The slope lengthgradient, rainfallrunoff erosivity, crop and vegetation cover and the support practice of each field were very important factors when considering soil erosion. Characterization of erodibility using soil strength and. While erodibility is an intrinsic material property resulting from characteristics, such as grain size and degree of cementation, erosivity depends upon hydraulic factors including discharge and channel curvature. One of the important variables used in the design of grassed waterways is the soil erodibility category. Average annual erosivity values range from 781 x 102 fttonsacre in the wet zone to 154 x 102 fttonsacre in the dry zone. Values used by rusle2 for average monthly temperatures and precipitation are available in. Download a pdf of all web pages for the student materials.
One key parameter for modelling soil erosion is the soil erodibility, expressed as the kfactor in the widely used soil erosion. Nearing, pasquale borrelli, and xiaochan xue the rainfall erosivity factor r factor is one of six erosion factors in the universal soil loss equation usle, which together reflect the combined effects that. Estimation of rainfall erosivity using 5 to 60minute fixedinterval rainfall data from china s. Assessing changes in wind erosion climatic erosivity in. Draft users reference guide revised universal soil loss equation version 2 rusle2 prepared for usdaagricultural research service washington, d. Rainfall erosivity is the capability of rainfall to cause soil loss from hillslopes by water. Soil erodibility factor k the soil erodibility factor k relate to the average longterm soil and soil profile response to the erosive power associated with rainfall and runoff. Table 2 soil erodibility k factor stewart et al 1975 soil.
When rainfall erosivity exceeds the soil erodibility, soil erosion occurs. Effect of land use types and slope on soil erodibility. However, no absolute numerical values can be determined for them because rainfall erosion results. Investigation and computation of the soil erodibility factor. Erosion sensitive lands are those less resistant to. They are used as surrogate measures of the impact that rainfall has on erosion from a particular site. Rock erodibility is a primary factor controlling erosion rates in channels and is incorporated into models to predict bedrock erosion rates. Rusle k values california state water resources control. Given a constant discharge, the product of erodibility and erosivity varies with. The procedure to obtain soil erodibility for a particular area is as follows.
Rusle2 is a powerful tool for conservation planning, inventorying erosion rates over large areas, and estimating sediment production that might become sediment yield in watersheds. A term connected to erosivity is erodibility as both are functions of erosion. Strong winds erode, and dryness increases the susceptibility of the. Relationship between soil erodibility, rainfall erosivity.
Downloadable versions of the instructor materials are available from this location on the instructor materials pages. Wanga a school of geography, beijing normal university, key laboratory of environmental change and natural disaster, ministry of education, beijing, china b usdaars, southwest watershed research center, united states. National pollutant discharge elimination system npdes please update your url link to the rainfall erosivity factor calculator for small construction sites to. Pdf isolating erosivity and erodibility components in erosion by. R is an indication of the two most important characteristics of storm erosivity. This factor also correlated with the siltfine sand soil population. Because the mechanics behind erosion depend upon the competence and coherence of the material, erodability is treated in different ways depending on the type of surface that eroded. Soil erosion assessment using gis and revised universal soil.
Soil erodibility and processes of water erosion on hillslope rorke b. Erosivity can be defined as the potential ability of the rain to cause erosion. Erosivity and erodibility 981 erosion by water erosion. Assessing changes in wind erosion climatic erosivity in chinas dryland region during 19612012 1265 has an annual mean temperature of 3. While rusle has been used before in europe, rusle2015 improves the quality of estimation. Historically, the terms erosivity and erodibility were originally associated with the r and k factors in the universal soil loss equation usle, a r k l s c p 1. Among these factors, soil erodibility factor k is one of the key factors that required for soil erosion determination andor prediction across the world 10 and was. Here we quantify variations in rock erodibility within channel cross sections using laboratory abrasion mill experiments on bedrock surfaces extracted from streams. A new map for 10 yr ei values was developed for use in rusle1. The results show moderate range of soil erodibility, the figure show that the soil erodibility ranges from 0. Soil where x 1 is % silt multiplied by 100 % clay, x 2 is % or ganic matter, x 3 is the soil structure code used in the u. Although the rainfall intensity and the erosivity of the simulated rainstorm between 900z. Erosivity and erodibility in encyclopedia of environmental management. Erodibility describes or is a measure of the inherent resistance of geologic materials soils and rocks to erosion.
Due to monsoon influence, the annual precipitation has a proportion of 61. R values vary a lot depending on regional weather patterns and local geography. Rainfall and runoff erosivity r factor student materials. Erodibility klc erosivity is a measure of the forces actually applied to the soil by the erosive agents of raindrop impact, waterdrops falling from plant canopy, and surface runoff. The soil erodibility factor, k for the area is greater than 0. The rainfall erosivity r and soil erodibility k factors of the universal soil loss equation. How to calculate rainfall erosivity factor using qgis.
The following soil properties were used to determine the appropriate soil erosion category for nearly all soil types in iowa. K soil erodibility factor provided gis map of k factor for the state or. Estimation of rainfall erosivity using 5 to 60minute. The gaussian process regression gpr model used to interpolate the rfactor point values to a map showed a good performance for both the crossvalidation dataset r 2 0. Land use map was used to produce coverage and management practice factor. Select county from the quick navigation menu au, select navigate by, state and county and click view. Overall, erosivity based on modern climate data is about 10% higher than based on the climate data previously used in the usle and rusle1.
Rainfall erosivity and erodibility of inceptisols in the southwest. Soil erodibility and processes of water erosion on hillslope. The greatest obstacle to soil erosion modelling at larger spatial scales is the lack of data on soil characteristics. Values of rainfall erosivity factor for the czech republic in. It is defined as the potential ability of rain to cause the erosion. The musgrave equation was the first to include a rainfall erosivity factor in the process of soil erosion estimation musgrave, 1947. See the bulletin section for additional information, including an erosivity map for the eastern us. As a result, erosion is directly proportional to these two factors, and erodibility is the amount of soil loss divided by rainfall erosivity index. A preliminary investigation of the erodibility of the. Erosivity is a measure of the potential ability of soil, regolith, or other weathered material to be eroded by rain, wind. Wind erosion climatic erosivity is a measure of the climatic tendency to produce con ditions conducive to wind erosion. Conceptually, rainfall erosivity is the capacity of rain to produce erosion where as soil erodibility is the susceptibility of the soil to be eroded.
The rainfall erosivity factor was defined as a powerlaw function with the 2yr, 30min rainfall as the base number and 1. The processing of ombrographic data from 29 meteorological stations of the czech hydrometeorological institute chmi, according to the terms of the universal soil loss equation for calculating long term loss of soil through water erosion, erosion hazard rains and their occurrence have been selected, with their relative amount and erosiveness rfactors determined for each month and. Rusle k values california state water resources control board. Assessment of soil particle erodibility and sediment trapping. So we will explain what rainfall erosivity factor is, why and when you need to calculate rainfall erosivity factor.
Highly erodible geologic materials are readily displaced and transported by water. The amount of erosion will, therefore, depend upon the combination of the power of the rain to cause erosion and the ability of the soil to withstand erosion. Generally, the quantity of erosion yield is dependent upon the ability of rain to detach the soil particles i. Rainfall erosivity is a term that is used to describe. Erodibility indices two indices for erodibility are given, the emerson test which measures soil aggregate stability and the k erodibility factor used in the universal soil loss equation usle. Finetextured soils that are high in clay have low k values about 0. Difference between erosivity and erodibility soil erosion. A high erodability implies that the same amount of work exerted by the erosion processes leads to a larger removal of material. The erodibility of soil particles was determined using the comparison of gsd between sediment and original soil. Rainfall erosivity factor calculator for small construction. Usle developpy,ed by scientists at ars, scs, purdue univ. Rusle revised universal soil loss equation more accurately represents longterm averages. The emerson tests were carried out by a laboratory staff and indicate the degree of moisture and work required to induce dispersion of the sample.
Prediction of soil erosion in pansoon subbasin, malaysia. Where a is the average annual soil loss in tonsacreyear, r is the rainfallrunoff erosivity factor, k is the soil erodibility. Spatial and temporal variation of wind erosion climatic. Pdf rainfall erosivity and erodibility of inceptisols in the. The problem is the high uncertainty of the main parameters of global change, leading to uncertainty in the response of soils and regoliths to these changes. Erodibility definition and meaning collins english. The erodibility of soil particles were strongly affected by the rainfall erosivity ei 30. Determining and mapping soil erodibility factor case study. Erodibility and infiltration characteristics of five major. Results also show that the study area has high rainfall erosivity hence making it very susceptible to erosion. Clay was the most erodible soil particle which showed 2.
K soil erodibility factor for specific soil horizon. R factors are estimates of annual erosivity values for sites throughout the country. The student materials are available for offline viewing below. Application of revised universal soil loss equation rusle.
The soil erosion hazard map was created by using all the five rusle layers, rainfallrunoff erosivity factor, soil erodibility factor, slope length and steepness factor, cover and management factor, and support and conservation practices factor. Both rusle models indicated problematic areas along the ramla valley system, namely, in nuffara hill and the upper part of the nadur slope. The rusle uses the simple equation a r x k x ls x c x p. Erodability or erodibility is the inherent yielding or nonresistance of soils and rocks to erosion. Soil loss erosion rate is com puted by substituting values for each rusle factor to represent conditions at a specific site. This article is a simplified guide on how to calculate rainfall erosivity factor using qgis. Thus, erosion is a function of the erosivity of the rain and the erodibility of the soil. Highly erodible soil map units a soil map unit with an erodibility of 8 or greater is highly erodible land hel.
Before we proceed, its important for us to mention a few points about rainfall erosivity factor. This form provides notice to epa that you, the project operator identified in section i of this form, are certifying that construction activity at the project site identified in section ii, will take place during a period when the rainfall erosivity factor is less than five 40 cfr 122. The result shows that 66% 7433 ha of the pansoon subbasin is classified. Erosivity r factor values for locations where a particular user will apply rusle are in a database file in the rusle computer program. Variability of rock erodibility in bedrockfloored stream. This means that the impact of soil, topography, and management on runoff and the resulting impact of runoff on sheet and rill erosion are subsumed in the other rusle factors k, soil erodibility. Originally, the terms erosivity and erodibility were associated with the rainfall factor r and the soil factor k in the universal soil loss equation where the event erosivity factor was given by the product of the kinetic energy of the storm e and the maximum 30minute rainfall intensity i. Pdf the rainfall erosivity r and soil erodibility k factors of the universal soil loss equation usle were determined on two sites in the. The ls topography, c soil cover and management and p support practices are nondimensional and have a value of 1 as the soil erodibility. Assessment of soil particle erodibility and sediment. The resulting value is called the rainfallrunoff erosivity factor, abbreviated with the letter r. R rainfall erosivity factor, expressed by an average erosion index. A direct link to the materials for this video can be.
Thus, the soil erosion is the function of both erosivity and erodibility. Erodibility and infiltration characteristics of five major soils of southwest spain s. Scientists are certain that changes in climate and land use will affect the erodibility of soils and regoliths and also the erosivity of rainstorms nearing et al. Erosivity is used around the world for assessing and predicting rates of soil erosion on agricultural lands. Bryan soil erosion laboratory, faculty of forestry, uni.
Stormwater technical guidance soil erodibility 4 map c and soils explorer d. Erosivity definition and meaning collins english dictionary. Rainfall erosivity and erodibility of inceptisols in the southwest colombian andes volume 32 issue 1 m. Rainfall erosivity is an index that describes the power of rainfall to cause soil erosion. Rainfall erosivity was calculated using data from rainfall gauging stations installed in the study area and the recommended method from rusle renard et al. Rusle2 uses six factors for climatic erosivity, soil erodibility, slope length, slope steepness, covermanagement, and support practices to compute soil loss. Soil erosive power of rainfall in the different climatic. Relationship between soil erodibility, rainfall erosivity and. Rusle2 also uses values for the bimonthly distribution of the erosivity. Mar 06, 2019 this article is a simplified guide on how to calculate rainfall erosivity factor using qgis.
Determining and mapping soil erodibility factor case. Mar 01, 2012 the national runoff and soil loss data rainfall erosivity factor soil erodibility factor topgraphy factor cover factor erosion control practices factor predicted soil loss tonsacrecenter was established at purdue university in 1954 to locate, assemble, and consolidate data from soil erosion studies throughout the unitedstates. Rainfall erosivity and erodibility of inceptisols in the. Gis on cameron highlands, malaysia for hydropower development soo huey teh a 30 ects credit units master. N2 conceptually, rainfall erosivity is the capacity of rain to produce erosion, whereas soil erodibility is the susceptibility of the soil to be eroded. It is dependent on the physical characteristics of rainfall, which include raindrop size, drop size distribution, kinetic energy, terminal velocity etc. Conceptually, rainfall erosivity is the capacity of rain to produce erosion, whereas soil erodibility is the susceptibility of the soil to be eroded. Because the mechanics behind erosion depend upon the competence and coherence of the material, erodability is. Calculating erodibility index the erodibility index ei for a soil map unit is determined by dividing the potential erodibility for the soil map unit by the loss tolerance t.
Currently, there are various models to quantify wind erosivity, among which the wind erosion equation weq and the revised wind erosion equation rweq are wellknown and widely used 7,8. Evaluation of usle and rusle estimated soil on rangeland. Epa has established the r factor of less than 5 as the criteria for determining waiver eligibilty. This page provides basic information about soil erodibility. Erosivity for a single storm is the product of the storms energy e and its maximum 30 minute intensity i30 for qualifying storms. The map of rainfall erosivity in europe gives a spatial overview of the erosive energy of rain. The samples of soil scope of the study the study focused on the characterization of erodibility using soil strength and stressstrain indices for soils in anambra state in southeastern nigeria and was limited to three sites in the state namely awka, agulu nanka and nnewi. Unified soil classification void ratio plasticity index. Modern definitions of rainfall erosivity began with the development of the universal soil loss equation usle, where rainfall characteristics were statistically related to soil loss from thousands of plotyears of natural rainfall and runoff data. An overview of methodologies and applications shuiqing yin, mark a. Download a zip file that includes all the web pages and downloadable files from the student materials.