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International Journal of Advanced Research in Engineering and Technology (IJARET) Volume 11, Issue 8, August 2020, pp. 168-183, Article ID: IJARET_11_08_017

Available online at http://www.iaeme.com/IJARET/issues.asp?JType=IJARET&VType=11&IType=8

ISSN Print: 0976-6480 and ISSN Online: 0976-6499

DOI: 10.34218/IJARET.11.8.2020.017

© IAEME Publication Scopus Indexed

STUDYING THE EFFECT OF USING CUTOFF

WALLS FOR MANAGING THE SALTWATER

INTRUSION IN HOMOGENOUS UNCONFINED

AQUIFERS: EXPERIMENTAL AND

NUMERICAL STUDY

Abdulrazak H. Almaliki

Ph.D., CE. Assistant Professor, Faculty of Engineering,

Civil Engineering Department, Taif University, Saudi Arabia

ABSTRACT

Saltwater intrusion is a global issue progressively influencing coastal aquifers,

because of climate changes and increasing ultimatum of fresh and pure water for

human consumption and irrigation. Therefore, The goal of this research was to

examine the performance of cut off walls in managing saline water intrusion and to

gain superior predictions of the saltwater wedge development and plan satisfactory

countermeasures to restrict the saltwater intrusion in homogenous coastal aquifers or

water level. This work presents a laboratory facility designed and built to simulate

saltwater intrusion in coastal aquifers, with the overall goal of providing benchmarks

for numerical models by means of different measurement techniques. Besides, the

magnitude of the solution permits us to observe the saline water wedge development

by contrasting with saltwater wedge collected at regular intervals during an

experiment in a homogeneous porous medium. The investigation comprises of two

experimental categories; the first group is for studying the saline water intrusion

without using any barriers (Base case), and the second group is for studying the effect

of substantial vertical barriers. The outcome manifest that the cutoff wall was

successful in decreasing the saltwater wedge in the examined cases with intrusion

length reduction of up to 83%.Moreover, The results showed that two zones could be

recognized; Saltwater and mixed zones. For the base case, the saltwater line and the

mixed line were high compared with the experiments used barriers. For the second

group (Vertical Solid barriers), it also noted that the saltwater and mixed lines were

decreasing by using several barriers depth. Numerical analysis showed that the cutoff

wall remained effective in repulsing the saline water wedge. The SEAWAT code

embraced to procreate the experimental outcomes. Consequently, the occurrence

between observed data and numerical simulations can give a fruitful criterion for later

researches of seawater intrusion.

Studying the Effect of Using Cutoff Walls for Managing the Saltwater Intrusion in Homogenous

Unconfined Aquifers: Experimental and Numerical Study


Key words: Head: Seawater intrusion, cutoff wall, coastal aquifers, laboratory

experiment, numerical simulation.

Cite this Article: Abdulrazak H. Almaliki, Studying the Effect of Using Cutoff Walls

for Managing the Saltwater Intrusion in Homogenous Unconfined Aquifers:

Experimental and Numerical Study, International Journal of Advanced Research in

Engineering and Technology, 11(8), 2020, pp. 168-183.

http://www.iaeme.com/IJARET/issues.asp?JType=IJARET&VType=11&IType=8

1. INTRODUCTION

Coastal areas are the mobile region of social activities and the social economy, which is

constructed by various cities and significant activities [1, 2]. The human activities quickly

demolish the chemical and physical equality of the coastal aquifer procedure, arising in the

issues of land sinking, the water of sea intrusion , and surroundings worsening. Including, the

seawater intrusion is an issue of global tension, the over-pumping of groundwater reasons that

sea-level getting up, change of weather, and alteration of land use in the coastal region [3–5].

With these elements, groundwater pumping or driving observed to be one of the most vital

dares that encourage the severity and extent of seawater intrusion [4, 5, 6]. Consequently,

groundwater coarseness can cause by seawater intrusion or intrusion due to the utilization of

groundwater [7]. The overexploitation of groundwater has immensely intensified the expanse

of seawater intrusion in coastal regions around the globe [4, 8–10]. As it is familiar to us, the

seawater intrusion procedure is a composite issue, because the seawater intrusion is

amalgamating with fresh groundwater twosome water flow and salt transfer. It includes the

variable density groundwater flow, which is hard to reproduce well. The numerical attitudes

have immensely used to reproduce seawater intrusion in the mixing circuitry [11, 12], which

involves FEFLOW [13] and SEAWAT [9]. Werner et al. (2009) evolved a directed lab

experiment to simulate the upcoming occurrence in two proportions, with various pumping

charges and various freshwater-saltwater density[14]. Many other researchers used an

amalgamation of lab investigations and numerical representatives to study problems

associated to seawater intrusion (Chang and Clement, 2012) and (Chang and Clement, 2013)

concentrated on the influence of regenerate fluxes difference and swing of groundwater flow

and transport procedures within the saltwater wedge , in the same manner, spotlighted by

attaching colorant to the saltwater[15] ,[16]. The same method was applied by Robinson et al.

(2015) [17], who made a process for automatic image examination to change the image light

potency to consolidation, and Abdoulhalik et al. (2017) [18], in a small-scale lab investigation

to research the impact of underground barrier. A common element of the investigation above

is that they were taken out in sandboxes or flukes of reduced size, both in terms of width and

length, the first being generally less than 1 m, with a few deviations (e.g., Kuan et al., 2012)

[19], and the latter being generally less than 10 cm and even as small in size as 1 or 2 cm.

Lab investigation was examined and completed the result of cutoff walls in the unconfined

aquifer, comprising a similar situation (two cases with four physical investigations). The

SEAWAT code embraced to evaluate the stability of the experimental outcomes with the

numerical assumptions and to give a forecast on the flow instability forced in each aquifer

situation experimented. A comparative study also carried out to assess the impact of the

aquifer parameters on the overall effectiveness of cutoff walls to control sea water intrusion

(SWI).



2. MATERIALS AND METHODS

2.1. Experimental Method and Implementation

The first set represented the saltwater intrusion scenarios occurring in aquifer setting prior to

the installation of the barrier, considered as base cases. In the next set, a cutoff wall fitted into

the process. The cutoff wall created by waterproof ingredients (plasticine or clay). To make

sure that the cutoff wall pinpointed within the indigenous area of the saline water wedge for

better success [20], the cutoff wall designed on the bases of the delineation of the saline water

wedge in the homogeneous scenario (case 2-1,2-2,2-3). The cutoff wall in the second

condition of three sets was placed positioned earlier to the packing at 24.5 cm from the

saltwater tank edge with a perforation depth 35.5 cm,29.9cm and 24.7cm from the peak of the

sandbox, observing that cutoff walls are usually pinpointed within a space of double the water

level height from the coastal or close [17] [18] [19] . The success of the cutoff wall was

indicated herein means of the decrease in the percentage of the intrusion length comparative

to the base case situations R = (TL0 - TLB)/TL0, where TL0 and TLB are the intrusion length

before and after the wall equipment [21], [18].

At the beginning of each investigation, a saltwater level of 39.8 cm was compelled. In

contrast, the freshwater level was placed high enough to permit the overall porous media to

remain thoroughly saturated with fresh water. An increased amount of saltwater mixture was

continuously contributed to the saltwater pond to make sure that any possible freshwater

buoyant at the exterior was thrilled out.

Figure 1 reveals the lab tank that is 148 cm long, 10.4 cm m wide and 63cm in height,

made of Plexiglas with the heaviness of 1.5 cm. The tank comprises three bits, which are the

saline water room, moderate region, and freshwater room, along with the length indications.

The moderate region and the side room at both ends are divided by two strainer plates with

small pits. The strainer plates on either side are 30 cm away from the left saltwater edge and

the freshwater right end, in the same manner. Saltwater is drawn up with an application equal

to that of the Red Sea (average concentration of 40000 mg/L (38%)). Geotextiles laid on

either end of the strainer plates, which acts as a barrier to sand transit. The seawater region

and freshwater region are attached to the reservoirs. The two reservoirs are built of PVC

boards, with a length of 140 cm, breadth of 120cm, and a height of 60 cm, placed on the

ground. The last was colored using green food color at a concentration of 0.15 g/L to

differentiating it from the freshwater.

The investigation needed the measurements of the water level. The sea level on the left

end of the tank measured using a meter pole fastened on the iron setting. There are almost

twelve observing points of pressure measuring tubes put at the base of the back of the sand

tank to measure the level of water variance with time. To save the sand particles from getting

into the pressure measuring tubes, a filter with a mesh diameter of 0.18 mm put at the relation

between the Piezometric tube and sand tank ; the interim between all pressure vessel is 50 cm

in the parallel direction. The already used sandbox tank (size of 82L) in the investigation has

the following pits as described in Table1.




Table 1 SandBox Model description regarding the needed experiments

No Device Description

1 Freshwater Reservoir A side tank apart from the sandbox tank with a width of 10.4 cm

2 Saltwater Reservoir A side tank apart from the sandbox tank with a breadth of 10.4

cm

3 Media Sand Silicon dioxide sand (from 0.71 to 1.18 mm)

4 Water pumps One pump is utilized to feed the saltwater side tanks or tank

5 Adjustable drainage

tubes

Two tubes are used to set both freshwater and saltwater heads as

constants.

5 Drainage tube outflow Utilize to estimate or guessed the hydraulic energy and fresh or

pure water glide from the freshwater edge to the saltwater edge

6 Base tanks A 96 L located below the sandbox tank and used to supply

freshwater or saltwater.

7 Barrier Wall/

Cutoff Wall and Piles

It’s an embedded wall with a certain depth through the media

sand at a certain distance from the side tanks with a width equal

to the sandbox tank width

8 Fine mesh screens Two perforated acrylic fine mesh screens are used in both sides of

the sandbox tank as a separation between both freshwater and

saltwater tanks and the media sand

9 Barrels Barrels with known volume (10 L) are used to preparing saltwater

11 Balance For measuring the density of both saltwater and freshwater

12 Small Tank 0.5L tank for freshwater Injection

13 Injectors Injectors

14 Manometers For measuring water pressures on the bed on different locations

15 Drainage tube For drainage water from the Sandbox tank

Figure 1 Sandbox Model

Dimensionless quantities are a simple procedure in the engineering studies for decreasing

the number of investigational variables influencing a given occurrence before the

investigation; for this reason, the dimensionless quantities are used in this research, as shown

in Table 2

Table 2 Dimensionless quantities Symbols and their Definition used in this work

Symbols Definition Ratios

H Piezometric head (variable) H/SWh

Lint Intrusion Length (variable) Repulsion rate Lint/Lint

Lint Final Intrusion Length(constant)

Lmix

SWh

Mixed length (variable)

Salt Water Head (constant)

Lmix/Lfint

Xpiz Piezometric Head Distance (variable) Xpiz/Lsand

Lsand Sand Media Length (constant)

Xb Barriers Distance (parameter) Xb/Lsand



2.2. Mathematical Model

The Mathematical representation for groundwater course or glide with variable density put in

to reproduce .The seawater intrusion procedures. Based on the licensed distinction

groundwater flow simulations represents MODFLOW, the numerical simulations model of

solute transfer in groundwater course or glide is accepted using SEAWAT, reflecting the

outcome of density on groundwater flow [22]. The program has immensely applicable in

seawater intrusion and submersible groundwater release [8]. The tow governing equations for

the groundwater flow and solute transport which are used in the SEAWAT model can be

expressed respectively as follow :

[ (

)]

[ (

)]

[ (

)]

=

( )

( ) ( )

( )

Where K f x, K f y, K f z are the hydraulic conductivities in different directions (LT-1

) ; θ

is the porosity; Sf is the specific storage (L-1

); hf is the equivalent freshwater head (L); ρ is the

density of sea or salt water (ML-3

); ρf is the density of freshwater (kg/m3); ρs is density of

water (the sources and sinks (ML-3

); qs is the volumetric flow rate of sources or sinks (T-1

); C

is the sea water concentration (ML-3

); x, y, z is the flow direction and t is the time (T). qs(T-1

)

is the volumetric flow rate per unit volume of aquifer representing sources and sinks, ν(LT-1

)

is the fluid viscosity, D(L2T-1

) is the hydrodynamic dispersion coefficient and Cs(ML-3

) is the

solute concentration of water entering from sources and sinks.

2.3. Numerical Procedure

For our purposes, we used the MODFLOW family variable, density flow rule SEAWAT. It

aided in identifying how much is investigational information or data consistent with the

numerical assumptions, offer an enhanced description of the experimental outcomes and also

realize the cut off walls’ production for multiple parameter mixture. The numerical model

made up of a rectangular domain, which measures 148 cm x 63cm constant discretized using

a size network of 0.5 cm. The longitudinal dispersivity is determined , after the trial and error

procedure, were, in the end, concluded at 0.2 cm. This result falls within the brackets of

dispersal figures described in [23]. The dispersivity and element dimensions provided

numerical stability by fulfilling the Peclet number basis [24]. Density of the freshwater and

saline water were 40000 mg/L and 0 g/L, respectively. The aquifer system was assumed to be

homogeneous. Moreover, we applied hydrostatic pressure at both the freshwater edge (C =

0%) and the coastal saline water edge (C = 38%). On the right side edge, a constant hydraulic

head of 39.8 cm for Case 1 and Case 2 set.

Additionally, the production procedures of the base case and the cutoff wall cases were

the same. To create the prediction of the cutoff wall, we rendered the cells inhabited by the

wall as inactive in the processes. In the previous scenario, the numerical model was that of a

fresh aquifer. The period for the simulation was 90 minutes, with a time step of the 20s. For

each time step, the hydraulic heads on the seafloor revised according to equation (1). At first,

in case 1, the transient simulations was used to determine the extent of saline water intrusion

without setting the cut off the wall in the aquifer. Whereas, in case 2, the transient production




used to identify the expansion of saline water intrusion under the scenario of the prevalent cut

off wall at space 24.5cm. It did not include the consideration of pumping in the aquifer.

3. RESULT AND DISCUSSION

Two group of experiments conducted to research the use of cut off wall effects on saltwater

intrusion and new groundwater level variation in the coastal unconfined aquifers. During both

group of experiments, the change of the port between water of the sea and freshwater and the

dissimilarity of the level of groundwater at each observing point considered until the process

reached the final stable state. In this region, we concentrate on the outcomes of both scenarios

with their discussion

In the base case, the saltwater line progresses less than the mixed line during the same

period determined for the experiment. Figure 2 illustrates the relation between the salt line

and mixed Line progress in time. The mixed line continues to advance until the end of the

experiment. This experiment conducted without using the barrier to see the natural progress of

saltwater to be the benchmark and reference in future experiments. Figure 3 shows the

transient hydraulic head variation along with the sandbox model. Moreover, Figure 4 shows

sample photos of the progress of both saltwater and mixed lines.

Figure 2 Progress of salt and mixed lines achieving Distance along with sandbox model (Base Case)

Figure 3 Relation between Piezometric Head and steady-state after 90 minutes (Base Case)

0

1

2

3

0 50

Lin

t/L

fin

t

Time (min)

M…S… 0.00

0.100.200.300.400.500.600.700.800.901.001.101.20

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

H/S

Wh

Xpiz/Lsand

T=0min T=5minT=10min T=15min

0

0.5

1

1.5

2

2.5

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Lm

ix/L

fin

t

Lint/Lfint

0

10

20

30

40

50

0 50 100

Intr

usi

on

len

gth

in

cm

Time



Figure 4 Photos showing the progress of saltwater and mixed lines with time (Base Case)

Figures 5, 7 and 9 present the variation of intrusion length, saltwater repulsion rates

(Lint/Lfint) of intrusion line, mixing line and simulated of the salt wedge with time in the

unconfined aquifer. It represents that the numerical model assumed correctly the intrusion

length and repulsion rate of the saltwater wedge considered in the real picture. As same to

Figures 5(b), 7(b) and 9(b) show that the intrusion length enlarging with time the start and

then tends to be a stable value under the requirement of using cut off the wall after 90 min. of

simulation. The final intrusion length of the steady-state for the base case without using cut

off the wall was 49cm. While The final intrusion lengths of the steady-state with using cut off

a wall at a distance of 24.5 cm from the seawater tank are 41,40.6 and 40.1 cm for case 2-1,2-

2 and 2-3, respectively. Then, the intrusion length enlarges with time when the cut off wall

placed higher than the bed, but it is still low.

When the depth of cut off wall decreased to 24.7, the seawater besides encroaches toward

freshwater until a new steady condition reached. The saltwater intrusion length enlarges with

time a bit until it is stable (Figure 9(a)). The saltwater repulsion rate Lint/Lfint enlarged with

time and extended the highest value at the time of 90 min (Figures 5(b), 7(b) and 9(b) ). It

designates that the stable-state of the seawater encroachment can conclude according to the

saltwater repulsion rate Lint/Lfin of seawater intrusion length. The maximum values of

saltwater intrusion length were 49cm without using cut off wall and 41 cm using cut off the

wall (Figures 5(b), 7(b) and 9(b)). The saltwater intrusion length with using cut off wall for

case 2-1 is larger than that of the case 2-3 because the depth of the cut off wall is higher than

that of the case 2-3. Therefore, as cut off wall penetrate more profound as the saltwater

intrusion decreases. Figures 5(C), 7(C), and 9(C) show the transient hydraulic head variation

along with the sandbox model. It indicates that the ground freshwater level increases with the

existence of a cut off wall.




Figure 5(a) Progress of salt and mixed lines achieving steady state after 90 minutes (Case 2-1)

Figure 5(b) Comparison between experimental and numerical intrusion length data in cutoff wall (case 2-1).

Figure 5(c) Relation between Piezometric Head and Distance along sand box model (Case 2-1)

0.80

0.90

1.00

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

H/S

Wh

Xpiz/Lsand

T=0min T=5min T=10min T=15min T=20min



T=75min T=80min T=85min T=90min

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

0 20 40 60 80

Lin

t/Lf

int

Time (min)

Mixed Line Salt Line

Simulated

15

20

25

30

35

40

45

0 20 40 60 80 100

intr

usi

on

len

gth

(cm

)

Time (min)

Salt Line Intrusion

simulated



Figure 5(d) Relation between Mixed Length and Intrusion Length (Case 2-1)

Figure 6 Photos showing the progress of saltwater and mixed lines with time (Case 2-1)

Regarding case2 (using vertical barriers), from Figure 5(a), Figure 7(a) and Figure 9(a), it

could be shown that the ratio Lint/Lfint is slightly increase with time until became a constant

value of 0.9 at 90 minutes. Moreover, from the same Figures, it could be shown that the

mixed zone is continually enlarged with time. As shown in Figure 5(c), Figure 7(c) and

Figure 9(c), The initial head difference between freshwater and saltwater side tanks fixed to

be 10cm. After running the experiment, the Piezometric heads increased with time until

reaching the same saltwater level. Figures 5(d), Figure 7(d) and Figure 9(d) show the relation

between the saltwater repulsion Lint/Lfint and mixed water intrusion Lmix/Lfint. For the

mixed line length represented by the ratio Lmix/Lfint, Figure 5(d), Figure 7(d) and Figure

9(d) illustrates that this ration is continued increasing with increasing the saltwater repulsion

(Lint/Lfint).

Figure 5(a), Figure 7(a) and Figure 9(a) show the observed values and measured values of

the seawater repulsion rate with using cut off wall at a distance 24.5 from the saltwater tank

with three deferent depths 35.5 cm,29.9 cm and 24.7 cm for Case 2-1,2-2,2-3 respectively.

The match between the observed and calculated saltwater intrusion is well, as shown in Figure

5(b), Figure 7(b) and Figure 9(b). As the cut off wall rises from the low depth (24.7 cm) to

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Lm

ix/L

fin

t

Lint/Lfint




high depth (35.5 cm), the intrusion decreases under the effect of using cut off wall depth

(green lines of Figures 5(a)–9(a)) with an improvement of 83%.


Figure 7(b) Comparison between experimental and numerical intrusion length data in cutoff wall (Case 2-2)

Figure 7(c): Relation between Piezometric Head and Distance along sand box model (Case 2-2)

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 10 20 30 40 50 60 70 80 90

Lin

t/L

fin

t

Time (min)

Mixed line

Salt Line

Simulated

15

20

25

30

35

40

45

0 20 40 60 80 100

Intr

usi

on

len

gth

cm

Time (min)

Salt Line Intrusion

Simulated

0.80

0.90

1.00

1.10

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

H/S

Wh

Xpiz/Lsand

T=0min T=5min T=10min T=15min T=20minT=25min T=30min T=35min T=40min T=45minT=50min T=55min T=60min T=65min T=70minT=75min T=80min T=85min T=90min



Figure 7(d) Relation between Mixed Length and Intrusion Length (Case 2-2).

Figure 8 Photos showing the progress of saltwater and mixed lines with time (Case 2-2)

Figure 5(c), 7(c) and 9(c) show the observed values of the groundwater level with using

cut off wall at a distance 24.5 from the saltwater tank with three deferent depths 35.5 cm,29.9

cm and 24.7 cm for Case 2-1,2-2 and 2-3 respectively. As the cut off wall rises from the low

depth (24.7 cm) to high depth (35.5 cm), the fresh groundwater level increases under the

effect of using cut off wall depth. Figure 6, Figure 8 and Figure 10 show sample photos of the

progress of both saltwater and mixed lines in case 2-1,2-2 and 2-3, respectively.


0.6

0.8

1

1.2

1.4

1.6

1.8

2

0 1 2

Lm

ix/L

fin

t

Lint/Lfint

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

2.2

0 20 40 60 80

Lin

t/L

fin

t

Time (min)

Mixed Line

Salt Line

Simulated




Figure 9(b) Comparison between experimental and numerical intrusion length data in cutoff wall

(Case 2-3)

Figure 9 (c) Relation between Piezometric Head and Distance along sand box model (Case 2-3

Figure 9(d) Relation between Mixed Length and Intrusion Length (Case 2-3).

15

20

25

30

35

40

45

0 20 40 60 80 100

Intr

usi

on

len

gth

in c

m

Time (min)

Salt Line Intrusion Simulated

0.80

0.90

1.00

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

H/S

Wh

Xpiz/Lsand

T=0min T=5min T=10min T=15minT=20min T=25min T=30min T=35minT=40min T=45min T=50min T=55min

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2

2.2

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Lm

ix/L

fin

t

Lint/Lfint



Figure 10 Photos showing the progress of salt water and mixed lines with time (Case 2-3)

Figure 11 (a) Comparison between experimental mixing zone length data in the base and cutoff wall

cases

From figures 11(a) and (b), it was noted that the saltwater line and the mixed line were

high in the base case, and it was also noted that the saltwater line was decreasing due to the

existence of the barrier. On the other hand, the saltwater progresses decreases with decreasing

the depth of the barrier. It may be because of the vertical currents formed below the barrier

depth. Moreover, with decreasing the depth of barrier, both salt and mixed lines are close in

results to the base case. The intruding migration rate in Case 2-1 was relatively more

significant than that in Case 2-2 and Case2-3. It means that faster seaward motion of the

seawater wedge would occur when the depth of cut off wall is small in the coastal aquifers.

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

2.00

0 10 20 30 40 50 60 70 80 90

Lm

ix/L

fin

t

Time (min)

Case1 ( Base case )

Case2-1(Vertical Barriers)

Case 2-2 ( Vertical Barriers)

Case 2-3 ( Vertical Barriers )




Figure 11 (b) Comparison between experimental sallt water intrusion length facts in the bottom and

cutoff wall cases

4. CONCLUSIONS

In this study, we have utilized lab experiments and numerical simulations to examined the

successfulness of cutoff walls in homogenous coastal aquifers. Four manifold scenarios were

examined, including a base case and cases with cut off at deferent depth 35.5,29.9 and 24.7

cm at a distance 24.5cm from the saltwater tank. The intrusion length data were investigated

by examining every experimental run. The SEAWAT model sensibly well assumed the

experimental repulsion and saltwater intrusion length in the four situations. The matches

between the measured and calculated repulsion and saltwater intrusion length outcome of the

three experimented scenarios are well. The simulations outcome for the cutoff wall

investigation yielded a good occurrence with the investigational data. The numerical model

established that the cutoff wall was successful in keeping the saline water on the coastal side

of the wall for all the head dissimilarities trialed out and in all the experimented arrangements,

in occurrence with the experimental observations. In the base case, the saltwater line

progresses less than the mixed line during the same period determined for the experiment. In

case 2-1, the barrier at a depth of (35cm), and note that the progress of saltwater and mixed in

saturated soil is less than the base case. For other cases (case 2-2 and 2-3), it noted that the

saltwater and the mixed lines decreased progressively from the last experiments and became

close relatively to the base case results in the last case (Case 2-3). Conclusively, with

decreasing the barrier depth, both the saltwater line and the mixed line were decreasing

toward the base case results, and the best results were found for the case 2-3. The outcomes

from this study will aid in future planning, design considerations and management of artificial

recharge well facilities to reduce and control seawater intrusion in unconfined coastal

aquifers.

ACKNOWLEDGEMENT

I thank my colleague in the water resources group in Taif university Dr. Wael Elham for

implementing the experiments and offering me the data for analyzing and finishing this

research.

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0 10 20 30 40 50 60 70 80 90

Lin

t/L

fin

t

Time (min)

Case1 ( Base case )Case2-1(Vertical Barriers)Case 2-2 ( Vertical Barriers)Case 2-3 ( Vertical Barriers )



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STUDYING THE EFFECT OF USING CUTOFF WALLS FOR …€¦ · freshwater or saltwater. 7 Barrier Wall/ Cutoff Wall and Piles It’s an embedded wall with a certain depth through the media