基于Kriging估计误差的县域耕地等级监测布样方法  

Sampling method for monitoring classification of cultivated land in county area based on Kriging estimation error

作　　者：杨建宇[1,2] 汤赛[1,2] 郧文聚[3,2] 张超[1,2] 朱德海[1,2] 陈彦清[1,2] 

机构地区：[1]中国农业大学信息与电气工程学院,北京100083 [2]国土资源部农用地质量与监控重点实验室,北京100035 [3]国土资源部土地整治中心,北京100035

出　　处：《农业工程学报》2013年第9期223-230,F0003,共9页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国土资源部公益性行业科研专项:耕地等级变化野外监测技术集成与应用示范项目(201011006-4和201011006-5)

摘　　要：为了监测耕地的质量等级,通常采取抽样调查的方法。由于空间样本间存在不独立性等原因,传统抽样方法效率低、精度不高。为此,该文提出基于Kriging估计误差的布样方法,定义了反映Kriging估计情况的统计量作为评估监测网的标准,通过分析样本量与抽样精度的变化趋势确定最优样本容量,将调整过的方形格网作为监测网的基础,在泰森多边形限制下对监测网优化增密,并选用部分标准样地作为监测点。以北京市大兴区为例对该方法进行验证,结果表明,当监测点数同为48时,该文方法均方根误差小于简单随机抽样、分层抽样以及单一使用格网布样的方法,预测总体均值的相对误差为0.07%。因此,该文方法使用较少的监测点反映县域耕地等级的分布状况和变化趋势,能够满足县域耕地等级监测的需求。China, an agricultural country, has a large population but not enough cultivated land. Until 2011, the cultivated land per capita was 1.38 mu （0.09 ha）, only 40% of the world average, and it is getting worse with industrialization and urbanization. The next task for the Ministry of Land and Resources： Dynamic monitoring of cultivated land classification in which a number of counties will be sampled; in each county, a sample-based monitoring network would be established that reflects the distribution and its tendency of cultivated land classification in county area and estimates of non-sampled locations. Due to the correlation among samples, traditional methods such as simple random sampling, stratified sampling, and systematic sampling are insufficient to achieve the goal. Therefore, in this paper we introduced a spatial sampling method based on the Kriging estimation error. For our case, natural classifications of cultivated land identified from the last Land Resource Survey and Cultivated Land Evaluation are regarded as the true value and classifications of non-sampled cultivated lands would be predicted by interpolating the sample data. Finally, RMSE （root-mean-square error） of Kriging interpolation is redefined to measure the performance of the network. To be specific, five steps are needed for the monitoring network. First, the optimal sample size is determined by analyzing the variation trend between the number and the accuracy of samples. Then, set up the basic monitoring network using square grids. The suitable grid size can be chosen by comparing the grid sizes and the corresponding RMSEs from the Kriging interpolation of the samples data. Because some centers of grids do not overlap the area of cultivated land, the third step is to add some points near the centers of grids to create the global monitoring network. These points are selected from centroids of cultivated land spots which are closest to the centers and inside the searching circles around the centers by a loop algorithm. The fourth

关 键 词：土地利用 等级 监测 耕地 空间抽样 泰森多边形 KRIGING 

分 类 号：F301.21[经济管理—产业经济] S126[农业科学—农业基础科学]