A physically based FVM watershed model fully coupling surface and subsurface water flows

Abstract

A sophisticated modeling approach for simulating-coupled surface and subsurface flows in a watershed is presented. The watershed model developed is a spatially distributed physically based model of composite dimension, consisting of 3-D variably saturated groundwater flow submodel, 2-D overland flow submodel and 1-D river flow submodel. The 3-D subsurface flow is represented by the complete Richards equation, while the 2-D and 1-D surface flows by the diffusive approximations of their complete dynamic equations. For piecewise integration of these equations, the finite volume method (FVM) is employed assuming unknown variables such as the water depth and the pressure head to be volume-averaged state ones. Problem plane geometry is meshed with the unstructured cells of triangular shape which conforms to external as well as internal irregular boundaries such as those between 1-D and 2-D flows. A cell size controlling scheme, referred to as quasi-adaptive meshing scheme, is introduced to keep the local discretization errors caused by topographic elevation gradient even over the entire-meshed geometry. Performance of the model is tested through its practical application to a rugged intermountain watershed. Tuning the values of the three key parameters ensures successful calibration of the model. Once the model is so calibrated, it could reproduce satisfactory runoff response to any rainfall event. Expansion and shrinkage of the contributing area importantly affecting the direct runoff, caused by the vicissitude of rainfall during its total duration, are well reproduced, like what the commonly accepted runoff theory argues. It is thus concluded that the model developed could serve as a powerful watershed simulator usable for investigating and assessing the hydrological aspect of a watershed.

Modelling the Hydraulic Behaviour of Growing Media with the Explicit Finite Volume Solution

“…Most of the existing models are based on numerical approximations of the Richards equation, which has no general analytical solution. The techniques employed include the Finite Difference method (FDM) [11]; the Finite Element Method (FEM) [12,13]; and the Finite Volume Method (FVM) [14][15][16][17][18]. The use of the FDM and FEM is reported in the literature most frequently, because they offer computational advantages for solving parabolic-elliptic equations, such as the Richards equation.…”

Development of a river flow forecast model by coupling a snow accumulation/melt model with a distributed run‐off model

“…In recent years, with the exponential increase in meteorological observation and computing power, it is feasible to apply high‐resolution distributed hydrological models to flood forecasting (Kozan et al ., ; Takeuchi et al ., ). Jacob et al .…”

“…In recent years, with the exponential increase in meteorological observation and computing power, it is feasible to apply high-resolution distributed hydrological models to flood forecasting (Kozan et al, 2009;Takeuchi et al, 2009). Jacob et al (2006) researched the trend of technology used in real-time forecasting and warning systems through experience from recent implementations of more than 40 systems worldwide.…”

Uma Aplicação dos Algoritmos Genéticos e do Método dos Volumes Finitos para Simular o Fluxo da Água na Zona Vadosa

“…A equação de Richards governa o movimento daágua em um meio poroso saturado/insaturado e, em geral, não possui solução analítica. O método das diferenças finitas [5], o método dos elementos finitos [8] e, mais recentemente, o método dos volumes finitos [7,29,35] são os mais utilizados para resolver de forma numérica a equação de Richards. No entanto, uma solução numérica robusta, capaz de propor acurácia e eficiência para problemas multidimensionais, continua sendo um desafio, devido ao comportamento não-linear da equação [15].…”