Taiwan is located in a subtropical region and issusceptible to typhoons and torrential rains during the summer seasons.Taiwan is also located on actively shifting tectonic plates that can cause dramatic terrain changes.Taiwan’s river terrain frequently sustains substantial changes

especially after typhoons and torrential rains.Presently

digital terrain maps or models made by airborne LiDAR technology are reliable

have sufficient resolutions

are accurate

convenient

and can filter out buildings or tree cover to restore the original ground topography.This type of map or model can meet the requirements of geological and topographical analysis studies.In 2008

the Lanyang River region experienced four major typhoon events:Kalmaegi

Fung-Wong

Sinlaku

and Jangmi.These typhoons changed the riverbed terrain dramatically.Therefore

we used two occasions of digital terrain data measured using the airborne LiDAR system to conduct analytical comparisons of the riverbed terrain and river sediment transportation changes before and after typhoon events.The study is the first of its kind to demonstrate the excellent applications of the airborne LiDAR system for measuring river terrains in a large watershed area;digital terrain data were produced for periods before and after a typhoon season.We used the elevation difference topography measurement method to calculate river terrain changes before and after a typhoon season.This study’s results showed that the airborne LiDAR high resolution digital terrain model data produced excellent results when used to calculate river terrain and sediment volume changes or change amounts.