Geoscience Reference
In-Depth Information
OPTIMIZATION MODEL FOR GROUNDWATER
DEVELOPMENT IN COASTAL AREAS
NAMSIK PARK
∗
and SUNG-HUN HONG
Department of Civil and Ocean Engineering, Dong-A University
Hadan-Dong, Saha-Gu, 840, Busan 604-714, Korea
∗
nspark@dau.ac.kr
An optimization model is developed for extraction and management of ground-
water in coastal areas. The model consists of a sharp-interface flow model and
a genetic algorithm optimization program. The flow model can simulate both
freshwater flow and saltwater flow. An objective function is formulated so that
the optimization model can determine not only the optimal extraction rates
and locations but also the optimal control of an intruding saltwater wedge. For
the latter, either freshwater injection or saltwater extraction can be consid-
ered. Impacts on groundwater environment are also considered. The proposed
optimization model provides a versatile and comprehensive tool for developing
and managing coastal groundwater.
1. Introduction
Pumping of groundwater affects both groundwater and surface water sys-
tems by interfering with the natural hydrologic cycle. Bear
1
indicated that
extensive extraction of groundwater has upset the long established bal-
ance between freshwater and saltwater flows, causing the encroachment of
saltwater into freshwater aquifers. As a large proportion (about 70%) of
the world's population dwells in coastal zones, determination of the opti-
mal development schemes of fresh groundwater and of the optimal control
methods of saltwater intrusion is a big challenge for both engineers and
managers to satisfy present-day and future water demands.
Recently, a number of studies have reported on optimal groundwater
development in coastal regions.
2
In most of these studies, the decision vari-
ables are limited to pumping rates at predetermined well locations. Park
and Aral
3
developed a model that can determine not only pumping rates,
but also locations. However, a major shortcoming of previous studies stems
from the use of analytical solutions. Use of analytical solutions limits the
application of the model to very simple problems, namely, homogeneous
and infinite aquifers, and stagnant saltwater.
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