Rainfallrunoff is the active agent of soil erosion which often resulted in land degradation and water quality deterioration. Rainfall erosivity estimation based on rainfall data collected over a. To use the rainfall erosivity factor calculator to determine your eligibility for the lew, you will need your projects location either latitudelongitude or address and the estimated start and end dates of construction. Until that time, dischargers shall calculate their project rfactor using the construction erosivity waiver fact sheet fact sheet provided by epa at. Worldclim data was used as the present baseline precipitation scenario for the study area. 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 cause soil loss by rill and. 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 30 min rainfall intensity i30. This study has a variety of applications in erosion prediction. Fact sheet for determining construction rainfall erosivity waiver requirements. Pdf the rainfall erosivity factor r factor is one of six erosion factors in the universal soil loss equation usle, which together reflect the. Revised determination of the rainfallrunoff erosivity factor r for.
Impacts of climate change on rainfall erosivity in the. Regionalization of monthly rainfall erosivity patterns in. Differences in precipitation patterns reflect differences in r. Rainfall erosivity factor calculator water data and tools us epa. Rainfall erosivity rfactor is an important variable used in soil erosion estimation models. 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. Its aggressiveness to induce erosion is usually termed as rainfall erosivity index or factor r.
The rainfall erosivity factor calculator determines if small construction projects can obtain a waiver from npdes stormwater permitting. Rfactor is one of the factors to be parameterized in the evaluation of. Seasonal variation and climate change impact in rainfall. The new general construction permit 20090009 includes the option allowing small construction site 1 and pdf is not rendering correctly, you can download the pdf file here. The drop of water makes the soil particles to scatter and loosen. Soil loss equation usle, which together reflect the. It represents the ability of rainfall to detach soil particles and erode the landscape and is. Rfactor is one of the factors to be parameterized in the evaluation of soil loss using the universal soil loss equation.
Rainfall erosivity southwest watershed research center. Rainfall erosivity is an index that describes the power of rainfall to cause soil erosion. The following two methods are widely used for computing the erosivity of rainfall. Soil erosion is a global problem that tends to become more extreme on the background of climate change. Rainfall erosivity rfactor is one of the 5 factors for estimating soil erosion using rusle model and is the only seasonally varying besides crops, but crop are manmade spatiotemporal resolution is critical for evaluating. Values of rainfall erosivity factor for the czech republic. Rainfall erosivity factor calculator water data and. The r factor of the revised universal soil loss equation rusle 1 is a useful tool for identifying areas with high soil loss potential and thereby determining area speci. Monthly variations of rainfall erosivity r factor in. Global rainfall erosivity assessment based on high. Despite its importance, rainfall erosivity is usually implemented in models with a low. Rainfall erosivity factor, also called r factor, is an attempt to measure the capability of rainfall to cause soil erosion.
Relationship between soil erodibility, rainfall erosivity. The rainfall erosivity of this extreme event was much greater than the annual average before 2004 6,499 mj mm ha1 h1 yr1 and was not typical of the. Rainfall erosivity waiver r factor determination parts. 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. You may need a pdf reader to view some of the files on this page. Regression equations were computed to estimate the rfactor for. Estimation of erosivity from rainfall data 2 methods. 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. The rainfall erosivity factor was defined as a powerlaw function with the 2yr, 30min rainfall as the base number and 1. The results presented here provide the much needed guidance to remove ambiguities regarding the rainfall erosivity factor in the indian context.
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 30. The rainfall erosivity factor in the czech republic and its uncertainty. Approximation of rainfall erosivity factors in north jordan. Longterm 105 years variability in rain erosivity as derived from 10min rainfall depth data for ukkel brussels, belgium. The erosive force of rainfall is expressed as rainfall erosivity. By submitting a complete and accurate form, the otherwise applicable npdes permitting requirements for stormwater discharges associated with construct ion activity, are waived. Shida kartli is one of the main agrarian regions in the country and research on soil. At global scale, this is the first time ever that an erosivity database of such dimension is compiled. Two approaches are used to model rainfall erosivity. A direct link to the materials for this video can be. United states environmental protection agency npdes. Using correlation analysis, longterm 30minute and 60minute rainfall data were used to develop storm erosion indices. Construction rainfall erosivity waiver fact sheet pdf 12 pp, 3 mb. Materials and methods rainfall erosivity has been calculated for brazilian regions using recording rain gauge data as the source of input.
The rainfall erosivity factor questions and estimated area to be disturbed that you answered on the first page of the lew process will appear on this page as well. Estimating the rainfall erosivity factor from monthly. When a drop of rain water lands on the earth it behaves like a meteor. One of these contributing factors is the rainfall erosivity factor r. The rainfall erosivity index, r, has been widely tested and applied in many countries and regions around the world whose rainfall intensity is characterized mainly as moderate to high 915. The rainfall erosivity factor ei 30 value is computed as follows. In computing the rainfall erosivity factor, the maximum 30min rainfall intensities for the storm and heavy storm events are generally computed on the basis of hyetograph data or highresolution rainfall.
The week of february, 2012 the rainfall erosivity factor calculator became unavailable due to maintenance. The results were not satisfactory because of the different behavior of each index. The period of construction activity begins at initial earth disturbance and ends with final stabilization. Rainfall erosivity considers the rainfall amount and intensity, and is most commonly expressed as the rfactor in the usle model and its revised version, rusle. How to calculate rainfall erosivity factor in arcmap. The requirements of the general npdes permit may be waived for small construction activities if the rainfall erosivity factor r is less than 5 during the construction period. 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. Once the particles are loosened it is easy for the flood to wash the soil particles away. The r factor was used as the index to show the rainfall erosivity. Spatial distribution and temporal trends of rainfall. Rainfall erosivity is one of the most important input parameters. The rainfall erosivity r factor of the revised universal soil loss equation rusle was used to determine rainfall erosivity.
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. Rainfall erosivity calculation because continuous rainfall data series with a high time resolution for calculating usle rainfall erosivity factor are rarely available, daily rainfall data have been widely used worldwide to estimate rainfall ero. If the land is devoid of grasses or vegetation, it will assumed be to be1 where there is a forest. For more information, please see the construction rainfall erosivity waiver fact sheet pdf 12 pp, 2. Spatial and temporal variability of rainfall erosivity. The rainfall erosivity is related to the kinetic energy of rainfall. Erosivity factor calculation the r factor erosivity is the potential for stormwater to erode exposed soil which has been disturbed by construction. Estimation of rainfall erosivity using 5 to 60minute. Rainfall erosivity is crucial to be considered at a monthly. Estimating rainfall erosivity from daily precipitation records.
The rainfall erosivity factor in the czech republic and. Epa has approximated that maintenance may take at least 1 month to complete. R, which reflects the potential capability of rainfall to cause soil loss from hillslopes. Rainfall erosivity r factor represents a measure of the erosive force of rain or its potential to cause soil erosion. One of the best indicators of the potential erosion risks is the rainfallrunoff erosivity factor r of the revised universal soil loss equation rusle. Rainfall erosivity waiver r factor determination parts a and b part a simplified method see part b for the alternative method a. This study on rainfall erosivity makes use of 101 years monthly rainfall data and 52 spatial points. Thus, the rainfall erosivity value of this month was 12,540 mj mm ha1 h1, exceeding the monthly average. Rainfall erosivity r factor is one of the important factors influencing soil erosion 6,7. Spatiotemporal average rainfall erosivity factor map has been generated for india. Rainfall erosivity waiver application rewa instructions. They were of the view that a more intense rainfall of short duration can cause gully erosion more than a less intense one. Pdf rainfall erosivity is the capability of rainfall to cause soil loss from.
Rainfall erosivity, considering rainfall amount and intensity, is an important parameter for soil erosion risk assessment under future land use and climate change. The exposure of the earths surface to aggressive rainfall is a key factor controlling the water erosion in. The evaluation indicated that by defining an erosive rainfall event as. This measure of erosivity is referred to as the ei 30 index and can be computed for individual storms, and the storm values can be added over periods of time to give weekly, monthly or yearly values of erosivity.
Predicting rainfall erosion losses from cropland east of the rocky mountains. The results show an increase in the future periods of. In the erosion equation proposed by van doren and bartelli 1956, the rainfall factor was the intensity and frequency of 30min rainfall. 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. 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 and runoff factor r of the universal soil loss equation usle was derived. In this video, i have clearly shown the steps required to calculate rainfall erosivity factor in arcmap. The rainfall erosivity factor r factor is one of six erosion factors in the universal.
Estimation of rainfall erosivity using 5 to 60minute fixedinterval rainfall data from china s. In this study, we developed rainfall erosivity r factors for the islands of pohnpei, chuuk, and yap. These results provided the main input information for this study, which used them to estimate the rfactor for costa rica. Rainfall erosivity factor for india using modified fourier. Rainfall erosivity is a major driver of sediment and nutrient losses worldwide, which may leave farmers vulnerable to crop failures and lead to unstable equilibrium states in landscapes 1,2. The erosivity factor r in the usle and rusle represents the impact of rainfall on soil erosion. These models have in common a rainfall erosivity factor.