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陕北黄土丘陵区聚湫坝和淤地坝众多,以子洲县黄土洼古聚湫为研究对象,采集了总深度达12.73m的沉积泥沙剖面样品.根据泥沙粒度和孢粉浓度的变化,将全剖面分为54个洪水沉积层.并根据剖面中融冻扰动层的分布,将54个洪水沉积层分为31个年度的洪水沉积层的组合.根据锥台法计算,每次暴雨洪水的产沙模数介于715.53～30376.47t.km-2,平均7105.87t.km-2;年产沙模数介于968.36～55579.37t.(km2.a)-1,平均12629.49t.(km2.a)-1,与淮宁河中游年输沙量相近,表明该地区明代的土壤侵蚀强度与现代接近.31个年度的后5年产沙模数急剧增加,5年内的年均产沙模数达31309.12t.(km2.a)-1,结合明代当地戍边屯垦的历史分析,这一现象应为滑坡灾害发生后新的土地大开发所造成.
In the loess hilly region of North Shaanxi, there are many polygamy dams and silt dam, taking the ancient polygamy of loess depression in Zizhou County as the research object, a sedimentary sediment profile sample with a total depth of 12.73m was collected.According to the sediment particle size and the pollen concentration According to the distribution of thawing disturbed layer in the section, the 54 flood sedimentary layers are divided into 31 annual flood sedimentary layers.According to the method of frustum method, every time The annual sediment yield of storm floods ranged from 715.53 to 30376.47t.km-2 with an average of 7105.87t.km-2. The annual sand production ranged from 968.36 to 55579.37t. (Km2.a) -1 with an average of 12629.49t. (km2.a) -1, which is similar to the annual sediment transport in the middle reaches of the Huai River, indicating that the intensity of soil erosion in the Ming Dynasty was close to that in the modern times. The sediment yield modulus in the latter five years of the 31 years increased sharply, According to the historical analysis of the local garrison settlement in Ming Dynasty, this phenomenon should be caused by the new land development after landslide disaster.