陕北黄土洼天然淤地坝沉积物粒度特征与降雨关系研究

摘要

Dating the sediments age with 137Cs ,using rainfall data from 1953 to 2010 ,was analyzed the relationship between rainfall and grain-size characteristics of sediments in natural dammed-lake of Huangtuwa .The results showed that:The sediments of 4 .1 m depth was formed in recent one hundred years and has recorded at least 42 times storm flood events .The flood formed by centralized rainfall ,mainly carried coarse sediment ,and had stronger soil erosion force .In wet years ,the grain size of sediments with annual precipitation ,rainfall from July to September ,and maximum rainfall in 30 days and 24 hours had significant correlation .While in dry years ,the correlation of grain size of sediments with annual precipitation was weaker than wet years .It can provide a scientific basis for inverting soil erosion and sedi-mentation processes and calculating erosion amount in Loess Plateau of Northern Shaanxi .%利用137 Cs断代技术进行沉积物的测年，结合1953—2010年的降雨资料，对黄土洼天然聚湫坝淤地沉积物粒度特征与降雨的关系进行了分析。结果表明，坝淤地4．1 m沉积物是在近百年内形成的，至少记录了42次较大的暴雨洪水事件；集中性降水形成的洪水，主要携带粗颗粒沉积物，对土壤的侵蚀力更强；在丰水年，沉积物粒度与年降水、7—9月降水、30日最大降水和24 h最大降水的相关性极显著，而在枯水年，沉积物粒度与降水因子的相关性较丰水年弱。本研究为反演陕北黄土高原土壤侵蚀产沙过程，推算侵蚀量提供理论依据。