西晋以来彭原古城附近沟谷的演变与复原

The Gullies Change and restoration Nearby Pengyuan Ancient Cities from Xijin Dynasty

根据历史文献和考古调查,确定出甘肃省庆阳市西峰区彭原乡的两座古城遗址分别是后汉富平县城(GC1)和唐宋彭原县城(GC2),唐宋彭原县是北魏永和元年(434年)以后从今庙头嘴村搬迁到南庄村。据此推断泾河四级支流、马莲河三级支流彭原沟(当地称湫沟)流域的现代侵蚀沟,是在此年以后开始发育的。利用黄土高原现代侵蚀沟地貌年龄计算公式,计算出彭原沟主干沟道现代侵蚀沟的地貌年龄为1669±819年,沟口附近的现代侵蚀沟发育于西晋成帝咸康五年(339年)前后,其主要分支沟谷现代侵蚀沟的地貌年龄介于900±442～1300±638年之间。沟头平均延伸速度为3.367m/a,沟谷平均下切速度为0.063m/a,平均加宽速度0.19m/a。公式计算结果与考古结果基本相符,研究结果具有较高的信度。依此结果,将彭原沟及其支流地貌复原至西晋时期。

This paper focuses on historical documents and archaeological investigation,the Ancient-Town Sites Determined that were Fuping county of Donghan Dynasty and Pengyuan county of Tang Dynasty and Song Dynasty in Pengyuan Town,Xifeng county,Gansu province.The county town of Donghan Dynasty and Pengyuan county of Tang Dynasty relocated from Miaotouzui Village to Nanzhuang Village after 434＇s A.D.,the 1th year of Yonghe,Beiwei Dynasty.It was speculate that contemporary erosion ditches of the 3th branches of Manlian River,the 4th branches of Jinghe River developed after this year.Based on the formula of geomorphologic ages of the contemporary erosion ditch,calculated the geomorphic ages of main Stream of contemporary erosion ditch of Pengyuangou was 1669±819 years old,developed after 339＇s A.D.,the 5th year of Xiankang,Xijin Dynasty.The geomorphic ages of its branches were 900±442~1300±638 years old.The average forward speedy of gullies head was 3.367m/a.The average speedy of vertical erosion of gullies was 0.063m/a.The average widened speedy of gullies was 0.19m/a.The two results is basically same that based on formula and archaeological study.The results had high reliability.Based on this results restored the landforms of the Pengyuangou drainage area and its branches to Xijin Dynasty.