Downstream River Channel Sinuosity Variation of the Distributive Fluvial System: A case study from the Golmud fluvial fan.

[Objective] We aimed to study the evolution of river patterns in the distributive fluvial system, establish a database of corresponding parameters, and provide a data basis for predicting the distribution of sedimentary systems within the forecast basin. [Methods] Using modern geographic information software such as Google Earth and Global Mapper, the channel sinuosity was measured based on a grid of equal proportions, analyzing the variation of the channel sinuosity along the course and establishing the depositional mode of the evolution of the Golmud fluvial fan. [Results] A total of 2 989 channel sinuosity data were measured, and based on the characteristics of the sinuosity of the Golmud fluvial fan, the Golmud fluvial fan can be divided into four sections: "braided river," "braided-meander coexistence," "large high-sinuosity meandering river," and "small low-sinuosity meandering river section": (1) The slope of the braided river section was 0.70%, developing both the straight and braided river with low sinuosity. The braided belt width was large. The channel sinuosity was 1.01-1.43, the average sinuosity was 1.08, and microfacies such as braided river, abandoned river, and flood plain were developed: (2) The slope of the braided-meander coexistence section was 0.63%, developing both braided and meandering river, and the development degree and river sinuosity varied in different positions. The channel sinuosity was 1.08-5.00, and the average sinuosity was 1.52: microfacies such as braided river, meandering river, abandoned river, crevasse splay, sand dunes, and flood plain were developed; (3) The slope of the large high-sinuosity meandering river section was 0.29%, mainly developing a large meandering river. The channel was wide, the river bend swing was large, the channel sinuosity was 1.12-5.00, and the average sinuosity was 1.83; microfacies such as meandering river, abandoned river, sand dunes, and flood plain were developed; (4) The slope of the small low-sinuosity meandering river section was 0.08%, mainly developing a small bifurcated meandering river, narrow channel, and small river bend swing; the channel sinuosity was 1.07-3.13, with an average sinuosity of 1.51, and microfacies such as meandering river, abandoned river, crevasse splay, sand dunes, and flood plain were developed. Conclusions The depositional model of river-type evolution of the Golmud fluvial fan was established, which provided a new knowledge base for the prediction of the distribution of underground sedimentary systems. [ABSTRACT FROM AUTHOR]