Exacerbation of Hydrologie Events due to Anthropogenic Causes in Arid Zones

Pino E.; Kuroiwa J.M.; Chavarri E.; Chuan W. · Proceedings of the IAHR World Congress (2022) · DOI: 10.3850/iahr-39wc2521716x20221674

Resumen

The effect of built structures on the outcome of extreme climatological events in an arid area is discussed. Devil's Creek, located on the northern end ofthe Atacama Desert, had been inactive for approximately 93 years. In recent years, an increase in precipitation has caused casualties and extensive property damage in several towns of the region. Devil's Creek encompasses 52.84 km2, is 24.3 km long and its average slope is 5.1 %. Road crossings were built along Devil's Creek. One of them, Camiara Pass, completely blocked the stream with a 13-meter-high embankment. When precipitation fell in the middle basin of Devil's Creek the embankment dammed the flow, and it was eroded away by overtopping thus generating a dam break. The creek's mouth and alluvial fan were partially settled without municipal authorization. Three people were dead, and 1945 homes, public buildings and city infrastructure were affected by the flood. This event was reconstructed using a hydrologic semi distributed simulation tool and a 2D hydraulic numerical model. The incoming peak flow for the February 21, 2020, event was estimated at 10.72 m3/s. Simulations showed that for the no embankment condition damage to people and property may have been significantly less severe that for the event with embankment and dam break. It was concluded that the road crossing embankment exacerbated the effects of flooding downstream and that local and regional authorities should not allow the construction of embankments along the creek. In addition, human settlements near the creek's mouth should be relocated.

Instituciones: Universidad Nacional Agraria La Molina; Universidad Nacional de Ingeniería; Universidad Nacional Jorge Basadre Grohmann