RESEARCH THE DISASTER BY REMOTE SENSING AND GIS (CASE STUDY THUA THIEN-HUE PROVINCE, VIETNAM)

摘要

Vietnam is situated in the tropical region and has long coastal line. Annually it has to face to the flood, typhoon, big tide..., which damage the houses, crops and kill the people also. It's put the duty to prevent those disasters. The 0 m. of sea level defined in geodesy is not always coincident with the boundary between seawater and land. So we can not to point out in the imagery wherever Ae 0 m. of sea level or boundary between seawater and land. The Landsat or SPOT imageries focus one region on the Earth at the same time for example: the Landsat passes the Vietnam territory during 9h30'-10h00, the SPOT: 10h30'-l lh00'. By that time, the tide is up, it means the seawater level is higher than 0 m. level but the change of coastal line between imageries of different days can be considered as the change of coastal line. That why we can say: The results of image analysis of the periods 1973-1997-2000 in the coastal zone of Thua Thien -Hue show us the coastal change likes: erosion or deposit... due to flood, wave, tide... As the remote sensing used in this study are from different sources (SPOT, Landsat, SOYUZ) we have to transfer them to unique base other way we have to standard the remote sensing data. Based on it and use the GIS we can calculate the areas of each object and evaluate the change. That's important to forecast some disasters and take the necessary measurements to limit the damage.