Description |
ANALYT is an analytical model for evaluation of water table changes (build-up or drawdown with respect to reference water-table) resulting from infiltration or discharge in a leaky, unconfined aquifer. The program can be used to compute water table changes due to leaking water mains, over-irrigation, abandoned wells, and drains, among others. Various boundary geometries and conditions are supported, as well as different infiltration or discharge area configurations. Based on a superposition-type modelling technique using numerical algorithms for computing integral equations as analytical solutions for 2D and 3D flow problems. The model simulates: an isotropic or anisotropic, homogeneous water-table aquifer with an impermeable or semipervious layer; different boundary conditions and geometry; and several independent recharge or discharge sources of different geometry, operational time, and flux rate. Includes 12 different analytical solutions by combining one element of each of the following three groups: linear, circular or rectangular source area; aquifer recharge given as an infiltration rate or as "mound levelling"; 2D or 3D flow system. Modelling for complex systems, including variable infiltration rates, different boundary conditions, and several independent sources is based on using the general design equation together with the principle of superposition and coordinate transformation. Boundary conditions are determined by the aquifer configuration and type of boundaries present in the study area. Each source is described by its configuration, size, and location. The model assumes that the existing water table (the reference level) and the lithological contacts of aquifer and aquitard are horizontal. The aquifer thickness is based on the existing water table elevation (prior to recharge), which makes the equations linear and allows superposition. If a hydraulic connection exists between the upper (water-table) aquifer and a lower aquifer through a semi-pervious layer, the hydraulic head in the lower aquifer is assumed to be constant and equal to the reference head in the water table aquifer. |