4. Sedimentation and Life Expectancy of Lake Amatitlán, Guatemala: Increased Vulnerability Under Future Climate Change

In the last few decades, Lake Amatitlán a highland lake (surface area 15 km², 1,188 masl) located south of Guatemala City, has been severely impacted by human activities. The western basin of the lake (Lago Oeste) receives high sediment loads and huge amounts of untreated industrial and domestic wastewater from the capital. In 2012, a bathymetric survey was conducted in Lake Amatitlán and sediment cores were retrieved to better understand the sediment input and to estimate the lake’s loss in storage capacity over time. The life span of Lake Amatitlán’s western basin, Lago Oeste, was estimated at ~114 years, from 2012, assuming constant annual sediment accumulation rates. A tephra layer in sediment cores was used as a temporal marker to assess the impact of extreme climate events on sedimentation. Our results indicate that in 2010, during the tropical cyclone Agatha, two days after the explosion of Pacaya volcano, sediment loads increased two-fold. It is likely, that future climate change will increase the frequency and intensity of extreme climate events such as tropical storms, heavy rains, and landslides and will consequently impact and enhance sedimentation of Lake Amatitlán. Climate change impacts will be exacerbated by increasing demographic pressures and unregulated settlements in the Lake Amatitlán watershed. Therefore, immediate management actions and adaptation strategies are urgently needed to protect the sedimentation and the disappearance of Lake Amatitlán.