CHARACTERIZATION OF DISTRIBUTION OF FLOATING VILLAGES IN TONLE SAP LAKE AND ITS ESTIMATION BASED ON GEOGRAPHICAL INFORMATION

Many people are living in floating villages on the Tonle Sap lake (TSL), Cambodia. People in the floating villages, who discharge domestic wastewater without any treatment, are recognized as one of the main sources of pollution of the lake water. On the other hand, they should have risk of health problems posed by using polluted lake water for their daily lives. Since the floating villages seasonally move depending on the change in the lake water level, it is difficult to analyze both the pollution load emitted by the villages and the exposure of villagers to the polluted lake water. In this paper, we tried to characterize the location and movement of the floating villages based on water depth and distance from rivers in the flooded forest analyzed from the satellite images. Analyzing Sentinel 2 images from Vega satellites enabled us to identify the floating villages which showed the seasonal movement. The distribution of such mobile floating villages, as well as immobile villages, was highly dependent on the region of the TSL. Mobile villages were frequently found in west and east regions of the TSL. Floating villages in the north region were immobile, while both types of villages existed in the northeast region and the Tonle Sap river connecting the Mekong river and the TSL. The mobile floating villages tended to locate in shallower rivers, which are surrounded by flooded forests, than the immobile ones in the rainy season. This is probably to avoid big waves on the lake which sometimes endanger the villages. In the dry season, the villages moved to the lake, some of which were 1,000 m away from the mouth of rivers. Based on these findings, we proposed a method to estimate where mobile floating villages are likely to be formed in the TSL.