osInternational Journal of Civil Engineering and Technology (IJCIET)
Volume 10, Issue 04, April 2019, pp. 1837-1848, Article ID: IJCIET_10_04_192
Available online at http://www.iaeme.com/ijciet/issues.asp?JType=IJCIET&VType=10&IType=04
ISSN Print: 0976-6308 and ISSN Online: 0976-6316
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SIMULATION OF LOWERING
GROUNDWATER IN THE RIGHT BANK OF
DERBENDIKHAN DAM
Dr. Maha R. Abdul Hameed
Center of Engineering Designs and Studies/Ministry of water and Resources
Dr.Yasser M. Kadhim
Civil Engineering Department, Dijlah University College
Yahya Saber Khudhair
Civil Engineering Department, Dijlah University College
Ethar H. Abbas
Building and construction Engineering/University of Technology
ABSTRACT
This study focuses on the simulation of groundwater flow and investigates the best
operation system for the pumping wells of the right bank of Derbendikhan Earth Dam.
This dam located at about 50 km south of Sulayamaniyah province, northeast of Iraq.
The right bank of the dam suffering from danger of landslides due to high elevations of
groundwater and difficulties in lowering the reservoir water level.
In order to avoid this sliding problem, this study suggested different scenarios to
examine and reduce the groundwater table at the bottom of the sliding zone of the Marl
clay layer based on computer software called ground modeling system (GMS)
MODFLOW-package to simulate the steady and unsteady states of flow based on three
dimensional finite difference techniques.
These scenarios are proposed to operate eight wells which are already exist as the
first scenario, and the second scenario suggested to drilled two wells in addition to
eight wells around the study area. Moreover, the pumping period and reservoir level
for all scenarios are ranged between (5-15) days and (450-440) m.a.s.l. respectively.
The simulation output found that the second scenario of ten wells, (15) days pumping
period and (440) m.a.s.l. reservoir level is the best operation system for groundwater
of the aquifer.
Keywords: GMS-MODFLOW.
‫محاكاة تخفيض المياه الجوفية في الكتف االيمن لسد دربندخان‬
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Dr. Maha R. Abdul Hameed, Dr.Yasser M. Kadhim, Yahya Saber Khudhair and Ethar H. Abbas
‫هذه الدراسة ركزت على محاكات جريان المياه الجوفية وتحقيق افضل نظام تشغيل البار الضخ للجانب االيمن من سد‬
‫ الجانب االيمن من السد يعاني من خطر االنزالقات االرضية نتيجة ارتفاع منسوب المياه الجوفية‬.‫دربندخان الترابي‬
.‫والصعوبات في خفض مستوى مياه الخزان‬
‫ هذه الدراسة أقترحت سيناريوهات مختلفة ألختاار ولتقليل منسوب المياه الجوفية في منطقة‬،‫لتجنب خطر االنزالق‬
( ‫ باستخدام برنامج نظـام نمذجــة الميـاه الجــوفيــة‬,‫( األنزالق في اسفل طاقة المارل الطينية‬GMS ‫الذي يشمـل برامـج‬
( ‫فرعيــة متعددة مــن أهمـها برنـامج ال‬MODFLOW ‫) لمحاكاة حالـتي االستقرارية وعـدم االستقـراريـة لجريان المياه‬
.‫الجوفية بطريقـة الفـروقات المتناهيـة ثالثية االبعاد‬
‫ وفي السيناريو الثاني‬،‫السيناريوهات أفترضت تشغيل ثمانية آبار والتي هي بالفعل موجودة كما في السيناريو األول‬
‫ تراوحت فترة الضخ‬،‫ عالوه على ذلك‬.‫أقترح حفر بئرين باإلضافة إلى ثمانية آبار الموجودة في جميع أنحاء منطقة الدراسة‬
.‫) م فوق مستوى سطح الاحر على التوالي‬004-054( ‫) أيام و‬55-5( ‫ومستوى المياه في الخزان لجميع السيناريوهات بين‬
‫) يوما وعند مستوى المياه في الاحيره‬55( ‫ فترة الضخ‬،‫وجد من نتائج المحاكاة أن السيناريو الثاني بوجود عشرة ابار‬
.‫) م فوق مستوى سطح الاحر هو أفضل نظام تشغيل للمياه الجوفية للخزان الجوفي‬004( ‫مقداره‬
Cite this Article: Dr. Maha R. Abdul Hameed, Dr.Yasser M. Kadhim, Yahya Saber
Khudhair and Ethar H. Abbas, Simulation of Lowering Groundwater in the Right
Bank of Derbendikhan Dam. International Journal of Civil Engineering and
Technology, 10(04), 2019, pp. 1837-1848
http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=10&IType=04
1. INTRODUCTION
Controlling and lowering of groundwater elevations is a complicated process requiring efforts
from a number of specialists in geotechnical engineering, hydrogeology, hydrology,
geochemistry, hydrochemistry. The main constraint of groundwater elevations control is the
avoid of the expected detrimental effects on the geometry and properties of site soil and so on
the existing adjacent structures due to soil subsidence resulting from rapid emptying of pores
from the water. Ground layers in nature can be anisotropic and heterogenic where descriptive
properties of the aquifer as conductivity, porosity and groundwater sources vary with location.
Numerical modeling is one of most important tool that are widely used around the world for
answering many questions raised during the controlling of the groundwater resources.
AL Salem T. H. et al., 2002 designed a mathematical model for the verification of ground
water system in Bashiqa area northern Iraq, by using Finite Difference Method (FDM) for
presenting the model. The results of model application were the determining ground water level
in the study area and the direction of flow of ground water. The future behavior of ground water
of the research area has been predicted, in the case of drilling new wells.
The present study deals with the problem of high groundwater elevations, which are
considered as a source of problems rather than a water resource. And, groundwater, which
interfere with and hamper the using of water level of reservoir for the different requirements,
whereas considered as a dead storage because it is balancing groundwater elevations inside the
right bank. Therefore, solving of this problem is very critical, special and very urgent measures
must be taken to protect the dam and the banks. Furthermore, there is no obvious plan or
operation system for the exits pumping wells which already founded to reduce the groundwater
elevation as one of most proper solution for slope failure. On the other hand, many restrictions
concerning techniques, cost limitations, security and lack of information lead to various
engineering problems as well as danger of slope failure of right bank of Derbendikhan Dam.
1.1. OBJECTIVES
This study aims to develop a methodology that provides guidance for lowering groundwater
elevations to preserve the stability of the slope. The developed method is based on the number
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Simulation of Lowering Groundwater in the Right Bank of Derbendikhan Dam
of wells that will be used to draw down groundwater with the different running time and critical
boundary conditions.
This methodology wills implementing and applying on the right bank of Derbendi khan
Dam to specify the suitable a three-dimensional mathematical model to simulate the
groundwater flow to estimate the distribution of groundwater elevation.
2. THEORITICAL DESCRIPTION
Mathematical descriptions of the movement of groundwater are based on Darcy’s law and
conservation of mass low. usually consists of a set of partial differential equations that known
as flow governing equations, a knowledge about system characteristics parameters, input
variables, initial and/or boundary conditions is the starting step to building a success a
mathematical model Fig. (1). successful model is that one describing the focusing phenomena
accurately as it possible. In general, mathematical model using a set of interrelated equations
may interdependence logically to describe the disposition of the system and to clarify the
relationship between variables and parameters [3].
Figure (1): Mathematical model components
Finite difference equations can be derived in two ways, from the physical stand point
involving Darcy's law and the principle of mass transfer, or by conventional mathematical
treatments, substituting the finite difference approximations for the derivatives of governing
equation. Both derivational routes lead to the same result. A general form of the governing
equation for an aquifer is:
(1)
Where x, y, z :Cartesian Coordinates, kx, ky, kz: Hydraulic conductivity along axes (L/T),
h :Head of groundwater pressure, (L), W: Flux per unit volume, it represents quantities
discharged (or recharged) to (or from) the aquifer, (L3/T), Sc :Specific storage of the porous
medium, (dimensionless), t : Time (T), x y Sc, k , k and z k are functions of space, while w and
h are functions ofspace and time.
The finite difference method replaces the partial differential equation of flow, Eq. (1), by
a set of difference equations in discretized space and time. The two dimensional areal and
quasi-three dimensional model depends on the perspective of the aquifer; while two
dimensional profile and full three dimensional models flow system, [2].
Beside the governing equation and initial conditions, mathematical models consist of
boundary conditions. These conditions are mathematical statements at the boundary of the
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problem domain. In model design, the process of selecting the right boundary condition
considered the most important and critical stride, as a wrong boundary may lead to serious
errors in the results. Boundary conditions can be divided into three types: Dirichlet condition,
Neumann condition and Cauchy condition [5, 6].
3. STUDY AREA
Derbendi khan city is situated in the northeast of Iraq, located on 35° 6' 35" N, 45° 41' 20" E
about 50 km south of Sulaymaniyah Province and 20 km west of the Iranian border, the
Derbendikhan Dam located at the narrowest end of Diyala River which created the
Derbendikhan Lake. Darbandikhan Lake is one of the three large lakes in Kurdistan, Northern
Iraq, and 230 km northeast of Baghdad. It is fed by two main tributaries the Tanjero River and
the Sirwan River [4].
Right bank of Darbandikhan dam inside modern clastic geological formations its
composition back to era Eocene such as clayey marl, Limestone, and Sandstone which forms
part of the slope of anticline in the region and vertical on the river axis in the sliding area, this
area is approximately 350m in length and 200m in width encompassing approximately 7
hectares in land Fig. (2).
Figure (2): Present study area
4. MODEL DISCRETIZATION
The model discretization, wells location and boundary conditions that introduced to GMS
software (MODFLOW Package) to simulate the study area are shown in Fig. (3).
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Simulation of Lowering Groundwater in the Right Bank of Derbendikhan Dam
Figure (3): Grid design, well location and boundary conditions for study region.
The model domain was divided into (25) rows and (35) columns, making a total (875) cells
and covering an area of approximately (8750 m2). All the cells have uniform lateral dimensions
of (10m) along rows (∆X) by (10m) along columns (∆Y).
4.1. MODEL APPLICATION
By using GMS software (MODFLOW package) two scenarios are discussed within this study
as proposed solutions to lower the groundwater in the study area. For these cases of scenarios,
the constant data is the discharge of all pumping wells and equal to 864 m3/d, characteristics
of the aquifer system as well as the boundary conditions is considered constant head. Eight
wells exist inside the site; have been used in the first scenario and this scenario represents the
actual situation. It was also suggested to drill two wells at the east of the studied region in
addition to 8 wells around the study area have been used in the second scenario and then
comparing the results for each scenario.
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Figure (4): scenario 1, drawdown of groundwater elevations (m), when the reservoir level (450)
m.a.s.l (a) at 5 days (b) at10 days (c) at 15 days of pumping period.
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Simulation of Lowering Groundwater in the Right Bank of Derbendikhan Dam
Figure (5): scenario 1, drawdown of groundwater elevations (m), when the reservoir level l is (445)
m.a.s.l (a) at 5 day (b) at10 day (c) at 15 day pumping period
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Dr. Maha R. Abdul Hameed, Dr.Yasser M. Kadhim, Yahya Saber Khudhair and Ethar H. Abbas
Figure (6): scenario 1, drawdown of groundwater elevations (m), when the reservoir level is (440)
m.a.s.l (a) at 5 day (b) at10 day (c) at 15 day pumping period.
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Simulation of Lowering Groundwater in the Right Bank of Derbendikhan Dam
Figure (7): scenario 2, drawdown of groundwater elevations (m), when the reservoir level is (450)
m.a.s.l (a) at 5 day (b) at10 day (c) at 15 day pumping period.
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Dr. Maha R. Abdul Hameed, Dr.Yasser M. Kadhim, Yahya Saber Khudhair and Ethar H. Abbas
Figure (8): scenario2, drawdown of groundwater elevations (m), when the reservoir level is (445)
m.a.s.l (a) at 5 day (b) at10 day (c) at 15 day pumping period.
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Figure (9): scenario 2, drawdown of groundwater elevations (m), when the reservoir level is (440)
m.a.s.l (a) at 5 day (b) at10 day (c) at 15 day pumping period.
The suggested models are operations only to lower the water table during the three different
durations set in order to see the changes in time 5, 10 and15 days, and study the influence of
reservoir level on the drawdown, which level varies between (450, 445 and 440) m.a.s.l for
each case in scenarios.
5. CONCLUSIONS
This study focused on the simulation of groundwater flow and investigates the best operation
system for the pumping wells of the right bank of Derbendikhan Earth Dam
Based on the overall results analysis of this study, the following conclusions can be
extracted:
1. The main influencing operating factor in two scenarios is the wells number while
the effect of pumping period on results is very little, especially after reaching the
steady state for the corresponding drawdown, whereas the reservoir level is
significantly affected groundwater elevations.
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2. Scenario-3 of operating ten wells is more efficient in lowering of groundwater
elevations in the studied region in comparison with first scenario of operating eight
wells. The groundwater elevations at the middle of the sliding area can be lowered
to about 46 m from its present elevation after the steady-state condition is reached
within a pumping period of 15 day and reservoir level of (440 m.a.s.l.).
6. RECOMMENDATIONS
To improve the management of groundwater should be developing the present wells system
and monitoring well system. Therefore, it is recommended to:
1. Record the piezometers readings existing in the region with periods of operation of
wells in order to use them in the calibration process in the unsteady state. As well,
record of reservoir levels at the same time.
2. Carry out other studies and observations in order to identify some hydraulic and
mechanical properties of the important rock of this aquifer to complete the database
of this aquifer.
3. Set up devices or sensors to monitor the stability of sliding mass during the
operation of wells and reducing the levels of the reservoir.
4. A multi-objective optimization study can be done to optimize groundwater
elevations.
REFERENCES
[1]
[2]
[3]
[4]
[5]
[6]
AL-Salem T.H., Mohammed, F. O. S., "Mathematical Model of Ground Water Flow of
Bashiqa Area, Northern Iraq", Iraqi Journal of Earth Sciences, Vol. 4, No. 2, p 84 -98.,
(2004).
Anderson M.P., Woessner W.W., "Applied Groundwater Modeling Simulation of Flow and
Vertical Transport", Academic press,Inc. San Diego, 246 P, 1992.
Clarke R.T., “A Review of Some Mathematical Models used in Hydrology, with
Observations on their Calibration and Use”, Journal of Hydrology 19: 1–20, 1973.
Ministry of Irrigation (MoI), "Derbendi Khan Dam main remedial works right bank
landslide complementary stability analysis"" unpublished report, 1981.
Neuman, S.P. and Witherspoon, P.A., “Theory of Flow in a Confined Two Aquifer
System”, Water Resources Research, Vol. 5, No. 4, pages 817-829, 1969.
Wang P.P., Zhang C., ''An Efficient Approach for Successively Perturbed Groundwater
Models'', Advances in Water Resources, Vol.21, pages 499-508, 1998.
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