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Data Assimilation in Groundwater Modeling
Published in Surendra Kumar Chandniha, Anil Kumar Lohani, Gopal Krishan, Ajay Krishna Prabhakar, Advances in Hydrology and Climate Change, 2023
Groundwater models are set of mathematical equations that mimic the natural groundwater system. Models help water managers in multiple ways to help understand the natural processes and enabling impact assessments. Models are useful to investigate the response of groundwater system under certain conditions, or to predict/hindcast the system behavior under anthropogenic or natural changes in groundwater recharge/abstraction, land scape, climate and hydrogeology. A verity of groundwater models have been developed in the past. Among these models, the physically based process-driven models remain the most widely used. These models use simplified laws of fluid dynamics and mimic the natural groundwater system utilizing various properties and parameters of the aquifer system. These models allow to handle the heterogeneity and anisotropy by discretizing the study domain into several spatial grids. Similarly, the temporal variations of aquifer stress can be considered by discretizing the temporal domain into several stress periods. The complex multidimensional flow equations are typically solved in these models utilizing numerical solution techniques, such as finite-difference method (FDM) and finite-element method (FEM).
Modelling Groundwater Flow in a Confined Aquifer with Dual Layers
Published in Abdon Atangana, Mathematical Analysis of Groundwater Flow Models, 2022
Disebo Venoliah Chaka, Abdon Atangana
Aquifers have been divided into different types, based on the geology and the existence or non-existence of the water table, as confined, unconfined, and leaky (Fetter, 1994). The aquifer is typically confined and has two types of layers in the saturated layer. These layers are classified as separate quantities because they have different lithologies and therefore cannot be simplified or reduced to one homogeneous layer. There are different types of groundwater flow conditions, which depend on the behaviour of water in certain situations, usually how it enters a system and how it exits the system. There are steady state, unsteady state, and pseudo-state flows. The modelling of groundwater was developed to conceptualize hydro-geological processes as well as to analyse information from the field by providing a quantitative framework. According to Wang and Anderson (1982), models are described as a “representation of the complex nature of the world”. The most common purpose of a groundwater model is to predict the behaviour of some hydrological actions and can be used to model conditions that occurred in the past (as hindcasting and as interpretative tools).
Groundwater Remediation
Published in Kathleen Sellers, Fundamentals of Hazardous Waste Site Remediation, 2018
Pumping induces groundwater flow to a well, imposing an artificial hydraulic gradient and creating a cone of depression in the water level around the well, as shown in Figure 3.3. The decrease in the water table or head caused by pumping is called drawdown. The pumping rate and the radius of influence of each well can be estimated by mathematical models of groundwater behavior and/or by pumping tests. Two- and three-dimensional simulations of the effects of a network of monitoring wells require computer models. “Real world” systems contain many complicated variables which cannot be readily modeled. Simplifying assumptions must be built into groundwater models in order to make the models manageable. In general, models of the flow from an extraction well assume equilibrium conditions and assume ideal, homogenous aquifer conditions. As a result, they only approximate the performance of a pumping system under actual (nonequilibrium, nonideal, non-homogeneous) conditions. Developing a practical design from model projections requires considerable professional judgment.
Groundwater flow modeling for cachar, India using MODFLOW: a case study
Published in ISH Journal of Hydraulic Engineering, 2022
Mrinal Kumar Singh, Susmita Ghosh
Groundwater models are mathematical representations of groundwater systems. It includes several assumptions and simplifications made simpler and capable to deal with various specific purposes. Groundwater model development involves a stepwise process. The first step is to choose the hydrogeological process which is to be simulated; then, selection of law and mathematical formula for this hydrogeological process; then, formulation of mathematical equation for this and the last step is an approximation of this equation using analytical or numerical methods (Kumar and Singh 2015). In this study, groundwater model was developed for flow simulation in the aquifer system. The governing partial-differential equation for the three-dimensional flow of groundwater of constant density through porous earth material is described in eq.1 (Todd and Mays 2005).
The social construction and consequences of groundwater modelling: insight from the Mancha Oriental aquifer, Spain
Published in International Journal of Water Resources Development, 2019
David Sanz, Jeroen Vos, Femke Rambags, Jaime Hoogesteger, Eduardo Cassiraga, Juan José Gómez-Alday
A groundwater model is a conceptual and mathematical representation of a real groundwater system (Anderson, Woessner, & Hunt, 2015). To analyze groundwater models, we suggest that these models have a structure that is formed by a set of factors (e.g. inputs, computational relationships, parameters and outputs/outcomes), and choices are made regarding those factors, which lead to specific model outcomes that, in turn, have social, economic and environmental consequences when used in policy making. Apart from standard modelling practices and practical feasibility, these choices depend on factors such as the objectives of the model, its desired outcomes, the stakeholders involved, data availability and time, funding, and the expertise of the model makers.