Một số dạng tai biến thiên nhiên ở Việt Nam và cảnh báo chúng trên cơ sở nghiên cứu địa mạo

Abstract

In recent years, the excessive exploitation of resource has led to the natural unbalance, increased natural hazards that caused heavy losses of people and properties. There are many difference types of natural hazard and some of them have close relationship of forming-origin. The most serious hazards in Vietnam often occur in the raining season. Strong rain combines to morphologic characteristics create good conditions to cause landslide, mud-debris flow, flash flood, riverbank and shoreline erosion,... Some geomorphologic signs for recognition and warning base of these natural hazards: the increase of erosion on slope; streams with steep profile cutting down a terrace having very thick weathering crust; river valleys that their bottom shapes are inserted narrow sections; alluvial fans; former rivers; sand bar at river mouth area...