历史时期周原地貌演变与土壤侵蚀

文章以渭北黄土台塬西部周原七星河流域为研究对象，采用实地考察、考古、历史文献等多种方法定量地研究了仰韶文化以来周原地貌演变与土壤侵蚀的过程和规律。通过恢复历史时期周原地貌演变过程得出周原地貌演变主要表现为沟谷的形成和发展，七星河流域沟谷密度从仰韶、龙山文化时期的0.1646km/km^2，增加到目前的0.7045km/km^2，西汉以来沟谷的下切速率为1.08m/100a。历史时期周原土壤侵蚀过程一直存在，且沟谷发育和土壤侵蚀呈加剧态势，沟谷密度、土壤侵蚀模数分别增加了76.64%、41.36%。金以后的元、明、清时期和二十世纪前半叶是周原沟谷发育、土壤侵蚀发展最快的时期，数量众多的切沟、冲沟主要形成于金以后至今770多年里，造成这一结果的主要原因是植被的人为破坏。

Landform Evolution and Soil Erosion on Zhouyuan During Human History Period

The loess platform is one of important landform types in the Loess Plateau. The Qixinghe River Drainage Basin (QRDB) is located on Zhouyuan loess platform, north bank of the Weihe River. The paper quantitatively studies the process and principle of Zhouyuan landform evolution and soil erosion during human history ( after Yangshao Culture) by the on-the-spot investigation, the archaeology and the historical documents. With recovery of Zhouyuan landform evolution process, the following results have been obtained. The primary form of Zhouyuan landform evolution is the gullies' development. Gully density of QRDB has increased from 0.1646 km/km2 to 0.7045 km/km2 after Yangshao and Longshan Culture until now. Since Han Dynasty, the dissected speed of QRDB is 1 .08m/100a. In human history, soil erosion has been always existing and it has been aggravated, and the gully density has been increased to 76.64% and soil erosion modulus also increased to 41.36% . The Yuan, the Ming and the early - middle Qing Dynasties, the early 20th century were a bloom of the gullies' developing and the soil erosion intensity. The large amount of gulleies and gurlgs were shaped after Jin Dynasty (about 770 years before now) . One of important reasons is resulted from forest cut which covered the Qishan Mountain before.