川中丘陵区土壤侵蚀的特征与行为方式

Characteristics and Pattern of Soil Erosion in Central Hills of Sichuan Basin

川中丘陵区土壤侵蚀普遍,其侵蚀面积之广,侵蚀强度之大仅次于我国北方的黄土高原。土壤侵蚀表现出类型多样而独特,强度极度超常,全层性流失,基岩物理风化迅速,母质侵蚀突出,丘陵体为侵蚀主体等特征;土壤侵蚀行为方式也颇具特色,表现为坡面产流快,土壤冲刷广泛,风化与侵蚀交替进行,流域水力侵蚀频率不高但集中,土壤侵蚀的垂直分带性,土壤侵蚀的季节变动性,土壤侵蚀与流域泥沙搬运不同步等现象;这些特征和行为方式与这里的紫色砂泥岩的广泛出露,复杂的地表物质结构和地貌组合,季节变动明显的季风气候和人类农业耕作活动等因素密切相关。

The Central Hills of the Sichuan Basin is one of the most severe soil erosion in China. The soil erosion is characterized by various erosion ways with special funnelshaped gully erosion, extreme soil erosion rate much higher than that ofthe natural erosion, soil loss from whole soil profile, strong physical weathering of bed rock, obvious parent material erosion and hillterrace erosion. The pattern of soil erosion shows these feathers of rapid runoff and extensive soil washing on hill slope, alterative operating of weathering and erosion, low frequency of water erosion but high strength of water erosion, vertical zoning of soil erosion, soil erosion seasonal variability and nonsynchronization of soil erosion on hill slope and sediment transportation of river. These characters and patterns of soil erosion in this region are related with extensive outcrop of purple sandstone and shale, complicated structures of the surface materials and landforms, obvious seasonal variations of rainfall and local activities of agricultural cultivation. 