Monitoring of Flooded Area and Water-Volume in Large Lake using Remote sensing/GIS Technology.---A Case Study of Dongting Lake in Changjiang River Basin---

摘要

By using Terra/MODIS satellite images and ground measured water level data in 2002, the dynamic variation of surface water area and water storage in Dongting Lake (Changjiang River Basin, China) was studied. Recently, middle reaches of Changjiang River faces a serious disaster caused by large flooding, which have resulted from cumulative impacts of excessive development in the upper stream. In order to mitigate the flooding and evaluate potential flood alleviation around Dongting Lake flooded, it is necessary to estimate the water volume of Dongting Lake using satellite based monitoring technology. We, at first, divided the whole Dongting Lake into three parts (WDL: West Dongting Lake, SDL: South Dongting Lake, EDL: East Dongting Lake from west side) based on geographical characteristics. Secondly, surface water area was detected according to spectral deference between water and terrestrial area using Terra/MODIS Vegetation-Index (VI) products (Level 3-16 Day). The time interval of monitoring period was 16 days. Thirdly, the surface water area was overlaid on the lake bottom DEM with a grid size of 50m by 50m so that the water level could be calculated. Finally the water storage was obtained by times relevant water depth (difference between water surface elevation and lake-bottom elevation.) with the grid area. The total water storage at Dongting Lake was calculated by accumulating all water column values in the whole lake. By comparing the estimated water level and storage with the measurements in the three parts of the Dongting Lake, we found that there are high correspondences between the two, which implies that our method is an effective approach to estimate water level and water storage of a large lake.