[H-TT17] Environmental Remote Sensing

[HTT17-P13] A Study on the Effectiveness of the Monitoring Frequencies of the Land Use Change

*Yu-Chen Yeh¹, Chi-Farn Chen¹ (1.Center for Space and Remote Sensing Research, National Central University)

Keywords:Land Use Change Detection, Monitoring Frequency

Because the limited slop-land resources have been excessively exploited in Taiwan, the government has developed a large-scale land use change detection program since 1996. This program aims to assist slop-land management using multi-temporal satellite images to regularly discover suspicious illegal land use changes. Firstly, the change detected by satellite images are dispatched to relevant agencies. Secondly, agencies will then perform onsite inspections to verify the legality of land use. At the beginning of the program, the monitoring frequency is irregular. However, the program regularly monitors and detects land use changes every two months since 2014. Then the monitoring frequency is adjusted to every month since 2018. In order to evaluate the effectiveness of increased monitoring frequency, this study uses two different monitoring frequency to perform the evaluation. For effectiveness comparison, we collect 845 illegal change areas from bimonthly monitoring in 2018 and 3,025 illegal change areas from monthly monitoring in 2021. The result shows that the monthly monitoring can detect more illegal land use areas than the bimonthly monitoring. That is because the frequent monitoring can constantly discover the illegal land development in a short period of time. In addition, this study adopts Kernel Density Estimation (KDE) to compare the sizes of illegal land areas detected by different monitoring frequencies. The comparison shows that the distribution of illegal land use areas is about a centering under 500 m² for monthly monitoring and over 1,000 m² for bimonthly monitoring. The smaller areas detected by monthly monitoring implies that the frequent detection is able to discover the illegal land development at an early stage. It is concluded that the illegal land development can be effectively and constantly monitored using multi-temporal satellite images. Additionally, the frequent monitoring can detect the illegal land development early and avoid the irrecoverable damage to the land.