Numerical modelling of debris flow and control measurement in colocaya creek

Juan Walter Cabrera Cabrera, Samuel Ismael Quisca Astocahuana

Monday 29 june 2015

17:33 - 17:36h at North America (level 0)

Themes: (T) Flood risk management and adaptation, (ST) Adaptation measures, Poster pitches

Parallel session: Poster pitch: 2I: FloodRisk - Adaption

On the Peruvian coast and mountains, it is quite common to find dry creeks which are activated only in wet seasons. These usually have strong slopes and drag mud and rocks, and produce mudflows and debris flows. These flows converge toward the main drain so that may cause the damming of the river and cause floods over its banks. In this document, we analyze the case of Colocaya creek that joins to Ilabaya river on its right bank forming an alluvial fan where the Ilabaya village is located. At present, materials transported by floods and landslides have reduced the marginal strip of Ilabaya river at the confluence area, and reduced the available area for hauled materials; this results in annual damming of the river and flooding of the population. To mitigate this situation, we propose to build a solid retention pond. The sizing of the pond was optimized using the FLO-2D model and analyzing two scenarios, with and without the project. Rheological fluid parameters to the model were set according to the similarity found between field samples and samples analyzed by O´Brien & Julien. These specimens were collected from natural deposits of mud flows in Colorado Rocky Mountain near the cities of Aspen and Glenwood Springs, USA and were used like precalibrated data set. As a result of the applied procedure, an optimized design of the pond with 6m height was obtained, reducing the cost of structure and the flood risk.