Satellite Imagery-Based Analysis of El Chaparral Hidroelectric Reservoir

Using digital terrain models and satellite images, El Chaparral hydroelectric dam's reservoir was analyzed. In 2010, natural hazards damaged the project forcing its redesign and causing dam's relocation. In 2023, just before inauguration day, due to several cracks on the dike the reservoir was voided with urgency. Government officials were afraid the dam could give away. We used satellite images to understand some issues surrounding this project. First, we look for ways to know if there was any explanation why the location of the dike was changed. A limited set of optical images corresponding to 2009–2011 were analyzed. Then, using SRTM data and the reservoir maximum height of 212 above sea level, capacity curve was built. Subsequently, 66 SAR images from Sentinel-IA satellite, levell, GRD product, from January 2022 to June 2023, were analyzed. Simple image segmentation techniques were used to determine flooded areas. Time Series were constructed allowing visualization of reservoir filling and its subsequent emptying. Finally, many indices were used for both optical and radar images. All those indices have been already established in the literature, such as the water occurrence index, the normalized difference vegetation index, and the normalized differential water index, among others. From these indices it has been possible to obtain some preliminary results about reservoir's behavior.