This article is a simplified guide on how to calculate rainfall erosivity factor using qgis. Before we proceed, its important for us to mention a few points about rainfall erosivity factor. Soil erodibility food and agriculture organization. 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.
Wind erosion climatic erosivity is a measure of the climatic tendency to produce con ditions conducive to wind erosion. Historically, the term erosivity was first associated with an rfactor rainfallrunoff erosivity factor in the universal soil loss equation usle. It should be possible in future to predict areas with high erosion risks based on these concepts. Such a correspondence should lead to the integration of geotechnical properties into soil erodibility calculations in the future.
Highly erodible geologic materials are readily displaced and transported by water. A r k ls c p where a estimated average soil loss in tons per acre per year r rainfallrunoff erosivity factor k soil erodibility factor l slope length factor s slope steepness factor c. 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. Soil erodibility factor k soils vary in their susceptibility to erosion. The relationship between soil erodibility, which is hard to measure, and modeled infiltration rate were rarely researched. Soil aggregation, erodibility and erosion rates in mountain soils nwalps, italy s. Given a constant discharge, the product of erodibility and erosivity varies with.
Erodibility definition and meaning collins english. The ls topography, c soil cover and management and p support practices are nondimensional and have a value of 1 as the soil erodibility. Highly erodible land definitions nrcs caribbean area. How to calculate rainfall erosivity factor using qgis. Pdf isolating erosivity and erodibility components in erosion by. 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 a function of the physical characteristics of the rainfall. R is an indication of the two most important characteristics of storm erosivity.
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. Erodability or erodibility is the inherent yielding or nonresistance of soils and rocks to erosion. Erodibility of agricultural soils, with examples in lake and mendocino counties anthony toby ogeen, uc cooperative extension assistant soil resource specialist, department of land, air, and water resources, uc davis. 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. Erodibility and infiltration characteristics of five major. Rainfall erosivity and erodibility of inceptisols in the. Rfactor as used in the usle and the revised usle rusle relates to the mean annual sum of ei 30 values. The soil erodibility factor k is a measure of erodibility for a standard condition.
A direct link to the materials for this video can be. R is the rainfallrunoff erosivity factor, k is the soil erodibility factor, ls is the slope length and degree, c is the landcover management factor, and p is the conservation practice factor2. 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. Erodibility definition of erodibility by the free dictionary. This model is based on the combination of the five factors erosivity, erodibility, topography, vegetation cover and support practices that directly influence this phenomenon. The soil erodibility factor kfactor is a quantitative description of the inherent erodibility of a particular soil.
Soil erosion assessment using gis and revised universal. Soil erodibility and processes of water erosion on hillslope. An overview of methodologies and applications shuiqing yin, mark a. Relationship between soil erodibility, rainfall erosivity and.
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. Erosivity definition and meaning collins english dictionary. In this study, we proposed a composite erodibility index dust occurrence ratio, dor and examined its interannual variation at a typical steppe site abagaqi in xilingol grassland, china, during spring of 1974. Rainfall erosivity and erodibility of inceptisols in the southwest. Rachel elkins, ucce pomology farm advisor, lake and mendocino counties. The study of erosion by soil scientists has been focused largely on estimating soil erodibility and rainfall erosivity. Sustainability free fulltext evaluation of climatic.
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. K soil erodibility factor for specific soil horizon. Estimation of rainfall erosivity using 5 to 60minute. This page provides basic information about soil erodibility. An official website of the united states government. Erosivity definition of erosivity by the free dictionary. The rainfall erosivity r and soil erodibility k factors of the universal soil loss equation. The effect of erodibility on dust occurrence remains poorly understood. For the usle, the concept of soil erodibility was introduced as the k factor, which is defined as the average rate of soil loss per unit of rainfall erosivity index from a unit plot zhang et al. For a particular soil, the soil erodibility factor is the rate of.
Rusle k values california state water resources control. Bonifacio1 1disafa, university of torino, largo braccini 2, 10095 grugliasco, to, italy 2natrisk, research centre on natural risks in mountain and hilly environments, university of torino, largo braccini 2, 10095 grugliasco, to. Erodibility is defined as the vulnerability or susceptibility of the soil to erosion. So we will explain what rainfall erosivity factor is, why and when you need to calculate rainfall erosivity factor. The soil erodibility factor k represents both susceptibility of soil to erosion and the amount and rate of runoff, as measured under the standard unit plot condition. Soil aggregation, erodibility and erosion rates in. Assessing changes in wind erosion climatic erosivity in. Each parameter will be described in more detail in this report. Pdf the rainfall erosivity r and soil erodibility k factors of the universal soil loss equation usle were determined on two sites in the. A number of other equations have been developed for soils. Ei 30 is the most commonly used rainfall erosivity index, where e is the total kinetic energy per unit area during a precipitation event mj. When rainfall erosivity exceeds the soil erodibility, soil erosion occurs. Rainfall erosivity and erodibility of inceptisols in the southwest colombian andes volume 32 issue 1 m. 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.
The greatest obstacle to soil erosion modelling at larger spatial scales is the lack of data on soil characteristics. Pdf rainfall erosivity and erodibility of inceptisols in the. Strong winds erode, and dryness increases the susceptibility of the. Average annual erosivity values range from 781 x 102 fttonsacre in the wet zone to 154 x 102 fttonsacre in the dry zone. Due to monsoon influence, the annual precipitation has a proportion of 61.
A term connected to erosivity is erodibility as both are functions of erosion. The map of rainfall erosivity in europe gives a spatial overview of the erosive energy of rain. Soil erosive power of rainfall in the different climatic. Determining and mapping soil erodibility factor case. Bryan soil erosion laboratory, faculty of forestry, uni. Erosivity and erodibility 981 erosion by water erosion. However, the term is often used more loosely dusan, 1982. A high erodability implies that the same amount of work exerted by the erosion processes leads to a larger removal of material. Estimation of rainfall erosivity using 5 to 60minute fixedinterval rainfall data from china s. Erosivity for a single storm is the product of the storms energy e and its maximum 30 minute intensity i30 for qualifying storms. The rainfall erosivity factor calculator can be used to help determine if your small construction site qualifies for stormwater discharge waivers. Erodibility describes or is a measure of the inherent resistance of geologic materials soils and rocks to erosion.
Soil erodibility and processes of water erosion on hillslope rorke b. Comparison of soil erodibility factors in usle, rusle2. Conceptually, rainfall erosivity is the capacity of rain to produce erosion where as soil erodibility is the susceptibility of the soil to be eroded. Wind erosion occurs when the shear stress exerted on the surface by the wind exceeds the ability of the surface materials to resist detach ment and transport. 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. Rainfall erosivity was calculated using data from rainfall gauging stations installed in the study area and the recommended method from rusle renard et al. Here, the soil erodibility factors k and k e in the usle, k i and k 1 in the wepp were calculated and the infiltration rates were modeled based on the designed laboratory simulation experiments and proposed infiltration model, in order to build their relationship.
Assessing changes in wind erosion climatic erosivity in chinas dryland region during 19612012 1265 has an annual mean temperature of 3. For a given soil conditions one storm can be compared quantitatively with another and a numerical scale of the values of erosivity can be developed. R rainfall erosivity factor, expressed by an average erosion index. The k factor is defined as the average annual rate of soil loss per unit erosivity index measured on a continuously cleantilled fallow plot with a gradient of 9% and a slope length of 22. Soil erodibility is usually regarded as the susceptibility of a soil to erode.
One key parameter for modelling soil erosion is the soil erodibility, expressed as the kfactor in the widely used soil erosion. Usle were determined on two sites in the colombian. A unit plot is defined as a ploughedcontinuous fallow land having a uniform 9% slope steepness and 22. Erodibility of agricultural soils, with examples in lake. Relationship between soil erodibility, rainfall erosivity. 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. Difference between erosivity and erodibility soil erosion.
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