震后龙溪河流域河床纵剖面变化和沟谷分形

The Longitudinal Change and Gully Bed Fractality of Longxi River Valley After the Earthquake

为了研究强震后次生地质灾害对河床结构的影响,以DEM数据、Quickbird数据和现场实测资料作为数据源,对地震重灾区龙溪河流域河床结构发育与沟谷分形特征进行研究.结果表明,龙溪河河床纵剖面形态变化较大,裂点增多,河口处淤积明显,河床升高;主槽纵剖面为凹型,地震前后其凹度值分别为1.45和1.28;在无标度区间内,沟谷水系的分形维数分别为1.37(2005年)和1.42(2009年),说明流域沟谷形态的复杂程度增加;次生地质灾害是影响龙溪河流域河道变化的主要因素.本研究将为强震后小流域灾害防治和流域综合规划等工作提供参考.

In order to study the secondary geological disaster impact on the riverbed structure after the earthquake, the DEM data, Quickbird data and field measured data has been collected and the study has been made on the valley riverbed structure and fractal characteristics of the quake-hit Longxi River basin. The results show that the Longxi River riverbed has experienced large longitudinal morphological changes with significant increase of split points, obvious siltation at the mouth, and the rise of the riverbed. The main longitudinal groove is concave with concavity values of 1.45 and 1.28 before and after the earthquake. In the non-scale interval, the river valley fractal dimensions are 1.37 （2005） and 1.42 （2009） respectively, which means that the complexity of the basin shape has been increased. The secondary geological disasters are the main factors affecting the change of the Longxi River Valley. This paper will provide reference on disaster prevention and integrated watershed planning after the earthquake.