澜沧江河道冲淤变化与来沙系数的格兰吉尔因果分析

Analysis of the Granger Causality Between the Scouring and Silting and the Coefficient of Incoming Sediments of the Lancang River

采用格兰吉尔因果关系模型以及时间序列平稳性的ADF检验技术,结合23年的实测资料数据,分析了澜沧江天然来沙量的变化是否会导致澜沧江河道冲淤发生变化。结果发现:(1)澜沧江历年来沙系数变化是一个不稳定的时间过程、但历年冲淤变化却是一个稳定的时间过程;(2)澜沧江河道(允景洪断面)历年来沙系数变化对于冲淤变化不存在格兰吉尔因果关系,或前者对后者无预测关系,因此澜沧江河道来沙系数的增加(或减少)都不一定导致断面淤积量增大(或冲刷量增大)。前人得出的"随来沙系数的增大,断面淤积量有所增加,反之,则冲刷量增加"的结论值得商榷。

The Lanchang-Meikon River is an important international river. In recent years, the basin of this river has gradually become the region where some countries or regioanl groups, located along both of its banks, have stressed research and development and invested a lot. The river is one of the most active factors in the environment of physical geography of the Lanchang River basin. Water flow and its bedload have important impact on shipment development, construction of water power stations, and land use. There Thus, a placement of stress on research of the impact of changes in the natural incoming sediments on the scouring and silting changes of the Lanchang River will provide an important basis for its terrace development. Using Granger causality model, the ADF time series stability test technique, and the available on-site collected data within a period of 23 years, this study conducts an analysis of whether or not changes in the incoming sediments of the Lanchang River will lead to scouring and silting changes. This study finds that: (1) the variable of the yearly coefficients of incoming sediments of the Lanchang River is a non-stability time series process; but in the contrary, the variable of the yearly scouring and silting changes is a stability one; (2) there are no Granger causal relations, or predictive relations, found from the changes in the incoming sediments of the Lanchang River (Yunjinghong Section) to those in the scouring and silting. Thus, an increase (or decrease) in the coefficient of incoming sediments of the Lanchang River will uncertainly lead to an increase in the section silting (or an increase in the section scouring). This does not accord with the suggstion in the past research. Thus, we suggest that the former study's suggestion may be discussible.