青藏高原河网统计规律及高原抬升的影响

Statistical features of the drainage network in the Qinghai-Tibet Plateau and the effect of the uplift

晚新生代以来青藏高原的持续抬升对高原的地形地貌甚至河流网络产生了极大的影响,使得高原河流网络显现不同于其它地区的特色。为揭示青藏高原河网的发育规律和研究高原抬升对河流网络及地形地貌的影响,该文基于数字高程模型分析技术,从航天飞机雷达地形测绘使命(SRTM)数据中系统提取了青藏高原雅鲁藏布、金沙江、雅砻江、澜沧江、怒江和黄河上游这6条大河的河流网络,分析其典型河网参数,如河网分支比、长度比、面积比及坡降比等。通过与Horton定律描述的一般性河流网络进行对比分析,结果表明:河网在高原内部的1到6级河流很好地符合一般性河网的规律,而处在高原边缘的最高级河流较大地偏离Horton定律,高原边缘的差异抬升和断裂构造是影响河网发育的主要因素。

The continued uplift of the Qinghai-Tibet Plateau since the Late Cenozoic Era has not only tremendously influenced the plateau topography,but has also resulted in unique river networks in this area.The features of the stream networks and the influence of the plateau uplift on the river morphology were studied by measuring the number of streams,stream lengths,slopes and areas of the drainage basins for the Yalutsangpo,Jinsha,Yalong,Lancang,Nujiang,and upper Yellow River from shuttle radar topography mission（SRTM）data.The networks of the 6rivers were mapped and analyzed by comparisons with the Horton Laws.The networks are represented by the Horton Laws for the streams from the first to sixth orders but deviate dramatically at the highest order.The results show that the plateau uplift is uniform in the inner part but the very different uplift speed at the plateau edge disrupts the stream networks.