Performance Evaluation of 2D-VPMM and 2DExplicit Schemes for Two-Dimensional Overland Flow Simulation

Abstract

Estimation of overland flow is essential in addressing many hydrological and environmental problems such as flood estimation, soil erosion and non-point source pollution. Modeling of overland flow can be done using the equation of continuity and motion. The literature is replete with modelling of overland flow using one-dimensional flow description. But a one-dimensional model generally may not be able to simulate runoff generation on land surfaces characterized by irregular slopes. To overcome this problem, attention is focused in the recent times on the development of two-dimensional overland flow model. Two-dimensional overland flow modelling require the use of continuity equation describing the flow variation in x and y directions and the flow depth variation in time. Generally simplified forms of the momentum equation describing momentum variation in x and y directions are employed. For all the practical purposes these equations are solved using the numerical methods. One of the solution procedures is based on the two-dimensional explicit finite difference scheme. To address these issues, the present study attempts to develop a computer code for two dimensional diffusion wave (DW) overland flow simulations using the explicit solution scheme (2D-DW-Explicit Model) in MATLAB R2013a software. In case of V-catchment in which two overland flow plane joining the channel at middle of these two planes, the channel routing is carried out by using 1D-VPMM method. The two-dimensional Variable Parameter Muskingum McCarthy method named as 2D-VPMM method which is developed by Perumal and coresearchers (PI of this study is also main contributor in the 2D-VPMM model development) for the simulation of two-dimensional overland flow (Shakya, 2015) and computer code written in MATLAB is used to verify the results by 2D-DW-Explicit Model and to compare the predictive abilities of these two computational schemes. A tilted V-Catchment used by Di Giammarco et al. (1996) and the data collected from the rainfall - runoff study of laboratory catchment of the University of Illinois, Urbana Champaign, USA has been used to verify as well as to compare the results by these two methods. Based on the conducted study, it was found that the 2D-VPMM method is performing better than the 2D-DW-Explicit Model in terms of accuracy and execution time.