DEBRIS FLOW MODELING FOR RISK ANALYSIS IN LOS CÓNDORES CATCHMENT, CHACLACAYO, LIMA, PERU

This research work aims to model the debris flow of great magnitude that was presented on January 16, 2017, for the risk analysis in Los Cóndores catchment, Chaclacayo district, Lima - Peru. The modeling process is performed using the Debris Flow module of the RAMMS model (Rapid Mass Movement Simulation) that allows modeling the debris flows for risk analysis. The main input of the model is the Digital Elevation Model, which was generated from the imagery of the PeruSAT-1 satellite through the semi-global matching method with PCI geomatics software; with all this data, it was generated a DEM of 0.7 of resolution.

The soil parameters were determined by tests in a soil mechanics laboratory, the parameters determined were direct cutting tests, soil density, soil granulometry; with these tests it was corroborated that the predominant soil in the area is not very cohesive.

Hydrology and climatology were studied with two rainfall stations, which are the closest to the basin. The analysis of probable maximum rains of 24 hours was carried out, to determine storms at different periods of return, which represented the risk scenarios. Then a hydrological model was generated with the HEC-HMS software to determine the volume of water for each scenario.

Calibration of the model was carried out from a filming of a section of the flow taken on the same day of the event. With this video and information of the study zone, it was possible to calculate the flow and volume of historic debris flow event of January 16, 2017.

Whit this model, it is possible to reproduce the simulation of five risk scenarios for Los Cóndores catchment that depend on probable maximum rainfall of 24 hours for different return periods. According to the results obtained, the RAMMS model is an appropriate method for debris flow modeling for risk analysis, through which risk scenarios are generated by debris flow for risk management.

Keywords: Debris flow, huaycos, PeruSAT, risk analysis, RAMMS.