The report, a part of the regular work programme of the Flood Studies Division of the National Institute of Hydrology presents a literature review on modeling debris flow. Occurrence of debris flows is a common natural phenomenon and denotes the rapid flow of debris with sufficient water to disperse grains uniformly throughout the entire depth. Dam break flows, landslides and flows in a mountainous terrain are some of the examples.
Two main characteristics of debris flow are high velocity and presence of wave front. Though it is a type of open channel flow, the wide range of variations in particle size distribution and their concentrations make it different. The Newtonian fluid approach is no more valid as the flowing debris is a non-homogenous and non-Newtonian fluid. The rheological properties of the debris are different. Therefore, estimation of the bed friction will be different unlike the case of ordinary open channel flows for which empirical relations (Manning formula, Chezy formula, Darcy-Weisbach formula) for bed friction are available.
Analysis of debris flows can be performed by experimental modeling and mathematical modeling. However, the rheological characteristics can only be found out by laboratory measurements. Some key issues in debris flow study are quality and quantity of data, categorisation of debris flow, field measurements of flow and evaluation of unsteady bed friction.
A systematic study by modeling of this flow is important to analyse the phenomenon and for implementing successful disaster management schemes associated with this. The report also presents the use of DAMBRK model for debris flow study.
The following studies may be useful in future:
- Numerical modeling of debris flow using two-dimensional Saint-Venant equations.
- Observed data for case study in India for validating the numerical model.
- Computations using DAMBRK.
- Sensitivity analysis of rheological parameters.
Download the report here: