Erosion Coefficient Research Articles

ESTABLISHMENT OF JET INDEX Ji FOR SOIL ERODIBILITY COEFFICIENTS USING JET EROSION DEVICE (JEd)

Soil erodibility has been identified as one of the major factors that govern threshold of resistance to erosion. Accurate measurement of soil erodibility in the field is indeed important for the determination of critical shear stresses. Critical shear stress is the stress that initiates particle movement that promotes shifting of the bankline. An attempt to establish soil erodibility parameters was successfully carried out using a newly fabricated Jet Erosion Device (JEd) based on soil properties. Soil erodibility coefficients are introduced to represent the erodibility of the soils under study. Statistical test is used to confirm the validity and accuracy of the proposed technique. Field data measurements were carried out on 3 rivers. Empirical models were developed using data from Selangor River and validated using data from Bernam and Lui rivers and other secondary river data. Analyses have shown high correlations and the parameters were further examined and analysed for the development of a predictive relationship for Ji. The most accurate model was selected based on the adjusted R2, standard error of the estimate and discrepancy ratio to illustrate its significance. Selection of the predictive variables was based on their ability to explain the variation of Ji. The models established could significantly reduce the cost, time and usage of water supply for field data collection using JEd.

Coupled studies of fluvial erosion and cantilever failure for cohesive riverbanks: Case studies in the experimental flumes and U-Tapao River

The main objective of this paper is to introduce a novel coupled method for simulating the fluvial erosion, cantilever failure and bedload sediment transport to describe the overhanging properties of experimental banks and natural riverbanks. For fluvial erosion results, the previous relationships between the critical shear stress, and the erodibility coefficient indicated that they do not follow the values of the experimental works and the U-Tapao River, Thailand. Therefore, it is necessary to determine these relationships locally. The cantilever failure results revealed that the dominant failure mechanism of the experimental works is beam-type failure, while shear-type failure is the dominant failure in the U-Tapao River. Finally, a numerical model was developed based on a triple-grid approach to simulate the behaviour of a cantilever within the framework of fluvial erosion, cantilever failure, and bedload transportation. The simulated results showed good agreement with experimental results, and the U-Tapoa River in terms of the temporal variations of spatially averaged bank width, dominant failure mechanism, and overhanging block dimensions.

Modeling blowing snow accumulation downwind of an obstruction: The Ohara Eulerian particle distribution equation

AbstractAn equation was proposed to model the height of blowing snow accumulation downwind of an obstacle such as vegetation, a snow fence, a building, or a topographic feature. The equation does not require aerodynamic flow condition parameters such as wind speed, allowing for the spatial distribution of snow to be determined at locations where meteorological data is not available. However, snow particle diffusion, drift, and erosion coefficients must be estimated for application of the equation. These coefficients can be used to provide insight into the relative magnitude of blowing snow processes at a field location. Further research is required to determine efficient methods for coefficient estimation. The equation could be used with other models of wind‐transported snow to predict snow accumulation downwind of an obstacle without the need for wind speed adjustments or correction equations. Applications for this equation include the design of snow fences, and the use of this equation with other hydrological models to predict snow distribution, climate change, drought, flooding, and avalanches.

USLE/RUSLE K-factors allocated through a linear mixed model for Uruguayan soils

Soil erosion by rainfall is a process that demands management, both for the prevention of excessive soil erosion and for the protection of the quality of freshwater bodies. Erosion coefficients (K-factors) of the universal soil loss equation (USLE)/revised USLE (RUSLE) model were assigned to 99 mapped Uruguayan soil types at 1:1,000,000 scale. This work developed a linear mixed model (LMM) with 79 soils with assigned K-factors, in which the following variables were considered: soil taxonomy, chemical composition, and parent material. The developed LMM had an R2=0.86, in which the soil taxonomy (p<0.0001), parent material (p=0.0174), clay (p=0.0005) and sand (p=0.017) contents had significant statistical effects. The prediction capacity of this model was assessed with 10 soils not previously used in development of the LMM with assigned K-factors. The prediction assessment had an R2=0.84 and a mean error of 9.08% of the mean K-factor value. The LMM developed was used for the allocation of K-factors to soils mapped at a 1:20,000-resolution. Thus, the use of LMM increased the soil area with assigned K-factors from 111,822 km2 (at a scale of 1:1,000,000) to 174,132 km2 (1:20,000).

Erodibility Parameters Derived from Jet and Flume Erosion Tests on Root‐Permeated Soils

AbstractFlume tests and in situ jet erosion tests (JETs) allow for the process‐based quantification of erodibility parameters of cohesive soils. In the excess shear stress model used to predict soil detachment, the critical shear stress (τc) corresponds to the stress at which fluvial forces can detach soil particles or aggregates and the erodibility coefficient (kd) governs the rate at which detachment occurs when the imposed shear exceeds τc. The primary objective of this research was to derive and compare erodibility parameters from flume tests and JETs on various root‐permeated soil samples. Based on statistical analysis, erodibility coefficients from the flume tests were typically statistically similar to those derived with JETs. In order to further determine the capability of the JET to indicate differences in erodibility of root‐permeated soils, this research then performed JETs on side‐by‐side in situ soils. The JETs on root‐permeated soils estimated significantly higher τc but insignificant differences in kd compared to JETs on adjacent bare soil. A significant correlation was observed between exposed root surface area (TRSA) and τc, but no correlation between TRSA and kd or the equilibrium scour depth was observed. More flume and JET experiments are needed to clarify the relationship between root‐permeated soils and erodibility parameters, and address a wider range of average root diameters than was considered in this research.

An Eulerian equation for snow accumulation downstream of an object

AbstractThis study investigated the form of the governing equation for the particle distribution by focusing on the particle motion processes rather than flow regime and particle characteristics. A linear erosion term for a fetch‐eddy effect was introduced to the advection dispersion equation. The equation formulated in this paper described most of the particle deposit patterns behind an object including porous and solid snow fences, and a tree. This theory may enable us to estimate particle motion parameters, such as diffusion, drift, and erosion coefficients, from field observed particle distributions. Snow stratigraphy observed by ground penetrating radar (GPR) was used verify to result of the modeled theoretical snow redistribution. These analyses confirmed the effectiveness of the linear erosion term at explaining the particle deposition patterns due to eddies around a porous snow fence.

Modeling Streambank Erosion on Composite Streambanks on a Watershed Scale

Abstract. Streambanks can be a significant source of sediment and phosphorus to aquatic ecosystems. Although the streambank-erosion routine in the Soil and Water Assessment Tool (SWAT) has improved in recent versions, the recently developed routine in SWAT 2012 has undergone limited testing, and the lack of site or watershed specific streambank data increases the uncertainty in the streambank-erosion predictions. There were two primary objectives of this research: (1) modify and test the 2012 SWAT streambank-erosion routine on composite streambanks, and (2) compare SWAT default and field-measured channel parameters and assess their influence on predicted streambank erosion. Three modifications were made to the SWAT 2012 streambank-erosion routine: (1) replacing the empirical effective shear stress equation with a process-based equation, (2) replacing bankfull width and depth measurements with top width and streambank height, and (3) incorporating an area-adjustment factor to account for non-trapezoidal cross-sections. The proposed streambank-erosion routine was tested on gravel-dominated streambanks on the Barren Fork Creek in northeastern Oklahoma. The study used data from 28 cross-sectional surveys, including streambank height and top width, side slope, thickness and texture of streambank layers, and an area-adjustment factor. Gravel d50 and kd-tc relationships were used to estimate the critical shear stress (tc) and the erodibility coefficient (kd), respectively. Incorporating the process-based shear stress equation, area-adjustment factor, or the top width and streambank height increased predicted streambank erosion by 85%, 31%, and -30%, respectively. Incorporating the process-based effective shear stress equation, sinuosity, radius of curvature, and measured bed slope improved the predicted versus observed streambank erosion Nash-Sutcliffe efficiency from -0.33 to 0.49 and the coefficient of determination (R2) from 0.02 to 0.65 at the ten study sites. Although the process-based effective shear stress equation was the most influential modification, incorporating the top width, streambank height, and area-adjustment factor more accurately represented the measured irregular cross-sections. Keywords: Composite streambanks, Fluvial erosion, Streambank erosion, SWAT.

Two – Dimensional Mathematical Model to Study Erosion Problem of Tigris River Banks at Nu’maniyah

The high and low water levels in Tigris River threaten the banks of the river. The study area is located on the main stream of Tigris River at Nu’maniyah City and the length of the considered reach is 5.4 km, especially the region from 400 m upstream Nu’maniyah Bridge and downstream of the bridge up to 1250 mwhich increased the risk ofthe problemthat itheading towardsthe streetand causingdanger tonearbyareas.&#x0D; The aim of this research is to identify the reason of slope collapse and find proper treatments for erosion problem in the river banks with the least cost. The modeling approach consisted of several steps, the first of which is by using “mini” JET (Jet Erosion Test) device provides a simple method of measuring scour depth with the time for the riverbank and finding values of critical shear stress and erodibility factor for ten soil samples taken from right bank and bottom of Tigris River; the second of which involved setting up a static BSTEM software for two models (with and without treatment), then calculating the erosion amounts and factor of safety for the ten soil samples; the third approach involved implementing a two dimensional RMA2 to simulate four scenarios to find the velocity, water depth, and water surface elevation distributions for two models (with and without treatment). Therefore, observed erosion in other discharges in natural case near the right bank [especially at cross section that are located in Tigris River at Nu’maniyah City from 500 m upstream Nu’maniyah Bridge and cross section that are located from 1800 m downstream Nu’maniyah Bridge] is high because of high erodibility coefficient in those cross sections that causes high erosion. Also, failure occurs in natural case of Tigris River at Nu’maniyah City because of erosion near the right bank and does not occur because of slope stability failure for right bank where the range of the velocities near the right bank for the study area for most discharges is between 0.67 and 0.91 m/s. In addition to experimental work using "mini" JET device shows high erodibility coefficient in those cross sections and (2+900) which confirms that this device is very good indicator for the possibility of bank scour. The velocities upstream of the island and near the right bank in the study area are between 0.64 and 1.47 m/s, while downstream of the island is between 0.64 and 1.04 m/s. In addition to soil of Tigris River right bank at Nu’maniyah is silty soil, the scour velocity is higher than 0.5 m/s, therefore the right bank is safe against scour only when the discharges of Tigris River are less than 500 m3/s. Thus, vegetation is unsafe treatment on right bank of Tigris River at Nu’maniyah City. The velocity causes removal of plants since treatment for river bank is 0.61 m/s where velocities near bank at most discharges are higher than this limit. Thus, treatment by riprap is the proper choice on the right bank of Tigris River at Nu’maniyah City because its cost with maintenance is 2 billion IQD less than gabion treatment in addition to velocity reduction ratio along the right bank by riprap ranges from 15% to 85%, while velocity reduction ratio along the right bank by gabion ranges from 8% to 25%, respectively.&#x0D;

Detachment characteristics of root-permeated soils from laboratory jet erosion tests

The influence of vegetation on flow and sediment dynamics at various spatial and temporal scales has been well documented. Vegetation may be one of the most effective measures in streambank stabilization. Traditionally, research on the influence of vegetation roots on streambank stabilization has focused on mechanical reinforcement and reduced applied shear stress due to above ground biomass. Few studies have investigated the effect of roots on fluvial detachment of sediment. This study conducted 36 mini-jet erosion tests (mini-JETs) on bare soil samples and 29 mini-JETs on root-permeated soil samples (average root diameters of 0.5 to 1.7mm) to determine the role of roots in erosion resistance. The research also estimated parameters of the linear excess shear stress model (erodibility coefficient, kd, and critical shear stress, τc) and a nonlinear detachment model called the Wilson Model (b0 and b1) and investigated the correlations between parameters of the two models and root characteristics. Root-permeated soil samples were more erosion resistant at higher shear stress as the τc and b1 parameters were on average higher for the vegetated samples than the bare soil samples. As root diameter increased in the soil samples, erosion rates at high shear stress decreased. The erodibility coefficient parameters (b0 and kd) of both the linear and nonlinear detachment models were negatively and significantly correlated to root diameter through power functions. No significant correlation was detected between critical shear stress or b1 and root parameters which supports conclusions of previous studies. Significant correlations were observed among the parameters of the excess shear stress model and the nonlinear detachment model; especially high correlation was observed between τc and b1 for the vegetated samples. In conclusion, root-permeated soils exhibited lower erosion rates primarily through increasing the required shear stress before detachment.

Probabilistic Models for Erosion Parameters and Reliability Analysis of Earth Dams and Levees

AbstractProbabilistic models for two soil erosion parameters needed to model the erodibility of water-retaining structures are developed. The models predict the values of the critical shear stress and the coefficient of erosion starting from other measurable soil properties. The models include both noncohesive and cohesive contributions to the erosion behavior. An importance sampling simulation method is parallelized to be implemented in parallel computing resources to calibrate the models and estimate the unknown parameters using laboratory data. The probabilistic models are then used to develop fragility curves that capture the vulnerability of a typical earth dam to internal erosion.

Variability of Erodibility Parameters from Laboratory Mini Jet Erosion Tests

AbstractApplication of jet erosion tests (JETs) to study in situ erodibility is gaining popularity. New versions of the JET (original JET versus mini-JET) and new data analysis techniques have introduced questions regarding their operation and data collection procedures. One of the major issues regarding JETs is the high degree of variability of the erodibility parameters (i.e., erodibility coefficient, kd, and critical shear stress, τc). This variability has been attributed to heterogeneity in different soil properties under natural field conditions, but limited research has quantified variability under controlled laboratory conditions, especially for the newer mini-JET. This study uniquely conducted 20 mini-JETs under controlled laboratory conditions on each of two soil types of contrasting texture. Mini-JETs were conducted in situ on streambanks of these same soils in previous research. The laboratory mini-JETs predicted similar values of most parameters with much less variability than in the field. Th...

JET EROSION DEVICE (JED) – MEASUREMENT OF SOIL ERODIBILITY COEFFICIENTS

Erosion from riverbank is most properly represented by the erodibility factor. One of the methods that can be used for in situ soil erodibility testing is the submerged jet test called Jet Erosion Test (JET). In this study, a newly modified version of the JET device namely Jet Erosion Device (JEd) is fabricated, with improved features and design that facilitates testing in the field and the laboratory. Analysis and calibration of the JEd tests were conducted to check on the reliability and performance of the Jet Erosion Device (JEd). Some preliminary results were shown to give some insights on the capabilities of the JEd. An evaluation of the erosion performance index i.e. jet index was performed to characterize the erosion resistance. The estimation of erodibility coefficients were made using the results of jet index obtained.

Impact of Lime, Cement, and Clay Treatments on the Internal Erosion of Compacted Soils

AbstractThe aim of this paper is to study the impact of certain soil treatments on the internal erosion characteristics of treated compacted silt. The experiments measured the internal erosion using the hole erosion test (HET). This study aims to describe the effects of clay, lime and cement soil treatments on the internal erosion, specifically with regard to the amount of treatment used and the curing time. A new enhanced HET was developed to apply a high inlet pressure up to 650 kPa and thus generate a hydraulic shear stress up to 10,000 Pa. The internal erosion resistance was quantified by the coefficient of soil erosion and the critical shear stress. The results demonstrated that clay treatment could reduce the coefficient of soil erosion depending on the nature and percentage of clay added to the soil. The results also showed that lime and cement treatment primarily increased the critical shear stress of the tested silt. This increase was higher with cement treatment and was dependent on the amount o...

Detection of transience in eroding landscapes

AbstractPast variations in climate and tectonics have led to spatially and temporally varying erosion rates across many landscapes. In this contribution I examine methods for detecting and quantifying the nature and timing of transience in eroding landscapes. At a single location, cosmogenic nuclides can detect the instantaneous removal of material or acceleration of erosion rates over millennial timescales using paired nuclides. Detection is possible only if one of the nuclides has a significantly shorter half‐life than the other. Currently, the only practical way of doing this is to use cosmogenicin situcarbon‐14 (14C) alongside a longer lived nuclide, such as beryllium‐10 (10Be). Hillslope information can complement or be used in lieu of cosmogenic information: in soil mantled landscapes, increased erosion rates can be detected for millennia after the increase by comparing relief and ridgetop curvature. This technique will work as long as the final erosion rate is greater than twice the initial rate. On a landscape scale, transience may be detected based upon disequilibria in channel profiles or ridgetops, but transience can be sensitive to the nature of transient forcing. Where forcing is periodic, landscapes display differing behavior if forcing is driven by changes in base level lowering rates versus changes in the efficiency of either channel or hillslope erosion (e.g. driven by climate change). Oscillations in base level lowering lead to basin averaged erosion rates that reflect a long term average erosion rate despite strong spatial heterogeneity in local erosion rates. This averaging is reflected in10Be concentrations in stream sediments. Changes in hillslope sediment transport coefficients can lead to large fluctuations in basin averaged erosion rates, which again are reflected in10Be concentrations. The variability of erosion rates in landscapes where both the sediment transport and channel erodibility coefficients vary is dominated by changes to the hillslope transport coefficient. Copyright © 2016 John Wiley &amp; Sons, Ltd.

Experimental Research on Trenching in Stiff Clay by Submerged Vertical Traveling Jets

ABSTRACT Zhang, S.; Zhao, M.; Ge, T., and Wang, C., 2016. Experimental research on trenching in stiff clay by submerged vertical traveling jets. This study investigated trenching by submerged circular traveling jets in stiff clay using an experimental method. The testing clay was prepared as mixtures of natural clay and cement with shear strength ranging from 60 kPa to 90 kPa. The jet pressure, the nozzle translational velocity, and the diameter of the nozzle all varied in the test. A cohesive sediment scouring theory was employed to reveal the mechanism of the jet trenching. It showed that the boundary layer shear force on the jet-soil interface might be the predominant mobilizing force for jet trenching. The trench depth was found to increase with the jet pressure, erodibility coefficient, and the diameter of the nozzle and decrease with the translational velocity of the nozzle and the threshold stress of the clay. The essence of the traveling jet trenching could be considered as jet erosion. The effici...

Negative erosion effect and the emergence of unstable combustion. 2. numerical simulation

This paper describes the numerical simulation of combustion with the manifestation of the Vilyunov–Dvoryashin effect that comes down to reduction of the burning rate in the case of blowing of gaseous combustion products past the propellant gasification surface. The cases of endothermic and exothermic reactions of gasification of the solid propellant are considered. The Vilyunov–Dvoryashin effect can terminate combustion even before the erosion coefficient reaches a minimum value of 0.61. Self-oscillating combustion may also occur. The simulation of propellant combustion similar in its properties to the propellant N shows qualitative agreement between the theoretical and experimental results. However, it also reveals the need for more accurate data with regard to performance conditions and experimental results. The existing models of solid-propellant combustion require significant updates as well.

Influence of Lead Pollution on Cohesive Soil Erodibility using Jet Erosion Tests

&lt;p class="1Body"&gt;Recent researches were investigated the high concentrations of Lead in Baghdad soils due to the emissions from Leaded fuel of cars, generators, and the industrials. These high concentrations in addition to their impact on human health may impact on the landscape and streambanks and may cause significant issues on soil erodibility. The erosion rate of cohesive soil was usually estimated using two alternative models, excess shear stress model which is depended on two major soil parameters: the critical shear stress, &lt;em&gt;τ&lt;sub&gt;c&lt;/sub&gt;&lt;/em&gt;, and the erodibility coefficient, &lt;em&gt;k&lt;sub&gt;d&lt;/sub&gt;&lt;/em&gt;, and Wilson model which is depended on two mechanistic soil parameters: &lt;em&gt;b&lt;sub&gt;0&lt;/sub&gt;&lt;/em&gt; and &lt;em&gt;b&lt;sub&gt;1&lt;/sub&gt;&lt;/em&gt;. A new miniature version of Jet Erosion Test (“mini” JET) was performed to derive both model parameters. The objective of this study was to investigate the influence of Lead pollution on cohesive soil erodibility using “mini” JET under controlled laboratory setups to predict soil erodibility. In order to observe the Lead contamination on soil erodibility, soil samples were mixed with different quantities of Lead concertation and the samples were packed at ASTM standard mold on two different bulk densities. Results show that the Lead pollution increased soil erodibility when the concentration of Lead increased. An inverse relationship between excess shear stress parameters &lt;em&gt;k&lt;sub&gt;d&lt;/sub&gt;&lt;/em&gt; and &lt;em&gt;τ&lt;sub&gt;c&lt;/sub&gt;&lt;/em&gt; was observed as well as between Wilson model parameters &lt;em&gt;b&lt;sub&gt;0&lt;/sub&gt;&lt;/em&gt; and &lt;em&gt;b&lt;sub&gt;1&lt;/sub&gt;&lt;/em&gt;. The Wilson model parameters were closely resembled the empirical excess shear stress parameters with benefit that Wilson model parameters are mechanistic parameters.&lt;/p&gt;

Deriving Erodibility Parameters of a Mechanistic Detachment Model for Gravels

<abstract> <b><sc>Abstract.</sc></b> Recent research has proposed the use of a mechanistic detachment model, called the Wilson model, in place of the excess shear stress equation for predicting the detachment of cohesive soils during erosion. However, this mechanistic detachment model was also proposed as being valid for noncohesive soils but with limited evaluation. Such erodibility parameters are often needed in erosion models developed using a single detachment rate approach for both cohesive and noncohesive soils. Therefore, the objectives of this research were to evaluate the applicability of the Wilson model for noncohesive soils and to evaluate a procedure for deriving the erodibility parameters (b₀ and b₁) from flume experiments. Gravel samples were extracted from composite streambanks on the Barren Fork Creek in eastern Oklahoma. The samples were sieved into particle size classes, and then at least triplicate flume experiments were performed (gravel sizes of 0.45, 0.60, 1.30, and 1.90 cm). Flow rate, water surface elevation, and scour depth were measured to estimate the energy slope, scour rate, and effective shear stress. The Wilson model was fit to the scour depth data to derive b₀ and b₁ using the generalized reduced gradient method to minimize the error between the predicted and measured scour. Constraints were required within the solver routine to limit potential solutions of b₁. Similar to cohesive soils, b₀ and b₁ had similar relationships to but different magnitudes than the erodibility coefficient (k_d) and critical shear stress (τ_c) for these gravels. Equivalent b₁-τ_c relationships were derived from the flume tests as compared to the theoretical b₁-τ_c relationship in the Wilson model. The b₀-b₁ and k_d-τ_c relationships followed power law relationships. This research supports the applicability of the nonlinear mechanistic detachment model for noncohesive gravels.

Correlating Site-Scale Erodibility Parameters from Jet Erosion Tests to Soil Physical Properties

Abstract. One of the most commonly used methods of measuring erodibility parameters, i.e., critical shear stress (τc) and erodibility coefficient (kd), of cohesive soils is the Jet Erosion Test (JET). While numerous factors influence the erodibility parameters, the JET provides an in situ measurement technique. However, in many cases where erodibility parameters are required for simulating channel erosion processes, the erodibility parameters are not characterized in situ but estimated empirically based on soil physical properties with relationships that may not be good predictors for all streambanks. The objectives of this study were to investigate the correlation between the erodibility parameters measured with JETs and soil physical properties at a site-specific scale and across three unique streambanks. A total of 74 JETs were conducted within visually homogeneous streambank layers at three sites in Oklahoma along with measurements of soil physical parameters such as texture, bulk density, moisture content, and water and soil temperatures. At the site scale, τc and kd varied by up to three orders of magnitude. Neither multiple linear regressions nor principal components regressions suggested any consistent strongly correlated variables. Therefore, erodibility parameters measured in this study could not be predicted based solely on soil physical properties. It was concluded that τc and kd must be measured in situ and cannot be estimated from empirical relationships due to the heterogeneous nature of soil and the variability in subaerial processes, even within visually homogeneous streambank layers. More research is needed in order to correlate erodibility parameters to other soil parameters and quantify the role of subaerial processes, such as seepage, soil desiccation, and freeze-thaw cycles, on erodibility in order to incorporate spatial variability of erodibility parameters into stability and channel evolution models.

Sensitivity Analysis of a Physically Based Distributed Model

The objective of this study is to perform a sensitivity analysis of the SHETRAN model on the example of the torrential Lukovska River catchment in Serbia. The sensitivity analysis of the model was performed for the following parameters: the vertical saturated hydraulic conductivity of the subsurface soil, the horizontal saturated hydraulic conductivity in the saturated zone, the Strickler roughness coefficients for overland flow and for streams, the available water content in the soil and the erodibility coefficients due to rain and due to overland flow. It can be concluded that the water and sediment discharge are very sensitive to the values of the vertical saturated hydraulic conductivity of the subsurface soil in the range of 0.001 to 0.1 m/day; to the values of the horizontal saturated hydraulic conductivity in the saturated zone in the range of 0.01 to 5 m/day and to the values of the Strickler’s coefficients for overland flow and for rivers in the range of 0.1 to 100 m1/3s-1 and 15 to 40 m1/3s, respectively. The sediment concentrations in a flow and sediment discharge are very sensitive to the values of erodibility coefficient due to overland flow in the range of 0.5 to 1.5 mg/m2s and to the values of erodibility coefficient due to rain in the range between 0.1 and 40 J-1. The obtained results could be used to simplify the parameter calibration procedure and to facilitate estimation of parameters in ungauged mountainous basins of similar characteristics.