Spatial Characteristics of Floods over the Sub-watershed of the Mekong River in Northeast Thailand using Multi-temporal RADARSAT DATA

摘要

Spatial characteristics of floods are dependent on the flood producing process in which is under the influence of rainfall variability, geomorphology and human action. Floods in the Mekong, Northeast Thailand, are annual events which occur during the second peak of rainy season with recurrence pattern over the same areas. With the cloud penetrability of RADARSAT data, the chronosequence of flood extents can be performed. This exploration aims to establish spatial characteristics of flood in relation to rainfall patterns, watershed characteristics and the river hydrology. The study area, sub-watershed of the Mekong river, covers an area of about 46,694.49 km~2 and has 28 sub-watersheds ranging in size from 440.78 km~2 to 3,469.86 km~2. The RADARSAT data acquired during the flood events for the years 2001, 2002, 2003, 2004 and 2007 were used to create the flood extents. The recurrence of flood areas was analyzed, based on the 5 years flood extents. We determined the inundation patterns as related to die parameters involved in which are rainfall, hydrology and land characteristics. The results provided the pattern of the flood recurrence and producing process as related to the spatial characteristics. The information obtained is restored in GIS database and can be used for advance prevention of the areas affected.