土壤侵蚀动态监测中的高分辨率影像土地利用解译精度分析

Accuracy analysis of land use interpretation of high resolution image in soil erosion dynamic monitoring

土壤侵蚀与土地利用有很大的相关性,土地利用直接影响土壤侵蚀的形式、空间分布和强度。高分辨率遥感影像是土地利用状况调查的主要信息源,是准确掌握土壤侵蚀动态的基础和前提。为进一步提高高分影像解译土地利用类型的判读正确率,全面支撑县域土壤侵蚀动态监测和水土保持规划,以河北省怀来县为例,基于高分影像解译和野外抽样调查获取的土地利用信息,将野外抽样调查所得的土地利用结果作为真值,从整个县域和抽样调查单元2个层面,通过土地利用变化转移矩阵,对比分析了遥感普查所得土地利用的类型、面积和分布等。结果表明:1)除园地和灌木林地比例相差较大之外,其他土地利用比例相当,因此遥感普查与野外抽样调查2种方法所得的土地利用结构具有较好的一致性;2)遥感普查土地利用的耕地、园地和草地精度较高,分别为85.3%、91%和89%,林地次之,为78.6%,灌木林地和其他土地再次之,分别为68.2%和64.2%;3)遥感普查灌木林地的解译正确率偏低,只有68.2%,是由于灌木林地和草地容易混淆导致误判,灌木林地误判为草地的比例高达30.5%。2种方法都可以作为获取土地利用信息的可靠手段,而且高分遥感影像在大比例尺水土流失调查与制图中具有较高的使用价值,灌木林地和草地二者之间的误判还需在解译时多加注意,可从纹理与明暗的分析,野外实地调查的增加和影像处理技术等方面提高其判读正确率。本文的研究方法及其结果,为提高土地利用高分遥感影像解译精度提供了定量的依据,为土地利用信息获取提供了可参考的技术路线与方法,对县域土壤侵蚀动态监测和水土保持规划具有重要意义。

[Background]Soil erosion has a great correlation with land use,and land use directly affects the form,spatial distribution and intensity of soil erosion. High resolution remote sensing image is the main information source of land use status survey,and it is the foundation and precondition to accuratelygrasp the dynamic soil erosion. The purpose of this study is to improve the interpretation accuracy of land use types for high-resolution images. [Methods] Comprehensively supporting soil erosion dynamic monitoring and soil and water conservation planning in county-level,this paper took Huailai county of Hebei province as the study case,and land use information was obtained based on high-resolution image interpretation and field sampling survey. The land use results by the field sampling survey were taken as actual values,and the types（ Cultivated land,garden plot,forest land,shrub land,grass land,and other）,area and distribution of land use by remote sensing survey were compared with the sampling survey unit analyzed by land use change transfer matrix at the two levels of the whole county. [Results]1） The proportion of cultivated land in remote sensing survey and field sampling survey was 16% and17. 1% respectively,with a difference of 1. 1%; the proportion of garden plot was 21. 8% and 10. 7%respectively,with a difference of 11. 1%; the proportion of forest land was 16. 5% and 8. 9%respectively,with a difference of 7. 6%; the proportion of shrub land was 14. 6% and 33. 9%respectively,with a difference of 19. 3%; the proportion of grass land was 18. 4% and 15. 5%respectively,with a difference of 2. 9%; the proportion of other land was 12. 7% and 13. 9%,with a difference of 1. 2%. In addition to the far different proportion of garden plot and shrub land,the proportion of other land uses was quite similar,therefore,the land use structure obtained by remote sensing survey and field sampling survey were in good consistency. 2） The precision of cultivated land,garden plot and grass land was higher by remote sensing,68. 2% and 64. 2%,respectively,and the forest land was in second,78. 6%,followed by shrub land and other land,68. 2% and 64. 2%,respectively. 3） The interpretation accuracy of shrub land by remote sensing was low,only 68. 2%,and it was because shrub land and grass land were easily confused so that led to misjudgment,the proportion of the shrub land misjudged to the grass land reached 30. 5%. [Conclusions]Both methods can be used as reliable means of obtaining land use information,moreover,high-resolution remote sensing images have high value in the investigation and mapping of large scale soil erosion,the misjudgment between the two of the shrub land and the grass land also needs to be paid more attention to the interpretation,the accuracy of interpretation can be improved from the analysis of texture and shade,the increase of field investigation and image processing technology.