Surface Water Interaction Modelling Using Visual MODFLOW and GIS

PHYLARESApproach and methodology / ch.2__________________________________________________________________________________________4Chapter 2Approach and Methodology2.1 General overview of ModelsModels are a substitute for a real system. Models are used when it is easier to work with asubstitute than with the actual system. Domenico (1972) defined a model as a representation ofreality that attempts to explain the behavior of some aspect of it and is always less complex thanthe system it represents. Wang & Anderson (1982) defined a model as a tool designed torepresent a simplified version of reality. Banks (1993) defines two types of models (1)consolidative: Consolidates facts regarding the system into a single model used as a surrogate tothe real system and (2) exploratory: a series of computational experiments to explore cause andeffect. Bredehoft et.al. Further subdivided ground water models into (1) Data driven exploratorymodels or “history matching” (2) policy question driven models and (3) conceptually drivenmodels.In studying a groundwater flow model we first develop a conceptual model descriptive of thepresent condition of a system. At this stage we identify relevant processes and physical elementscontrolling groundwater flow in the aquifer, namely: the Geologic framework, the Hydrologicframework, the Hydraulic properties, and the Sources & sinks (water budget) and determine datadeficiencies. Conceptual model dictates how we translate the real world to a mathematical Model.To make predictions of future behavior, a dynamic model is needed that is capable ofmanipulation. Mathematical models are one type of dynamic models and use equations torepresent the interconnections in a system. The simplest mathematical model of groundwaterflow is Darcy’s law. To apply Darcy’s law we need to have a conceptual model of the aquiferand to develop data on the physical properties of the aquifer system, the potential field and thefluid properties. The process of formulating and solving a mathematical model is referred to asmathematical modeling. The methods of obtaining the solution to a mathematical model can be______________________________________________________________________________________Groundwater – Surface water interaction modeling using visual MODFLOW and GIS