黑河分支河流体系地貌特征和沉积模式

The geomorphological characteristics and sedimentary model for Heihe distributive fluvial system

为探究温带干旱区分支河流体系(DFS)的沉积模式,选取黑河DFS为靶区,利用卫星遥感影像和地貌、气候等资料,首先确定了黑河DFS的宏观形态、内部组成和地貌类型,进而研究了黑河DFS的控制因素及沉积模式。研究表明:①黑河DFS面积约3.01×10^(4) km^(2),最大半径超过300km,近五十年来黑河DFS的边界、河道位置和河流类型保持稳定,但内部湖泊的水体面积波动明显;②根据地貌、沉积和水系特征将黑河DFS分为近端、中部和远端三部分,DFS发育有冲积平原、冲洪积平原和沙地等30种地貌类型,其中湖泊地貌和风积地貌分布广泛;③黑河DFS形态受构造控制,气候和径流是其演化的主要控制因素;④黑河DFS是第四纪干旱气候下形成的巨型扇,主要沉积动力为河流、洪水、湖泊和风,近端、中部主体为冲积平原和冲洪积平原,远端主体为泛滥平原和DFS终端湖泊,具有3类河道沉积模式,分别为单一曲辫转化、复杂放射性曲辫共存和萎缩放射性曲辫共存。

In order to explore the sedimentary model of distributive fluvial systems(DFS)in temperate arid area,taking Heihe DFS as the target area,using satellite remote sensing images,geomorphic data and climate data,this paper first determines the macro morphology,internal composition and landform types of Heihe DFS,with the controlling factors and sedimentary model of Heihe DFS studied.The results are as follows.①The area of Heihe DFS is 3.01×10^(4) km^(2) and its biggest radius is over 300 km;the boundary,the river location and type of Heihe DFS remains stable but the area of internal lake changes visibly in recent 50 years.②According to the characteristics of landform,sedimentation and water system,Heihe DFS is divided into three zones:proximal zone,middle zone,and distal zone;there are 30 landform types such as alluvial plain,alluvial-proluvial plain and sandy land,and the landform of lake and aeolian are widely distributed.③The form of Heihe DFS is limited by structure,and climate and runoff are the main controlling factors of its evolution.④Heihe DFS is a megafan formed in the arid climate in Quaternary;its sedimentary dynamics are river,flood,lake and wind;the main area of the proximal zone and middle zone are alluvial plain and alluvial-proluvial plain,and the main area of the distal zone is flood plain and DFS’s terminal lakes.There are three types of the channel sedimentary model-single channel form meandering river to braided river,complex radial meandering rivers and braided rivers,atrophic radial meandering rivers and braided rivers.