Development of Dam Safety Monitoring with InSAR Time Series Technology

Abstract

Monitoring the safety of dams in Thailand is one of the crucial processes that the responsible authorities should continuously and systematically monitor. Problems due to the displacement of the dam structure and surrounding areas may affect the dam's stability depending on a variety of internal and external factors, including the structural characteristics of the dam. They will damage the water supply system, drainage system, likelihood of dam break, and others. Therefore, dam safety monitoring is an important task requiring surveying techniques with high precision and spatial resolution. Monitoring reduces the cost of time and labour in the survey. As the displacement is a slow process, we used time-series data from Sentinel-1 satellites from January 2017 to January 2022. The data was analyzed by InSAR time series technology, the study site: Mae Kuang Dam, Chiang Mai. The dam is a large Earth Fill (Zoned Type) dam that is very important to Chiang Mai. The dimension includes a height of 68 meters, a dam ridge length of 610 meters, a dam ridge width of 10 meters, and a water capacity of up to 295 million cubic meters. The research results showed that the Mae Kuang Udom Thara dam is slowly subsiding, about -3 to -5 millimetres per year. This subsidence rate could be used as one of the factors to consider with other deformation surveying measurements. In the future, if a more significant displacement is detected, a dam break could occur. Furthermore, the researcher used HEC-RAS 6.0 model to analyze and process flooded areas in 3D and prepare for an Emergency Action Plan (EAP). The warning process is to be developed as standard criteria and guidelines for operations in the next step of future operation.