基于RS和GIS的2008年长江中下游雪灾监测——以湖北省为例

2008年1月中旬至2月初，我国长江中下游地区出现了大范围持续低温、雨雪、冰冻天气气候事件，造成了特大积雪灾害。以湖北省为例，基于RS和GIS技术对这次雪灾进行了动态的监测评估。利用连续多天的卫星遥感资料和积雪深度观测资料，在GIS的支持下，计算归一化差分积雪指数（NDSI），提取积雪分布信息，并根据不同海拔高度，确定了积雪深度的NDSI分层阈值，实现了3层积雪深度(0～10、10～20 和20～30 cm)的判识。针对积雪区内不同的土地利用类型，统计了不同深度的积雪面积。结果表明：湖北省近90%面积被雪覆盖，其中江汉平原、鄂东北和鄂东南等地雪灾最为严重，部分地区积雪深度在20 cm以上；水田、旱地等农业用地以及湖泊、水库、河渠等水系积雪最为严重，居民点用地也有较大范围的积雪，居民生活受较大影响；2月2日以后积雪面积逐日减少，到2月8日，积雪基本融化。在上述研究基础上形成了基于RS和GIS的长江中下游积雪监测的业务流程.

SNOW DISASTER MONITORING IN 2008 IN THE MIDDLE AND LOWER REACHES OF THE YANGTZE RIVER BASED ON RS AND GIS——A CASE STUDY OF HUBEI PROVINCE

From the middle Jan.to the beginning of Feb.in 2008，an extreme weather and climate event with continuous low temperature，snow and sleet had occurred in the middle and lower reaches of the Yangtze River.The event had caused heavy snow disaster.Taking Hubei Province as an example，the snow disaster is dynamically monitored and evaluated based on RS and GIS.Using many days of successive satellite data from EOS/MODIS and observation data of snow depth from Hubei weather stations，the normalized difference snow index (NDSI) was calculated，and then the snow distribution information was obtained with the support of geographical information system.According to different height above sea level，the thresholds of NDSI related to the snow depth at different levels were determined，and then the recognition of three levels snow depth (0~10，10~20 and 20~30 cm) was implemented.Snow areas of different depth in the different land use type were respectively counted according to different land use classification data and snow distribution data.Dynamic monitoring result of the heavy snow disaster process expressly shows that about 90% land areas in Hubei Province were covered by heavy snow，the snow disasters in Jianghan plain，northeast and southeast Hubei were the worst，snow depth in parts of region in Hubei Province was above 20 cm；heavy snow worst affects farm land such as paddy field，dry land and water body such as lake，reservoir，ditch；biggish range in residential areas was also hit by snow；since Feb.2，2008，the area of heavy snow had gradually reduced；after Feb.8，2008，heavy snow almost thawed.Based on the study above，the operation flow of heavy snow monitoring in the middle and lower reaches of the Yangtze River with the support of remote sensing and geographical information system has been formed.