嘉陵江古河道的河曲特征

基于遥感信息和野外实地调查，查明了嘉陵江古河道的分布；共发现古河道13处，主要分布在嘉陵江中游的阆中-南充段.河曲参数统计表明，13处古河道的单个河曲的曲折率C值都在3.00以上，平均值为7.80；4段河曲带的C值在2.20以上；整个中游段的C值为2.75，远远高于弯曲性河型临界值的1.50，表明嘉陵江古河道具有蜿蜒性河型的特征.此外，通过将古今河道参数进行对比发现，古河流的C值要比现代河道的C值大(分析认为较大的C值，可能与较低缓的坡降J有关)，即有更大的弯曲度.表明嘉陵江曾发生过一次自然截弯取直过程. 

Meander Characteristics of the Jialing River's Old Channels

Based on data of the remote sensing and field surveys, the distribution of old channels in the Jialing River is explored. A total of 13 old channels are found and determined. They are distributed mainly in the reach of Langzhong-Nanchong of the Jialing River. Statistical meander parameters indicate that their meander ratio C values are all larger than 3.00, with an average value of 7.80. C values of 4 meander belts are larger than 2.20, and the C value of the whole middle reach of ancient Jialing River is 2.75. All these values are much larger than 1.50, the critical value of meandering rivers, suggesting that the ancient Jialing River has characteristics of meandering river pattern. In addition, it is found that the C value of the ancient river is larger than that of modern channel (It is believed that the larger C value may be associated with the lower gradient value J), indicating a lager degree of curve. It can be concluded that a process of natural cutoff of river has once occurred in the Jialing River.