In periods when insufficient water is available to meet all water rights, junior rights are curtailed, in order of priority date, to provide full supply to more senior rights. Models can be physical, analytical or numerical. A physical model is a physical representation of a larger, more complex system. Examples of physical models are Darcy s cylinder filled with sand and water and the sand and plexiglass ground-water flow model. An analytical model is a mathematical representation of a physical system which can be solved using analytical methods.
Analytical models are highly dependent upon simplifying assumptions.
A numerical model is a discretized representation of a physical system which is solved iteratively using a computer. Numerical models are less dependent upon simplifying assumptions but are highly data and computation-intensive. Numerical models have the advantage of enabling representation of different areas of the physical system using different physical properties. 3-dimensional volume used in a numerical model to represent a discretized portion of a physical system. Numerical models calculate the flows in and out of each model cell balancing with the flows of the surrounding model cells.