汶川震区北川县城泥石流源地特征的遥感动态分析

针对一种充气前缘(inflatable leading edge, ILE)增升技术，建立了其充气结构与流场耦合作用的运动方程. 将方程写成状态空间形式， 采用时域推进方法求解. 对使用了变前缘增升技术的NACA 63-212翼型进行了充气结构静变形的数值计算，结果表明充气结构的刚度对翼型的气动特性 有明显影响. 与原翼型相比，在不考虑充气结构变形时, 该增升技术大约能使翼型的失速迎角 增加30{\%}，最大升力系数增加22{\%}；考虑结构变形后增升效果有所降低. 刚度较低的薄 膜在前缘吸力峰的作用下会隆起形成鼓包，容易引起流动分离.

REMOTE SENSING IMAGES BASED OBSERVATIONAL ANALYSIS ON CHARACTERS OF DEBRIS FLOW SOURCE AREAS IN BEICHUAN COUNTY OF WENCHUAN EARTHQUAKE EPICENTER REGION

Wenchuan Earthquake produced abundant debris left behind on the hillside slopes. The debris would later serve as the source materials for rainfall induced debris flow hazard. On 24th September 2008,a total of 72 debris flows were triggered by heavy rainfall in the central part of the epicenter region affected by the Wenchuan Earthquake. The Beichuan County in the central epicenter region is chosen for analyzing the change of debris flow source area after the earthquake and also following a rainstorm. Significant differences after the earthquake are noticed in producing a large amount of landslides for debris flow occurrence. Interpretations of aerial photographs and SPOT images as well as field investigations are used to identify landslide occurrences in the debris flow watershed for exploring the initial conditions triggering debris flows. Comparison of the aerial photographs taken on 18th May 2008(after the 512 Wenchuan earthquake) with the SPOT 5 images taken on 14th October 2008(after the rainstorm event on 24th September 2008)indicates that the landslide area in eight debris flow watersheds increased from 1537×104 m2 to 1912×104 m2 during that period of time. Measurement of the SPOT images reveals that the loose sediment areas on the channel beds had further expanded to 97×104 m2 after the rainstorm. The present results show the Wenchuan Earthquake affected area is particularly susceptible to debris flow occurrence after heavy rainfall events．