Dataset for UAV-Based Quantification of Lahar Channel Dynamics at Volcán de Fuego, Guatemala

Abstract

This study quantifies erosional and depositional processes for secondary lahars at intermediate distances (~5-10 km) from the summit of Volcán de Fuego, Guatemala over the 2021 rainy season in the Las Lajas drainage. Volcán de Fuego in Guatemala erupts pyroclastic material in small Strombolian eruptions occurring every ~10 minutes as well as during paroxysmal eruptions producing larger pyroclastic currents at intervals from months to years. This intermediate distance is commonly where lahars impact infrastructure, agricultural resources, and can threaten local populations. A study region 5-10 km from the summit was surveyed with an Unoccupied Aerial Vehicle (UAV) at semi-regular monthly time intervals. Acquired imagery was processed into time-lapse structure from motion digital elevation models and stitched together to cover the target region. Repeat missions were differenced to find volumetric changes to time lapse digital elevation models. Analysis of morphological changes is binned in 500 m sections to track the evolution of the channel over time. This study’s objective is to determine how much material is mobilized by lahars during a typical rainy season at Fuego (May through October), and how that movement changes the morphology of the drainage. The largest secondary lahar volume changes at Fuego were a net 493 m^3/day loss in the upper reach and a net 438 m^3/day gain in the lower reach. The natural channel constriction and immediate widening of Las Lajas controls the behavior and stability of the stream below that point. Above that point, the channel is downcutting and meandering within an old flood plain, which was filled by a set of pyroclastic currents in 2018 spanning 16 hours with the main phase accounting for 5 hours, causing a diversion from the previous flow path.