基于构造地貌学的南盘江与红河分水岭特征分析

Migration characteristics of the watershed between Nanpan River and Red River based on morphotectonics

红河曾经在古新世—始新世晚期发源于青藏高原内部,大约渐新世开始其流域面积逐渐缩小。自渐新世至今,青藏高原东南缘发育了一系列大规模走滑断裂。走滑断裂能够影响河流的流向、坡度以及河道形态等。在这些走滑断裂影响下,红河的流域面积是否会发生规律性的变化?本文以南盘江和红河流域分水岭为研究对象,探究红河在红河断裂、建水断裂及文麻断裂等走滑断裂的影响下,其分水岭的迁移特征。本文利用90 m分辨率的DEM提取了红河、南盘江的33条子流域,通过计算获得面积高程积分(HI)、谷底宽高比(VF)、河流陡峭指数(K_(sn))和chi(χ)值4个地貌参数,结合野外调查揭示研究区构造活动性差异及分水岭的变化规律。结果显示,研究区分水岭呈分段性变化:龙树村—店房村段向南盘江迁移;店房村—腊梅村段向红河迁移,HI值、VF值及Ksn值三者所得结果与chi(χ)值结果对马鹿山—龙树村段存在不同认识。从整体上看,红河在逐渐失去其流域面积。非构造因素(降雨和岩性)不是控制研究区分水岭迁移的主要因素,研究区分水岭迁移主要受研究区内红河断裂、建水断裂、曲江断裂、文麻断裂及小江断裂南段的构造活动性强弱影响。

The Red River once originated in the Tibetan Plateau in the Late Paleocene-Eocene,and its drainage area gradually shrank since the Oligocene.Since the Oligocene,a series of large-scale strike-slip faults have developed in the southeastern margin of the Qinghai-Tibet Plateau,which can affect the flow direction,slope and channel morphology of rivers.Under the influence of these strike-slip faults,does the basin area of the Red River Basin change regularly?This paper takes the watershed of Nanpan River and Red River as the research object to explore the migration characteristics of the watershed of Honghe River under the influence of strike-slip faults such as Honghe fault,Jianshui fault and Wenma fault.In this paper,a 90 m resolution DEM was used to extract 33 sub-basins of the Honghe River and Nanpan River,and four geomorphic parameters were obtained by calculating the area elevation integral(HI),valley floor width-height ratio(VF),river steepness index(K_(sn))and chi(χ)value.Combined with field investigation,the difference of tectonic activity and the variation of watershed in the study area were revealed.The results show that the watershed changes in the study area are segmentally:the section from Longshu village to Dianfang village migrates to Nanpan River;as the Dianfangcun-Lameicun section migrated to the Red River,the results of HI value,VF value and Ksn value were different from those of chi(χ)value for Malushan-Longshu section.On the whole,the Red River is gradually losing its drainage area.Non-structural factors(rainfall and lithology)are not the main factors controlling the migration of the watershed in the study area.The migration of the watershed in the study area is mainly affected by the tectonic activity of Honghe fault,Jianshui fault,Qujiang fault,Wenma fault and the southern section of Xiaojiang fault.