分支河流体系河网形态演变规律——以格尔木河流扇为例

Evolution law of river network patterns in distributive fluvial systems——A case study of Golmud fluvial fan

为了探索分支河流体系河网分布规律,为创建储层建模训练图像提供知识库信息。利用Google Earth、Global Mapper、91卫图助手等现代地理信息软件,系统测量了现代格尔木河流扇表面河道分叉特征,应用Horton定律和分形方法建立了河流扇的河网形态模型。结果表明:①格尔木河流扇从顶点到入湖段共识别出26级河道,882个节点和2162个河道段,泉线上、下的河道表现出不同的河网形态;②泉线上部共发育64个节点,每级河道数目增长是上一级河道的R_(B)=1.8900倍,每级河道平均长度是下一级河道的R_(L)=1.0095倍,即河网形态特征参数R_(B)=1.8900和R_(L)=1.0095;泉线下部共发育818个节点,每级河道数目增长是上一级河道的R_(B)=1.0279倍,每级河道平均长度是下一级河道的R_(L)=0.9899倍,即河网形态特征参数是R_(B)=1.0279和R_(L)=0.9899;③河网形态特征参数受坡度影响变化较大,坡度较大则河网形态特征参数较大,坡度较小则河网形态特征参数较小。河网形态特征参数定量表征促进了分支河流体系沉积学发展,为开展陆相盆地储层建模和砂体预测提供了新的知识库信息.

Objectives:To explore the river network distribution of distributive fluvial systems,and to provide knowledge base information for creating reservoir modeling training images.Methods:Using modern geographic information software tools such as Google Earth,Global Mapper,and 91 Satellite Map Assistant,the surface river channel bifurcation characteristics of the modern Golmud Fluvial Fan were systematically measured.The river network pattern model of the fluvial fan was established using Horton's law and fractal methods.Results:The results show that:①The Golmud River Fan has identified 26 river channels from the apex to the lake inlet section,882 nodes and 2162 river sections.The river channels along the spring line and below show different river network patterns;②There are a total of 64 nodes developed in the upper part of the spring line,with an increase of R_(B)=1.8900 times the number of rivers in each level compared to the previous level,and an average length of R_(L)=1.0095 times that of the next level,indicating that the characteristic parameters of river network morphology are R_(B)=1.8900 and R_(L)=1.0095;There are a total of 818 nodes developed in the lower part of the spring line,with an increase of R_(B)=1.0279 times the number of rivers in each level compared to the previous level.The average length of each level of river is R_(L)=0.9899 times that of the next level of river,which means that the characteristic parameters of river network morphology are R_(B)=1.0279 and R_(L)=0.9899;③The characteristic parameters of river network morphology vary greatly due to the influence of slope.If the slope is larger,the characteristic parameters of river network morphology are larger,and if the slope is smaller,the characteristic parameters of river network morphology are smaller.Conclusions:The quantitative characterization of river network pattern characteristic parameters has promoted the development of sedimentology in distributive fluvial systems,providing new knowledge base information for conducting reservoir modeling and sand body prediction in continental basins.