库布齐沙漠南缘风水交互特征及其对抛物线形沙丘发育的影响

通过对内蒙古库布齐沙漠南缘气象水文数据的监测、多期高分辨率遥感影像的分析以及实地考察，探讨区域风水交互特征及其对抛物线形沙丘形成发育的影响。结果表明：从1970年到2014年，研究区水沙作用方式逐渐由水沙平衡交互转变为流水侵蚀主导，期间叭尔洞沟发生多次高输沙量的洪水，河流大幅度改道，流水对上风向西岸横向沙丘的切割作用使得一部分残余沙丘留在东岸，成为沿岸抛物线形沙丘的初始沙源。在西北风作用下，河床内积累的沙物质通过东岸的输沙沟槽为沿岸抛物线形沙丘提供外来沙源。1970-2014年该区域合成输沙势持续下降，河床积累沙物质逐渐减少，在流水侵蚀主导阶段，洪水对河床沙丘的搬运以及降雨对河道沿岸阶地的坡面侵蚀使得河流对西岸沙丘的截沙作用增强，流水逐渐阻断外来沙源供给，为东岸首先发育新月形沙丘创造条件。随着风沙作用减弱，降水增加，新月形沙丘在植被"翼角固定"的转换机制下逐渐演变为抛物线形沙丘。库布齐沙漠南缘的风水交互作用对叭尔洞沟沿岸抛物线形沙丘形成发育产生较大影响，是区域风沙地貌形成演化的重要因素。

Aeolian-Fluvial Interaction Characteristics and Its Effect on Parabolic Dunes in the Southern Fringe of Hobq Desert

By analyzing the meteorological and hydrological data, high-resolution remote-sensing images, and field survey, we discussed the regional aeolian-fluvial interaction characteristics and its effect on parabolic dunes in the southern fringe of Hobq Desert, China. The results showed that from 1971 to 2014, the interaction between fluvial and aeolian processes in the study area gradually changed from "aeolian-fluvial balance" to "fully fluvial dominant". There were many floods occurred in the Baerdong River with high sediment transport during this period, which resulted in re-channelization. The river encroached into and cut the riverine transverse dune fields on the western bank. Consequently, several residual dunes remained on the east bank and became incipient sand source of parabolic dunes. The sediment accumulated on the riverbed provided external sand source for riverine parabolic dunes on the eastern bank through gullies under northwest wind erosion. Because of continuous dropping of resultant drift potential in the study area from 1970 to 2014, the sand sediment accumulated in the riverbed decreased gradually. In the stage of "fully fluvial dominant", the transportation of sand sediment in the riverbed by floods and the erosion of riverside terrace slope by rainfall may have enhanced "capture" effect on the west bank dunes. And then floods gradually blocked the supply of external sand source. The limited sand source is the basic condition for the development of barchans. With the weakening of aeolian erosion and the increasing of precipitation in the study area, the barchans gradually transformed into parabolic dunes under the "horn-anchoring" mechanism by vegetation. Parabolic dunes in the study area are the result of specific local factors which are the product of the local climatic regime. Therefore, The aeolian-fluvial interaction characteristics has a great influence on the formation and development of parabolic dunes next to the Baerdong River, which is an important factor to study the formation and evolution of sandy landforms and rivers.