分层抽样法在退耕还林工程水土流失监测中的应用

Application of Stratified Sampling Method to the Monitoring of Soi and Water Erosion in the Land Conversion to Forest Program

在预调查的基础上,运用分层抽样技术,计算出了既定可靠性下,退耕还林工程(陕西富县2002年)造林地监测样点的样本容量。在90％可靠性和92％的估计精度下,退耕还林造林地植被盖度估计值和误差限分别为15．81％和1．2％;在90％可靠性和90．52％的估计精度下,土壤侵蚀强度估计值和误差限分别为1715．14 t／km2和162．595 t／km2。

On the basis of pre-investigation, stratified sampling was applied to determining the quantity of sampling for monitoring at expected reliability for the land conversion to forest program （Fu County）. Given reliability at 90% and estimation precision at 92%, estimation value of the vegetation coverage was 15.81% with its estimation error at 1.2%. Given the reliability at 90% and estimation precision at 90. 52%, the estimation of soil erosion intensity was 1715.14 t/km^2, with its estimation error at 162. 595 t/km^2.