Rainfall erosivity considers the effects of rainfall amount and intensity on soil detachment. Rainfall erosivity is most commonly expressed as the R-factor in the Universal Soil Loss Equation (USLE) and its revised version, RUSLE. Several studies focus on spatial analysis of rainfall erosivity ignoring the intra-annual variability of this factor. This study assesses rainfall erosivity in Greece on a monthly basis in the form of the RUSLE R-factor, based on a 30-min data from 80 precipitation stations covering an average period of almost 30 years. The spatial interpolation was done through a Generalised Additive Model (GAM). The observed intra-annual variability of rainfall erosivity proved to be high. The warm season is 3 times less erosive than the cold one. November, December and October are the most erosive months contrary to July, August and May which are the least erosive. The proportion between rainfall erosivity and precipitation, expressed as erosivity density, varies throughout the year. Erosivity density is low in the first 5 months (January–May) and is relatively high in the remaining 7 months (June–December) of the year. The R-factor maps reveal also a high spatial variability with elevated values in the western Greece and Peloponnesus and very low values in Western Macedonia, Thessaly, Attica and Cyclades. The East–West gradient of rainfall erosivity differs per month with a smoother distribution in summer and a more pronounced gradient during the winter months. The aggregated data for the 12 months result in an average R-factor of 807 MJ mm ha− 1 h− 1 year− 1 with a range from 84 to 2825 MJ mm ha− 1 h− 1 year− 1. The combination of monthly R-factor maps with vegetation coverage and tillage maps contributes to better monitor soil erosion risk at national level and monthly basis.
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机译:降雨侵蚀力考虑降雨量和强度对土壤脱离的影响。降雨侵蚀力通常在通用土壤流失方程(USLE)及其修订版RUSLE中用R因子表示。有几项研究侧重于降雨侵蚀力的空间分析,而忽略了该因素的年内变化。这项研究以RUSLE R因子的形式,每月评估希腊的降雨侵蚀力,基于来自80个降水站的30分钟数据,涵盖了将近30年的平均时间。空间插值是通过通用加性模型(GAM)进行的。观测到的降雨侵蚀力的年内变化被证明很高。温暖的季节比寒冷的季节少侵蚀3倍。 11月,12月和10月是侵蚀最大的月份,而7月,8月和5月则是侵蚀最小的月份。降雨侵蚀力与降水之间的比例,以侵蚀力密度表示,全年变化。在头5个月(1月至5月)中,侵蚀度密度较低,而在该年的其余7个月(6月至12月)中,侵蚀度密度相对较高。 R因子图还显示出高度的空间变异性,在希腊西部和伯罗奔尼撒半岛的值较高,而在马其顿西部,色萨利,阿提卡和基克拉泽斯的值却很低。降雨侵蚀力的东西向梯度每月不同,夏季分布更平滑,而冬季则梯度更明显。这12个月的汇总数据得出的平均R因子为807 MJ mm ha-1 h-1 year-1,范围从84到2825 MJ mm ha-1 h-1 year-1。具有植被覆盖率的R因子图和耕作图有助于更好地监控国家和每月的土壤侵蚀风险。
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