Temporal and Spatial Analysis of Water Extent in Poyang Lake using HJ-1 data

Temporal and Spatial Analysis of Water Extent in Poyang Lake is significant to reveal ecological environment evolution and drought formation mechanism and the influence in the Poyang lake basin. Water extent is the key index to characterize the scale and intensity of drought disaster. The seasonal water change of Poyang Lake is obvious. There is high landscape heterogeneity because the terrain features distribution is highly complex and discontinuous in the dry season. At the same time spectral characteristics of water and its surroundings are complicated in that the microscopic formation mechanism of water is complicated. It is difficult to perform water information extraction. The commonly used water information extraction methods such as classification method, image segmentation method, threshold method, region growing method can´t meet the requirements on the efficiency and accuracy. In this paper, Water information extraction and validation of 2011 was performed using HJ-1 CCD data based on decision tree method. Then temporal and spatial analysis of water extent was performed. At last, the relationship between the water extent and disaster loss information was analyzed. The results indicated that the decision tree method significantly improved the efficiency and accuracy compared to the traditional classification method and visual interpretation. It spent 2 hour in extracting water of dry season which need 2 days using visual interpretation method. The accuracy of the method was 94.5 percent of the accuracy using visual interpretation. It can meet the requirement of disaster reduction and solve the problem in dynamic extracting water extent of high landscape heterogeneity. There is high correlation between the temporal and spatial change of the water extent and the drought event.