Change Detection of Hydrologic Networks Using Landsat Imageries from 1972 to 2013 in Mekong Delta

The hydrologic networks play a paramount significance in paddy rice cultivation. The aerial photographs and satellite images, the latter were acquired from the Multispectral Scanner (MSS), Thematic Mapper (TM), Enhanced Thematic Mapper Plus (ETM+), and Operational Land Imager (OLI) were utilized to extract the fundamental information about the natural rivers and manmade canals over the past forty years from late 1972 to early 2013 in three districts which belong to Long An Province in Mekong Delta, Vietnam. The optimal threshold method was used to extract the hydrologic networks from Landsats 1, 5, 7 and 8 images. It was found that the total length of l canals had an obvious increase from 116 km to 2306.8 km through 1972 to 2013. The increment rate was faster from 1990 to 2000 than other ages, which was consistent with the national economic development in Vietnam.