasonalities of monthly precipitation and runoff. Circular statistics are used to quantify the seasonalities of annual maximum daily precipitation and annual maximum daily runoff. The results suggest that much larger spatial variation in seasonality in Peru is because of the large diversity in climate and topography. In the dry Peruvian lowlands of the North, the strength of the monthly runoff seasonality is smaller than that of precipitation due to a relatively short rainy period from January to March, catchment storage and the effect of upstream runoff contributions that are more uniform within the year. In the Peruvian highlands in the South, the strength of the monthly runoff seasonality is greater than that of precipitation, or similar, due to relatively little annual precipitation and rather uniform evaporation within the year. In the Austrian transect, the strength of the runoff seasonality is greater than that of precipitation due to the influence of snowmelt in April to June. The strength of monthly regime of precipitation and runoff controls the concentration of floods and extreme precipitation in Peruvian transects. The regions with strong monthly seasonality of runoff have also extreme events concentrated along the same time of the year and the occurrence of floods is mainly controlled by the seasonality of precipitation. In Austria, the monthly runoff maxima and floods occur in the same season in the Alps. In the lowlands, the flood seasonality is controlled mainly by summer extreme precipitation and its interplay with larger soil moisture. The analyses of precipitation and runoff data along topographic gradients in Peru and Austria showed that, overall, in Peru the spatial variation in seasonality is much larger than in Austria. This is because of the larger diversity in climate and topography.
  
  KEY WORDS: Seasonality; Regime; Precipitation; Runoff; Floods; Austria; Peru; Transect; Pardé coefficient.
  
  Address:
  - Maria M. Cárdenas Gaudry, Institute for Hydraulic and Water Resources Engineering, Vienna University of Technology, Karlsplatz 13/223, A-1040 Vienna, Austria.
  - Dieter Gutknecht, Institute for Hydraulic and Water Resources Engineering, Vienna University of Technology, Karlsplatz 13/223, A-1040 Vienna, Austria.
  - Juraj Parajka, Institute for Hydraulic and Water Resources Engineering, Vienna University of Technology, Karlsplatz 13/223, A-1040 Vienna, Austria. (Corresponding author. Tel.: Fax.: Email: parajka@hydro.tuwien.ac.at)
  - Rui A.P. Perdigao, Institute for Hydraulic and Water Resources Engineering, Vienna University of Technology, Karlsplatz 13/223, A-1040 Vienna, Austria.
  - Günter Blöschl, Institute for Hydraulic and Water Resources Engineering, Vienna University of Technology, Karlsplatz 13/223, A-1040 Vienna, Austria.

J. Hydrol. Hydromech., Vol. 65, No. 4, 2017, p. 359 - 365, doi: 10.1515/johh-2017-0024
Scientific Paper, English

Javier Senent-Aparicio, Jesús Soto, Julio Pérez-Sánchez, Jorge Garrido: A novel fuzzy clustering approach to regionalise watersheds with an automatic determination of optimal number of clusters

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• One of the most important problems faced in hydrology is the estimation of flood magnitudes and frequencies in ungauged basins. Hydrological regionalisation is used to transfer information from gauged watersheds to ungauged watersheds. However, to obtain reliable results, the watersheds involved must have a similar hydrological behaviour. In this study, two different clustering approaches are used and compared to identify the hydrologically homogeneous regions. Fuzzy C-Means algorithm (FCM), which is widely used for regionalisation studies, needs the calculation of cluster validity indices in order to determine the optimal number of clusters. Fuzzy Minimals algorithm (FM), which presents an advantage compared with others fuzzy clustering algorithms, does not need to know a priori the number of clusters, so cluster validity indices are not used. Regional homogeneity test based on L-moments approach is used to check homogeneity of regions identified by both cluster analysis approaches. The validation of the FM algorithm in deriving homogeneous regions for flood frequency analysis is illustrated through its application to data from the watersheds in Alto Genil (South Spain). According to the results, FM algorithm is recommended for identifying the hydrologically homogeneous regions for regional frequency analysis.
  
  KEY WORDS: Fuzzy Clustering; Regionalisation; Alto Genil; Hydrological homogeneity; Regional flood frequency analysis.
  
  Address:
  - Javier Senent-Aparicio, Civil Engineering Department, UCAM Universidad Católica San Antonio de Murcia (UCAM), Campus de los Jerónimos, no 135, 30107 Murcia, Spain. (Corresponding author. Tel.:+34 968 278 818 Fax.: Email: jsenent@ucam.edu)
  - Jesús Soto, Civil Engineering Department, UCAM Universidad Católica San Antonio de Murcia (UCAM), Campus de los Jerónimos, no 135, 30107 Murcia, Spain.
  - Julio Pérez-Sánchez, Civil Engineering Department, UCAM Universidad Católica San Antonio de Murcia (UCAM), Campus de los Jerónimos, no 135, 30107 Murcia, Spain.
  - Jorge Garrido, Civil Engineering Department, UCAM Universidad Católica San Antonio de Murcia (UCAM), Campus de los Jerónimos, no 135, 30107 Murcia, Spain.

J. Hydrol. Hydromech., Vol. 65, No. 4, 2017, p. 366 - 377, doi: 10.1515/johh-2017-0023
Scientific Paper, English

Hossein Afzalimehr, Mohammad Reza Maddahi, Jueyi Sui: Bedform characteristics in a gravel-bed river

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• Estimation of hydraulic and geometric parameters of a gravel-bed river such as dimensions of bedforms is very difficult task, although they play a fundamental role in river engineering projects. One of the methods to get essential information regarding the bedform characteristics is to find the relations between the flow parameters and bedform dimensions. We conducted this field study in the Babolroud River in northern Iran to investigate the application of double averaged method in unspecific gravel bedforms to evaluate friction factor. Using data collected from several river reaches with total length of 356 m of a gravel-bed river, the relationship between bedform geometry (height and the length of bedforms) and flow parameters including shear velocity, transport stage parameter with friction factor is investigated. Different methods for estimating bedforms dimensions are examined to assess the ability of predicting bedform parameters (length and height) in a gravel-bed river. Using bedform parameters, the contribution of particle and form friction is estimated. Results confirm the application of the double averaged method and existing bedform parameters for unspecific bedforms. There exists a similar trend between aspect ratio and friction factor in gravel bedforms.
  
  KEY WORDS: Bedform characteristics; Gravel-bed river; Field measurements; Form friction factor.
  
  Address:
  - Hossein Afzalimehr, Department of Civil Engineering, Iran University of Science and Technology, Tehran, Iran.
  - Mohammad Reza Maddahi, Department of Water Engineering, Shahid Bahonar University of Kerman, Kerman, Iran.
  - Jueyi Sui, Environmental Engineering Program, University of Northern British Columbia, Prince George, BC, Canada. (Corresponding author. Tel.: Fax.: Email: Jueyi.sui@unbc.ca)

J. Hydrol. Hydromech., Vol. 65, No. 4, 2017, p. 378 - 384, doi: 10.1515/johh-2017-0025
Scientific Paper, English

Filippo Carlo Bossi, Oleksandr Barannyk, Mostafa Rahimpour, Stefano Malavasi, Peter Oshkai: Effect of transverse perforations on fluid loading on a long, slender plate at zero incidence

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• This paper reports the results of experimental investigations of flow-induced loading on perforated and solid flat plates at zero incidence with respect to the incoming flow. The plates had a streamwise length to transverse thickness ratio of 23.5. The effect of the perforations was investigated for three different perforation diameters. The results corresponding to the perforated plates were compared with the reference case of the solid plate (no perforations) at five inflow velocities. We quantified the effect of the perforations on the unsteady fluid loading on the plate in terms of the variations of the corresponding Strouhal number, the mean drag coefficient and the fluctuating lift coefficient as functions of the Reynolds number and the perforation diameter. The results indicate that the loading was dominated by the dynamics of the wake. In particular, increasing the perforation diameter resulted in a wider wake, corresponding to the increase in mean drag coefficient and the decrease in the Strouhal number. Onset of coupling between the vortex shedding and the transverse oscillations of the plate was manifested as a rapid increase in the fluctuating lift coefficient, as the perforation diameter exceeds the plate thickness.
  
  KEY WORDS: Perforated plate; Flow-induced loading; Flow-induced vibration.
  
  Address:
  - Filippo Carlo Bossi, Department of Civil and Environmental Engineering, Hydraulic Section, Politecnico di Milano, piazza Leonardo da Vinci 32, 20133, Milano, Italy. (Corresponding author. Tel.:+39 02 2399 6260 Fax.: +39 02 2399 6298 Email: filippocarlo.bossi@polimi.it)
  - Oleksandr Barannyk, Department of Mechanical Engineering, Institute for Integrated Energy System, P.O. Box 1700, Stn. CSC, Victoria, BC V8W 2Y2, Canada.
  - Mostafa Rahimpour, Department of Mechanical Engineering, Institute for Integrated Energy System, P.O. Box 1700, Stn. CSC, Victoria, BC V8W 2Y2, Canada.
  - Stefano Malavasi, Department of Civil and Environmental Engineering, Hydraulic Section, Politecnico di Milano, piazza Leonardo da Vinci 32, 20133, Milano, Italy.
  - Peter Oshkai, Department of Mechanical Engineering, Institute for Integrated Energy System, P.O. Box 1700, Stn. CSC, Victoria, BC V8W 2Y2, Canada.

J. Hydrol. Hydromech., Vol. 65, No. 4, 2017, p. 385 - 394, doi: 10.1515/johh-2017-0026
Scientific Paper, English

Adam Kozioł, Janusz Urbański, Adam Kiczko, Marcin Krukowski, Piotr Siwicki, Marek Kalenik: Turbulence intensity and spatial scales of turbulence after hydraulic jump over scour hole in rectangular channel

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• The study presents experimental investigations of spatial turbulence intensity and scales of turbulent eddies (macroeddies) in a rectangular channel and the impact of the hydraulic jump on their vertical and streamwise distributions over a flat and scoured bed. The results of four tests and two different discharge rates are presented. Intensive mixing caused by the hydraulic jump has an impact on the instantaneous velocity, turbulence intensity and sizes of macroeddies, as well as their vertical and longitudinal distributions along the channel. The largest differences in turbulence characteristics were reported directly after the hydraulic jump, above the eroded bed. The interaction between the stream of the increased turbulence and the bed is a direct cause of formation of scour downstream water structures, which has a great effect on overall flow characteristics. The scour hole that arose downstream the jump moderated, in a small degree, the turbulence intensity at its end. Just next to the hydraulic jump only the small longitudinal relative sizes of macroeddies were present, while at the end of the analyzed reach, downstream of the scour, the relative scale reached around 1.5 depth of the stream.
  
  KEY WORDS: Turbulent intensity; Eddies; Hydraulic jump; Scour hole; Rectangular channel.
  
  Address:
  - Adam Kozioł, Department of Hydraulics, Faculty of Civil and Environmental Engineering, Warsaw University of Life Sciences - SGGW, Warszawa, Poland. (Corresponding author. Tel.:+48 225935276 Fax.: Email: adam_koziol@sggw.pl)
  - Janusz Urbański, Department of Hydraulics, Faculty of Civil and Environmental Engineering, Warsaw University of Life Sciences - SGGW, Warszawa, Poland.
  - Adam Kiczko, Department of Hydraulics, Faculty of Civil and Environmental Engineering, Warsaw University of Life Sciences - SGGW, Warszawa, Poland.
  - Marcin Krukowski, Department of Hydraulics, Faculty of Civil and Environmental Engineering, Warsaw University of Life Sciences - SGGW, Warszawa, Poland.
  - Piotr Siwicki, Department of Hydraulics, Faculty of Civil and Environmental Engineering, Warsaw University of Life Sciences - SGGW, Warszawa, Poland.
  - Marek Kalenik, Department of Civil Engineering, Faculty of Civil and Environmental Engineering, Warsaw University of Life Sciences - SGGW, Warszawa, Poland.

J. Hydrol. Hydromech., Vol. 65, No. 4, 2017, p. 395 - 401, doi: 10.1515/johh-2017-0030
Scientific Paper, English

Tomas Orfanus, Abdel-Monem Mohamed Amer, Grzegorz Jozefaciuk, Emil Fulajtar, Anežka Čelková: Water vapour adsorption on water repellent sandy soils

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• Soil sorptivity is considered a key parameter describing early stages of water (rain) infiltration into a relatively dry soil and it is related to build-up complexity of the capillary system and soil wettability (contact angles of soil pore walls). During the last decade an increasing water repellency of sandy soils under pine forest and grassland vegetation has been frequently observed at Mlaky II location in SW Slovakia. The dry seasons result in uneven wetting of soil and up to hundredfold decrease in soil sorptivity in these vegetated soil as compared to reference sandy material, which was out of the reach of ambient vegetation and therefore readily wettable. As far as water binding to low moisture soils is governed by adsorption processes, we hypothesized that soil water repellency detected by water drop penetration test and by index of water repellency should also influence the water vapour adsorption parameters (monolayer water content, Wm, specific surface area, A, maximum adsorption water, Wa, maximum hygroscopic water MH, fractal dimension, DS and adsorption energies, Ea) derived from BET model of adsorption isotherms. We found however, that the connection of these parameters to water repellency level is difficult to interpret; nevertheless the centres with higher adsorption energy prevailed evidently in wettable materials. The water repellent forest and grassland soils reached less than 80% of the adsorption energy measured on wettable reference material. To get more conclusive results, which would not be influenced by small but still present variability of field materials, commercially available homogeneous siliceous sand was artificially hydrophobized and studied in the same way, as were the field materials. This extremely water repellent material had two-times lower surface area, very low fractal dimension (close to 2) and substantially lower adsorption energy as compared to the same siliceous sand when not hydrophobized.
  
  KEY WORDS: Soil sorptivity; Hydrophobization; Adsorption isotherm; Fractal dimension; Specific surface area.
  
  Address:
  - Tomas Orfanus, Institute of Hydrology, Slovak Academy of Sciences, Dúbravská cesta 9, 841 04 Bratislava, Slovakia. (Corresponding author. Tel.: Fax.: Email: orfanus@uh.savba.sk)
  - Abdel-Monem Mohamed Amer, Soil Science Department, Faculty of Agriculture, Menoufia University, Shebin El-Kom, Egypt.
  - Grzegorz Jozefaciuk, Polish Academy of Sciences, Institute of Agrophysics, ul. Doswiadczalna 4, P.O. Box 201 20-290, Lublin, Poland.
  - Emil Fulajtar, Soil Science and Conservation Institute, Rožňavská 23, 831 04 Bratislava, Slovakia.
  - Anežka Čelková, Institute of Hydrology, Slovak Academy of Sciences, Dúbravská cesta 9, 841 04 Bratislava, Slovakia.

J. Hydrol. Hydromech., Vol. 65, No. 4, 2017, p. 402 - 409, doi: 10.1515/johh-2017-0022
Scientific Paper, English

Jesús Rodrigo-Comino, Christine Brings, Thomas Iserloh, Markus C. Casper, Manuel Seeger, José M. Senciales, Eric C. Brevik, José D. Ruiz-Sinoga, Johannes B. Ries: Temporal changes in soil water erosion on sloping vineyards in the Ruwer- Mosel Valley. The impact of age and plantation works in young and old vines

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• It is well known that rainfall causes soil erosion in sloping German vineyards, but little is known about the effect of age of plantation on soil erosion, which is relevant to understand and design sustainable management systems. In the Ruwer-Mosel valley, young (1- to 4-years) and old (35- to 38-years after the plantation) vineyards were selected to assess soil and water losses by using two-paired Gerlach troughs over three years (2013–2015). In the young vineyard, the overland flow was 107 L m–1 and soil loss 1000 g m–1 in the year of the plantation, and decreased drastically over the two subsequent years (19 L m–1; 428 g m–1). In the old vineyard, soil (from 1081 g m–1 to 1308 g m–1) and water (from 67 L m–1 to 102 L m–1) losses were 1.2 and 1.63 times higher, respectively, than in the young vineyard.
  
  KEY WORDS: Soil erosion; Old vineyard; Young vineyard; Rainfall; Tillage; Ruwer-Mosel valley.
  
  Address:
  - Jesús Rodrigo-Comino, Instituto de Geomorfología y Suelos, Department of Geography, University of Málaga, 29071, Málaga, Spain. Department of Physical Geography, Trier University, D-54286 Trier, Germany. (Corresponding author. Tel.: Fax.: Email: rodrigo-comino@uma.es)
  - Christine Brings, Department of Physical Geography, Trier University, D-54286 Trier, Germany.
  - Thomas Iserloh, Department of Physical Geography, Trier University, D-54286 Trier, Germany.
  - Markus C. Casper, Department of Physical Geography, Trier University, D-54286 Trier, Germany.
  - Manuel Seeger, Department of Physical Geography, Trier University, D-54286 Trier, Germany.
  - José M. Senciales, Department of Geography, Málaga University, Campus of Teatinos s/n, 29071 Málaga, Spain.
  - Eric C. Brevik, Department of Natural Sciences, Dickinson State University, Dickinson, ND, USA.
  - José D. Ruiz-Sinoga, Instituto de Geomorfología y Suelos, Department of Geography, University of Málaga, 29071, Málaga, Spain. Department of Geography, Málaga University, Campus of Teatinos s/n, 29071 Málaga, Spain.
  - Johannes B. Ries, Instituto de Geomorfología y Suelos, Department of Geography, University of Málaga, 29071, Málaga, Spain.

J. Hydrol. Hydromech., Vol. 65, No. 4, 2017, p. 410 - 425, doi: 10.1515/johh-2017-0038
Scientific Paper, English

Wei Shao, Ye Su, Jakub Langhammer: Simulations of coupled non-isothermal soil moisture transport and evaporation fluxes in a forest area

 Full Text in PDF     42 DOWNLOADS

• This study focuses on the quantification of non-isothermal soil moisture transport and evaporation fluxes in vegetated area. A one-dimensional numerical model is developed by integrating a multi-phase flow model with a twolayer energy-balance model. The non-isothermal multi-phase flow model solves four governing equations for coupled air, vapour, moisture, and heat transport in soil porous medium. The two-layer energy balance model estimates evaporation fluxes from transpiration, interception, and soil surface. The model was implemented to an oak forest area in Missouri, USA. For model calibration and validation, measurements of energy fluxes, soil moisture, and soil temperature were used. The proposed model is compared with a simple model that couples the Penman-Monteith equation with the Richards’ equation. The results indicate that the simple model underestimate the total evaporation rate. On the contrary, the proposed model includes a more detailed description of energy transfer, which could improve the accuracy in estimating evaporation rates. The proposed model could be a promising tool to quantify the energy and moisture fluxes in a soil-vegetation-atmosphere continuum in vegetated area.
  
  KEY WORDS: Soil–vegetation–atmosphere transfer model; Evaporation flux; Soil moisture transport; Forest meteorology.
  
  Address:
  - Wei Shao, College of Hydrometeorology, Nanjing University of Information Science and Technology, Nanjing 210044, Jiangsu, China.
  - Ye Su, Department of Physical Geography and Geoecology, Faculty of Science, Charles University, Albertov 6, 128 43 Prague 2, Czech Republic.
  - Jakub Langhammer, Department of Physical Geography and Geoecology, Faculty of Science, Charles University, Albertov 6, 128 43 Prague 2, Czech Republic. (Corresponding author. Tel.:+420-221951415 Fax.: +420-221951415 Email: jakub.langhammer@natur.cuni.cz)

J. Hydrol. Hydromech., Vol. 65, No. 4, 2017, p. 426 - 432, doi: 10.1515/johh-2017-0040
Technical note, English

Alexandar Djordjevich, Svetislav Savović, Aco Janićijević: Explicit finite-difference solution of two-dimensional solute transport with periodic flow in homogenous porous media

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• The two-dimensional advection-diffusion equation with variable coefficients is solved by the explicit finitedifference method for the transport of solutes through a homogenous two-dimensional domain that is finite and porous. Retardation by adsorption, periodic seepage velocity, and a dispersion coefficient proportional to this velocity are permitted. The transport is from a pulse-type point source (that ceases after a period of activity). Included are the firstorder decay and zero-order production parameters proportional to the seepage velocity, and periodic boundary conditions at the origin and at the end of the domain. Results agree well with analytical solutions that were reported in the literature for special cases. It is shown that the solute concentration profile is influenced strongly by periodic velocity fluctuations. Solutions for a variety of combinations of unsteadiness of the coefficients in the advection-diffusion equation are obtainable as particular cases of the one demonstrated here. This further attests to the effectiveness of the explicit finite difference method for solving two-dimensional advection-diffusion equation with variable coefficients in finite media, which is especially important when arbitrary initial and boundary conditions are required.
  
  KEY WORDS: Two dimensional advection-diffusion equation; Mass transfer; Finite difference method.
  
  Address:
  - Alexandar Djordjevich, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong, China.
  - Svetislav Savović, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong, China. University of Kragujevac, Faculty of Science, R. Domanovića 12, 34000 Kragujevac, Serbia. (Corresponding author. Tel.: Fax.: +381-34-335040 Email: savovic@kg.ac.rs)
  - Aco Janićijević, Faculty of Technology and Metallurgy, University of Belgrade, Belgrade, Serbia.