专题制图仪影像分析湖区水位变化对钉螺孳生分布的影响

The impact of water level changes on distribution of snails around lake areas reacted by thematic mapper images

目的探索水位变化对湖区钉螺孳生分布的影响，并初步探索利用遥感影像反映水位信息预测螺情变化趋势的可能性。方法收集1997-2007年星子水文站的水位资料，以及鄱阳湖区1998-2006年间的12景专题制图仪（thematicmapper，TM）图像，采用校正的归一化水体指数（MNDWI）阈值法提取水体面积，分析其与水文站水位之间的相关关系；2007年选取星子县渚溪村马家湾及门前滩作为研究现场设框查螺2991框，并收集其1998--2006年螺情资料，分析其与水位之间的相关关系。结果根据1998--2006年问的12景遥感影像提取的鄱阳湖区水域面积在1658．73～5873．48km。之间，相应的星子水文站当日水位在9．96～21．72m之间，经相关分析，两者之间呈正相关，r=0．96（P〈0．01），两者之间建立模型为S：5189．96×In（h）一10284．97；1998—2007年渚溪村活螺框出现率在28．33％～77．46％之间，1997--2006年星子站8月份月平均水位在13．19～21．96m之间，年最高水位在15．97～21．96m之间，经相关分析，渚溪村活螺框出现率与相应的星子站上一年度8月份月平均水位及年最高水位间均呈负相关，r值分别为-0．69（P〈0．05）及-0．77（P〈0．01）。结论遥感影像提取的水域面积可以很好地反映实际水位变化情况，而查螺前一年的年最高水位变化影响着钉螺的分布，从而推断可根据遥感影像判断湖区钉螺孳生分布的变化状况。

Objective To study the impact of water level changes on the distribution of snails around lakes, and to study the possibility of forecasting the distribution of snails according to changes of water level reacted by remote sensing images. Methods All information including water level information of Xingzi Hydrometric Station from 1997 to 2007, twelve TM images of Poyang Lake between 1998 and 2006 were collected. The water areas of Poyang Lake was extracted by MNDWI threshold approach, and the relationships between water areas from TM images and water level from Hydrometric Station was analyzed ; Majiawan and Menqiantan marshland of Zhuxi village, Xingzi county was chosen as study pilot to set frames and investigate snails 2991 frames in 2007, and the information of snails of this pilot from 1998 to 2006 was collected to analyze the relationships between snails and water level. Results The water areas of Poyang Lake extracted from Remote Sensing images from 1998 to 2006 was 1658. 73 -5873.48 km2, and the corresponding daily water level of Xingzi Hydrometric Station was 9. 96 -21.72 m, according to correlation analysis, they were positive correlation relationship, the correlation coefficient was 0. 96 （P 〈 0. 01 ）, and build a model： S = 5189. 96 x in（h） -10 284. 97; the percent of frames with living snail of zhuxi pilot from 1998 - 2007 was 28.33% - 77.46%, the corresponding monthly average water level of last August was 13.19 -21.96 m, the corresponding highest water level of last year was 15.97 -21.96 m, according to correlation analysis. The percent of frames with living snail of zhuxi pilot was negatively correlated with the corresponding monthly average water level of last August and the corresponding highest water level of last year, and the correlation coefficient 0.69 （ P〈 0.05 ）, and 0.77 （ P〈 0.01 ） respectively. Conclusion Water areas of Poyang Lake extracted from remote sensing images could well express the actual changes of water level, and the highest water level ahead of the year investigating snails influence the distribution of snails, thus we can estimate the distribution of snails around lakes by remote sensing images.