The Application of a Three-Dimensional Deterministic Model in the Study of Debris Flow Prediction Based on the Rainfall-Unstable Soil Coupling Mechanism

Zhongjun Ma,Shengwu Qin,Shuangshuang Qiao,Junjun Chen,Xiuyu Hu

doi:10.3390/pr7020099

Abstract

As debris flow is one of the most destructive natural disasters in many parts of the world, the assessment and management of future debris flows with proper forecasting methods are crucial for the safety of life and property. So increasing attention has been paid to the forecasting methods on debris flows. A debris flow forecasting method based on the rainfall-unstable soil coupling mechanism (R-USCM) is presented in the current study. This method is based on the debris flow formation mechanism. The density of sediment is introduced as an evaluation index to determine the susceptibility of debris flow occurrence. The forecasting method includes two phases: (1) rainfall and soil coupling and (2) runoff and unstable soil coupling. Scoops3D, a three-dimensional (3D) model for analyzing slope stability, was introduced into the debris flow forecasting method. In order to test the forecasting accuracy of this method, Jiaohe County was selected as a research area, and the serious debris flow disasters attributed to strong rainfall on 20 July 2017 were taken as the research case. By comparing the forecasting results with the debris flow distribution map for Jiaohe County, the method based on the R-USCM is feasible for forecasting debris flows at the regional scale. The application of the Scoops3D model can more reasonably analyze the slope stability than the traditional two dimensional (2D) method and improve the forecasting ability of debris flows.

Highlights

Rainfall-induced debris flow is a mixture of unconsolidated sediment and is one of the most important of all natural hazards, occurring in many areas [1]
According to the rainfall-unstable soil coupling mechanism (R-USCM), the process of debris flow formation can be simplified into two phases: The first phase is the soil on the slope becomes unstable due to rainfall, which provides a sufficient source basis for the generation of debris flows; the second phase is that the unstable soil will form a debris flow when it encounters runoff
Early alerts for areas susceptible to debris flows can be derived from the maps of forecast results (Figure 13)

Summary

Introduction

Rainfall-induced debris flow is a mixture of unconsolidated sediment and is one of the most important of all natural hazards, occurring in many areas [1]. To reduce debris flow-related disasters, the assessment and management of future debris flows that can be achieved through appropriate forecasting methods cannot be overlooked [3]. The current debris flow forecasting methods mostly establish the critical threshold triggering debris flow formation in the study area based on commonly used precipitation parameters [4]. Took Piedmont Region in the northwest of Italy as the study area and determined the precipitation threshold leading to debris flows by studying the statistical relationship between precipitation events and debris flows occurrence [5]. As a region changes, so does the threshold of the rainfall [6]

Methods

Results

Conclusion