遥感技术用于洲滩型血吸虫病流行区钉螺孳生地生态的监测

目的 应用遥感技术探索适于洲滩型血吸虫病流行区钉螺孳生地生态监测的合理指标。方法 选择长江安徽段东至县境内的一洲滩型血吸虫病流行区3个相邻的洲滩作为遥感分析的研究现场。运用Idrisi遥感分析软件对遥感数据进行多波段信息合成并进行计算机非监督分类,计算反映地物绿度和亮度的校正植被指数(NDVI)、穗帽变换绿色植被指数(GVI)和亮度指数(BI)值,结合现场调查情况,对上述各类处理结果进行综合分析。结果 NDVI、GVI和BI能够定量描叙地物特征,不同类型的地物,其NDVI、BI和GVI值有所差异,其中适宜钉螺孳生环境的NDVI、GVI和BI值的95％可信区间分别为0．0522～0．3566、2．4162～28．2672和29．3404～40．3135。结果显示NDVI模型标记出的第5、6类区域为钉螺的主要孳生地,第4类区域为钉螺潜在扩散区域,其NDVI值为0～0．1。GVI模型分类显示钉螺的孳生环境主要为第5～7类区域,第4类区域是钉螺迁移扩散的潜在区域,其GVI值为2～10。NDVI、GVI均显示第2、3类区域暂不适宜钉螺孳生。结论 通过合理分组重新形成的NDVI和GVI指数图不仅能够反映洲滩钉螺孳生地以及钉螺潜在扩散区域的分布范围,而且能够反映洲滩的演变规律,即新生滩地的形成和植被的生长情况。

Ecological surveillance on breeding ground for Oncomelania hupensis snails in the areas prevalent with islet-type schistosomiasis using remote sensing technology

OBJECTIVE: To probe rational indices suitable for ecological surveillance on breeding ground for Oncomelania hupensis snails in areas prevalent with islet-type schisitosomiasis using remote sensing technology. METHODS: Three adjacent islets, prevalent with islet-type schistosomiasis, along the Yangtze River within the boundaries of Dongzhi County, Anhui Province were selected as study field for remote sensing analysis. Multi-spectral data were composed and non-supervisedly classified in computer with Idisi software for remote sensing analysis. Values of the normalized difference vegetation index (NDVI), green vegetation index (GVI), bright index (BI), which reflect the greenness and brightness of landscape, were also calculated. Finally, all the results were comprehensively analyzed, combined with data from the field investigation. RESULTS: NDVI, GVI and BI could depict characteristics of the landscape quantitatively. Values of NDVI, BI and GVI were varied in different types of landscapes, and 95% confidence interval of these values suitable for breeding of snails was 0.0522 approximately 0.3566, 2.4162 approximately 28.2672 and 29.3404 approximately 40.3135, respectively. Classification of NDVI showed that type 5 anf type 6 were main breeding ground for snails, and type 4 with values of NDVI from 0 to 0.1 was potential areas for snail propagation. Classification of GVI showed that types 5, 6 and 7 were main breeding ground for snails, and also type 4 with values of GVI from 2 to 10 was potential areas for snail propagation. Both NDVI and GVI showed type 2 and type 3 were temporarily not suitable for snail breeding. CONCLUSION: Index figures of NDVI and GVI re-formed by reasonable classification could reflect not only breeding ground for snails and range of the areas for snail propagation in islets, but also their evolving rules, i.e., status of new marshland formation and vegetation growth.