Open Journal of Geology, 2013, 3, 50-54

doi:10.4236/ojg.2013.32B012 Published Online April 2013 (http://www.scirp.org/journal/ojg)

A Method for Setting the Artificial Boundary

Conditions of Groundwater Model

Yipeng Zhou1,2, Zhaoli Shen1, Weijun Shi2, Jinhui L iu 2, Yajie Liu2

1School of Water Resources and Environment, China University of Geosciences, Beijing, China

2Department of Civil and Envir onmental Engineerin g , East China Institute of Technology, Nanchang, China

Email: zyp721@163.com, wjshiecit@163.com

Received 2013

ABSTRACT

Numerical simulation technolog y is nowadays an important means for groundwater issues because of its efficiency and

economical advantages. But in case of natural hydrogeological boundaries are not within the interest area, it may be a

big trouble to set boundary conditions of the model artificially without enough field investigation information. This pa-

per introduced a method for solving such problem applying field pumping test and recovery test. The method was ap-

plied to build an in-situ leaching of uranium model. Results show ed that the model boundary conditions can be set sat-

isfactorily, and also the calculated heads matched the observed data well in both two models.

Keywords: Groundwater; Numerical Model; Artificial Bound ary Conditions

1. Introduction

Since the 1960s, with the development of computer

technology, the method of numerical simulation had been

widely used to solve groundwater flow and solute trans-

port problems because of its effectiveness, flexibility and

relatively economical with spend, and gradually become

an important method for groundwater issues [1-7].

However, although lots of models have been built in

various applications, few people care about the real ef-

fects of those models in practices [8]. One of important

factors influencing the reliability of the groundwater

model is geology and hydrogeology investigation; and

usually making reasonable understandings on boundary

conditions is a big challenge [9]. Once the boundary

conditions are distorted to the truth, it is bound to lead to

significant deviation of the model calibration parameters

from actual values, and then serious impact on the reli-

ability of the mo del would not be avoided.

Model boundary conditions are usually set according

to field investigations. When the interest area is small

that the model boundaries are far away from natural hy-

drogeological boundaries, artificial model boundary con-

ditions need to be set according to a long-term observa-

tion of groundwater at those boundaries. However, in

many cases, the required observation data are often un-

available; in this dilemma, one alternative way is to ex-

pand model extent so that the groundwater can be as-

sumed not to be affected by human activities (such as

pumping test) taken placed in the interest area; then the

boundary conditions of first type or of second type can

be set at model’s boundaries [9]. Bu t this kind of so lu tion

also has shortcomings, one of which is that to estab lish of

model hydrogeology configuration beyond the interest

area without supplementary geology investigation infor-

mation may bring unexpected serious error to the simula-

tion results [10,11]. In this pap er, in order to build a flow

model of groundwater and leaching solution during in-

situ leaching of uranium process, a method has been em-

ployed to set artificial model boundaries by combining

theoretical calculation according groundwater unsteady

flow theory and the model iterative calibration using ob-

servation data of pumping test and recovery test inde-

pendently.

2. Methods

2.1. Basic Principles

The basic principle is using field pumping test and re-

covery test to calibrate the model parameters and bound -

ary conditions simultaneously. First, get the head draw-

down function derived from Jacob formula of ground-

water unsteady flow at the boundaries located within the

cone depression; Then set initial heads generalized from

the head drawdown function of the model boundaries for

model building and calibration; finally, calibrate model

parameters and boundary conditions iteratively using the

observation data of pumping test and recovery test inde-

pendently and then make the results fit the facts to the

most degree.

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