Pumping of Brackish and Saline Water in Coastal Aquifers: An Effective Tool for Alleviation of Seawater Intrusion

Mohsen SherifCivil and Environmental Eng. DepartmentCollege of Engineering, UAE University

United Arab Emirates

23 June 2008

Anvar KacimovDepartment of Soils, Water and

Agricultural Engineering, SQU UniversitySultanate of Oman

Factors Affecting Seawater Intrusion

Seawater Intrusion into Coastal Aquifers

• Type of aquifer and its geometry and geology • Water table and pizometric heads• Natural rates of flow• Irrigation and agricultural practices • Pumping and recharge events• Rainfall intensities and frequencies

• Seawater concentration and density• Characteristics and parameters of the porous medium• Geometric and hydraulic boundaries • Tidal effects

• Earthquakes and vibrational effects• Others

Which of these factors are important? It depends on the problem

• Inevitable process

• Pumping activities and intrusion rates

Measures to Control Seawater Intrusion

• Reduce the pumping rates• Reallocation of pumping fields• Land use and agriculture practices• Artificial recharge of groundwater• Use of Scavenger wells

Mitigation of Seawater Intrusion

Objective and Study Domain

• Examine the possibility of reducing seawater intrusion by pumping of saline (brackish) groundwater.

n = 0.25, kx = 10-6 m2, ky = 10-7 m2, α = 5 mρf = 1000 kg/m3 , ρs = 1025 kg/m3

6 m (asl) 4 m (asl)

50 m

1000 m

H2 = 4 + k (50 –y)

Hmax = 5.25 m

4000 elements (5.0 x 2.5 m)4221 nodes

Tested Scenarios

140 m 105 m

277 m 196 m

6 m4 m

5 m 4 m

Run 1

Run 2

Steady State equi-concentration lines

Steady State velocity vectors

Reduced hydraulic head at the land side

6 m 4 m

Pumping 86 m3/d: Steady state

Q1

Run 3

Q1 Q1

Pumping 86 m3/d from two locations at land and sea side boundaries: Steady state

Effect of Pumping

Effect of Pumping

6 m 4 m

Run 5

Q1 Q2

Q1 = 86 m3/d and Q2 = 130 m3/dSteady State equi-concentration lines

Pumping from a single well

Basic Run Group 1Run 1

Group 1Run 2

Group 1Run 3

Group 2Run 4

Group 2Run 6

Group 3Run 7

Group 3Run 8

Group 3Run 9

Thank You