Relationship between Solid Concentration and Bed Slope to the Beginning of Movement in Water-soil Mix

Hydrographically, Peru is divided into two large drainages areas: western, which drains its waters to the Pacific Ocean, and eastern, which drains to the Atlantic Ocean. The first one is characterized by semi-arid highlands and an arid coastal band, with few permanent rivers and a large number of ephemeral streams which are activated only in the wet period. The second one is characterized by a tropical climate, with high precipitations and permanent rivers. Semi-arid characteristic is one factor by the occurrence of the natural phenomena that recurrently affect the western Andes of Peru: the occurrence of debris flow, usually known as "huaycos". Huaycos occurs when high-intensity rains fall on a creek causing soil saturation, failure and consequently flow. These phenomena are common throughout the western Andes of Peru however, in recent years, they begin to manifest more frequently in the eastern Andes as a consequence of deforestation processes.

This article presents the study of the initial conditions of the movement for different concentrations of solids of a water-soil mixture at different inclinations in a rectangular steep channel. For this purpose, a channel of 4m length and cross-section of 0.33x0.40m was designed and built, which allows reaching slopes of up to 60% slope. The experimental protocol includes defining an initial water-soil mixture with a weight solid concentration (Cwi), which is placed in the channel and next to modify the slope until it reaches flow. The reiteration of the experiment allows obtaining a set of points and evaluating a possible empirical relationship between variables. The final result shows a logarithmic relationship between variables.

This article is the first advance of much broader development research that aims to improve knowledge of the "huayco" phenomenon for its subsequent application in management and control and mitigation measures.