Propagation Characteristics of Debris Flows Considering Entrainment Effect

Abstract

Background/Objectives: Due to the extreme climate and the localized heavy rain, the frequency of debris flow has been increasing. Therefore, there is a growing expectation for accurate numerical analysis.Methods/Statistical analysis: We present a prediction method that can calculate the propagation length of the debris flow. This analysis indicates the relationship between the potential energy and the propagation length of the debris flow. To study the behavior of the debris flow accurately, the change in the momentum force must be considered; otherwise the calculation accuracy of the debris flow behavior is inevitably low.Findings: Entrainment is a common behavior in a debris flow that leads to changes in the momentum force. Here, we analyzed the change in the momentum force using a 2D simulation model that included entrainment. The results show how the debris flow behaves with changes in the momentum force. When entrainment is considered, the propagation length tends to be underestimated. With detailed information, the uncertainty in the prediction accuracy can be reduced.Improvements/Applications: If studies on the material properties of debris flow would be added, it will be possible to carry out various and accurate analysis of the debris flow

­­Dynamics of rain-triggered lahars and destructive power inferred from seismo-acoustic arrays and time-lapse camera correlation at Volcán de Fuego, Guatemala.

“…Many of the signals observed in our events can be attributed to hydraulic, physical, and rheological characteristics of flows. For example, studies (e.g., Jeong et al 2018;Coviello et al 2019) infer that debris flow seismic amplitudes correlate directly to the energy of the debris flow and the destructive power a flow possesses is due to its mass and velocity. Physical and rheological thresholds also determine the extent of damage.…”

Assessment of Debris Flow Impact Based on Experimental Analysis along a Deposition Area

“…In this study, three levels of flume angle (°) were studied to represent the initiation level of debris flow: high (25°), intermediate (20°), and low (15°) levels. This is based on the fact that the average slope angle of the channel bed at the prospective area for debris flows typically ranges from 10° to 25° [8,20,[32][33][34]. The inclination of the flume is shown in Figure 8.…”

“…Equation ( 1), developed by [20], was used to determine the position and volume of the sediment in the flume and the size of the deposition board. Three runout distances calculated for three different slopes met the equation with a runout distance of less than 1000 mm.…”

“…Through abrupt changes in the flow volume and its rheological behavior, such entrainment mechanisms have the ability to drastically change the mobility of the flow [1]. For researchers to predict the behavior of a debris flow in this zone, parameters such as runout distance are essential [20]. Efforts to analyze, predict, and evaluate the runout flow are necessary for identifying the hazardous region that can be potentially impacted and determining the intensity of the disaster for hazard and risk assessment.…”