基于地统计学的四川省降雨侵蚀力时空分布特征

Spatiotemporal distribution of rainfall erosivity in Sichuan Province based on geostatistics

利用四川省147个气象站点近52年的日降雨量数据计算各台站的降雨侵蚀力，应用SPSS和ArcGIS地统计模块，分析降雨侵蚀力的统计特征，提出适宜的插值方法，并对全省降雨侵蚀力的时空分布特征进行了研究。结果表明：四川省多年平均降雨侵蚀力属中等变异，空间插值方法选取普通克里格，采用球状模型能够较好地拟合降雨侵蚀力；其空间分布总体表现为盆地、攀西地区相对较高，川西高原较低，大致的趋势是从东向西逐渐降低；近52年来，四川省降雨侵蚀力倾向率从东向西整体呈现“增-减-增”的变化趋势；降雨侵蚀力的年内集中度较高，从东向西呈现低-高-低-高的近似带状分布，高值区域主要集中在盆地中、西部地区和川西高原的西部；12个代表站点中，降雨侵蚀力年内半月分布多呈现双峰型，可分为高值期、中值期、低值期3个不同时期，发生侵蚀的时段集中分布在第8～19个半月，累计降雨侵蚀力占全年降雨侵蚀力的95%～99%。大型土木工程的开发应根据四川省降雨侵蚀力的时空分布特征，尽量避开土壤侵蚀高发期；横坡种植可降低坡耕地的水土流失。

Based on the daily rainfall data of 147 meteorological stations in Sichuan Province during 1961-2012, we analyzed the statistical characteristics of rainfall erosivity by SPSS and ArcGIS, and proposed an appropriate interpolate method. The characteristics of spatial and temporal distributions of rainfall erosivity in Sichuan Province were then analyzed. Results showed that the rainfall erosivity variation was moderate. The ordinary Kriging interpolation method with spherical model could well represent the rainfall erosivity. The rainfall erosivity was relatively high in the basin and Panxi areas, and relatively low in the western Sichuan plateau. The rainfall erosivity gradually decreased from east to west. The tendency rate of the rainfall erosivity for last 52 years presented an ‘increase-decreaseincrease’ feature from east to west. The concentration degree of annual rainfall erosivity was relatively high and showed belt distribution characteristics of ‘low-high-low-high’ from east to west. The high-value areas were mainly distributed in the central and western basin and the western part of western Sichuan Plateau. The intra-annual distribution of the rainfall erosivity presented a bimodal pattern at 12 typical stations, which could be divided into high-value period, median-value period and low-value period. The occurrence of erosion was concentrated in the period from 8th to 19th semi-month, which accounted for 95%-99% of the total annual rainfall erosivity. Therefore, the development of large-scale civil projects should try to avoid the high incidence season of rainfall erosion according to the characteristics of spatial and temporal distribution of rainfall erosivity in Sichuan. Cross slope cultivation is recommended for slope farmland in order to reduce soil erosion.