Chronological Analysis of Wind Erosion of Kitakami Highland using Satellite Images

利用卫星影像对岩手县北上高地的风蚀区进行了识别，并分析了其与环境因子的关系。并对防治风蚀对策的效果进行了人类学分析。为了进行定量分析，对卫星图像进行了几何校正和光照校正。针对利用模拟地形图像进行几何校正的优化方法不能适用于大面积区域的问题，提出了一种改进算法，将场景中心位置的偏移作为线性回归函数进行建模。通过新算法，整个北上高地被卫星图像无缝覆盖。在光照校正方面，我们采用了改进的余弦法，得到了阴影起伏较小的图像。由于研究区地表高度较高，我们没有进行特殊的大气校正。利用校正后的卫星影像w . More进行土地覆盖分类：首先利用金字塔连接法对影像进行空间分割，然后利用K-Mean方法对片段进行聚类，最后将影像划分为5类：(1)侵蚀土、(2)毛土、(3)草地、(4)森林。*****利用年龄分析其与以下环境因子的关系：(a)地表高程，(b)坡角，(c)坡向角，(d)向西开阔度，(e)西部有无森林，(d)春季太阳辐射。分析各因素对侵蚀速率的影响，并将各因素纳入广义线性模型。分析表明，森林的存在是冬季抵御西风的最重要因素。确定侵蚀区有一定的困难。例如，从卫星图像上看，超过35度的陡坡和哈亚廷山的岩石峰顶看起来像是侵蚀区。这些地区被小心地从侵蚀类别中剔除。然而，利用卫星图像识别大面积侵蚀区域被证明是非常有效的，我们发现了一些迄今为止尚未确定的侵蚀区域。少

In this research, wind erosion areas in Kitakami highland of Iwate Prefecture were identified by using satellite images, and its relationship with environmental factors was analyzed. In addition, the effect of counter measures for wind erosion prevention were cholonologically analysed.For quantitative analysis, the satellite images were carefully processed with geometric correction and illumination correction. As the optimization method for geometric correction using simulated relief image cannot be applied to wide area, we proposed a modified algorithm, which model the shift of scene center position as a linear regression function. By using the new algorithm, the whole Kitakami highland was covered by the satellite images seamlessly. For illumination correction, we applied the modified cosine method and obtained the images with less shading relief. We did not apply any special atomospheric correction because of high surface altitude of the study region.The corrected satellite images w … More ere used for land cover classification : first the images were spatial segmented by using pyramid linking method, then the segments were clustered using K-Mean method, finally they were classified into five categories : (1)eroded soil, (2)bair soil, (3)grass, (4)forest *****ages were used for analyzing its relationship with following environmental factors : (a)surface elevation, (b)slope angle, (c)aspect angle, (d)openness to the west, (e)forest existence on the west, (d)solar radiation in spring. Each factor was analysied for its effect on the erosion rate, and all factors were incorporated into the generalized linear model. The analysis revealed that the forest existence was the most important factor, which prevent the west wind in winter.There was some difficulties to identify the erosion area. For example, acute slope of more than 35 degree and the rocked summit of Mt.Hayatine looked like erosion area from the satellite image. These areas were carefully eliminated from the erosion category. Utilization of satellite images, however, was proved to be very effective to identify the erosion area over a wide region, and we found some erosion area which had not been identified so far. Less