Digital Computer Representation of a Potential Flow Model of Ground-Water Recharge

Abstract

Artificial recharge or the replenishment of water bearing strata has been practiced in Europe since the beginning of nineteenth century, first in Scotland and France, later in England, Germany, and Sweden. In New Jersey, the Perth Amboy Water Work for more than fifty years has artificially recharged the old Bridge sand of the Upper Cretaceous Age and has derived four to five mgd of water from this source. One of the main purposes of artificial recharge is water conservation. The source of recharge may be storm runoff, river water, water used for cooling purposes, industrial waste water and treated sewage water. What will be considered here is the recharge of water into the ground-water strata. In particular, recharge, through wells, into a uniform ground-water flow will be investigated. Recently constructed waste water plants on Maui and Oahu have been using the recharge method to inject waste water through several wells into the ground-water flow underneath. Subsequently, the waste water is carried out to the ocean with the residual flow. On a design basis, one is interested in the streamline pattern of the resultant ground-water system in the vicinity of the wells. As in the case of the waste water plant, the designer might be particularly interested in the lateral extent of the flow pattern that intersects the coastline, as well as the location of the dividing streamline. The purpose of this study is to write a computer program, whose output will describe the streamline pattern of such a case. For the purpose of illustration, the case of one well and three wells located on a straight line normal to the uniform field and parallel to the coast, will be treated. In order to have a better visualization of the resultant flow field structure, a specially designed program, SYMAP, is used for producing the flow maps. The SYMAP program is available at the University of Hawaii computing center and is written in Fortran IV. It is primarily a computer program for producing maps which graphically depict spatially disposed quantitative and qualitative information and is suited to a broad range of applications.