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In the framework of the EU-INTERREG-IVb-project ForeStClim (Transnational Forestry Management Strategies in Response to Regional Climate Change Impacts) a combination of experimental methods has been applied for the investigation of the spatial and temporal variation and intensity of overland flow generation and soil erosion processes. In the presented study, the influences of land-use type and land-management practices on overland flow generation and soil erosion are investigated for three low mountain range catchments in Luxembourg and in Rhineland-Palatinate, Germany. The key questions of the study can be summarized as follows: Can Hortonian overland flow generation be observed on all land-use types in the investigated areas in the Central European low mountain range? How can the contribution of forested areas to the flood and erosion dynamics be evaluated under humid climate conditions in Central Europe and what are the most important factors of influence? The results of the presented study show that forest areas can also be sources for overland flow and sediment, particularly artificial linear structures like unpaved roads and harvester tracks, where runoff coefficients between 41.2 and 97.1%, and erosion values between 2.6 and 122.5 g m− 2 were determined using rainfall experiments. Another important factor is soil water repellency, this factor can pre-eminently be observed under rather dry soil moisture conditions in summer and can have severe influence on overland flow generation particularly in forested areas. The results of the rainfall experiments in coniferous forests show runoff coefficients ranging from 0 to 86.9%, here the high values can all be traced back to water repellency influence, as the field observations suggest. In the context of flood generation, it is becoming more and more important to improve knowledge on overland flow generation and soil erosion processes occurring in forested catchments, particularly considering the expected climate change.

Fire is a natural factor of landscape evolution in Mediterranean ecosystems. The middle Ebro Valley has extreme aridity, which results in a low plant cover and high soil erodibility, especially on gypseous substrates. The aim of this research is to analyze the effects of moderate heating on physical and chemical soil properties, mineralogical composition and susceptibility to splash erosion. Topsoil samples (15 cm depth) were taken in the Remolinos mountain slopes (Ebro Valley, NE Spain) from two soil types: Leptic Gypsisol (LP) in a convex slope and Haplic Gypsisol (GY) in a concave slope. To assess the heating effects on the mineralogy we burned the soils at 105 and 205 °C in an oven and to assess the splash effects we used a rainfall simulator under laboratory conditions using undisturbed topsoil subsamples (0–5 cm depth of Ah horizon). LP soil has lower soil organic matter (SOM) and soil aggregate stability (SAS) and higher gypsum content than GY soil. Gypsum and dolomite are the main minerals (>80%) in the LP soil, while gypsum, dolomite, calcite and quartz have similar proportions in GY soil. Clay minerals (kaolinite and illite) are scarce in both soils. Heating at 105 °C has no effect on soil mineralogy. However, heating to 205 °C transforms gypsum to bassanite, increases significantly the soil salinity (EC) in both soil units (LP and GY) and decreases pH only in GY soil. Despite differences in the content of organic matter and structural stability, both soils show no significant differences (P < 0.01) in the splash erosion rates. The size of pores is reduced by heating, as derived from variations in soil water retention capacity.

28 páginas, 6 figuras, 2 tablas.- The definitive version is available on: http://www.sciencedirect.com/science/article/pii/S0341816213001252, [EN] Small-scale portable rainfall simulators are an essential research tool for investigating the process dynamics of soil erosion and surface hydrology. There is no standardisation of rainfall simulation and such rainfall simulators differ in design, rainfall intensities, rain spectra and research questions, which impede drawing a meaningful comparison between results. Nevertheless, these data become progressively important for soil erosion assessment and therefore, the basis for decision-makers in application-oriented erosion protection. The artificially generated rainfall of the simulators used at the Universities Basel, La Rioja, Malaga, Trier, Tübingen, Valencia, Wageningen, Zaragoza, and at different CSIC (Spanish Scientific Research Council) institutes (Almeria, Cordoba, Granada, Murcia and Zaragoza) was measured with the same methods (Laser Precipitation Monitor for drop spectra and rain collectors for spatial distribution). Data are very beneficial for improvements of simulators and comparison of simulators and results. Furthermore, they can be used for comparative studies, e.g. with measured natural rainfall spectra. A broad range of rainfall data was measured (e.g. intensity: 37–360 mm h− 1; Christiansen Coefficient for spatial rainfall distribution: 61–98%; median volumetric drop diameter: 0.375–6.5 mm; mean kinetic energy expenditure: 25–1322 J m− 2 h− 1; mean kinetic energy per unit area and unit depth of rainfall: 0.77–50 J m− 2 mm− 1). Similarities among the simulators could be found e.g. concerning drop size distributions (maximum drop numbers are reached within the smallest drop classes < 1 mm) and low fall velocities of bigger drops due to a general physical restriction. The comparison represents a good data-base for improvements and provides a consistent picture of the different parameters of the simulators that were tested., The research for this study was funded by the Deutsche Forschungsgemeinschaft (DFG) project number Ri-835/6-1. We would like to thank the anonymous reviewers for their remarks.

The results from several rainfall simulations performed on two abandoned fields of different ages in the Central Ebro Depression have been analysed by application of the physically based hydraulic model HILLFLOW 1D. The data gained by the simulations was used to parame - terise the model. Afterwards, the runoff generation characteristics were determined by simulation of different rainfall intensities and different macroporosities of the soil. The young fallow land shows a minimum inten - sity for runoff generation of 6 mm h-1. An increase of the rainfall intensity leads rapidly to a growing runoff coefficient, being the value modelled for 30 mm h-1 nearly the same as the simulated one (40 mm h-1). Another con - clusion of the simulations and their modelling is the homogeneity of the soils on the young fallow land, with no macroporosity all over the profile. On the other hand, the rainfall simulations and the modelling on the old fallow land show a high variability of rainfall-runo ff response patterns, strongly conditioned by the presence of macropores. They are distributed very irregularly throughout the soil of the old fallow land. In both cases, water infiltrates only little into the soil matrix, for that measures for enhan- cing soil hydraulic properties are needed. RESUMEN: Se han analizado los resultados de numerosas simulacio - nes de lluvia en campos abandonados de diferente antuguedad en la Depresion central del Ebro aplicando el modelo hidrologico de base fisi ca HILLFLOW 1D. Los datos de las simulaciones se utilizaron para para - metrizar el modelo. A continuacion, las caracteristicas de la generacion de escorrentia se analizaron modelizando diferentes intensidades de lluvia y volumenes de macroporos en el suelo. En el campo recientemente aban - donado se pudo calcular una intensidad de llluvia minima para la gene- racion de escor rentia de 6 mm h-1. Una intensidad de precipitacion cr e - ciente produce un incremento muy fuerte del coeficiente de escor rentia, de modo que precipitaciones de 30 mm h-1 se diferencian poco de las simu- ladas con 40 mm h-1. Otra conclusion es que los suelos del campo recien - temente abandonado son muy homogeneos y estan caracterizados por la ausencia de macroporos. La respuesta de la generacion de escor rentia a la precipitacion es en cambio muy variable en el campo abandonado anti

This paper tackles two main questions by linking observations, determination of hydraulic parameters and measurement of sediment transport with the formulae used in soil erosion models. First, do constant shear stress values in different rills with constant soil parameters result in the same soil detachment values? Secondly, deterministic soil erosion models make the assumption that there is a relationship (often further assumed to be linear) between shear stress and soil detachment; is this suitable for representing real erosion process combinations in natural rills? Following most process based deterministic soil erosion models, derived hydraulic and erosion parameters should be similar. However, the results from the different experiments showed clear differences in sediment concentration, transport rates and other measured as well as calculated values. In contrast to our experimental results, a model simulation would produce erosion parameters with low variations, represented by the relative measurement error and the empirical variation coefficient. This reveals the general problems of using process based deterministic models for erosion in shallow rills. While soil erosion models simulate the processes resulting from the shear forces of flowing water on the soil surface, other processes like side wall failure, headcut retreat and plunge pool dynamics are not taken into account. Our results suggested that these other processes may contribute substantially to rill erosion processes. The results of this study strongly suggested that the model concept of most physical based soil erosion models is inadequate for modeling rill erosion processes. Measured total rill erosion rates were the sum of erosion rates caused by a combination of different soil erosion processes with different spatial and temporal distribution. This combination cannot be described by a single equation.

The present paper is based on several field investigations (monitoring soil and rill erosion by aerial photography, rainfall simulations with portable rainfall simulators, and manmade rill flooding) in southern Spain. Experiments lead now to a closer understanding of the dynamics and power of different soil erosion processes in a gully catchment area. The test site Freila (Andalusia, Spain) covers an area of 10.01 ha with a rill density of 169 m ha−1, corresponding to a total rill length of 1694 m. Assuming an average rill width of 0.15 m, the total rill surface can be calculated at 250 m2 (0.025 ha). Given that, the surface covered by rills makes up only 0.25% of the total test site. Since the rill network drains 1.98 ha, 20% of the total runoff comes from rills. The rills’ sediment erosion was measured and the total soil loss was then calculated for detachment rates between 1685 g m−2 and 3018 g m−2. The interrill areas (99.75% of the test site) show values between 29 and 143 g m−2. This suggests an important role of rill erosion concerning runoff and soil detachment.

Terrestrial Laser Scanners (TLS) provide a non-contact method to measure soil microtopography of relatively large surface areas. The appropriateness of the technology in relatation to the derived Digital Elevation Models (DEM) however has not been reported. The suitability of TLS for soil microtopography measurements was tested on-field for three large soil surface areas in agricultural fields. The acquired point clouds were filtered with a custom cloud import algorithm, and converted into digital elevation models (DEM) of different resolutions. To assess DEM quality, point clouds measured from different viewpoints were statistically compared. The statistical fit between point clouds from different viewpoints depends on spatial resolution of the DEM. The best results were obtained at the higher resolutions (0.02 to 0.04?cm), where less than 5 % of the grid cells showed significant differences between one viewpoint and the next (p?

The importance of distinguishing and discretely studying the subprocesses of runoff generation and erosion has led to the development of rainfall simulations on small plots. We methodically upgraded a small portable rainfall simulator with particular respect to (1) rainfall characteristics that include homogeneous spatial rainfall distribution and drop spectrum, (2) handling, and (3) control of test conditions. We measured simulator characteristics with rain gauges, calibration plate and Laser Precipitation Monitor by Thies (LPM). The upgraded small rainfall simulator, and measurements of the improved rainfall characteristics are presented in this paper.The upgraded configuration shows the desired improvements: regarding drop size distribution, a close relationship to natural rainfall (Marshall & Palmer Distribution) can be observed. Due to low fall heights, measured drop fall velocities are slow; maximum velocities range between 3.4 and 5 m s1. Mean kinetic energy expenditure, mean kinetic energy per unit area and unit depth of rainfall and mean momentum are 214 J m2 h1, 5.8 J m2 mm1 and 0.016 kg m s1, respectively. The spatial rainfall distribution of the upgraded simulator is homogenous with a Christiansen-Uniformity Coefficient of 91%. The measured variables show extremely low variation throughout all tests and should therefore be reproducible in field investigations at any time.

Within this paper a standardized method to quantify sediment transport and runoff in natural rills is described. In order to achieve this, several rill experiments (RE) were accomplished in March 2007 in the Arnás catchment in the Spanish Pyrenees. Both, anthropogenically initiated and naturally developed rills were flushed with a total water quantity of 72 l in 8 minutes (equivalent to 9 l min-1). For the characterisation of the rill, slope is measured and micromorphological features like scours are registered. The experiments are characterised by the flow velocities along the whole flushed rill, sediment concentrations at different points and different times during the experiment. Runoff is measured after 25 m continuously. With this data, a set of characteristic variables is generated, which reflects the infiltration and flow behaviour along the rill. By means of rainfall simulations within the rills catchments, their contributing runoff was estimated also. The tested rills were developed on average slopes oscillating between 7.6° and 11.3°, the steepest slope reached 16°. The sediment concentrations reached average values between 0.69 and 2.21 g l-1, the maximum values ranged between 1.59 and 6.31 g l-1. Comparing the sediment concentrations measured in the rills to the sediment concentrations in the runoff of the river Arnás, it can be stated that the concentrations in the rills are usually higher. Though, the runoff was to low to cause erosion. Accordingly, the runoff amount that can be produced within the rills catchments was found to be about 10-25 times higher. By means of the developed rill experiments, for which easy to handle devices were built and are described in detail, it becomes possible to assess the effectivity of individual rills in a catchment and to evaluate their hydraulic functioning as well as their geomorphodynamic activity

The Pyrenean and Pre-Pyrenean mountain areas have been intensively used at least since roman times, but nowadays depopulation has lead to widespread land abandonment without a steering land-management. Vegetation recovery is weak in most abandoned fields. Soil formation and characteristics are conditioned by this fact, and for this, soils show past degradation processes and are mostly predominant factors for continuing land degradation or restoration. Three study areas were set up along a climatic gradient with increasing summer water deficit in the sub-humid zone between the Central Pyrenees and Pre-Pyrenees. Soil survey combined with experiments for the determination of infiltration, runoff and erosion were applied for understanding the degradation history and the future development of the soils. All areas are dominated by Entisols, but also Inceptisols and Alfisols are found, and even soils with hydromorphic features. The soils show signs of heavy erosion. The parental material determines the nutrient supply and the general chemical properties. All sites show a weak water storing capacity, as a result of the removal of fine material by erosion and due to the depletion of soil organic matter. In addition, infiltration capacity and runoff generation are high within the studied areas, averaging between 27 and 37 per cent. The driest area studied shows an ongoing trend to degradation, with high erosion rates combined with a high degradations status of the soil. The other areas are characterised by a patchy pattern of soil degradation and regradation processes. Copyright © 2008 John Wiley & Sons, Ltd.

The aim of this study was to enable a quantitative comparison of initial soil erosion processes in European vineyards using the same methodology and equipment. The study was conducted in four viticultural areas with different characteristics (Valencia and Málaga in Spain, Ruwer-Mosel valley and Saar-Mosel valley in Germany). Old and young vineyards, with conventional and ecological planting and management systems were compared. The same portable rainfall simulator with identical rainfall intensity (40 mm h− 1) and sampling intervals (30 min of test duration, collecting the samples at 5-min-intervals) was used over a circular test plot with 0.28 m2. The results of 83 simulations have been analysed and correlation coefficients were calculated for each study area to identify the relationship between environmental plot characteristics, soil texture, soil erosion, runoff and infiltration. The results allow for identification of the main factors related to soil properties, topography and management, which control soil erosion processes in vineyards. The most important factors influencing soil erosion and runoff were the vegetation cover for the ecological German vineyards (with 97.6 ± 8% infiltration coefficients) and stone cover, soil moisture and slope steepness for the conventional land uses.

Small portable rainfall simulators are considered a useful tool to analyze soil erosion processes in cultivated lands. European research groups in Spain (Valencia, Málaga, Lleida, Madrid and La Rioja), France (Reims) and Germany (Trier) have used different rainfall simulators (varying in drop size distribution and fall velocities, kinetic energy, plot forms and sizes, and field of application) to study soil loss, surface flow, runoff and infiltration coefficients in different experimental plots (Valencia, Montes de Málaga, Penedès, Campo Real and La Rioja in Spain, Champagne in France and Mosel-Ruwer valley in Germany). The measurements and experiments developed by these research teams give an overview of the variety of methodologies used in rainfall simulations to study the problem of soil erosion and describe the erosion features in different climatic environments, management practices and soil types. The aims of this study are: (i) to investigate where, how and why researchers from different wine-growing regions applied rainfall simulations with successful results as a tool to measure soil erosion processes; (ii) to make a qualitative comparison about the general soil erosion processes in European terroirs; (iii) to demonstrate the importance of the development of standard method for measurement of soil erosion processes in vineyards, using rainfall simulators; and (iv) and to analyze the key factors that should be taken into account to carry out rainfall simulations. The rainfall simulations in all cases allowed infiltration capacity, susceptibility of the soil to detachment and generation of sediment loads to runoff to be determined. Despite using small plots, the experiments were useful to analyze the influence of soil cover to reduce soil erosion, to make comparisons between different locations, and to evaluate the influence of different soil characteristics. The comparative analysis of the studies performed in different study areas points out the need to define an operational methodology to carry out rainfall simulations, which allows us to obtain representative and comparable results and to avoid errors in the interpretation in order to achieve comparable information about runoff and soil loss., We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)., We acknowledge all the co-authors for the fast and friendly response to take part in this paper and their useful suggestions and corrections. Furthermore, we also thank the Caixa-Bank and DAAD (Deutscher Akademischer Austauschdienst) for the Scholarship grant awarded to J. Rodrigo-Comino.

Steep slopes, erodible soils, rill and ephemeral gullies, compaction due to wheel. traffic and human trampling are common features in vineyards around the world and result in high soil erosion rates. However, little is known about seasonal and spatial variations of soil erosion rates due to factors such as the impact of the vine plantation, harvest, and tillage on the soil redistribution over the long-term temporal scale. The goal of this study is to assess long-term soil erosion rates and the impact of management on sediment and runoff yield by means of Gerlach troughs and a topographical approach based on botanic benchmarks in two paired vineyards with different ages (3 and 35 years) located on the hillslope of the Ruwer-Mosel Valley (Germany). We studied: i) soil profiles and properties at different hillslope locations and ii) soil redistribution and erosion by means of topsoil level maps applying botanic benchmarks using the Stock Unearthing Method (SUM), RUSLE (Revised Unviersal Soil Loss Equation) and Gerlach troughs. The SUM showed that the old vineyard's erosion rates ranged from 3.3 to 3.8 Mg ha(-1) yr(-1), which was similar to the Gerlach trough measurements, and we demonstrated that the soil erosion rates depended on rainfall characteristics and human disturbances due to tillage, harvest trampling, and compaction by heavy machinery. Data from the SUM in the young vineyard showed 62.5 Mg ha(-1) yr(-1) of soil loss, which is a consequence of severe soil disturbance during the planting of the new vineyard. Finally, to prove the reliability data, RUSLE showed higher soil loss in the young vineyards (19.46 Mg ha(-1) yr(-1)) than in the old ones (11.28 Mg ha(-1) yr(-1)).

Rainfall simulations at different scales have been used for understanding the influence of different factors on runoff generation and erosion. They are an accepted method for calibrating and validating physically based rainfall and erosion models. Nevertheless, it is proven that not only the patterns of rainfall are highly variable over space and time. Soil parameters responsible for runoff generation and erosion – e.g. infiltration capacity, soil moisture, aggregate stability – are highly variable, too. The results of more than 100 plot scale rainfall simulations on abandoned fields in different areas of Spain are analysed for identifying and quantifying factors affecting runoff and erosion processes. The variability of superficial runoff and suspended sediment yield is very high within most of the test areas, reaching values up to a runoff coefficient of 1 and yielding 130 g per experiment. Only within the semi-arid areas we can find a significant and high correlation between vegetation cover and sediment yield (and sediment concentration), whereas most of the other investigated surface parameters show no influence on runoff and erosion. For this, even in simulations on small plots more complex processes can be assumed. The factors controlling them have to be searched, even at detailed scales, within the geo-ecological characteristics of the investigated areas at chorological scales.

Within this Editorial, we put the articles included in the Special Issue into a historical and actual context of experimental research in Earth system sciences.

Vineyards are one of the most German conditioned eco-geomorphological systems by human activity. Precisely, the vineyards of the Ruwer Valley (Germany) is characterized by high soil erosion rates and rill problems on steep slopes (between 23–26°) caused by the increasingly frequent heavy rainfall events, what is sometimes enhanced by incorrect land use managements. Soil tillage before and after vintage, application of vine training systems and anthropic rills generated by wheel tracks and footsteps are observed along these cultivated area. The objective of this paper is to determine and to quantify the hydrological and erosive phenomena in two chosen vineyards, during diverse seasons and under different management conditions (before, during and after vintage). For this purpose, a combined methodology was applied. Investigating climatic, pedological, geomorphological and botanic-marks variables was suggested on the two experimental plot in the village of Waldrach (Trier, region of Rhineland-Palatinate). First, high infiltration rates (near 100%) and subsurface flow was detected by rainfall simulations performed at different times of the year. The second method to investigate the geomorphological response of slope inclination, two 10 m and one 30 m long rills were measured using geometrical channel cross-section index, depth and width. The highest variations (lateral and frontal movements) were noted before and during vintage, when footsteps occurred in a concentrated short time. Finally, two maps were generated of soil loss, indicated by the botanic marks on the graft union of the vines. As results 62.5 t−1 ha−1 yr−1 soil loss rate was registered (one year) on the experimental plots of the new vineyards, while 4.3 t−1 ha−1 yr−1 on the old one.

In the Central Inner Ebro Basin, valleys infilled with young alluvial sediments are very common. They are usually incised by deep gullies. Previously, these sediments were assumed to be of Holocene age, and their infilling was seen in connection with different periods of climatic deterioration and increasing human impact. In the Barranco de las Lenas, an eastern tributary of the Huerva River south of Zaragoza, the sediments are up to 15 m thick and consist of 20–60 cm thick interbedded layers, of argillaceous silt, pure silt, sandy-loamy silt, sandy silt with fine grit which are interrupted by 5–25 cm thick discontinuous cobble and gravel layers with silty matrix. The sediments contain horizontal organic layers and charcoal pieces of remarkable size. A 2.2 m high outcrop in the upper part near the recent end of the incision was radiocarbon dated, with the ages ranging from 17765–15440 cal BP to 13140–12650 cal BP. A 1.2 m sediment sequence between two organic mud layers with an age of 14040–12975 cal BP at the base and 13140–12650 cal BP at the top indicates a climatically induced highly active phase of morphodynamic processes within a period of 1400 years at the longest. Older sediments from the Pleniglacial have been reworked. The analyses of the sediments and data suggest that these few single events are indicators for strong climatic changes in the Late Glacial (Allerod Period). The results show that similar highly dynamic processes can occur without human impact. These results strongly contrast with previously published investigations that dated such fillings as Younger Holocene.

El proyecto EPRODESERT (Evaluation of Processes Leading to Land degradation and Desertfication under Extensified Farming Systems) estudia el complejosucesión de vegetación/morfodinámica/uso del suelo en Aragón. Un primer análisis socioeconómico considera las razones y la dinámica del abandono de tierras. Utilizando fotos aéreas a gran escala, tomadas desde un zeppelin aerostática teledirigido y combinándolas con una clasificación de la morfodinámicay la vegetación, se estudia detalladamente la evolución de los campos abandonados. Con métodos experimentales se cuantifican los procesos de infiltración, escorrentía y erosión hídrica. Destaca como primer resultado el diverso comportamiento ante la precipitación de los campos abandonadns de diferente antigüedad y de las costras edáficas que los cubren.

The usage of small Remotely Piloted Aircraft Systems (RPAS) is an interesting perspective for modern agriculture. These systems place strict demands on the weight and size of their onboard sensors. In this paper a polarimetric 24 GHz FMCW radar is presented. First experimental results demonstrate the feasibility of airborne soil / surface characterization

We present a comparison study on how well capacitance and time domain reflectometry water content sensors can estimate average water content values in non-uniformly wetted soils. This ability is important in studies where accurate average values are crucial. The averaging behavior of two capacitance water content sensors in nonuniform wetted sand samples was assessed and compared with the averaging behavior of a time domain reflectometry (TDR) water content sensor in identical samples. Four different nonuniform wetting situations were assessed. In one of the four experiments, the orientation of the capacitance sensor was altered, while in another the sensitivity along the length of the sensor was tested. For one of the tested sensor types, the overestimation of the volumetric water content (VWC) was 0.034 compared with the value determined by drying, while the corresponding TDR value deviated 0.009. The conclusion is that in a nonuniform wetted soil profile, the capacitance sensors tested weigh the wet parts more heavily than the dry parts, resulting in an overestimation of the average VWC. Therefore we conclude that the capacitance sensors tested are less suitable for applications in situations where both nonuniform wetted profiles are encountered and accurate VWC measurements are required.

Fire is a natural factor of landscape evolution in Mediterranean ecosystems. Middle Ebro Valley has extreme aridity, which determines a low plant cover and high soil erodibility of the soils, especially on gypseous substrates. The aim of this research is to analyze the effects of a moderate heating, on physical and chemical soil properties, mineralogical composition and susceptibility to splash erosion. Topsoil samples (15 cm soil depth) were taken in the Remolinos mountain slopes (Ebro Valley, NE-Spain) from two soil types: Leptic Gypsisol (LP) in a convex slope and Haplic Gypsisol (GY) in a concave slope. To assess the heating effects on the mineralogy we burned the soils at 105 °C and 205 °C in an oven and to assess the splash effects we used a rainfall simulator under laboratory conditions using undisturbed topsoil subsamples (0–5 cm soil depth of Ah horizon). LP soil has lower SOM and SAS and higher gypsum content than GY soil. Gypsum and dolomite are the main minerals (>80%) in the LP soil, while gypsum, dolomite, calcite and quartz have similar proportions in GY soil. Clay minerals (kaolinite and illite) are scarce in both soils. Heating at 105 °C has no effect on soil mineralogy. However heating to 205 °C transforms gypsum to bassanite, increases significantly EC in both soil units (LP and GY) and decreases pH only in GY soil. Despite differences in the content of organic matter and structural stability, both soils show no significant differences (P < 0.01) in the splash erosion rates. The size of pores is reduced by heating treatment or fire effect, as derived from variations in pF.

Recent research has shown that wind can have a signififi cant inflfl uence on velocity, impact angle and kinetic energy of raindrops, and subsequently increases soil erosion. The aims of this study were to 1) quantify the inflfl uence of wind on water erosion, 2) specififi cally observe the difference in processes betweenwindless rain (WLR) and wind-driven rain (WDR) simulations and 3) test the device’s and test sequence’s practicability. The Portable Wind and Rainfall Simulator (PWRS), recently developed at Trier University for plot-scale in situ assessment of differences in soil erosion with and without the inflfl uence of wind on raindrops, wasused. To facilitate extraction of the inflfl uences of WDR on soil erosion, to avoid systematic errors, and to reduce variability between test plots, a defifi ned order of four consecutive test runs was established: 0) wind simulation, 1) WLR simulation on dry soil, 2) WLR simulation on moist soil, 3) WDR simulation. The tests were conducted on homogenous sandy substrate deposited on an area of 15.2 m 60 m with uniform and smooth surface and low inclination (1°) in the Willem Genet Tunnel of Wageningen University. The results show an increase of eroded sediment ranging from 113 % up to 1108 % for WDR simulations in comparisonto WLR simulations. The increase in runoff was considerably lower (15 % to 71 %), resulting in an increase of sediment concentration between 56 % and 894 %. The results indicate an immense impact of WDR on soil erosion of sandy cohesionless substrate. The experimental setting and measurement proved reliable and reproducible and enables a clear process observation and quantififi cation in the fifi eld.

To assess the inflfl uence of rainfall simulator type and plot dimensions on runoff and erosion, seven small portable rainfall simulators from Freiberg, Tubingen, Trier (all Germany), Valencia, Zaragoza (both Spain), Basel (Switzerland) and Wageningen (the Netherlands) were compared on a prepared bare fallow fifi eld. The experiments were carried out during an international rainfall simulator workshop, organized at Trier University (Germany) from 30th of June to 1st of July 2011.The tested rainfall simulators differ in design, rainfall intensities, rain spectra, etc. and represent most of the devices which have been used over the last decade in Europe. The plots for the different rainfall simulators were selected as similar as possible concerning soil physical and chemical properties, aspect and inclination and were chosen to be placed side by side in horizontal direction. Test procedure was standardized in order to examine the inflfl uence of the rainfall simulator andplot dimension only. The results show a clear and consistent relationship in runoff, erosion and infifi ltration behaviour of the different used rainfall simulators. With all the devices total soil loss is measurable, but different plot sizes, intensities and kinetic energies of the simulated rainfall caused differences in soil loss and runoff quantities per unit of area. Regarding course characteristics over runs, similarities could be observed especially in runoff behaviour. The rainfall simulators (> 1 m² plot size) are able to reproduce infifi ltration and interrillerosion processes. With an increase of plot size (≥ 1 m²), rill-erosion will be also reflfl ected. Therefore it can be concluded that up to a certain plot size, the results of the different simulators are comparable and depend in their magnitude on the properties of the applied rainfall. The increase in process complexity with increasing plot size shows, that the scale of the simulation is one of the most important parameters to be taken intoaccount when comparing values of erosion and runoff.

In aeolian research, field measurements are important for studying complex wind-driven processes for land management evaluation and model validation. Consequently, there have been many devices developed, tested, and applied to investigate a range of aeolian-based phenomena. However, determining the most effective application and data analysis techniques is widely debated in the literature. Here we investigate the effectiveness of two different sediment traps (the BEST trap and the MWAC catcher) in measuring vertical sediment flux. The study was performed in a wind tunnel with sediment fluxes characterized using saltiphones. Contrary to most studies, we used the analogue output of five saltiphones mounted on top of each other to determine the total kinetic energy, which was then used to calculate aeolian sediment budgets. Absolute sediment losses during the experiments were determined using a balance located beneath the test tray. Test runs were conducted with different sand sizes and at different wind speeds. The efficiency of the two traps did not vary with the wind speed or sediment size but was affected by both the experimental setup (position of the lowest trap above the surface and number of traps in the saltation layer) and the technique used to calculate the sediment flux. Despite this, good agreement was found between sediment losses calculated from the saltiphone and those measured using the balance. The results of this study provide a framework for measuring sediment fluxes at small time resolution (seconds to milliseconds) in the field.In aeolian research, field measurements are important for studying complex wind-driven processes for land management evaluation and model validation. Consequently, there have been many devices developed, tested, and applied to investigate a range of aeolian-based phenomena. However, determining the most effective application and data analysis techniques is widely debated in the literature. Here we investigate the effectiveness of two different sediment traps (the BEST trap and the MWAC catcher) in measuring vertical sediment flux. The study was performed in a wind tunnel with sediment fluxes characterized using saltiphones. Contrary to most studies, we used the analogue output of five saltiphones mounted on top of each other to determine the total kinetic energy, which was then used to calculate aeolian sediment budgets. Absolute sediment losses during the experiments were determined using a balance located beneath the test tray. Test runs were conducted with different sand sizes and at different wind speeds. The efficiency of the two traps did not vary with the wind speed or sediment size but was affected by both the experimental setup (position of the lowest trap above the surface and number of traps in the saltation layer) and the technique used to calculate the sediment flux. Despite this, good agreement was found between sediment losses calculated from the saltiphone and those measured using the balance. The results of this study provide a framework for measuring sediment fluxes at small time resolution (seconds to milliseconds) in the field.

El pastoreo extensivo de campos en barbecho o abandonados entre la Depresión Central del Ebro y el Pirineo Central impide la regeneración de la cubierta vegetal. Se desarrolla un patrón típico de areas con geomorfodinárnica muy activa en los senderos del ganado, junto a otras extensas superficies estables. En el Prepirineo y el Pirineo Central, se puede incluso observar la reducción de la cubierta de matorral ya existente, de forma simultánea al incremento de la geomorfodinámica. Las zonas afectadas por fuerte erosión lineal aumentan a lo largo de los senderos, ya que éstos muestran tasas de escorrentia superficial y de erosión muy altas. A causa de estos efectos, los incentivos comunitarios a la ganadería ovina han de ser revisados de forma crítica.

This study presents the comparison of experimental results with assumptions used in numerical models. The aim of the field experiments is to test the linear relationship between different hydraulic parameters and soil detachment. For example correlations between shear stress, unit length shear force, stream power, unit stream power and effective stream power and the detachment rate does not reveal a single parameter which consistently displays the best correlation. More importantly, the best fit does not only vary from one experiment to another, but even between distinct measurement points. Different processes in rill erosion are responsible for the changing correlations. However, not all these procedures are considered in soil erosion models. Hence, hydraulic parameters alone are not sufficient to predict detachment rates. They predict the fluvial incising in the rill's bottom, but the main sediment sources are not considered sufficiently in its equations. The results of this study show that there is still a lack of understanding of the physical processes underlying soil erosion. Exerted forces, soil stability and its expression, the abstraction of the detachment and transport processes in shallow flowing water remain still subject of unclear description and dependence.

Despite many efforts over the last decades to understand rill erosion processes, they remain unclear. This paper presents the results of rill experiments accomplished in Andalusia in September 2008 using a novel experimental set up. 72 L of water are introduced with an intensity of 9 L min(-1) into a rill. Rill cross sections, slope values, flow velocities and sediment concentrations were measured and these values were used to calculate sediment detachment and transport. Each experiment was repeated once within 15 min. With this new experimental setup it is possible to calculate several hydraulic parameters like hydraulic radius, wetted perimeter, flow cross section, transport rate and transport capacity which are usually estimated from coarse flow and rill parameters. In rill experiments, four different natural rills were flooded with the same experimental setup. Several processes like transport of loose material, erosion, bank failure and knickpoint retreat and the runoff effectiveness showed different and variable intensities. The sediment concentrations ranged between 5.2 and 438 g L-1. most cases, detachment rates are close to the transport capacity and, in some cases, the transport capacity is even exceeded. This can be explained by the occurrence of different erosion processes within a rill (e.g. detachment, bank failure, and headcut retreat) which are not all explained by the given equations. The results suggest that the existing soil erosion equations based on shear forces exerted by the flowing water are not able to describe rill erosion processes satisfactory. Too many different processes with a high spatial and temporal variability are responsible for rill development. (C) 2010 Elsevier B.V. All rights reserved.

The state of river channels and their riparian zones in terms of geomorphology and vegetation has a significant effect on water and sediment transport in headwater catchments. High roughness in natural rivers due to vegetation and geomorphological attributes generate drag on flowing water. This drag will slow water discharge, which in turn influences the sediment dynamics of the flow. The impacts of changes in the management of rivers and their riparian zone (either by catchment managers or river restoration plans) impacts both up- as well as downstream reaches, and should be assessed holistically prior to the implementation of these plans.To assess the river's current state as well as any possible changes in geomorphology and vegetation in and around the river, effective approaches to characterise the river are needed. In this paper, we present a practical approach for making detailed surveys of relevant river attributes. This methodology has the benefit of being both detailed – describing river depth, width, channel morphology, erosive features and vegetation types – but also being practical in terms of time management. This is accomplished by identifying and describing characteristic benchmark reaches (typical sites) in detail against which the remainder of the river course can be rated. Using this method, a large river stretch can be assessed in a relatively short period while still retrieving high quality data for the total river course. In this way, models with high data requirements for assessing the condition of a river course, can be parameterised without major investments on field surveys.In a small headwater catchment (23 km2) in southwestern Poland, this field methodology was used to retrieve data to run an existing model (HEC-GeoRAS) which can assess the impact of changes in the riparian and channel vegetation and channel management on sedimentation processes and stream flow velocity. This model determines the impact of channel morphology and in-channel and riparian vegetation on stream flow and sediment transport. Using four return periods of flooding (2, 10, 20 and 100 years), two opposing channel management / morphology scenarios were run; a natural channel and a fully regulated channel. The modelling results show an increase in the effect of riparian vegetation / geomorphology with an increase in return period of the modeled peak discharge. More natural channel form and increased roughness reduces the stream flow velocity due to increasing drag from flow obstructions (vegetation and channel morphological features). The higher the flood water stage, the greater the drag due to vegetation on the floodplains of natural river reaches compared to channelised sections. Slower flow rates have an impact on sediment mobilisation and transport in the river.

Precise estimation of mean flow velocity (U-mean) is imperative for accurate prediction of hydrographs and sediment yield. For overland flow, U-mean is normally estimated by multiplying the dye or salt based velocity measurement with a correction factor (alpha). A wide range of correction factors is available in the literature, all of which were derived under different experimental conditions. The selection of a suitable a has become a main challenge for accurate mean flow calculations. This study aimed to assess the variability of a with grain size (D-50) and slope (S), and to evaluate the dependency of U-mean on flow rate (Q), D-50 and S by regression analysis. Flume experiments were performed at Q varying from 33 to 1033 x 10(-6) m(3) s(-1), S ranging from 3 degrees to 10 degrees, and D-50 ranging from 0.233 to 1.022 mm. Flow velocities were measured directly with the dye tracing technique (U-dye), and derived indirectly from flow depth measurements (U-depth). The Udepth measurements were considered as U-mean. The derived alpha (U-depth/U-dye) values did not remain constant with sediment size and increase significantly with the increase of D-50. The mean alpha values for 0.230, 0.536, 0.719 and 1.022 mm sands were 0.44, 0.77, 0.82 and 0.82, respectively. Hence, due to the substantial variation of alpha with D-50, no absolute alpha value is applicable to all hydraulic and sedimentary conditions. However, mean alpha values for 0.230, 0.536 and 0.719 mm sands were found comparable with alpha values available in the literature for similar grain sizes. The influence of Q S. and D-50 on U-mean was studied by regression analysis. Regression analysis depicted the significant influence of Q and D-50 on U-mean. while the effect of slope was found to be non-significant. Comparison of the derived regression equation with five literature datasets showed that the model can predict mean flow velocities in overland flow at a reasonable accuracy as long as the mean velocity is below 0.4 m s(-1). At higher velocities the error becomes unacceptably large.

In this study two approaches are presented to identify Dominant Runoff Processes (DRP) with respect to regionalization. The approaches are a simplification of an existing method to determine DRP by means of an extensive field campaign. The first approach combines the permeability of the substratum, land-use and slope of the basin in a GIS-based analysis. The second approach makes use of discriminant analysis of the physiographic characteristics of the basin and links it to the GIS analysis. The results of the developed approaches are maps, which identify dominant runoff processes and represent a spatial distribution of the hydrological behaviour of the soil during prolonged rainfall events. The approaches have been developed in a micro-scale basin (Germany). An additional meso-scale basin was introduced in which the two approaches were applied for quality control. The thus generated maps for the micro-scale basin were compared with an existing DRP map, which was derived with the existing method. The first approach showed a resemblance of 79% when compared to this map, whereas the second approach showed only a resemblance of 51%. The generated maps for the meso-scale basin were compared to DRP that were determined point wise according to the existing method. The first approach showed in this case a resemblance of 81%, whereas the second approach showed a resemblance of 68%. Therefore, the first approach is preferred to the second approach when accuracy, data input and calculation time are concerned.

Field techniques allow accurate direct measurements on gully geometry, even in three-dimensional (3D) coordinates. Accuracy and detail reproduction is limited mainly by experimental setup and density of measurements, and less so by the precision of the measuring equipment. In contrast, remote-sensing techniques permit the coverage of large study areas with a minimum of time and effort. However, the indirect measurements from imagery are known to depend on factors like image resolution, quality of ground control, vegetation cover and image evaluation technique, which strongly influence the measurement accuracy. The objective of the present study was to investigate to what extent the accuracy of 3D gully measurement using photogrammetric techniques depends on gully morphology. At a study site in the Bardenas Reales (Navarre, Spain), field measurements of cross-sections were taken for five gullies with contrasting morphology and dimensions and used as reference data for analysing the errors associated with a corresponding dataset obtained using small-format aerial photogrammetry whose pixel size on the ground is 16 mm. Results show that volumetric gully measurements by means of photogrammetric techniques are strongly affected by the gully morphology; in particular by its width/depth (W/D) ratio, because of the increasing sun-shadowing and sight-shadowing effects associated with narrower gullies. Only wide, shallow gullies are little affected by this problem. For gullies of an intermediate typology (W/D between 0·5 and 2·5), the accuracy of photogrammetric measurements will much depend on the time of day and the period of the year when the photographs are taken, and narrow/deep gullies (W/D

Rainfall simulation is a widely used method for soil erosion studies on agricultural land. Major problem of this experimental research method is the comparability between different simulators due to differences in simulated rainfall. Therefore the purpose of this study is to characterize the rainfall produced by a rainfall simulator which was widely used during the last decades. Four different calibration methods were used to assess the drop size distribution: (1) Indication Paper, (2) Plaster Micro Plot, (3) Joss–Waldvogel Disdrometer and (4) Laser Distrometer (Thies). Additionally, the latter one was used to measure drop fall velocity in combination with drop diameter. The spatial rainfall distribution pattern on the plot was measured with 100 rainfall gauges. The spatial rainfall distribution pattern clearly shows a heterogeneity, which is caused by the used nozzle configuration. Considerable differences in drop-size distribution can be observed depending on the used measurement technique. Laser Disdrometer and Plaster Micro Plot cover the whole produced drop size spectrum ranging from 3.0 mm, whereas Indication Paper as well as the Joss–Waldvogel Disdrometer primarily show drops smaller than 2.0 mm. Characterisation of rainfall is therefore strongly dependent on the used method and if different methods are used, may lead to contradictory results. The volume drop size distribution reflected by the Laser Distrometer is very similar to that one produced by rain with an intensity of 40 mm h −1 . Nevertheless, with maximum velocities above 10 m s −1 small drops are by far too fast and large drops with velocities dominantly below 5 m s −1 are too slow compared to natural rainfall. As an overall result, the simulator can be characterised as suitable for runoff and infiltration measurements, but with constraints due to the low reproducibility of the spatial rain distribution. As a consequence of the produced drop spectrum and fall velocity the erosion quantities may be underestimated systematically. For this, methodological development has to be focussed on homogeneous spatial rainfall distributions and on increasing the amount of large drops with higher fall velocities.

22 Pag., 3 Tabl., 7 Fig., This paper studies the hydrological response to rainstorm events of a small experimental catchment in the Central Spanish Pyrenees. The Arnás catchment was cultivated until 40 years ago, and then abandoned and affected by plant recolonisation, especially shrubs. A rainfall of a few millimeters is enough to produce a sudden increase in discharge, due most probably to the steep gradients and the small size of the catchment and the extensive areas with low vegetation density and thin soils. The intensity of the response shows a very high variability, depending on the intensity of precipitation and soil humidity conditions before the flood. This paper identifies two types of floods according to the relationships between precipitation and discharge, and confirms that antecedent soil moisture explains much of the response. The shape of the hydrograph, very similar to the hyetograph, suggests that the Arnás catchment is dominated by overland flow processes. However, more intense rainstorms do not generate higher peak flows, thus demonstrating the existence of different runoff-generating areas., This paper has been supported by the following projects: “Water resources management in a changing environment: the impact of sediment on sustainability” (WARMICE, ENV4-CT98-0789) funded by the European Commission; and “Assessment of sediment sources and runoff generation areas in relation to land use changes” (HIDROESCALA, REN2000-1709-C04-01/GLO), “Hydrological processes in seminatural Mediterranean areas” (PROHISEM, REN 2001-2268-C02-01/HID), and “Hydrological processes in Pyrenean catchments in relation to land use and climate changes” (REN 2003-08678/HID), all funded by the CICYT. Monitoring of the catchment has been supported by agreement between the CSIC and the Spanish Ministry of Environment (RESEL).

Las cuencas experimentales de Arnás y San Salvador, localizadas en la cuenca alta del río Aragón, han sido equipadas con estación meteorológica completa, flume e instrumentos para la medición continua del caudal y del sedimentos transportado (en solución y en suspensión). Una trampa de sedimento a la entrada del flume permite controlar periódicamente la carga de fondo. Los resultados obtenidos confirman la existencia de grandes diferencias en la respuesta hidrológica y el transporte de sedimento entre la cuenca forestal (San Salvador) y la cuenca de campos abandonados (Arnás). La primera muestra una respuesta mucho más moderada debido básicamente a los procesos de interceptación y a la mayor profundidad de los suelos. Las relaciones entre precipitación y pico de caudal, así como entre este último y la concentración de sedimento en suspensión son muy bajas, aumentando notablemente si se contemplan por separado las crecidas de estación fría. La escorrentía se genera sobre todo por procesos de saturación. Las fuentes de sedimento se localizan en el cauce y sus proximidades.

Plans to increase the amount of irrigated land in Mediterranean countries should consider how changes in climate and land-use affect water resources. In this study, both precipitation and temperature were used to analyze regional trends in discharge in the basins of the Central Spanish Pyrenees since the mid-20th century. Annual variations in the relationship between precipitation and discharge suggested that discharge was relatively lower in the second half of the study period, coinciding with major changes in land use. On a monthly scale, precipitation increased significantly in October, April, and July, and decreased in March, and temperature increased in January and February and decreased in April. Nevertheless, discharge has decreased significantly in most months in the past 50 years. Land-use and plant-cover changes are the only nonclimatic factor that can explain the loss of around 30% of the average annual discharge., Funding for this research was provided by the following projects: "Water resources management in a changing environment: the impact of sediment in sustainability" (WARMICE, ENV4-CT98-0789), funded by the European Community, and "Assessment of sediment and runoff sources in relation to land-use changes", (HIDROESCALA, REN2000-1709-C04-01/GLO) and "Hydrological processes in semi-natural Mediterranean areas" (PROHISEM, REN2001-2268-C02-01/HID), both funded by CICYT.

27 Pags.- 11 Tabls.- 8 Figs. © Author(s) 2018. This work is distributed under the Creative Commons Attribution 4.0 License., In this paper, we present and analyze a novel global database of soil infiltration measurements, the Soil Water Infiltration Global (SWIG) database. In total, 5023 infiltration curves were collected across all continents in the SWIG database. These data were either provided and quality checked by the scientists who performed the experiments or they were digitized from published articles. Data from 54 different countries were included in the database with major contributions from Iran, China, and the USA. In addition to its extensive geographical coverage, the collected infiltration curves cover research from 1976 to late 2017. Basic information on measurement location and method, soil properties, and land use was gathered along with the infiltration data, making the database valuable for the development of pedotransfer functions (PTFs) for estimating soil hydraulic properties, for the evaluation of infiltration measurement methods, and for developing and validating infiltration models. Soil textural information (clay, silt, and sand content) is available for 3842 out of 5023 infiltration measurements ( ∼ 76%) covering nearly all soil USDA textural classes except for the sandy clay and silt classes. Information on land use is available for 76 % of the experimental sites with agricultural land use as the dominant type (∼ 40%). We are convinced that the SWIG database will allow for a better parameterization of the infiltration process in land surface models and for testing infiltration models. All collected data and related soil characteristics are provided online in *.xlsx and *.csv formats for reference, and we add a disclaimer that the database is for public domain use only and can be copied freely by referencing it. Supplementary data are available at https://doi.org/10.1594/PANGAEA.885492 (Rahmati et al., 2018). Data quality assessment is strongly advised prior to any use of this database. Finally, we would like to encourage scientists to extend and update the SWIG database by uploading new data to it., First author thanks the International and Scientific Cooperation Office of the University of Maragheh, Iran, as well as the research committee and board members of the university for their assistance in conducting the current work. The financial support received from the Forschungszentrum Jülich GmbH is gratefully acknowledged by the first author. Parts of the database were made available through research work carried out in the framework of LIFE+ projects funded by the EC. The support of the Spanish Ministry of Economy through project CGL2014-53017-C2-1-R is acknowledged. The support of the Czech Science Foundation through project no. 16-05665S is acknowledged. The support of the Slovak Research and Development Agency through project no. APVV-15-0160 is acknowledged.

Soil erosion is a common global problem that has negative impacts on agriculture production, water storage facilities, water conveyance system, and water quality. To assess water erosion problems in catchments, scientists have developed several spatially distributed soil erosion models with various degree of sophistication. Examples are CREAMS, KYERMO, PRORILL, KINEROS2, LISEM, RUSLE, EUROSEM, EGEM, GLEAMS, and WEPP. Precise estimation of mean flow velocity and sediment transport capacity play a vital role in the accuracy of the outcomes of each spatially distributed soil erosion model. Worldwide, Manning and Darcy-Weisbach formulae are commonly used for the quantification of mean flow velocity in shallow overland flows, which were actually derived for stream flow. Likewise, majority of the functions used for sediment transport estimation were originally derived for channel flow. The applicability of stream flow functions has become questionable under overland flow, because the water layer depths and discharges are usually much smaller in overland flow. Moreover, hillslope surfaces are usually rougher than streams. Hence, the main aims of this study were (i) How suitable are the existing approaches and functions that are used for mean flow velocity and sediment transport capacity quantification under overland flow conditions? (ii) Which hydrological and morphological factors affect and control the mean flow velocity and sediment transport capacity? (iii) What are optimal functions for the quantification of mean flow velocity and sediment transport capacity? To address all the research objectives of this study, it was necessary to precisely measure the hydraulic and sediment parameters under overland flow conditions, which was accomplished by conducting flume experiments under controlled conditions. Experiments were carried out in a 3.0 m long and 0.5 m wide rectangular hydraulic flume. Four non-cohesive, narrowly graded, commercially available sands with median grain diameter equal to 0.233, 0.536, 0.719, and 1.022 mm were selected for study of the variation in mean flow velocity and sediment transport capacity with grain size. In order to analyze the impact of slope and flow discharge on mean flow velocity and sediment transport capacity, the flume was inclined at four slope gradients (5.2, 8.7, 13.2 and 17.6%) and applied inflow discharges ranged from 33 to 1033 x 10-6 m3 s-1. To study the impact of the bed geometry on mean flow velocity and also the variation in bed form evolution with grain size, the flume bed was scanned before and after a run with a profile laser scanner. The performance of the five existing sediment transport capacity functions was evaluated for overland flow conditions using graphical and statistical analysis. The results show that the application of these functions is limited to the range of hydraulic and sediment conditions for which each was formulated. Regression analysis was carried out to examine the impact of different hydraulic and sediment parameters i.e. flow discharge, slope gradient, and median grain size on mean flow velocity and sediment transport capacity. The main aim of the regression analysis was to better understand the processes entailed in flow velocity and sediment transport. In view of the strong impact of flow discharge and median grain size on mean flow velocity, an empirical equation was derived for the estimation of mean flow velocity that was calibrated with five literature datasets. In-addition to this, the results of this study exhibit that unit stream power is an optimal composite force predictor for estimating transport capacity. Based on the unit stream power concept, a new physically based transport capacity function was derived by dimensional analysis using the experimental results. The newly derived function was calibrated using the flume experiment results, but validation is still needed for cohesive soils.