青海共和盆地多石在沟河道沙丘现代风水交互过程

CONTEMPORARY PROCESS OF AEOLIAN-FLUVIAL INTERACTION ON SAND DUNES IN THE CHANNEL OF DUOSHIZAIGOU VALLEY,GONGHE BASIN,QINGHAI PROVINCE

选择青海共和盆地多石在沟河道中6道新月形沙丘链作为研究对象,采用Trimble4700DGPS与常规测量手段,结合野外风沙观测与自动气象站数据,初步观测分析了2006年多石在沟河道沙丘在不同季节的形态变化过程,计算出2006年风季前比雨季后多石在沟河道沙丘体积减小了548.3m3,风积量为2351m3,流水的蚀平量为2899m3,2006年风水两相营力对河道沙丘的侵蚀贡献率约为45%∶55%,流水的搬运作用强于风力的堆积作用。但从较长的时间尺度来看,研究区的风力侵蚀作用强于流水侵蚀作用,河道沙丘不断增大。多石在沟河道沙丘是一个典型的风水交互作用系统,河道成为风力与流水交互作用的"中转站",在风水的交替作用下,沉积物由风积环境进入流水环境中。

Aeolian-fluvial interaction is an important surface process to form geomorphologic landscape in arid and semiarid regions. Sometimes the hazardous degree of the interaction could be larger than that of each of the two individual erosion which quantitative process. Aeolian-fluvial interaction on sand dunes in the river channel is an important process, on observation data and dynamic analysis results at the micro-scale are lacking. With the aim of investigating aeolian-fluvial interaction on sand dunes in different seasons, six sand barchan dunes in the channel of Duoshizaigou valley, Gonghe Basin, Qinghai Province, are monitored by Trimble 4700 DGPS and ordinary manual surveying. Based on data of blownsand flow observation in field and meteorological data of windy season collected by Davis automatic weather station,we primarily investigated the morphologic change process of the sand dunes in the channel in different seasons of 2006. The results show that volume of the sand dunes in the channel of Duoshizaigou valley before windy season was 38051.4m3, and 37503. lm3 after rainy season in 2006; volume of aeolian sand blew into the channel is estimated 2351m3 in the windy season and the fluvial erosion volume in the rainy season is 2899m3. So the ratio of erosion rate of aeolian to fluvial is 45%： 55% and the magnitude of transportation by water is higher than that of aeolian sediments by wind in the study area in 2006. But the wind erosion is higher than water erosion at longer time scale and the sand dunes constantly enlarge and extend. The sand dunes in the channel of Duoshizaigou valley are typical system of aeolian-fluvial interaction and they can be regarded as a transfer station where sediments are transported from aeolian environment to fluvial environment.