20th-SWIM20th-SWIMH.F.Abd-ElhamidH.F.Abd-Elhamid 11

An Investigation into Control of Saltwater Intrusion

Considering the Effects of Climate Change and Sea Level Rise

H. F. Abd-Elhamid

A.A. Javadi

20th - SWIMSchool of Engineering,

Computing and Mathematics

Computational Geomechanics Group School of Engineering, Computing and Mathematics,

University of Exeter, Exeter, UK.

20th-SWIM20th-SWIMH.F.Abd-ElhamidH.F.Abd-Elhamid 22

Saltwater intrusion problem Saltwater intrusion problem

The main causes of Saltwater intrusion The main causes of Saltwater intrusion

The impact of climate changes and sea level rise on SWIThe impact of climate changes and sea level rise on SWI

Measures to control SWIMeasures to control SWI

The limitations of the previous methods to control SWIThe limitations of the previous methods to control SWI

The proposed methodology to control SWIThe proposed methodology to control SWI

The objectives of The objectives of 2D-FEST2D-FEST model model

Model resultsModel results

Conclusions Conclusions

Outline

20th - SWIMSchool of Engineering,

Computing and Mathematics

20th-SWIM20th-SWIMH.F.Abd-ElhamidH.F.Abd-Elhamid 33

Saltwater IntrusionSaltwater Intrusion

Coastal regions (70% of population)Coastal regions (70% of population)

Population growthPopulation growth Increase water demands Increase water demands

Increase the extraction from aquifers Saltwater intrusion migration Saltwater intrusion migration

Salinization (2-3%)Salinization (2-3%)

Abandonment of freshwater supplyAbandonment of freshwater supply

SWI control SWI control

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The main causes of Saltwater intrusionThe main causes of Saltwater intrusion

1- Human activities - Over-pumping

2- Natural events- Climate changes - Sea level rise- Tides

Climate change - Human activities (global worming) - Natural changes (volcanoes, sun)

Sea level rise - Thermal expansion of seas & oceans - Melting of glaciers and ice caps - Melting of Antarctic ice sheets

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Estimation of sea level rise -- Last Century (10-20) cm (IPCC1996) -- Current Century (20-88) cm (IPCC2001)

The combined impact of sea level rise and over-pumping on SWI

http://whyfiles.org

20th-SWIM20th-SWIMH.F.Abd-ElhamidH.F.Abd-Elhamid 66

Measures to control Saltwater Intrusion Measures to control Saltwater Intrusion

1.1.Reduce pumping rates.Reduce pumping rates.

2. Relocate pumping wells.2. Relocate pumping wells.

3. Subsurface barrier 3. Subsurface barrier

4. Natural recharge4. Natural recharge

5. Artificial recharge (injection wells)5. Artificial recharge (injection wells)

6. Extraction wells6. Extraction wells

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6- Extraction wells6- Extraction wells -- Extract brackish water - Dispose it to the sea- Dispose it to the sea

5- Artificial recharge (injection wells)5- Artificial recharge (injection wells)

- Surface spread (unconfined)- Surface spread (unconfined)-- injection wellsinjection wells (confined)(confined)- Injected water may be from - Injected water may be from (surface water, ground water, (surface water, ground water, treated waste, desalinated treated waste, desalinated seawater.)seawater.)

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The limitations of the previous methods to control SWIThe limitations of the previous methods to control SWI

Short term solution (population growth)

Not efficient for deep aquifers Not efficient for deep aquifers

Availability of fresh water for rechargeAvailability of fresh water for recharge

The cost of Fresh water The cost of Fresh water

Using treated waste water for rechargereated waste water for recharge

Using desalinated sea water for rechargeesalinated sea water for recharge

Disposal of brackish water to the sea and the effects on marines, fishing and tourism Disposal of brackish water to the sea and the effects on marines, fishing and tourism

Sea level rise due to climate change not considered

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The proposed methodology (ADR)

1-1-((AA)) Abstract brackish waterAbstract brackish water2-2-((DD)) Desalinate brackish water using Desalinate brackish water using (RO)(RO) 3-3-((RR)) Recharge the Recharge the desalinated brackish water (part)

Advantages 1-1- Increase fresh water storage ncrease fresh water storage 2- Decrease saline water volume 2- Decrease saline water volume 3- Control saltwater intrusion3- Control saltwater intrusion4- Increase water resources4- Increase water resources

Overcomes shortcomings of previous methods - RORO: availability and cost of fresh watervailability and cost of fresh water-- Recovery rate (70-90%)Recovery rate (70-90%)-- Disposal of brine (30-10%) Disposal of brine (30-10%)

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The objectives of the 2D-FEST ModelThe objectives of the 2D-FEST Model

Develop a coupled transient finite element model for computing solute transport Develop a coupled transient finite element model for computing solute transport through saturated/unsaturated soils.through saturated/unsaturated soils.

Study saltwater intrusion of miscible solute transport (density-dependant)Study saltwater intrusion of miscible solute transport (density-dependant) Use the developed model predict the extent and solute concentrations Use the developed model predict the extent and solute concentrations

Study the effect of sea level rise due to climate change on saltwater intrusion for Study the effect of sea level rise due to climate change on saltwater intrusion for the current century (IPCC 2001).the current century (IPCC 2001).

Use the developed model to study the control of saltwater intrusion using different Use the developed model to study the control of saltwater intrusion using different scenarios.scenarios.

Study the efficiency of the proposed methodology to provide a new source of Study the efficiency of the proposed methodology to provide a new source of water for coastal regions. water for coastal regions.

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The steps of the proposed project The steps of the proposed project

Fresh waterBrackish water

D

L

Aw Rw

Sea

1- Simulate SWI and predict salts extent and concentrations

2- Simulate the effect of sea level rise due to climate changes (20-

88 cm/century)

3- Simulate different scenarios to control SWI (Recharge wells -

Abstraction wells - Combination of Abstraction Recharge wells)

4- Simulation - Optimization (location – depth - rates)(location – depth - rates)

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Model resultsModel resultsConcentration distribution at the bottom

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T=2

T=3

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T=20

T=50

T=100

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- 2D-FEST Model- Henry (1964)

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Model resultsModel results- 2D-FEST Model- Henry (1964)

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Sea level rise

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Model resultsModel results

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- 2D-FEST Model- SUTRA Code- INTERA Code - Henry (1964)

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Conclusions Conclusions

The developed coupled transient finite element model gave good results to predict the extent The developed coupled transient finite element model gave good results to predict the extent

and solute concentrations in coastal aquifers.and solute concentrations in coastal aquifers.

The developed model can be used to Study saltwater intrusion of miscible solute transport The developed model can be used to Study saltwater intrusion of miscible solute transport

(density-dependant).(density-dependant). The developed model can be used to study the effects of sea level rise on saltwater intrusion.The developed model can be used to study the effects of sea level rise on saltwater intrusion.

Future (cont. current) workFuture (cont. current) work

Use the developed model to study the control of saltwater intrusion using different Use the developed model to study the control of saltwater intrusion using different scenarios.scenarios.

Simulation - Optimization models.Simulation - Optimization models.

21th SWIM. 21th SWIM.

20th-SWIM20th-SWIMH.F.Abd-ElhamidH.F.Abd-Elhamid 1717

ThanksQ & A

20th - SWIMSchool of Engineering,

Computing and Mathematics