Typical mechanisms of natural discharge are evapotranspiration by phreatophytes, springs, and drains to surface water bodies. Pumping is a man-caused discharge. In this situation, changes in water table change the rate at which a surface water body will gain water from, or lose water to the aquifer. A water right is junior to another right if the junior right was established at a later date. 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.