ABSTRACT
The steady-state flow toward or away from a well, fracture, or ditch has theoretical as well as practical significance and implications. Physically, steady-state flow occurs either after or before an unsteady-state flow. Initially the groundwater is in the steady state before pumping but after a long period of continuous pumping the groundwater flow approach is in a quasisteady state depending on the geological environment as explained in Chapter 3. Mathematically, the steady or quasi-state provides relatively easier solutions which are special cases for the unsteady state. The practical significance of steady-state flow is due to the simplicity of equations, necessary field measurements, and evaluation of some basic decision variables relating to the discharge, well spacing, design and construction, and pump and piping system. Basic formulations were developed by Thiem (1906) and Muskat (1937) and later supplemented by many investigators. However, all formulations assume ideal aquifer and well behaviors. Computed values are therefore regarded as approximations for natural systems. It is suggested at this point that any result should be related to geology prior to its use in further planning, design, and operation of groundwater resources. The steady-state groundwater flow formulations show how basic variables regarding the well and the aquifer are combined together to determine the consequences of any decision variable. It is also possible to grasp the validity of the basic assumptions and the impact of the final decision variables if some of the assumptions were incorrect. These variables are the discharge, maximum drawdown, or radius of influence depending on the objectives.
