DSM derived stereo pair photogrammetry: Multitemporal morphometric analysis of a quarry in karst terrain

Bukit Merah karst has been deteriorating dramatically over 40 years due to intensifica-tion of human activities as a result of fast rate of lateral urbanization and extensive dimensionalexpansion of surface mining activities for instance, quarrying. Application of morphometric tech-niques to karst landforms provides a quantitative measurement and analysis of the configurationof karst landform variations. The objective of this study is to demonstrate the viability of usingan integrated approach based on digital terrain model (DTM) derived time-series of steriopair aerialphotography for monitoring the long-term geological karst response to environmental changes. Theaerial photo stereo pairs were used to extract digital terrain model of the years 1981 and 2004, whichin turn produced the TIN profiles of selected karst sites in the study area to define the karstmorphology changes and to develop 3D representation and visualization. A detailed visualizationof the karst terrain and its surface changes were represented using 3D virtual reality tool to substan-tiate the impact of surface mining in the Bukit Merah. Topographical characteristics of limestonehills, mountainous areas and flat areas were presented in 3D prospective. The results show thesimulation topographical analysis results have confirmed that there were changes in elevation overthe period from 1981 to 2004 especially in the limestone hill area as detected by the digital elevationmodel. It showed a dramatic variation in elevation has increased over a time interval. This meansthere has occurred an interference with the terrain attributed to human intervention or naturalcauses during the time interval. The result shows that the digital terrain model (DTM) derivedtime-series of steriopair aerial photography is able to delineate the changes in karst topography.