The results obtained allow observation of differences in space and time of the distribution of this index. This is actually the kinetic energy of rainfall events k soil erodibility factor l slope length factor s slope steepness factor c plant cover. The rainfall erosivity classes determined by means of the fournier index oliver, 1980, qtd. The 30min rainfall erosivity index ei 30 is commonly used in the universal soil loss equation for predicting soil loss from agricultural hillslopes. Therefore, in the universal soil loss equation usle 8, the rainfall erosivity factor r was introduced as the product of the rainfall kinetic energy of a storm, classified as erosive by certain criteria, and its maximum 30 min intensity. Rainfall erosivity index pdf rainfall erosivity is defined as the aggressiveness of the rain to punyavachanam mantras pdf cause erosion. Spatiotemporal average rainfall erosivity factor map has been generated for india. The erosivity is computed for individual daily storms and then added altogether to get the weekly, monthly or annual erosivity values. Numerous indices of rainfall aggressivity erosivity have been. He also showed, that the fm index is a good approximation of r rainfall erosivity. The greater is the proportion of above content in the soil, more will be the soil resistant to erosion. The rainfall parameter that expresses the capacity to promote soil erosion is called rainfall erosivity r, and is commonly represented by the indexes ei 30 and ke25.
The sum of the ei30 values corresponds to rainfall erosivity, also called the rfactor of. Rainfall erosivity for erosive events was calculated using different set interval data. Rainfall erosivity calculations the erosivity of a single erosive rainfall event. Assessing changes in wind erosion climatic erosivity in. R rainfall runoff erosivity factor the rainfall index plus erosion index plus a factor for any significant runoff from snowmelt. Improving rainfall erosivity estimates using merged trmm. Predicting rusle revised universal soil loss equation. Ei 30 is the most commonly used rainfall erosivity in. Rainfall erosivity estimation based on rainfall data. The coefficient a is given by two values, a and a, where a is used for the warm months of april through. Usda developed the erosivity index table ei table, provided here in table 1, to show how the annual erosivity factor is distributed throughout the year in twoweek increments. This is the result of an extensive data collection of high temporal resolution rainfall data from the maximum possible number of countries.
Sum of ei30 of each month, was the annual rainfall erosivity. The lowest values are mainly found in mid and high. Finally licznar 2004b suggested the necessity of elevation use to aid the geostatistical mapping of rainfall erosivity. Seasonal rainfall erosion index values computed by adding the ei values of storms 0. To obtain annual rainfall erosivity values for this period, historical rainfall erosivity was based on measured data 19982004. Pdf on jan 1, 2017, o o okorafor and others published determination of rainfall erosivity index r for imo state, nigeria find, read and. Return period determination the theoretical return period is the inverse of the probability that the event will be exceeded in any given year. The rainfall erosivity is determined as the product of ke and maximum 30minutes rainfall intensity.
An erosivity map was also produced by shamshad et al. Using correlation analysis, longterm 30minute and 60minute rainfall data were used to develop storm erosion indices ei30. On the other hand, hourly rainfall data are widely and readily available in china. Estimating rainfall erosivity from daily precipitation. Rusle2 uses six factors for climatic erosivity, soil erodibility, slope length, slope steepness, covermanagement, and support practices to compute soil loss. Oct 01, 2017 rainfall erosivity is an index that describes the power of rainfall to cause soil erosion.
If your small construction project is located in an area where epa is the permitting authority and your r factor is less than five, you qualify for a low erosivity. Pdf determination of rainfall erosivity index r for imo state. This describes intensity and duration of rainfall in a given geographical area. Rr average annual rainfall erosivity factor, mj ha1 cm h1, h elevation, m a. All items must be completed accurately and in their entirety for the application. Preliminary results of rainfall erosivity mapping for poland. Pdf determination of rainfall erosivity index r for. The rainfall erosivity and the other climatic data is.
The calculations of these indexes requires pluviographical records, that are difficult to obtain in brazil. Among the factors of rusle, the calculation of rainfall erosivity factor as per rusle. Pdf determination of rainfall erosivity index r for imo. The global rainfall erosivity database, named hereafter as gloreda, contains erosivity values estimated as rfactors refer to the method section from 3,625 stations distributed in 63 countries worldwide. The rainfall erosivity index for a rainfall event energyintensity values ei30 is calculated from the total kinetic energy and maximum 30min intensity of individual events. Attempts were therefore made to estimate the erosivity index by using a few rainfall data such as storm amount and duration istok et al. Erosivity is used around the world for assessing and predicting rates of soil erosion on agricultural lands. Index values, e, where e is the total storm kinetic energy per unit area, and is. Rainfall erosivity factor for india using modified fourier index. On the other hand, having in mind encouraging results obtained by goovaerts 1999 at.
Relationship between soil erodibility, rainfall erosivity and. Evaluation of annual rainfall erosivity index based on daily. A the estimated average annual soil loss metric tons hectare 1 r the rainfall and runoff erosivity index. Finally, the anual average rainfall erosivity was obtained for the period evaluated performing the sum of annual rainfall erosivity divided by number of years. Assessing rainfall erosivity indices through synthetic precipitation series and artificial neural networks. When the index approaches zero, the annual erosivity is uniformly distributed in each month, and when it equals 1, the erosivity is concentrated in one month. Globally, the mean rainfall erosivity is estimated to be 2,190 mj mm ha1 h1 yr1 and broadly reflects climatic patterns, with the highest values, which are 3 three times highergreater than the mean are found in south america especially around the amazon basin and the caribbean countries, central and parts of east western africa and south east asia.
Assessing rainfall erosivity indices through synthetic. Therefore, the present study aimed to zone rainfall erosivity index r factor as. Estimating rainfall erosivity from daily precipitation using. Erosivity index calculator results an erosivity index value of 11.
Fm takes into account the seasonal variation in the precipitation, analyzing data on fm, for different european regions bergsma, 1980. The objective of this study was to develop average annual rainfall erosivity rvalues for selected rainfall stations in the fsm by using local rainfall data for each station. Jan 21, 2016 ei 30 is the most commonly used rainfall erosivity index, where e is the total kinetic energy per unit area during a precipitation event mjha 1 and i 30 is its peak 30min intensity mmha. This example is for region 7 colorado river basin region. Soil erosion assessment using remotely sensed data and. The rainfall stations that were considered were those that had longterm rainfall data with 30 or 60 minutes interval. By submitting a complete and accurate form, the otherwise applicable npdes permitting requirements for stormwater discharges associated with. If your small construction project is located in an area where epa is the permitting authority and your r factor is less than five, you qualify for a low erosivity waiver lew from. Jan 21, 2017 analysis of eventbased soil erosion magnitude with special return periods is essential to appropriately design strategies and adopt soil conservation practices. The literature illustrates the successful use of this index which provides a summary assessment of the probability of rainfall with significant erosive effects. Ei 30 is calculated from the total kinetic energy and the maximum 30min rainfall intensity of a storm.
Investigating rainfall erosivity indices in arid and. Ei daily rainfall erosivity on day t mjmmhahr, a seasonal erosivity coefficient, normally distributed random variable with mean zero and standard deviation 0. Rainfall erosivity is an index that describes the power of rainfall to cause soil erosion. The rfactor is a multiannual average index that measures rainfalls kinetic energy and. Estimation of erosivity from rainfall data 2 methods. Provide the annual erosivity factor number from figure 3 for montana this will be an interpolated whole number ranging from 10 to 40 annual erosivity factor 6. Rainfall erosivity in europe esdac european commission. Detailed instructions for calculating a project r factor are provided later in this fact sheet. Improving rainfall erosivity estimates using merged trmm and.
United states environmental protection agency npdes. In this study, within the erosivity index, the use of 6 min rainfall intervals during erosive rainfall give estimates of around 10% more erosivity than the 30 min time intervals and 33% more rainfall erosivity than the 60 min rainfall measurements. The most common rainfall erosivity index is the r factor of usle. Rainfall erosivity, measured with the rfactor in rusle, accounts for the erosive power of rainfall and the subsequent runoff 4. Estimation of rainfall erosivity using 5 to 60minute. Finally rainfall purchase order template pdf erosivity map for isfahan province created by using cokriging method. However, these data are often unavailable in many areas of the world. Erosivity estimations from different resolution data in a. The new general construction permit 20090009 includes the option allowing small construction site 1 and rainfall erosivity value rvalue for their sites given location and time frame compute to less than or equal to 5.
Investigating rainfall erosivity indices in arid and semiarid climates of iran 366 th e subject of rainfall erosivity has been studied worldwide, and various properties of raindrops, such as intensity, velocity, size, and kinetic energy, are among the most frequently used parameters to develop erosivity indices. Spatiotemporal mapping of rainfall erosivity index for. Estimation of rainfall erosivity using 5 to 60minute fixed. Relationship between soil erodibility, rainfall erosivity.
Date received month day year colorado discharge permit. High temporal resolution rainfall measurements, for example 15 min or 30 min, are important for the calculation of erosivity. Estimating the rainfall erosivity factor from monthly precipitation data. From empirical equations rainfall intensities and erosivity index were obtained at 30, 45 and 60 minutes duration of rainfall respectively, and based on 30minute maximum erosive rainfall rainfall. The r factor was developed from the relationship between rainfall and elevation of the gauge stations adjud 103 m, bacau 184 m and tg. Rainfall erosivity event daily rainfall erosivity monthly rainfall erosivity annual rainfall erosivity rainfall data rainfall data rainfall data applicability of regression models rmse, mape, and bias spatial distribution comparison of regression models kriging assessment of three regression equations rj p j 12.
You do not qualify for a waiver from npdes permitting requirements. Soil erosion assessment using remotely sensed data and ancillary data in the desert of tabernas, southeast spain by yared jillo gobena thesis submitted to the international institute for geoinformation science and earth observation in. Global rainfall erosivity esdac european commission. This precipitation variability led to an important variation over time of the value of the rainfall and runoff erosivity factor. Rainfall erosivity factor r to calculate the rainfall erosivity factor r for the proposed construction project, the applicant for a waiver must obtain a copy of fact sheet 3. Table 1 is based on 120 rainfall distribution zones for the continental u. Erosivity is a measure of the potential ability of soil, regolith, or other weathered material to be eroded by rain, wind, or surface runoff. Amount of erosion thus depends upon the combination of the power of rain to cause erosion and the. He also showed, that the fm index is a good approximation of r rainfall erosivity to which it is linearly correlated. Rainfall erosivity is the power of rainfall to cause soil erosion by water.
Rusle2 is a powerful tool for conservation planning, inventorying erosion rates over large. However, the spatiotemporal variations of soil erosion with different return periods, especially at national level, have not been adequately considered. Assessing changes in wind erosion climatic erosivity in china. One of these contributing factors is the rainfall erosivity factor r. Pdf rainfall erosivity is the capability of rainfall to cause soil loss from hillslopes by water. The erosive force of rainfall is expressed as rainfall erosivity. Rainfall erosivity results in detachments of soil particles and their transport by. Thus, erosivity of precipitation events is a function of their intensity and duration, and of the mass, diameter, and velocity of the raindrops. Global rainfall erosivity assessment based on hightemporal. Later arnoldus, in 1980 modified the original index so the formula transformed to.
K soil erodibility factor the soil rate per erosion index unit for a specified soil as measured on a standard plot, which is defined as a 72. This variable explained from 72 to 97% of the variation in individual. Rainfall erosivity and extreme precipitation in the pannonian basin. Evaluation of annual rainfall erosivity index based on. The rfactor is a multiannual average index that measures rainfalls kinetic energy. Rainfall erosivity rfactor in europe is a key parameter for estimating soil erosion.
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