贵州省降雨侵蚀力时空分布规律分析

An Analysis on Spatial—Temporal Distribution of Rainfall Erosivity in Guizhou Province

降水是导致土壤侵蚀的主要动力因素,降雨侵蚀力反映了降雨对土壤侵蚀的潜在能力。贵州省是我国典型的生态环境脆弱区之一,水土流失十分严重。以全省19个气象台站1951—2001年逐日降雨资料,利用日降雨侵蚀力模型,估算了贵州省降雨侵蚀力,分析了其时空分异规律。结果显示近50a来贵州省降雨侵蚀力呈增加趋势,即由降雨引起的土壤水蚀潜在能力增加。降雨侵蚀力年内分配主要集中在夏季,占年均降雨侵蚀力的68.48%。在空间分布上,降雨侵蚀力由南向北递减,并且在西南部和东南边缘形成侵蚀力高值中心,在西北部形成低值中心。根据年降雨侵蚀力的季节分配特征,可以将贵州省划分为3个类型区。

Rainfall is the main dynamic factor that causes soil loss and rainfall erosivity, it shows the potential ability of the soil loss caused by rainfall. Estimating the rainfall erosivity accurately is significant to predict soil loss quantitatively and make soil and water conservation program. Guizhou Province, with serious soil erosion, is one of the typical regions whose ecological environment is very fragile. In order to estimate rainfall erosivity accurately and analyze the spatial distribution and temporal change of rainfall erosivity, a daily rainfall erosivity model was adopted to calculate the rainfall erosivity of Guizhou Province using daily rainfall data during 1951-2001 from 19 weather stations. The results indicate that rainfall erosivity show increasing trend during the last 50 years which indicates that the potential ability of the soil loss caused by rainfall increase in Guizhou Province. The seasonal distribution of annual average rainfall erosivity is centralized and the percentage of rainfall erosivity in summer is 68. 48%. The spatial distribution of rainfall erosivity shows decreasing trend from the south to the north. The center with the largest rainfall erosivity is located in the `southwest and .southeast regions in Guizhou Province, while the center with the smallest rainfall erosivity is located in the northwest regions. However, rainfall erosivity is influenced by rainfall amount and intensity, there are a lot of differences between the distribution of rainfall and rainfall erosivity. According to the seasonal changing character of rainfall erosivity of whether stations, three regions are classified in Guizhou Province. With the increase of longitude from the west to the east regions, the centralization degree in seasonal distribution of annual rainfall erosivity decreases.