Hydraulic models for the simulation of flow routing in drainage canals

Abstract

<p>In order to design a network of drainage canals, it is essential to consider the excess water from the agricultural land (overland flow) and to evaluate the characteristics of flow routing, such as the flow depths and discharges in the system of tertiary and main drainage canals of various order. In this paper models based on the Saint-Venant equations are presented, simulating the flow routing in a system of drainage canals. In these models, the lateral inflow towards tertiary drainage canals is the overland flow from adjacent fields. The Saint-Venant equations in their complete form (dynamic model) or in simplified forms, such as the diffusion wave equations (diffusion model) and the kinematic wave equations (kinematic model) are numerically solved by using the MacCormack explicit computational scheme which is a two-step predictor-corrector scheme, conditionally stable and convergent. In modeling flow through the system of drainage canals, emphasis was given to the simulation of flow at the junction points of two or more canals by applying the characteristic equations (negative and positive equations) in addition to the mass and energy conservation principles. Applications of the models for the simulation of flow within the system of drainage canals, subject to lateral inflow owing to overland flow, were also conducted in order to study the effect of various parameters of the drainage canals, on the hydrographs’ formation and also on the accuracy of the diffusion and kinematic equations in predicting flow in a drainage network.</p>