Thus, a rainfall erosivity parameter designed specifically for the country cannot be derived at the present time. Pdf rainfall erosivity index for the ghana atomic energy. At global scale, this is the first time ever that an erosivity database of such dimension is compiled. Assessing rainfall erosivity indices through synthetic.
To determine the erosivity index ei 30, two specific parameters of erosive rainfall had to be multiplied. Construction rainfall erosivity waiver fact sheet pdf 12 pp, 3 mb. Development of daily rainfall erosivity model for dehradun. Definition of erosivity from the collins english dictionary. In other words, the estimation model based on the annual precipitation data provides a reliable means of predicting the longterm annual rainfall erosivity in southern. Rainfall and runoff erosivity r factor student materials. The results presented here provide the much needed guidance to remove ambiguities regarding the rainfall erosivity factor in the indian context. Fm takes into account the seasonal variation in the precipitation, analyzing data on fm, for different european regions bergsma, 1980. Conversion factors for different time resolutions and regional assessments. Hence there is a connection between rainfall erosivity, saturated hydraulic conductivity and these atterberg limits. Mannkendall, pearsons correlation and sens slope tests were used to establish the trend in time series rainfall data and their correlation. These examples have been automatically selected and may contain sensitive content. Rainfall erosivity estimation for northern and southern peninsular.
Remo, aladin, pregis, the number of predicted rainfall events decreases, but they are not accompanied by considerably less precipitation. Svetla rousseva, kazimierz banasik, christine alewell 2016, monthly rainfall erosivity. The peak rainfall amount of a rainfall tpr was a comprehensive index reflecting peak number, peak value and peak width, and the correlation between it and the sediment yield and runoff reached 0. Investigating rainfall erosivity indices in arid and. Thus, erosivity of precipitation events is a function of their intensity and duration, and of the mass, diameter, and velocity of the raindrops. 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. Rainfall erosivity was mainly concentrated in summer and autumn, accounting for 67. The rainfall parameter that expresses the capacity to promote soil erosion is called rainfall erosivity r, and is commonly represented by the indexes ei30 and. How to calculate rainfall erosivity factor using qgis. Rainfall erosivity database at european scale redes. This study on rainfall erosivity makes use of 101 years monthly rainfall data and 52 spatial points. Arnoldus 1980 attempted to correlate this index with the known values of the rainfall erosivity factor for 164 rainfall stations in the united states and 14 stations in west africa. Erosivity and erodibility in encyclopedia of environmental management. If the inline pdf is not rendering correctly, you can download the pdf file here.
Determination of rainfall erosivity index r for imo. This method is based on the concept, that the erosion takes place only at. The rfactor is a multiannual average index that measures rainfalls. The annual rainfall erosivity map shows a range of 3116 to 20,035 mj mm ha 1 h 1 year 1. For this reason, investigating the accuracy of rainfall erosivity. Construction rainfall erosivity waiver fact sheet pdf 12 pp, 3 mb contact us to ask a question, provide feedback, or report a. Fournier indexes were used to determine the effect of extreme rainfall events towards soil erosivity. Spatiotemporal average rainfall erosivity factor map has been generated for india. Estimation of rainfall erosivity using 5 to 60minute fixedinterval rainfall data from china s. Estimating the rainfall erosivity factor from monthly. 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. With previously calculated rfactor values for eight.
Spatial and temporal variability of rainfall erosivity factor for. The rainfall erosivity factor r is defined as the average annual sum of. Rainfall erosivity values similar to those in the universal soil loss equation were derived from average monthly and yearly. The purpose of this study was to estimate the rainfall erosivity index for the ghana atomic energy commission site in. Ke time, and kinetic energy content ke mm and rainfall intensity i. Rainfall erosivity in iraq journal of soil and water. Pdf determination of rainfall erosivity index r for imo state. N2 conceptually, rainfall erosivity is the capacity of rain to produce erosion, whereas soil erodibility is the susceptibility of the soil to be eroded. The relations between the rainfall erosivity index ai and. The purpose of this study was to estimate the rainfall erosivity index for the ghana atomic energy commission site in order to compute the surface erosion rate.
The results were not satisfactory because of the different behavior of each index. According to the forecasts of numerous regional models eg. The resulting value is called the rainfallrunoff erosivity factor, abbreviated with the letter r. This study was conducted to determine the significance of elevation in predicting the rainfall erosivity index r in addition to the average annual precipitation and to develop an isoerodent map for honduras. The region with the lowest values is represented by the northeastern region, while the highest values are found in the northern region the amazon region fig. These models have in common a rainfall erosivity factor. Sea surface temperature sst and rainfall erosivity in. Table 1 also includes the results of particle size analysis in the form of coarse sand, medium sand and fine sand.
These changes are expected to have significant effect on rainfall erosivity and soil erosion by water, but the magnitude of the impact is not well quantified because of the nonlinear and dynamic nature of the relationship between rainfall amount and rainfall. He also showed, that the fm index is a good approximation of r rainfall erosivity to which it is linearly correlated. Rainfall erosivity is crucial to be considered at a monthly resolution for the. Globally, the mean rainfall erosivity is estimated to be 2,190 mj mm ha 1 h 1 yr 1 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. This article is a simplified guide on how to calculate rainfall erosivity factor using qgis.
Statistical determination of rainfallrunoff erosivity. Global rainfall erosivity assessment based on high. The rainfall erosivity is related to the kinetic energy of rainfall. Content uploaded by christopher oluwakunmi akinbile. Before we proceed, its important for us to mention a few points about rainfall erosivity factor. Sea surface temperature sst and rainfall erosivity in the upper grande river basin, southeast brazil author. The results show that, for 49 of the 55 stations, a strong positive correlation r 2 0.
A single index of rainfall erosivity that can measure the composite effect of various rainstorm characteristics on soil erosion is highly desirable for predicting soil loss 1, 2. Water 2020, 12, 1293 2 of 16 software such as the environment for visualizing images envi. The erosivity factor in the universal soil loss equation usle provides an effective means of evaluating the erosivity power of rainfall. Considerable seasonal and interannual changes exist in rainfall amount and intensity in new south wales nsw, australia. The study, published last month july in scientific reports, has developed the firstever global rainfall erosivity database and a global erosivity map. Universal index for calculating rainfall erosivity. Epa has updated its rainfall erosivity factor calculator to correct known problems and to use updated data from the natural resources conservation services nrcs revised universal soil loss equation, version 2 rusle2 database. Erosivity is used around the world for assessing and predicting rates of. 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 high.
This will increase the water content of the soil and make it more erodible. Rainfall erosivity is the potential ability for rainfall to cause soil loss. So we will explain what rainfall erosivity factor is, why and when you need to calculate rainfall erosivity factor. The rainfall erosivity index is one of the most important factors influencing soil erosion. You may need a pdf reader to view some of the files on this page. It is well known that soil losses are frequently due to a few intense rainfall events 1, 3. 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. Yearly variation of the erosivity index shows an intermittent trend as depicted in table 2. Estimation of erosivity from rainfall data 2 methods. What matters for the longterm sustainability of soils is the average erosion force in a normal years rain.
Rainfall erosivity estimation for sierra leone using non. Relationship between soil erodibility, rainfall erosivity. Rainfall erosivity factor for india using modified fourier. Pdf a scenario of rainfall erosivity index research researchgate. Wischmeier and smith 6 developed the first iteration of the modern rainfall erosivity index used today 2,6,7 and has also proved ei 30 s applicability in the loess plateau of china during the. This is calculated by taking into account the amount of rainfall and the peak intensity of each storm and finding the longterm average. Estimation of rainfall erosivity using 5 to 60minute. Rainfall erosivity estimation based on rainfall data collected over a. Isoerodent maps can be used in soil conservation planning to identify regions with high rainfall erosive potential. Global rainfall erosivity assessment based on hightemporal. Erosivity definition and meaning collins english dictionary. The rainfall erosivity index r, determined for imo state was based on data made available from one station. A direct link to the materials for this video can be.
Rainfall erosivity is an index that describes the power of rainfall to cause soil erosion. Fact sheet for determining construction rainfall erosivity waiver requirements. This map provides a complete rainfall erosivity dataset for european union 28 member states and switzerland based on 1541 precipitation stations and 26,394 years of measurements. 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. From empirical equations rainfall intensities and erosivity index were obtained at 30. Rainfall erosivity r factor has been determined for sierra leone using monthly precipitation data covering 196020 using fournier fi and modified fournier mfi indices.
These results provided the main input information for this study, which used them to estimate the rfactor for costa rica. The data obtained was analyzed using raster distribution from arcgis 10. The purpose of this study is to investigate the effects of rainfall erosivity index ai on the hydraulics of overland flow parameters such as the flow velocity, the flow depth, the flow regime, overland flow power and on soil surface characteristics, such. Dynamic changes of soil erosion in the taohe river basin. 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 interrill erosion on hillslopes by precipitation. Estimating the rainfall erosivity factor from monthly precipitation data in the madrid region spain. Pdf rainfall erosivity is the capability of rainfall to cause soil loss from hillslopes by water. Gaussian process regressiongpr model was used to interpolate the rainfall erosivity values of single stations and to generate the rfactor map. An estimation of rainfall erosivity in iraq is essential for the prediction of sheet and rill erosion. The purpose of this study is to assess rainfall erosivity in europe in the form of the rusle rfactor, based on the best available datasets. Data have been collected from 1541 precipitation stations in all european union eu member states and switzerland, with temporal resolutions of. Rainfall erosivity indicates the potential of a storm to erode soil.
Global rainfall erosivity esdac european commission. An assessment of tropical cyclones rainfall erosivity for. Euskadi 5 1 monthly rainfall erosivity in soil degradation general information description rainfall erosivity is a factor of soil loss by water erosion. Evaluation of annual rainfall erosivity index based on. Rainfall erosivity index for the ghana atomic energy. 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. Monthly rainfall data, for the period 20032012 were used to compute annual rainfall erosivity indices for the site, using the modified fournier.
The following two methods are widely used for computing the erosivity of rainfall. Estimation of the changes in the rainfall erosivity in hungary in. The estimated high erosivity index for the study area presages further risk of soil erosion hazards, especially under conditions of increasing rainfall. Materials and methods this section describes the collection and formulation of rainfall data, determination of erosivity index, development of relationships between erosivity index and rainfall and quantitative performance of the models based on statistical indices. Evaluation of annual rainfall erosivity index based on daily. It notes that while rainfall provides moisture critical for plant growth, it is also one of the prime causes of soil degradation, referred to as rainfall erosivity, which threatens food and.
315 710 707 1135 1093 1484 1187 880 1182 948 561 539 347 866 183 1116 166 1318 1456 753 1472 182 1017 540 1246 1245 1188 699 1364 415 1219 1381 641 1083 1109 119 920 482 711 935 372 136 824 862