Flood risk forecsting and disaster countermeasures
information system in the Dongting Lake region
Lu Guonian
Laboratory of Resources and Environment Information System,
Chinese Academy of Sciences, Beijing, China
Wan Qing Dai, Tiefu
Hunan Remote Sensing Centre, Beijing, China
Abstract
In conjunction with the results of remote sensing application experiment to flood risk and disaster development monitoring in the Dongting Lake Region over the years, the paper discusses the design, establishment and application of the Flood Risk Forecasting and Disaster Countermeasures Information System in the Dongting Lake Region (DLIS) as well as other many-sided problems. By means of the analyses of the peculiarities of the regional landscape, the authors have put forward the viewpoint that the spatial logic structure of a geographic database is the combination of the river system in which the lakes form the main body with the polygon of dykes, explored some methods for DEM updating and developed many application analysis models. Practice has demonstrated that the application of the geographic information system (GIS) in regions can on one hand provide new technical method for flood prevention and disaster relief, and on other hand promote the development of GIS itself.
Introduction
Dongting Lake, the second largest fresh water lake in China, is situated in the middle reaches of Changjiang River. However, for a quite long time, siltation of mud and sand in addition to the building of dykes for flood prevention purpose and the reclaiming land from the lowland has led to rapid reduction of the lake area and lake storage capacity and to the ever increasing deterioration of the flood diversion and flood storage function, hence the frequent occurrence of flood disasters and the tendency of the increased frequency. With flood passing the region during each flood season, serious losses result from the floods outside the dyke surrounded area (DSA) and the water-logging inside it. Take the special big flood in 1954 for example, the dykes broke in 356 spots within the Region with 3, 849,000 mu of the cultivated land submersed and the area of the cultivated land suffering water- logging being 1, 533,000 mu;at that time, 3300 people drowned, and 30,000 people died of the following pestilence. In the year of 1983, which was expected to be a normal water year, a rare flood occurred with the flood water stage even higher than that of 1954 in many places of the Region. Consequently, the broken dykes amounted to 145 spots with 288, 000 mu of the cultivated land submerged and the area of the cultivated land suffering the disaster effects being 1, 380,000 mu. It can be seen that the regional planning for flood prevention purpose in the Region has become an urgent task for the present. Owing to the considerable investment and long cycle needed by building engineering projects for flood prevention as well as some adverse effects which might be produced, the execution of the non-engineering measures for flood prevention is being sped up. The establishment of the DLIS is an important aspect of the job, which bears important significance to the timely grasping of information of flood risk and disaster development by the flood control departments, to the important decision making with relation to flood control and disaster relief work as well as to the guarantee of the safety of the people's lives and properties, and will also produce profound influences on the environmental management of the Region, maintenance of ecological balance and creation of benefits to future generations.
