Computation of Seawater Intrusion in Coastal Area

Computation of Seawater Intrusion in Coastal Area

Tencymol Jose 1

Student

Department of Civil Engineering Mangalam College of Engineering Ettumanoor, India

Rahul K. S 2

Student

Department of Civil Engineering Mangalam College of Engineering Ettumanoor, India

Amal Joseph 3

Student

Department of Civil Engineering Mangalam College of Engineering Ettumanoor, India

Jaison K Varghese 4

Student

Department of Civil Engineering Mangalam College of Engineering Ettumanoor, India

Linu Joy 5

Assistant Professor Department of Civil Engineering Mangalam College of Engineering

Ettumanoor, India

AbstractSea water intrusion is one of the most serious environmental problems in many coastal regions all over the world. It affects the water quality, vegetation, soil conditions. It causes variation in pH, chloride contents, quality, colour, turbidity etc of the existing water. So the main difficulty we can see from the coastal regions is unavailability of drinking water. Sea water intrusion occurs naturally in most coastal aquifers which are caused by hydraulic connections and density difference between groundwater and sea water. The amount of dissolved salt in groundwater causes the variation in properties of the existing water by analysing the water samples by checking each properties in the lab we can find the amount of variations, and compare the values with standard index we can find the area is prone to sea water intrusion or not. Its objectives includes to understand the change in the water table and the water potential zone and Preparation of the various thematic maps or graphs for the representation of the problem.

Keywords: seawater intrusion, coastal areas, index, parameters, Ground water

I.INTRODUCTION

Coastal aquifers are one of the most important water resources in the world. Sea water intrusion is one of the most serious environmental problems in many coastal regions. It affects the water quality, vegetation, soil conditions. So the main difficulty we can see from the coastal regions is unavailability of drinking water. In addition to that the natural discharge of freshwater to the sea as submarine groundwater discharge (SGD) which has an important role in the ecology of marine environments and the sustainable development. The dynamics of seawater and freshwater within coastal aquifers are highly sensitive to disturbances, and their inappropriate management may lead to the deterioration of water quality. In many coastal aquifers, seawater intrusion has become the major constraint imposed on groundwater utilization.

Groundwater exploitation and climate variations create dynamic conditions, which can significantly increase the intrusion of seawater into the aquifer and may result in the Stalinization of wells. They may also reduce SGD and affect the water budget of marine systems. The excess seawater intrusion entirely changes the parameters of the water and destroys its quality, Hence it cannot be used for any purposes

II. LITERATURE REVIEW

The studies bring about the salient points of published literatures and other reported works.

1. P. Prusty, S. H. Farooq(2020)Seawater intrusion in the coastal aquifers of India Is a study of buried paleochannels is of scientific interest to understand hydrogeology. It use direct methods: geochemical methods, indirect methods: geophysical methods. It conclude that the seawater intrusion is more prominent on the east coast than the west coast of India.

2. C. P Kumar (2016)Sea water intrusion in coastal aquifers Hydrological aspects, control measures and modeling by Ghyben-Herzberg principle are used as objectives in this study. Physical, Analytical and numerical Models are used to analyze and it conclude that it provide better withdrawal of groundwater from networks so to reduce seawater intrusion.

3. Setyawan Purnama (2019),Groundwater vulnerability from seawater intrusion in coastal area It analyze groundwater vulnerability to the SWI using the method GALDIT by using Dupuit Gheyben-Herzberg method. It reaches the conclusion that the area which located closer to the shoreline had higher vulnerability to SWI.

4. Soumaya Hajji &Nabila Allouche (2021), Assessment of seawater intrusion in coastal aquifer using hydrochemical facies Is a study of detoriation of groundwater by sea intrusion. By testing physio- chemical properties from 37 wells and integrated in GIS. Conclude that high level of Na and Cl ions in groundwater indicate significant effect of sea water.

5. Mark Saadeh, Elie Wakim(2017), Deterioration of Groundwater in Beirut Due to Seawater Intrusion TDS and pH were measured using individually calibrated portable test and principle dynamics, myriad methods may then be employed. It concluded that study emphasize the need for immediate implementation of (IWRM)

6. Min Wang, Mei Han, Hongkuan Hui,and Yunlong Li(2019), Study on seawater intrusion in Laizhou bay coastal zone Studied that seawater intrusion area was approaching inland time went on, and transverse distributionwas irregular. Regional, Data and Detection method are used for evaluating. Conclude that the groundwater chlorinity decreased with the increase of the distance with the coast.

1. Sample Details

1. MATERIALS USED

   1. A .A. Javed, M. S. Hussain, M. M. Sheriff(2013), Optimal control of seawater intrusion in coastal aquifers Aims to Optimize control of seawater. Uses method based on combination of saline near shore land and recharge of aquifer of surface ponds. Conclude that the resulting in least cost and salt concentration in aquifer

      III. OBJECTIVES OF WORK

      • To understand various parameters which getsaffected by sea water intrusion

      • Identify the parameters includes ph, acidity,alkalinity, hardness, turbidity etc

      • To understand the change in the water table and thewater potential zone.

        Map. 1 : Showing the area from which the sample is collected.

        (Note: Samples are numbered from top to bottom. That is sample 1-8 in the first column comes 1st then sample 9-15 then sample 16-21 and remaining are marked as 22,23&24)

        Sample No.	Samples collected from	Place	War d	Panchayat
        1	Joseph T, puthenpurackal	Andhakaranazhy	19	Pattanakaad
        2	Vishvan Nair, Pathilchira	Andhakaranazhy	19	Pattanakaad
        3	Jhony scaria,Mundak athil	Andhakaranazhy	17	Pattanakaad
        4	Mathew K, Kadavath	Andhakaranazhy	17	Pattanakaad
        5	Benedict philp,Vazhayil	Ottamacheriy il	1	Pattanakaad
        6	Daniel chacko, Veliyakunnel	Ottamacheriy il	1	Pattanakaad

        1. METHODLOGY

           This test is to be carried out in coastal areas of Alappuzha district. Samples needed for the project are collected from places in and near Cherthala Taluk. Firstly we need to collect samples form that places, usually we are taking samples from the wells. Then after collecting samples we are testing that samples in the laboratory for evaluating the pH, acidity, akalinity, turbidity, hardness for identifying thequality of the water samples. After getting the datas of various samples, we are plotting graphs related to each parameter and analyse the places whether it is prone to sea water intrusion or not. After analyzing we are providing suitable remedial measures to avoid the excess Seawater intrusion.

           7	Philp Zacharia, Palaparambil	Thyckal	14	Pattanakaad
           8	Joseph M, Veliyakulangara	Thyckal	12	Pattanakaad
           9	Wilson chacko, Thalaparampil	Andhakaranazhy	1	Pattanakaad
           10	Dominic Cherian, Thavalaparamp il	Andhakaranazhy	18	Pattanakaad
           11	Edison Regi, Palathara	Vettakal	16	Pattanakaad
           12	Eldho Manuel, koyithra	Arassupuram	16	Pattanakaad
           13	Lijo Varkey, Kottarathil	Arassupuram	2	Pattanakaad
           14	David Samuel, Kalapurackal	Thyckal	13	Pattanakaad
           15	Jacob mathew, Thyparampil	Thyckal	13	Pattanakaad
           16	Antony Varghese, Mangalacheriy il	Thyckal	11	Pattanakaad
           17	Saju K, Kadamaat	Andhakaranazhy	1	Pattanakaad
           18	Udayakumar, Puthenchira	Andhakaranazhy	18	Pattanakaad
           19	Common Panchayath well	Maniyampuzhy	13	Pattanakaad
           20	Thresia Jose, Kumbalacheriyil	Vettakal	14	Pattanakaad
           21	Emmanuel, Edavazhikal	Kanattusheriyil	15	Pattanakaad
           22	Common panchayath well	Kanattusheriyil	15	Pattanakaad
           23	Nagarajj, Pathinanjil chira	Kandamanga lam	5	Pattanakaad
           24	Tom Chacko,Pidikayil	Thyckal	7	Pattanakaad

           2. Reagents Required For Testing

           • Reagents used for testing acidity are,

        1. .02N Standard NAOH solution

        2. Methyl Orange indicator

        3. Phenolphthalein indicator

        4. .1Normal Sodium Thiosulphate

   • Reagents required for testing alkalinityare,

   1. Standard Sulphuric acid

   2. Methyl Orange indicator

   3. Phenolphthalein indicator

   • Reagents used for testing hardness are asfollows,

   Fig.a: shows the collected 25 samples

   1. Ammonia Buffer Solution

   2. ErichromeBlack T

   3. Standard EDTA Titrant .01M

2. TESTS TO BE CONDUCTED

   Following are the tests to be conducted to check the changein parameters. It includes

   1. pH Test

   2. Acidity Test

   3. Alkalinity Test

   4. Hardness Test

   5. Turbidity Test

   1. pH TEST

      Clean the electrode using distilled water and dry it using tissue paper. Calibrate the equipment with known buffer solution. Dip the combined electrode in the solution to determine its ph value. pH of drinking water should be in the range 6.5-8.5

      Fig. a :Shows the ph test

   2. ACIDITY TEST

   Pipette 500ml of the sample into a Erlenmeyer flask. Add one drop of 0.1N sodium thiosulphate solution if residual chlorine is present. Add two drops of methyl orange indicator. Titrate the sample against O.2N NaoH solution. Note the volume of titrant at the end point when the color changes from orange red to yellow. Add 3 drops of phenolphthalein indicators to the above & continue titration till an appearance of faint pink colour. Note the volume of titrant. Acidity for potable water should be less than 50mg/l

   Fig. b :shows the Acidity test

   3. ALKALINITY TEST

   Pipette 50ml of sample into Erlenmeyer flask. Add 1 drops of sodium thiosulphate if residual chlorine is present. Add two drops of phenolphthalein indicator ( if PH is above 8.3 colour of solution becomes pink).Titrate the sample against standard acid taken in the burette till the colour just disappears. Add two drops of methyl orange indicator the colour turns to yellow. Again titrate against acid till the

   yellow colour changes to orange yellow or orange red. Note down the volume of the titrate used from the initial reading. Alkalinity of potable water should be less than200mg/l

   Fig. c:Shows the Alkalinity Test

   1. HARDNESS

      Take a sample which will acquire less than 15 ml EDTD titrant.Dilute 25 ml of the sample about 50 ml by adding distilled water (v). In case of samples of low hardness take a larger sample volume.Add 1 or 2 ml of buffer solution to being the ph 10 + or -. 01Add 1 or 2 drops of indicator solution if ca or mg hardness is present, the solution turn wine red.Titrate against EDTA titrant till the sample turn blue.Note the volume of the titrant. Hardness of potable water is less than 60mg/l

      Fig. d:Shows the Hardness Test

   2. TURBIDITY

   Transfer the sample to the test. Open the lid of the sample compartment of the instrument calibrated as above and insert the test tube into the sample compartment. Close the lid. Note the reading and read out as turbidity of sample in NTU. Turbidity value of potable water is less than 5 NTU

3. OBSERVATIONS

   Following are the observations obtained while testing the samples,

   Sl No	pH valu e	Acidic/Al kaline	Acidity (mg/l)	Alkalinity (mg/l)	Hardness (mg/l)	Turbidity (NTU)
   1	7.59	Acidic	134	0	43.6	19
   2	8.46	Alkaline	0	206	23.5	5
   3	8.00	Alkaline	0	222	28.00	4
   4	7.32	Acidic	110	0	27. 5	6
   5	8.89	Alkaline	0	228	30.4	4
   6	8.37	Alkaline	0	94	35.5	21
   7	6.34	Acidic	190	0	32.4	17
   8	6.85	Acidic	170	0	38.7	11
   9	7.4	Acidic	130	0	9.4	11
   10	8.24	Acidic	118	0	10.3	6
   11	7.7	Acidic	154	0	10.5	6
   12	7.95	Acidic	198	0	11.3	7
   13	8.05	Acidic	174	0	12.3	8
   14	8.01	Acidic	170	0	14.3	9
   15	7.95	Acidic	158	0	10.4	9
   16	7.9	Acidic	135	0	13.7	10
   17	7.79	Acidic	170	0	24.7	15
   18	6.99	Acidic	228	0	41.3	9
   19	8.60	Alkaline	0	118	29.5	10
   20	6.7	Acidic	180	0	31.2	9
   21	8.34	Alkaline	0	136	28.7	8
   22	8.54	Alkaline	0	224	32.3	13
   23	8.9	Alkaline	0	214	40.7	16
   24	8.4	Alkaline	0	238	35.4	10

   • PH-ACIDIC/ALKALINE-ACIDITY- ALKALINITY-HARDNESS-TURBIDITY

4. RESULTS

   Value ranges for Potable water are:

   • The pH of most drinking-water lies within the range 6.58.5

   • Turbidity (NTU):<5

   • Acidity(mg/L):<50

   • Alkalinity (as CaCO3) (mg/L):<200

   • Hardness:<60

     That means the samples 3&5 are within the limit for the conditions of turbidity. All samples are within the limits of hardness. Ph for the samples 5,19,22,23 are not in the limit, their for cannot be used for drinking purpose. As per alkalinity test samples 6, 19,21 are portable and no samples

     are portable according to acidity test. Hence it proves that the area which is along the coastal area faces more difficulties due to seawater intrusion.

     Graph. a: shows the details of the results getting after the test and Graph showing the details

     Graph.b: shows the results obtained from testing the samples for acidity

     Graph.c: shows the results obtained from testing the samples for alkalinity

5. CONCLUSIONS

   Saline water intrusion is controlled by maintaining the appropriate balance between water being extracted and the quantity of water recharging into aquifers. Regular monitoring of saline water interface is essential in calculating the accurate management technique. Six methods are normally recognized as methods for controllingor preventing saline water ingression.

   • Keeping basin water level high

   • Creating a fresh water ridge near sea

   • Creating pumping trough or extraction barriertrough

   • Developing artificial subsurface barriers

   • Adopting rainwater harvesting technology andartificial recharging structures

6. ADVANTAGES

• Method is very simple

• Cost effective

• Doesnt require theoretical knowledge

  • Doesnt require skilled persons XII.DISADVANTAGES

• Doesnt provide an accurate result

• There is a chance of occurrence of manual errors

• Time required for testing the samples are too large

• This method cannot be used alone for analysing seawater intrusion in an area.

• Need skilled persons for analysing the graph and suggest appropriate remedial measure

XIII. REFERENCES

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University of Oklahoma, Norman, Oklahoma, Lewis Publishers [2] Cantatore, W. P. and Volker, R. E. (1974), Numerical solution of

the steady interface in a Confined coastal aquifer, Institute of Engineers Australian Civil Engineering Transactions, Vol. CE 16, No. 2.

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[12] Soumaya Hajji,Nabila Allouche, Salem Bouri,Awad M. Aljuaid and Wafik Hachicha, (2021) Assessment of Seawater Intrusion in Coastal Aquifers UsingMultivariate Statistical Analyses and

Hydrochemical FaciesEvolution Based Model, MDPI

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saturated-unsaturated fluid-densitydependent groundwater flow with energy transport or Chemically reactive single-species solute transport, USGS Water Resources Investigations Report 84- 4369, 409 p.

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[16] Mark Saadeh, Elie Wakim, Deterioration of groundwater in beirut due to seawater intrusion American University of Technology (AUT) Halat,Lebanon(November, 2017)