珠江口门海堤堤型的选择

珠江口站地区面临南海、大陆岸线长４５７ｋｍ，遭受洪水。潮汐、台风的影响，河口滩涂 发育迅速，以约１００ｍ／ａ的速度向大海延伸。随着沿海地区的经济发展，滨海－２ｍ高程以上的滩涂的４万ｈｍ＾２正在和将要建堤围垦和开发利用，原有海堤也亟待加固提高，因此，对珠江口门坝有海堤堤型资料进行收集、整理，分析总结，选择经济可行的海堤堤型，具有重要的现实意义。文中收集了珠江口门的几种主要堤型，通过对各种堤基工程地质     

洞庭湖植被对降水的响应

We analyzed the Normalized Difference Vegetation Index (NDVI) from satellite images and precipitation data from meteorological stations from 1998 to 2007 in the Dongting Lake wetland watershed to better understand the eco-hydrological effect of atmospheric precipitation and its relationship with vegetation. First, we analyzed its general spatio-temporal distribution using its mean, standard deviation and linear trend. Then, we used the Empirical Orthogonal Functions (EOF) method to decompose the NDVl and precipitation data into spatial and temporal modes. We selected four leading modes based on North and Scree test rules and analyzed the synchronous seasonal and inter-annual variability between the vegetation index and precipitation, distinguishing time-lagged correlations between EOF modes with the correlative degree analysis method. According to our detailed analyses, the vegetation index and precipitation exhibit a prominent correlation in spatial distribution and seasonal variation. At the 90% confidence level, the time lag is around 110 to 140 days,which matches well with the seasonal variation.     

基于决策树分类技术的遥感影像分类方法研究

以河北唐山为研究区,应用Landsat ETM+影像数据和GIS数据,对决策树分类技术和传统计算机自动分类方法进行了比较。研究表明:决策树与传统自动分类方法相比,分类精度提高了18.29%,Kappa系数提高0.1878。在地形起伏的山区,应用DEM及其衍生数据等GIS数据作为辅助数据可以提高分类精度19.52%,Kappa系数提高0.281;反射率影像分类效果比原始DN值影像的分类效果好,分类精度提高15.86%;缨帽变换在压缩数据量的同时,分类精度有所降低。