Evaluation of flexible barrier and sabo dam to control effects of debris flow in Santo Domingo Ravine

Abstract

The coast of Peru is characterized by the presence of ephemeral creeks, which drain water only during the wet season. The extremely dry soil and pebbles combined with precipitation produces debris flows in a seasonal geodynamic. This is the case of Santo Domingo ravine, which is located at eastern Lima and drains its water to Rimac River. In this article, the vulnerability of villages near to Santo Domingo ravine by debris flow and use of flexible barrier and sabo dams are analyzed. In the first stage, the liquid hydrograph of a 100 year return period was built, and a solid hydrograph, a relationship between volume concentration and time, was essayed. Then, both the liquid and the solid hydrograph are calibrated in a debris flow numerical model, and the vulnerability map is built. Finally, this model is coupled to the Rimac River to analyze the possible damming effect. Calibration of a numerical model was done in base to previous estimated volumes by the Japanese International Cooperation Agency (JICA). These first results permitted the definition of high-vulnerability zones, which will be a reference to evaluate efficiency of control measures. In a second stage, mitigation effects of flexible barriers application is simulated in base to Debris Flow Barrier from Geobrugg®. Also, the application of sabo dams was evaluated to by using “Kanako” debris flow simulator from Laboratory of Erosion Control, Division of Forest Science, Graduate School of Agriculture, Kyoto University, & SABO Technical Center. Results permit researchers to evaluate efficiency and select the most economical option.