J. Hydrol. Hydromech., Vol. 62, No. 4, 2014, p. 253 - 257, doi: 10.2478/johh-2014-0041
Information, English

Ľubomír Lichner, Artemi Cerda, Kálmán Rajkai, Miroslav Tesař: Biohydrology research after Landau 2013 conference

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• Data not available
  
  KEY WORDS: Data not available
  
  Address:
  - Ľubomír Lichner, Institute of Hydrology, Slovak Academy of Sciences, Račianska 75, 83102 Bratislava, Slovakia.
  - Artemi Cerda, Departament de Geografia, Universitat de Valencia, Blasco Ibanez, 28, 46010-Valencia, Spain.
  - Kálmán Rajkai, Centre for Agricultural Research, Hungarian Academy of Sciences, Institute for Soil Science and Agricultural Chemistry, Herman Ottó u. 15, H-1022 Budapest, Hungary.
  - Miroslav Tesař, Institute of Hydrodynamics of the Academy of Sciences of the Czech Republic, Pod Paťankou 5, Prague 6, Czech Republic.

J. Hydrol. Hydromech., Vol. 62, No. 4, 2014, p. 258 - 268, doi: 10.2478/johh-2014-0033
Scientific Paper, English

Yolanda Cantón, Jose Raúl Román, Sonia Chamizo, Emilio Rodríguez-Caballero, María José Moro: Dynamics of organic carbon losses by water erosion after biocrust removal

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• In arid and semiarid ecosystems, plant interspaces are frequently covered by communities of cyanobacteria, algae, lichens and mosses, known as biocrusts. These crusts often act as runoff sources and are involved in soil stabilization and fertility, as they prevent erosion by water and wind, fix atmospheric C and N and contribute large amounts of C to soil. Their contribution to the C balance as photosynthetically active surfaces in arid and semiarid regions is receiving growing attention. However, very few studies have explicitly evaluated their contribution to organic carbon (OC) lost from runoff and erosion, which is necessary to ascertain the role of biocrusts in the ecosystem C balance. Furthermore, biocrusts are not resilient to physical disturbances, which generally cause the loss of the biocrust and thus, an increase in runoff and erosion, dust emissions, and sediment and nutrient losses. The aim of this study was to find out the influence of biocrusts and their removal on dissolved and sediment organic carbon losses. One-hour extreme rainfall simulations (50 mm h–1) were performed on small plots set up on physical soil crusts and three types of biocrusts, representing a development gradient, and also on plots where these crusts were removed from. Runoff and erosion rates, dissolved organic carbon (DOC) and organic carbon bonded to sediments (SdOC) were measured during the simulated rain. Our results showed different SdOC and DOC for the different biocrusts and also that the presence of biocrusts substantially decreased total organic carbon (TOC) (average 1.80±1.86 g m–2) compared to physical soil crusts (7.83±3.27 g m–2). Within biocrusts, TOC losses decreased as biocrusts developed, and erosion rates were lower. Thus, erosion drove TOC losses while no significant direct relationships were found between TOC losses and runoff. In both physical crusts and biocrusts, DOC and SdOC concentrations were higher during the first minutes after runoff began and decreased over time as nutrient-enriched fine particles were washed away by runoff water. Crust removal caused a strong increase in water erosion and TOC losses. The strongest impacts on TOC losses after crust removal occurred on the lichen plots, due to the increased erosion when they were removed. DOC concentration was higher in biocrust–removed soils than in intact biocrusts, probably because OC is more strongly retained by BSC structures, but easily blown away in soils devoid of them. However, SdOC concentration was higher in intact than removed biocrusts associated with greater OC content in the top crust than in the soil once the crust is scraped off. Consequently, the loss of biocrusts leads to OC impoverishment of nutrient–limited interplant spaces in arid and semiarid areas and the reduction of soil OC heterogeneity, essential for vegetation productivity and functioning of this type of ecosystems.
  
  KEY WORDS: Biological soil crust; Dissolved OC; Sediment OC; Runoff; Biocrust disturbance; Physical crust.
  
  Address:
  - Yolanda Cantón, Department of Agronomy, Higher Polytechnic School and Experimental Science College, University of Almeria, Ctra. Sacramento s/n La Canada de San Urbano, 04120 Almería, Spain. (Corresponding author. Tel.: Fax.: Email: ycanton@ual.es)
  - Jose Raúl Román, Department of Agronomy, Higher Polytechnic School and Experimental Science College, University of Almeria, Ctra. Sacramento s/n La Canada de San Urbano, 04120 Almería, Spain.
  - Sonia Chamizo, Department of Agronomy, Higher Polytechnic School and Experimental Science College, University of Almeria, Ctra. Sacramento s/n La Canada de San Urbano, 04120 Almería, Spain.
  - Emilio Rodríguez-Caballero, Department of Agronomy, Higher Polytechnic School and Experimental Science College, University of Almeria, Ctra. Sacramento s/n La Canada de San Urbano, 04120 Almería, Spain.
  - María José Moro, Department of Ecology, University of Alicante, Ctra de San Vicente del Raspeig, sn. 03690 San Vicente del Raspeig, Alicante, Spain.

J. Hydrol. Hydromech., Vol. 62, No. 4, 2014, p. 269 - 276, doi: 10.2478/johh-2014-0036
Scientific Paper, English

Szilveszter Csorba, Andrea Raveloson, Eszter Tóth, Viliam Nagy, Csilla Farkas: Modelling soil water content variations under drought stress on soil column cropped with winter wheat

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• Mathematical models are effective tools for evaluating the impact of predicted climate change on agricultural production, but it is difficult to test their applicability to future weather conditions. We applied the SWAP model to assess its applicability to climate conditions, differing from those, for which the model was developed. We used a database obtained from a winter wheat drought stress experiment. Winter wheat was grown in six soil columns, three having optimal water supply (NS), while three were kept under drought-stressed conditions (S). The SWAP model was successfully calibrated against measured values of potential evapotranspiration (PET), potential evaporation (PE) and total amount of water (TSW) in the soil columns. The Nash-Sutcliffe model efficiency coefficient (N-S) for TWS for the stressed columns was 0.92. For the NS treatment, we applied temporally variable soil hydraulic properties because of soil consolidation caused by regular irrigation. This approach improved the N-S values for the wetting-drying cycle from –1.77 to 0.54. We concluded that the model could be used for assessing the effects of climate change on soil water regime. Our results indicate that soil water balance studies should put more focus on the time variability of structure-dependent soil properties.
  
  KEY WORDS: Climatic room; SWAP model; Soil water balance elements; Drought stress; Temporal variability of soil properties.
  
  Address:
  - Szilveszter Csorba, Szent István University, Páter Károly u. 1, Gödöllő 2100, Hungary.
  - Andrea Raveloson, Eötvös Loránd University, Pázmány Péter sétány 1/A, Budapest 1117, Hungary.
  - Eszter Tóth, Institute for Soil Sciences and Agricultural Chemistry, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman O. u. 15, Budapest 1022, Hungary.
  - Viliam Nagy, Institute of Hydrology, Slovak Academy of Sciences, Racianska 75, 81302 Bratislava, Slovak Republic.
  - Csilla Farkas, Bioforsk, Norwegian Institute for Agricultural and Environmental Research, Fr. A. Dahlsvei 20, As 1430, Norway. (Corresponding author. Tel.:+47 9481-4727 Fax.: Email: csilla.farkas@bioforsk.no)

J. Hydrol. Hydromech., Vol. 62, No. 4, 2014, p. 277 - 284, doi: 10.2478/johh-2014-0037
Scientific Paper, English

Michal Dohnal, Tomáš Černý, Jana Votrubová, Miroslav Tesař: Rainfall interception and spatial variability of throughfall in spruce stand

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• The interception was recognized as an important part of the catchment water balance in temperate climate. The mountainous forest ecosystem at experimental headwater catchment Liz has been subject of long-term monitoring. Unique dataset in terms of time resolution serves to determine canopy storage capacity and free throughfall. Spatial variability of throughfall was studied using one weighing and five tipping bucket rain gauges. The basic characteristics of forest affecting interception process were determined for the Norway spruce stand at the experimental area – the leaf area index was 5.66 – 6.00 m2 m–2, the basal area was 55.7 m2 ha–1, and the crown closure above individual rain gauges was between 19 and 95%. The total interception loss in both growing seasons analyzed was 34.5%. The mean value of the interception capacity determined was about 2 mm. Throughfall exhibited high variability from place to place and it was strongly affected by character of rainfall. On the other hand, spatial pattern of throughfall in average showed low variability.
  
  KEY WORDS: Interception loss; Interception capacity; Free throughfall; Evaporation; Hydrological balance of vegetation cover.
  
  Address:
  - Michal Dohnal, Czech Technical University in Prague, Faculty of Civil Engineering, Thakurova 7, 166 29, Prague, Czech Republic. (Corresponding author. Tel.:+420 22435 5404 Fax.: Email: dohnalm@mat.fsv.cvut.cz)
  - Tomáš Černý, Czech Technical University in Prague, Faculty of Civil Engineering, Thakurova 7, 166 29, Prague, Czech Republic.
  - Jana Votrubová, Czech Technical University in Prague, Faculty of Civil Engineering, Thakurova 7, 166 29, Prague, Czech Republic.
  - Miroslav Tesař, Institute of Hydrodynamics of the Academy of Sciences of the Czech Republic, Pod Paťankou 5, Prague 6, Czech Republic.

J. Hydrol. Hydromech., Vol. 62, No. 4, 2014, p. 285 - 292, doi: 10.2478/johh-2014-0039
Scientific Paper, English

Šárka Dvořáková, Pavel Kovář, Josef Zeman: Impact of evapotranspiration on discharge in small catchments

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• We apply the Linear Storage Model (LSM) to simulate the influence of the evapotranspiration on discharges. High resolution discharge data from two small catchments in the Czech Republic, the Teply Brook and the Starosuchdolsky Brook catchment are used. The results show the runoff process is simpler in a deeper valley of the Starosuchdolsky catchment where the soil zone is deeper and the valley bottom recharges runoff even during very dry periods. Two-soil zone model is adequate to simulate the diurnal runoff variability. Three-soil zone model is needed in the Teply Brook catchment due to the absence of water transport in the most-upper soil zone. Time delays between minimum and maximum discharge during the day reach up to about 20 hours. Evapotranspiration and hydraulic resistances are as high as 14% of catchment daily runoff in the urbanized Starosuchdolsky Brook catchment and 25% of catchment daily runoff in the forested, less impacted Teply Brook catchment.
  
  KEY WORDS: Catchment water depletion; Diurnal streamflow variability; Evapotranspiration; Linear Storage Model (LSM).
  
  Address:
  - Šárka Dvořáková, Faculty of Engineering, Department of Mathematics, Czech University of Life Sciences, (CULS Prague), Kamycka 129, 165 21 Prague 6, Czech Republic. (Corresponding author. Tel.:+420 22438 3240 Fax.: Email: dvorakovas@tf.czu.cz)
  - Pavel Kovář, Faculty of Environmental Sciences, Department of Land Use and Improvement, CULS Prague, Czech Republic.
  - Josef Zeman, Faculty of Engineering, Department of Physics, CULS Prague, Czech Republic.

J. Hydrol. Hydromech., Vol. 62, No. 4, 2014, p. 293 - 302, doi: 10.2478/johh-2014-0038
Scientific Paper, English

Thomas Fischer, Stella Gypser, Maria Subbotina, Maik Veste: Synergic hydraulic and nutritional feedback mechanisms control surface patchiness of biological soil crusts on tertiary sands at a post-mining site

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• In a recultivation area located in Brandenburg, Germany, five types of biocrusts (initial BSC1, developed BSC2 and BSC3, mosses, lichens) and non-crusted mineral substrate were sampled on tertiary sand deposited in 1985–1986 to investigate hydrologic interactions between crust patches. Crust biomass was lowest in the non-crusted substrate, increased to the initial BSC1 and peaked in the developed BSC2, BSC3, the lichens and the mosses. Water infiltration was highest on the substrate, and decreased to BSC2, BSC1 and BSC3. Non-metric multidimensional scaling revealed that the lichens and BSC3 were associated with water soluble nutrients and with pyrite weathering products, thus representing a high nutrient low hydraulic feedback mode. The mosses and BSC2 represented a low nutrient high hydraulic feedback mode. These feedback mechanisms were considered as synergic, consisting of run-off generating (low hydraulic) and run-on receiving (high hydraulic) BSC patches. Three scenarios for BSC succession were proposed. (1) Initial BSCs sealed the surface until they reached a successional stage (represented by BSC1) from which the development into either of the feedback modes was triggered, (2) initial heterogeneities of the mineral substrate controlled the development of the feedback mode, and (3) complex interactions between lichens and mosses occurred at later stages of system development.
  
  KEY WORDS: Recultivation; Pyrite weathering; Bistable ecosystems.
  
  Address:
  - Thomas Fischer, Brandenburg University of Technology Cottbus-Senftenberg, Central Analytical Laboratory, Konrad-Wachsmann-Allee 6, 03046 Cottbus, Germany. (Corresponding author. Tel.: Fax.: Email: thomas.fischer@tu-cottbus.de)
  - Stella Gypser, Brandenburg University of Technology Cottbus-Senftenberg, Central Analytical Laboratory, Konrad-Wachsmann-Allee 6, 03046 Cottbus, Germany.
  - Maria Subbotina, Permian State Agricultural Academy, 23 Petropavlovskaya str., Perm 614990, Russia.
  - Maik Veste, CEBra - Centre for Energy Technology Brandenburg e.V., Friedlieb-Runge-Straße 3, 03046 Cottbus, Germany.

J. Hydrol. Hydromech., Vol. 62, No. 4, 2014, p. 303 - 308, doi: 10.2478/johh-2014-0032
Scientific Paper, English

Giora J. Kidron: Sink plot for runoff measurements on semi-flat terrains: preliminary data and their potential hydrological and ecological implications

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• In arid and semiarid regions where water is the main limiting factor, water redistribution is regarded as an important hydrological process of great ecological value. By providing additional water to certain loci, moist pockets of great productivity are formed, characterized by high plant biomass and biological activity. These moist pockets are often a result of runon. Yet, although runoff may take place on semi-flat undulating surfaces, runoff measurements are thus far confined to slopes, where a sufficient gradient facilitates downslope water harvesting. On undulating surfaces of mounds and depressions, such as in interdunes, no quantification of the amount of water reaching depressions is feasible due to the fact that no reliable method for measuring the runoff amounts in semi-flat terrains is available. The current paper describes specific runoff plots, designed to measure runoff in depressions (sinks). These plots, termed sink plots (SPs), were operative in the Hallamish dunefield (Negev Desert, Israel). The paper presents measurements of runoff yield that were carried out between January 2013 and January 2014 on SPs and compared them to runoff obtained from crusted slope plots and fine-grained (playa) surfaces. The potential hydrological and ecological implications of water redistribution within semi-flat terrains for this and other arid ecosystems are discussed.
  
  KEY WORDS: Infiltration; Playa surfaces; Sand dunes; Negev Desert.
  
  Address:
  - Giora J. Kidron, Institute of Earth Sciences, The Hebrew University of Jerusalem, Givat Ram Campus, Jerusalem 91904, Israel. (Corresponding author. Tel.:+972-54-4967-271 Fax.: 972-2-566-2581 Email: kidron@mail.huji.ac.il)

J. Hydrol. Hydromech., Vol. 62, No. 4, 2014, p. 309 - 315, doi: 10.2478/johh-2014-0040
Scientific Paper, English

D.A.L. Leelamanie: Initial water repellency affected organic matter depletion rates of manure amended soils in Sri Lanka

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• The wetting rate of soil is a measure of water repellency, which is a property of soils that prevents water from wetting or penetrating into dry soil. The objective of the present research was to examine the initial water repellency of organic manure amended soil, and its relation to the soil organic matter (SOM) depletion rates in the laboratory. Soil collected from the Wilpita natural forest, Sri Lanka, was mixed with organic manure to prepare soil samples with 0, 5, 10, 25, and 50% organic manure contents. Locally available cattle manure (CM), goat manure (GM), and Casuarina equisetifolia leaves (CE) were used as the organic manure amendments. Organic matter content of soils was measured in 1, 3, 7, 14, and 30 days intervals under the laboratory conditions with 74±5% relative humidity at 28±1°C. Initial water repellency of soil samples was measured as the wetting rates using the water drop penetration time (WDPT) test. Initial water repellency increased with increasing SOM content showing higher increasing rate for hydrophobic CE amended samples compared with those amended with CM and GM. The relation between water repellency and SOM content was considered to be governed by the original hydrophobicities of added manures. The SOM contents of all the soil samples decreased with the time to reach almost steady level at about 30 d. The initial SOM depletion rates were negatively related with the initial water repellency. However, all the CE amended samples initially showed prominent low SOM depletion rates, which were not significantly differed with the amended manure content or the difference in initial water repellency. It is explicable that the original hydrophobicity of the manure as well has a potentially important effect on initiation of SOM decomposition. In contrast, the overall SOM depletion rate can be attributed to the initial water repellency of the manure amended sample, however, not to the original hydrophobicity of the amended manure. Hydrophobic protection may prevent rapid microbial decomposition of SOM and it is conceivable that hydrophobic substances in appropriate composition may reduce organic matter mineralization in soil. These results suggest the contribution of hydrophobic organic substances in bioresistance of SOM and their long-term accumulation in soils.
  
  KEY WORDS: Carbon mineralization; Hydrophobicity; Organic manure; Water drop penetration time; Water repellency.
  
  Address:
  - 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. 62, No. 4, 2014, p. 316 - 323, doi: 10.2478/johh-2014-0028
Scientific Paper, English

Dario Mantovani, Maik Veste, Stella Gypser, Christian Halke, Laurie Koning, Dirk Freese, Stefan Lebzien: Transpiration and biomass production of the bioenergy crop Giant Knotweed Igniscum under various supplies of water and nutrients

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• Soil water availability, nutrient supply and climatic conditions are key factors for plant production. For a sustainable integration of bioenergy plants into agricultural systems, detailed studies on their water uses and growth performances are needed. The new bioenergy plant Igniscum Candy is a cultivar of the Sakhalin Knotweed (Fallopia sachalinensis), which is characterized by a high annual biomass production. For the determination of transpiration-yield relations at the whole plant level we used wicked lysimeters at multiple irrigation levels associated with the soil water availability (25, 35, 70, 100%) and nitrogen fertilization (0, 50, 100, 150 kg N ha–1). Leaf transpiration and net photosynthesis were determined with a portable minicuvette system. The maximum mean transpiration rate was 10.6 mmol m–2 s–1 for well-watered plants, while the mean net photosynthesis was 9.1 μmol m–2 s–1. The cumulative transpiration of the plants during the growing seasons varied between 49 l (drought stressed) and 141 l (well-watered) per plant. The calculated transpiration coefficient for Fallopia over all of the treatments applied was 485.6 l kg–1. The transpiration-yield relation of Igniscum is comparable to rye and barley. Its growth performance making Fallopia a potentially good second generation bioenergy crop.
  
  KEY WORDS: Water use efficiency; Transpiration coefficient; Photosynthesis; Nitrogen; Ecophysiology; Lysimeter; Fallopia.
  
  Address:
  - Dario Mantovani, Brandenburg University of Technology Cottbus-Senftenberg, Chair of Soil Protection and Recultivation, Konrad-Wachsmann-Allee 6, D-03046 Cottbus, Germany.
  - Maik Veste, CEBra - Centre for Energy Technology Brandenburg e.V., Friedlieb-Runge-Strasse 3, D-03046 Cottbus, Germany. (Corresponding author. Tel.: Fax.: Email: maik.veste@me.com)
  - Stella Gypser, Brandenburg University of Technology Cottbus-Senftenberg, Chair of Soil Protection and Recultivation, Konrad-Wachsmann-Allee 6, D-03046 Cottbus, Germany.
  - Christian Halke, Brandenburg University of Technology Cottbus-Senftenberg, Chair of Soil Protection and Recultivation, Konrad-Wachsmann-Allee 6, D-03046 Cottbus, Germany.
  - Laurie Koning, Brandenburg University of Technology Cottbus-Senftenberg, Chair of Soil Protection and Recultivation, Konrad-Wachsmann-Allee 6, D-03046 Cottbus, Germany.
  - Dirk Freese, Brandenburg University of Technology Cottbus-Senftenberg, Chair of Soil Protection and Recultivation, Konrad-Wachsmann-Allee 6, D-03046 Cottbus, Germany.
  - Stefan Lebzien, ENAGRA Biomasse GmbH, Auf der Grub 1, D-54472 Monzelfeld, Germany.

J. Hydrol. Hydromech., Vol. 62, No. 4, 2014, p. 324 - 333, doi: 10.2478/johh-2014-0034
Scientific Paper, English

Emilia Urbanek, Rainer Horn, Alwin J.M. Smucker: Tensile and erosive strength of soil macro-aggregates from soils under different management system

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• Reduced soil tillage practices are claimed to improve soil health, fertility and productivity through improved soil structure and higher soil organic matter contents. This study compares soil structure stability of soil aggregates under three different tillage practices: conventional, reduced and no tillage. The erosive strength of soil aggregates has been determined using the abrasion technique with the soil aggregate erosion chambers (SAE). During abrasion soil aggregates have been separated into the exterior, transitional and interior regions. The forces needed to remove the material from the aggregate were calculated as erosive strength and compared with the tensile strength of the aggregates derived from crushing tests. The relationship between aggregate strength and other soil properties such as organic carbon and hydrophobic groups’ content has also been identified. The results show that erosive and tensile strength of soil aggregates is very low in topsoil under conventional and reduced tillage comparing with the subsoil horizons. Negative correlation was found between the content of organic carbon, hydrophobic compounds and erosive aggregate strength which suggests that the stabilising effect of soils organic carbon may be lost with drying. The positive relationship between the tensile strength and erosive strength for aggregates of 8–5 mm size suggests that the total strength of these aggregates is controlled by the sum of strength of all concentric layers.
  
  KEY WORDS: Tensile strength; Erosive strength; Exterior/interior aggregate region; Aggregate; Concentric layers; Dry aggregate stability; Reduced tillage.
  
  Address:
  - Emilia Urbanek, Royal Society Research Fellow, Swansea University, College of Science, Department of Geography, Singleton Park, Swansea, UK. Institute for Plant Nutrition and Soil Science, Christian-Albrechts-University of Kiel, Kiel, Germany. (Corresponding author. Tel.: Fax.: Email: e.urbanek@swansea.ac.uk)
  - Rainer Horn, Institute for Plant Nutrition and Soil Science, Christian-Albrechts-University of Kiel, Kiel, Germany.
  - Alwin J.M. Smucker, Institute for Plant Nutrition and Soil Science, Christian-Albrechts-University of Kiel, Kiel, Germany. Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, Michigan, USA.

J. Hydrol. Hydromech., Vol. 62, No. 4, 2014, p. 334 - 342, doi: 10.2478/johh-2014-0035
Scientific Paper, English

Guanhua Zhang, Guobin Liu, Liang Yi, Pingcang Zhang: Effects of patterned Artemisia capillaris on overland flow resistance under varied rainfall intensities in the Loess Plateau of China

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• In this paper simulated rainfall experiments in laboratory were conducted to quantify the effects of patchy distributed Artemisia capillaris on spatial and temporal variations of the Darcy-Weisbach friction coefficient (f). Different intensities of 60, 90, 120, and 150 mm h–1 were applied on a bare plot (CK) and four different patched patterns: a checkerboard pattern (CP), a banded pattern perpendicular to slope direction (BP), a single long strip parallel to slope direction (LP), and a pattern with small patches distributed like the letter ‘X’ (XP). Each plot underwent two sets of experiments, intact plant and root plots (the above-ground parts were removed). Results showed that mean f for A. capillaris patterned treatments was 1.25–13.0 times of that for CK. BP, CP, and XP performed more effectively than LP in increasing hydraulic roughness. The removal of grass shoots significantly reduced f. A negative relationship was found between mean f for the bare plot and rainfall intensity, whereas for grass patterned plots fr (mean f in patterned plots divided by that for CK) increased exponentially with rainfall intensity. The f –Re relation was best fitted by a power function. Soil erosion rate can be well described using f by a power-law relationship.
  
  KEY WORDS: Overland flow; Darcy-Weisbach friction coefficient; Patch pattern; Vegetation structure; Simulated rainfall; Loess Plateau.
  
  Address:
  - Guanhua Zhang, Department of Soil and Water Conservation, Changjiang River Scientific Research Institute, Wuhan, Hubei 430010, China. State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100, China.
  - Guobin Liu, State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100, China. (Corresponding author. Tel.:+86 02987012411 Fax.: +86 02987012210 Email: gbliu@ms.iswc.ac.cn)
  - Liang Yi, Hubei Academy of Environmental Sciences, Wuhan, Hubei 430072, China.
  - Pingcang Zhang, Department of Soil and Water Conservation, Changjiang River Scientific Research Institute, Wuhan, Hubei 430010, China.