J. Hydrol. Hydromech., Vol. 72, No. 1, 2024, p. 1 - 14, doi: 10.2478/johh-2023-0038
Scientific Paper, English

Sanandam Bordoloi, Jia-Xin Liao, Charles Wang Wai Ng: Tree morphology dependent transpiration reduction function of Schefflera arboricola for landfill cover restoration

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• Changes in hydrological processes and water resources required to sustain vegetation for ecological restoration of landfill covers and post mining sites in arid environments pose challenges in the context of extended droughts. Knowledge of actual threshold and wilting suction values based on tree morphological feature or plant age is essential for understanding the variation of root water uptake with drought stress and numerically predict the pore water pressure profile in root zone. The objective of this study is to quantify the transpiration reduction function (TRF; in terms of stomatal conductance (SC) and xylem sap flow (SF)) of Schefflera arboricola, considering the effects of tree morphology. Continuous drought condition was applied on the plant quantified with leaf area index (LAI) values at 0.5, 2 and 3.5, wherein each LAI represent tree age. The soil matric suction (ψ) and volumetric water content were measured by embedded sensors in the root zone. Based on the TRF obtained from SC values, a unique threshold suction (ψNTRt) ranging from 30 to 50 kPa was identified. Beyond this ψNTRt, measured leaf abscisic acid concentration increased up to 35 ng/mL, indicating the start of water stress avoidance mechanism. It is evident that ψNTRt is independent of tree morphological parameter- leaf area to root length ratio (LA/RL). On the contrary, a threshold suction ψSAPt, depending on LA/RL ratio, can be determined, indicating the start of xylem cavitation. This ψSAPt values ranging from 80 to 500 kPa depending on the LA/RL value, imply that the plant could significantly resist xylem embolization at higher LA/RL. In contrast, the plant with low LA/RL values have less tolerance of drought stress and hence low survivability. The results from this research study can be vital for devising and predicting plant available water in water scarce arid environments by a flux-based approach which is dependent on the tree age.
  
  KEY WORDS: Vegetation; Suction; Transpiration; Partial saturation; Drought.
  
  Address:
  - Sanandam Bordoloi, School of Engineering, Aalto University, Espoo, Finland. (Corresponding author. Tel.: Fax.: Email: sanandam.bordoloi@aalto.fi)
  - Jia-Xin Liao, Department of Civil and Environmental Engineering, Hong Kong University of Science and Technology, Hong Kong SAR.
  - Charles Wang Wai Ng, Department of Civil and Environmental Engineering, Hong Kong University of Science and Technology, Hong Kong SAR.

J. Hydrol. Hydromech., Vol. 72, No. 1, 2024, p. 15 - 24, doi: 10.2478/johh-2023-0037
Scientific Paper, English

Vesna Nikolić Jokanović, Dušan Jokanović, Radovan Savić, Nenad Petrović, Marko Marinković, Bojan Tubić, Ivana Vasić: Soil moisture regime in lowland forests – quantity and availability of water

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• Water is one of the key ecological factors that has a great impact to development and productivity of lowland species such as Quercus robur. This paper deals with water regime influence to site conditions of these species and how actually changeable soil moisture affects Q. robur. Studied area includes a protective embankment built on the river bank in order to eliminate flooding effect, which means that all needs for water these associations provide from rainfalls and groundwater. Water regime was monitored during two critical years (extremely dry and extremely wet) on four soil types – Planosol, Fluvisol and Gleysol that belong to hydromorphic (three experimental plots) and Chernozem which belongs to automorphic soils (three experimental plots), respectively. It was studied the distribution of rainfalls and groundwater during the growing seasons and how it affects total and available water amount in the soil. The main focus should be given to available water, because it is located in capillary pores and plants can utilize it. Bearing in mind rainfalls makes just 15–20% of the total water amount in the soil it is much more significant to evaluate its proportion in available water. Based on obtained results, we can deduce that much more suitable site conditions for Q. robur are present on hydromorphic soils due to much greater proportion of groundwater.
  
  KEY WORDS: Quercus robur; Soil moisture; Available water; Groundwater; Precipitation.
  
  Address:
  - Vesna Nikolić Jokanović, University of Belgrade, Faculty of Forestry, Kneza Višeslava 1, 11030 Belgrade, Republic of Serbia. (Corresponding author. Tel.:+ 381 11 3053846 Fax.: Email: vesna.nikolic@sfb.bg.ac.rs)
  - Dušan Jokanović, University of Belgrade, Faculty of Forestry, Kneza Višeslava 1, 11030 Belgrade, Republic of Serbia.
  - Radovan Savić, University of Novi Sad, Faculty of Agriculture, Trg D. Obradovica 8, 21000 Novi Sad, Serbia.
  - Nenad Petrović, University of Belgrade, Faculty of Forestry, Kneza Višeslava 1, 11030 Belgrade, Republic of Serbia.
  - Marko Marinković, Public Enterprise “Vojvodinasume”, Preradoviceva 2, 21131 Petrovaradin, Novi Sad, Serbia.
  - Bojan Tubić, Public Enterprise “Vojvodinasume”, Preradoviceva 2, 21131 Petrovaradin, Novi Sad, Serbia.
  - Ivana Vasić, Public Enterprise “Vojvodinasume”, Preradoviceva 2, 21131 Petrovaradin, Novi Sad, Serbia.

J. Hydrol. Hydromech., Vol. 72, No. 1, 2024, p. 25 - 33, doi: 10.2478/johh-2023-0035
Scientific Paper, English

H.T.M. Perera, Yasushi Mori, Morihiro Maeda, D.A.L. Leelamanie: Heat-induced alterations in moisture-dependent repellency of water-repellent forest soils: A laboratory approach with Japanese Andosols

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• Soil water repellency (SWR) is a phenomenon that prevents the spontaneous wetting of numerous forest soils. It is a moisture-dependent characteristic, which disappears when soil moisture reaches near saturation. The heat generated during forest fires affects soil characteristics including SWR. The possibility of heat influencing moisture-dependent repellency (MDR) is not well understood. The present study aimed to investigate the effects of different heating temperatures (HT) and exposure durations (ED) on MDR using water-repellent Japanese Cedar (CED) and Japanese Cypress (CYP) forest soils. Soil samples collected from 0–5 cm depth were exposed to heat separately at 50, 100, and 150 °C (HT) for 1 h and 2 h durations (ED). The MDR of heated and non-heated soils was determined using the water drop penetration time (WDPT) test in a drying process. During the drying process of the tested soils, SWR appeared and then increased with drying to reach an extreme level (WDPT ≥3600 s) that persisted for a range of decreasing moisture contents, and declined to be non-repellent again (WDPT = 0 s). The critical moisture content at which soils become water-repellent with drying (CMC), the highest and the lowest moisture contents when soils showed maximum SWR (HMCmax and LMCmax, respectively), and the integrated area below the MDR curve (SWR) decreased with increasing HT in both CED and CYP soils. The moisture content at which soils become non-repellent again during drying, MCNR, was independent of the type of soil and heat treatment. The range of moisture contents between HMCmax and LMCmax, where soils show maximum SWR during drying, decreased with increasing HT, from 50 to 150 °C in CED and from 100–150 °C in CYP. The SWR showed strong positive linear correlations with CMC and HMCmax. The heat generated during wildfires can alter the MDR and all the related repellency parameters of water-repellent forest soils. SWR prevails over a narrower range of moisture contents in heated soil compared with non-heated soils. Further investigations with higher temperature levels using different soil types would be important for a comprehensive understanding of the heat impacts on MDR.
  
  KEY WORDS: Forest soils; Japanese Andosols; Laboratory heating; Moisture-dependent repellency; Soil water repellency.
  
  Address:
  - H.T.M. Perera, Department of Soil Science, Faculty of Agriculture, University of Ruhuna, Mapalana, Kamburupitiya 81100, Sri Lanka.
  - Yasushi Mori, Graduate School of Environmental and Life Science, Okayama University, 3-1-1, Tsushima-Naka, Kita-Ku, Okayama 700-8530, Japan.
  - Morihiro Maeda, Graduate School of Environmental and Life Science, Okayama University, 3-1-1, Tsushima-Naka, Kita-Ku, Okayama 700-8530, Japan.
  - D.A.L. Leelamanie, Department of Soil Science, Faculty of Agriculture, University of Ruhuna, Mapalana, Kamburupitiya 81100, Sri Lanka. (Corresponding author. Tel.:+94-71-861-4380 Fax.: +94-41-2292384 Email: leelamanie@soil.ruh.ac.lk; leelamaniee@yahoo.co.uk)

J. Hydrol. Hydromech., Vol. 72, No. 1, 2024, p. 34 - 48, doi: 10.2478/johh-2023-0041
Scientific Paper, English

Elnaz Bodaghi, Chonoor Abdi Chooplou, Masoud Ghodsian: Experimental investigation of scour downstream of a type A trapezoidal piano key weir under free and submerged flow conditions

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• In this paper, the scour downstream of a trapezoidal Piano key weir (PKW) is investigated under free and submerged flow conditions. For this purpose, an experimental model was used in a laboratory channel with a length of 10 m, width of 0.75 m, and height of 0.8 m at various discharges and tailwater depths. The results showed an increase and decrease in the maximum scour depth with an increase in the discharge and submergence ratio, respectively. In addition, increasing the particle Froude number enhanced the geometric features of the scour hole downstream of the PKW. The rate of bed changes slowed down over time. The average values of maximum scour depth, the distance of the maximum scour depth from the weir toe, maximum scour hole length and weir toe scour depth increased in the free flow compared to the submerged flow. The scour hole volume and scour hole area in the submerged flow were less compared to the free flow. The average maximum level of the sedimentary ridge in the free flow is less than the submerged flow. New equations for calculating the geometric characteristics of the scour hole downstream of the trapezoidal PKW are presented with acceptable accuracy.
  
  KEY WORDS: Free flow; Particle Froude number; Piano key weir; Scouring; Submerged flow.
  
  Address:
  - Elnaz Bodaghi, Faculty of Civil and Environmental Engineering, Tarbiat Modares University, Tehran, Iran.
  - Chonoor Abdi Chooplou, Faculty of Civil and Environmental Engineering, Tarbiat Modares University, Tehran, Iran.
  - Masoud Ghodsian, (Corresponding author. Tel.:009882883317 Fax.: Email: ghods@modares.ac.ir)

J. Hydrol. Hydromech., Vol. 72, No. 1, 2024, p. 49 - 63, doi: 10.2478/johh-2023-0036
Scientific Paper, English

Tiejie Cheng, Jun Wang, Jueyi Sui, Feihu Song, Hui Fu, Tao Wang, Xinlei Guo: Simulation and prediction of water temperature in a water transfer channel during winter periods using a new approach based on the wavelet noise reduction-deep learning method

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• In winter, the water transfer channel of the Middle Route of South-to-North Water Transfer Project (MR-StNWTP) in China always encounters ice problems. The preciously simulation and prediction of water temperature is essential for analyzing the ice condition, which is important for the safety control of the water transfer channel in winter. Due to the difference of specific heat between water and air, when the air temperature rises and falls dramatically, the range of change of water temperature is relatively small and has a lag, which often affects the accuracy of simulation and prediction of water temperature based on air temperature. In the present study, a new approach for simulating and predicting water temperature in water transfer channels in winter has been proposed. By coupling the neural network theory to equations describing water temperature, a model has been developed for predicting water temperature. The temperature data of prototype observations in winter are preprocessed through the wavelet decomposition and noise reduction. Then, the wavelet soft threshold denoising method is used to eliminate the fluctuation of certain temperature data of prototype observations, and the corresponding water temperature is calculated afterward. Compared to calculation results using both general neural network and multiple regression approaches, the calculation results using the proposed model agree well with those of prototype measurements and can effectively improve the accuracy of prediction of water temperature.
  
  KEY WORDS: Neural network; Water transfer project; Water temperature; Wavelet noise reduction.
  
  Address:
  - Tiejie Cheng, School of Civil Engineering, Hefei University of Technology, 193 Tunxi Road, Hefei, Anhui, China.
  - Jun Wang, School of Civil Engineering, Hefei University of Technology, 193 Tunxi Road, Hefei, Anhui, China.
  - Jueyi Sui, School of Engineering, University of Northern British Columbia, 3333 University Way, Prince George, BC, Canada. (Corresponding author. Tel.: Fax.: Email: jueyi.sui@unbc.ca)
  - Feihu Song, School of Civil Engineering, Hefei University of Technology, 193 Tunxi Road, Hefei, Anhui, China.
  - Hui Fu, State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing, China.
  - Tao Wang, State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing, China.
  - Xinlei Guo, State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing, China.

J. Hydrol. Hydromech., Vol. 72, No. 1, 2024, p. 64 - 79, doi: 10.2478/johh-2023-0039
Scientific Paper, English

Edwin de Hoog, Tjalie van der Voort, Arno Talmon, Cees van Rhee: A 1-dimensional-two-layer transient drift-flux model for hydraulic transport pipelines: modelling and experiments of bed layer erosion and density wave amplification

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• Hydraulic transport pipelines in the dredging, mining and deep sea mining are designed using steady-state methods. However, these methods cannot predict density wave formation. Density waves form a risk for pipeline blockages, therefore there is a need to understand and preferably be able to model the process. The density waves studied in this research are caused by a stationary sediment deposit in the pipeline. This article explores the development of a new transient design model, based on 1-dimensional-two-layer Driftflux CFD. The two layers model the exchange of sediment between the turbulent suspension, and a stationary bed layer, and can therefore model density wave amplification. An empirical erosion-sedimentation closure relationship is applied to model the sediment exchange between the two layers, and is calibrated using experiments. The final model is also validated against a second experiment, specifically for density wave amplification. The experiments and the model show good agreement on the erosion of a stationary bed layer and the growth rate of a density wave and the amplitude of the density wave.
  
  KEY WORDS: Hydraulic transport; Dredging; Deep sea mining; Transients; Flow assurance; Driftflux.
  
  Address:
  - Edwin de Hoog, Royal IHC, Smitweg 6, 2961 AW Kinderdijk, The Netherlands. Department of Dredging engineering, Delft University of Technology, Mekelweg 2, 2628CD Delft. (Corresponding author. Tel.: Fax.: Email: e.dehoog@royalihc.com)
  - Tjalie van der Voort, Royal IHC, Smitweg 6, 2961 AW Kinderdijk, The Netherlands.
  - Arno Talmon, Department of Dredging Engineering, Delft University of Technology, Mekelweg 2, 2628CD Delft. Deltares, Boussinesqweg 1, 2629 HV Delft.
  - Cees van Rhee, Department of Dredging engineering, Delft University of Technology, Mekelweg 2, 2628CD Delft.

J. Hydrol. Hydromech., Vol. 72, No. 1, 2024, p. 80 - 94, doi: 10.2478/johh-2023-0040
Scientific Paper, English

Alireza Khoshkonesh, Blaise Nsom, Saeid Okhravi, Fariba Ahmadi Dehrashid, Payam Heidarian, Silvia DiFrancesco: Numerical investigation of dam break flow over erodible beds with diverse substrate level variations

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• This study aimed to comprehensively investigate the influence of substrate level difference and material composition on dam break wave evolution over two different erodible beds. Utilizing the Volume of Fluid (VOF) method, we tracked free surface advection and reproduced wave evolution using experimental data from the literature. For model validation, a comprehensive sensitivity analysis encompassed mesh resolution, turbulence simulation methods, and bed load transport equations. The implementation of Large Eddy Simulation (LES), non-equilibrium sediment flux, and van Rijn’s (1984) bed load formula yielded higher accuracy compared to alternative approaches. The findings emphasize the significant effect of substrate level difference and material composition on dam break morphodynamic characteristics. Decreasing substrate level disparity led to reduced flow velocity, wavefront progression, free surface height, substrate erosion, and other pertinent parameters. Initial air entrapment proved substantial at the wavefront, illustrating pronounced air-water interaction along the bottom interface. The Shields parameter experienced a one-third reduction as substrate level difference quadrupled, with the highest near-bed concentration observed at the wavefront. This research provides fresh insights into the complex interplay of factors governing dam break wave propagation and morphological changes, advancing our comprehension of this intricate phenomenon.
  
  KEY WORDS: Dam break; Substrate level difference; Erodible bed; Sediment transport; Computational fluid dynamics CFD.
  
  Address:
  - Alireza Khoshkonesh, Department of Geography, School of Social Sciences, History, and Philosophy, Birkbeck University of London, London, UK.
  - Blaise Nsom, Université de Bretagne Occidentale. IRDL/UBO UMR CNRS 6027. Rue de Kergoat, 29285 Brest, France.
  - Saeid Okhravi, Institute of Hydrology, Slovak Academy of Sciences, Dúbravská cesta 9, 84104, Bratislava, Slovak Republic. (Corresponding author. Tel.:+421-944624921 Fax.: Email: saeid.okhravi@savba.sk)
  - Fariba Ahmadi Dehrashid, Department of Water Science and Engineering, Faculty of Agriculture, Bu-Ali Sina University, 65178-38695, Hamedan, Iran.
  - Payam Heidarian, Department of Civil, Environmental, Architectural Engineering and Mathematics, University of Brescia, 25123 Brescia, Italy.
  - Silvia DiFrancesco, Niccol`o Cusano University, via Don C. Gnocchi 3, 00166 Rome, Italy.

J. Hydrol. Hydromech., Vol. 72, No. 1, 2024, p. 95 - 112, doi: 10.2478/johh-2023-0042
Scientific Paper, English

Stanislav Kotaška, David Duchan, Petr Pelikán, Miroslav Špano: Spectral analysis of oscillatory wind wave parameters in fetch-limited deep-water conditions at a small reservoir and their prediction: Case Study of the Hulín Reservoir in the Czech Republic

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• The dams and banks of small water reservoirs face significant erosion from wind-generated oscillatory waves. Proper design of structure height is crucial to protect such banks against erosion, considering the maximum characteristics of wind waves. Long-term measurements at the Hulín reservoir revealed that the wave spectrum aligns best with the Bretschneider type. This spectrum serves as a basis for simulating oscillatory waves and their impact on shore protection structure design. Empirical models were evaluated using wind and wave data from Hulín reservoir in the Czech Republic. The measured wind speeds attained a maximum of 8 m/s, and wave heights reached up to 15 cm. The Bretschneider (SMB) empirical formula provided the most accurate estimation of wave height (Hm0), with an average underestimate of RMSE = 0.038 m. On the other hand, Wilson revisited (WIL rev.) performed less effectively, with an average RMSE = 0.304 m. For wave period (T) estimation, Bretschneider (SMB) yielded the best results, with an average RMSE = 0.062 s. Conversely, Wilson revisited (WIL rev.) showed poorer performance, with an average underestimate of RMSE = 2.196 s. The discrepancy between the empirical formulas and measured values, particularly in underestimating Hm0, can be attributed to inaccurate determination of fetch length and wind speed.
  
  KEY WORDS: Data not available
  
  Address:
  - Stanislav Kotaška, Faculty of Civil Engineering, Institute of Water Structures, Brno University of Technology, Veveří 331/95, Brno, 602 00, Czech Republic. (Corresponding author. Tel.: Fax.: Email: kotaska.s@fce.vutbr.cz)
  - David Duchan, Faculty of Civil Engineering, Institute of Water Structures, Brno University of Technology, Veveří 331/95, Brno, 602 00, Czech Republic.
  - Petr Pelikán, Department of Landscape Management, Faculty of Forestry and Wood Technology, Mendel University, Zemědělská 3, Brno, 613 00, Czech Republic.
  - Miroslav Špano, Faculty of Civil Engineering, Institute of Water Structures, Brno University of Technology, Veveří 331/95, Brno, 602 00, Czech Republic.

J. Hydrol. Hydromech., Vol. 72, No. 1, 2024, p. 113 - 130, doi: 10.2478/johh-2023-0043
Scientific Paper, English

Seyed Morteza Seyedian, Ozgur Kisi: Uncertainty analysis of discharge coefficient predicted for rectangular side weir using machine learning methods

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• The present study used three machine learning models, including Least Square Support Vector Regression (LSSVR) and two non-parametric models, namely, Quantile Regression Forest (QRF) and Gaussian Process Regression (GPR), to quantify uncertainty and precisely predict the side weir discharge coefficient (Cd) in rectangular channels. So, 15 input structures were examined to develop the models. The results revealed that the machine learning models used in the study offered better accuracy compared to the classical equations. While the LSSVR and QRF models provided a good prediction performance, the GPR slightly outperformed them. The best input structure that was developed included all four dimensionless parameters. Sensitivity analysis was conducted to identify the effective parameters. To evaluate the uncertainty in the predictions, the LSSVR, QRF, and GPR were used to generate prediction intervals (PI), which quantify the uncertainty coupled with point prediction. Among the implemented models, the GPR and LSSVR models provided more reliable results based on PI width and the percentage of observed data covered by PI. According to point prediction and uncertainty analysis, it was concluded that the GPR model had a lower uncertainty and could be successfully used to predict Cd.
  
  KEY WORDS: Machine learning; Prediction intervals; Sensitivity analysis; Side weir discharge coefficient; Uncertainty analysis.
  
  Address:
  - Seyed Morteza Seyedian, Department of Range and Watershed Management, Gonbad Kavous University, Gonbad Kavous, Iran. (Corresponding author. Tel.: Fax.: Email: s.m.seyedian@gmail.com)
  - Ozgur Kisi, Department of Civil Engineering, Technical University of Lübeck, 23562, Lübeck, Germany. Department of Civil Engineering, Ilia State University, 0162, Tbilisi, Georgia.

J. Hydrol. Hydromech., Vol. 72, No. 1, 2024, p. 131 - 147, doi: 10.2478/johh-2023-0044
Scientific Paper, English

Doudou Ba, Jakub Langhammer, Petr Maca, Ansoumana Bodian: Testing sensitivity of BILAN and GR2M models to climate conditions in the Gambia River Basin

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• This study investigates the performance of two lumped hydrological models, BILAN and GR2M, in simulating runoff across six catchments in the Gambia River Basin (Senegal) over a 30-year period employing a 7-year sliding window under different climatic conditions. The results revealed differences in overall performance and variable sensitivity of the models to hydrological conditions and calibration period lengths, stemming from their different structure and complexity. In particular, the BILAN model, which is based on a more complex set of parameters, showed better overall results in simulating dry conditions, while the GR2M model had superior performance in wet conditions. The study emphasized the importance of the length of the calibration period on model performance and on the reduction of uncertainty in the results. Extended calibration periods for both models narrowed the range of the Kling-Gupta Efficiency (KGE) values and reduced the loss of performance during the parameter transfer from calibration to validation. For the BILAN model, a longer calibration period also significantly reduced the variability of performance metric values. Conversely, for the GR2M model, the variability rate did not decrease with the length of the calibration periods. Testing both models under variable conditions underscored the crucial role of comprehending model structure, hydrological sensitivity, and calibration strategy effects on simulation accuracy and uncertainty for reliable results.
  
  KEY WORDS: Rainfall-runoff model; BILAN; GR2M; Lumped models; The Gambia River Basin; Crash test.
  
  Address:
  - Doudou Ba, Department of Physical Geography and Geoecology, Faculty of Science, Charles University in Prague, Albertov 6, Praha 2128 43, Prague, Czech Republic. Department of Water Resources and Environmental Modelling, Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamycka 1176, Suchdol, 16521 Prague 6, Czech Republic.
  - Jakub Langhammer, Department of Physical Geography and Geoecology, Faculty of Science, Charles University in Prague, Albertov 6, Praha 2128 43, Prague, Czech Republic. (Corresponding author. Tel.: Fax.: Email: jakub.langhammer@natur.cuni.cz)
  - Petr Maca, Department of Water Resources and Environmental Modelling, Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamycka 1176, Suchdol, 16521 Prague 6, Czech Republic.
  - Ansoumana Bodian, Laboratoire Leidi "Dynamique des Territoires et Développement", Université Gaston Berger (UGB), Saint Louis, Sénégal.