Few halophytes can effectively reduce salinity

Thanks Dr. Mitra for your time in responding my question.

Best regards,

Ajay

My answer is related to sea-level rise and salt water intrusion into coastal groundwater and agricultural lands  

Saline intrusion caused by sea-level rise (SLR) would cause the most significant impact on coastal groundwater resources along low-lying coasts. Freshwater aquifers in coastal areas are used for drinking water. Many Pacific Island nations are in the danger of losing their fresh-water supplies as SLR pushes saltwater into their aquifers causing contamination by salt. Sea level rise would also cause loss of coastal agricultural land due to flooding, therefore agriculture in low-lying coastal area or adjacent to deltas may be affected.

Some of the adaptation and mitigation options to counter SLR may be (a) building coastal defences (flood barrier to prevent exceptionally high tides and storm surges moving up from the sea), (b) rainwater harvesting, (c) growing salt tolerant rice in affected rice areas (d)  growing brackish water prawn and fish in inundated areas to take advantages of the salty water. 

References 

https://www.researchgate.net/publication/266794121_Sea-Level-Rise_and_Its_Impact_on_Environment_Biodiversity_and_Human_Health-_A_Short_Review

Nicholls, R. J. and A. Cazenave 2010. Sea-Level Rise and Its Impact on Coastal Zones. Science 328: 1517-1520. 

Brown, S., R. J. Nicholls., C. D. Woodroffe., S. Hanson., J. Hinkel, A. S. Kebede, B. Neumann and A. T. Vafeidis  2013. Chapter 5: Sea-level rise impacts and responses: A Global perspective. pp. 117-149. W. Finkl (ed.), Coastal Hazards, Coastal Research Library 6, DOI 10.1007/978-94-007-5234-4_5, # Springer Science+Business Media Dordrecht 2013.

Technical Report Sea-level rise and its impact on wetlands, water, agricultur...

Dear Golam,

Thanks for providing this nice reply and useful references.

Bets regards,

Ajay

Hi Dr Ajay Singh ji; Seawater intrusion is an active research field with substantial unresolved issues. My experiences during my stay in USA at Salinas Valley project and Red Rock Ranch Project in California are the best way to manage sea water intrusion in these areas is only through management and controlled withdrawal of ground waters. The following link may be useful for you.

http://www.sciencedirect.com/science/article/pii/S030917081200053X

Regards

Thank you very much Dr. Dubey jee for sharing your experiences and useful link in response to my query.

Best regards,

Ajay

May be not the best but the first step must be controlled irrigation if there is any ..

@Duygu, thanks for your response, but your answer is inconclusive could you please elaborate?

I do not think that there is a unique answer. The problem is complicated and depends on several parameters e.g., confined, unconfined, aquifer depth, geology, anthropogenic pressures etc. In order to decide the management approach it is very important to delineate the saltwater intrusion zone, either with filed measurement (if you have significant amount of money) or using management tools as simulation models. If the problem is created due to overpumoing activities then is a mater of a management problem controlling pumping. In any case the solution of the problem is not easy and will take many years to improve the situation and not to remediate the aquifer completely.  Obviously, the problem is easier for shallow coastal aquifers. In all cases a continuous monitoring is necessary.

Dear George, Thanks for this nice reply.

Regards

the pumping at constant-head.

Dear @Gianpietro, Thanks for your response, could you please elaborate it!

read this paper: "Experiment of pumping at constant-head: an alternative possibility to the sustainable yield of a well".

so, select the constant-level above the salt/fresh interface witn pump above the interface and the problem is solved.

In alternative you can select the pumping  control with conductivity probe.

Thanks again @Gianpietro, Seawater intrusion problem is a very complex and time taking and needs a long time to improve the situation.

For protecting the fresh ground water aquifers/resources from ingression/intrusion of sea water, the following steps may be important :

1.  Excessive withdrawal/pumping  of ground water  should not be allowed in coastal regions. (Kindly go through well known Ghyben-Herzberg relation).

2 deep drilling of bore wells in coastal region should be avoided.

3. Aquaculture in coastal areas increase the sea water intrusion.

4. Abundant dug wells and other stagnant type of reservoir should be taken into care.

Dear Dr. Saxena, Thanks for your useful comments regarding the management of seawater management problem of water resources in coastal areas.

Regards

I think the best option is Artificial groundwater recharge. Like you rightly said " indiscriminate and unplanned groundwater withdrawal" so there is that urgent need to replace that which has been withdraw. Thanks

Dear @Ambe, Nice comments but quantification of exact amount of recharge-withdrawal itself is a problem because groundwater movement is a very complex phenomena.

Regards

You are right Ajay!! Artificial recharge in many cases does not work!!! 

Sea water intrusion is a main and common environmental problem in the coastal aquifers. In arid areas, it is mainly caused by groundwater depletion associated in most cases with a decrease in groundwater recharge. There are several technical suggested solutions for this problem. Among these solutions is the integrated water resources management, water demand management, water conservation, and aquifer storage and recovery (ASR).

Yes @Ebraheem, Integrated water resources management, water demand management, water conservation, and aquifer storage and recovery (ASR) are useful up to some extent in managing the seawater intrusion problem, though none of them except the last one is directly related with the management of this problem.

Regards

Thank you Dr. Ajay. I am living in an arid area where groundwater depletion and the improper groundwater resources management are the main cause for saltwater intrusion.  Al the available technical solutions for this problem will not work without the demand and IWRM management. What I mean that there is no immediate( in the short run scale of time) solution. 

Kind Regards

It is the responsibility of governments to: 1) Halt pumping from coastal freshwater wells in order to stop the advance of saltwater intrusion. 2) Get rid of navigation channels or agricultural & drainage channels, which provide means for saltwater to move into land.

Before governments take actions, they ought to establish quickly reverse osmosis plants which convert seawater into drinkable water & plants for treatment of waste & sewage water to obtain suitable water for irrigation. If this issue is ignored, grave consequences are envisaged in the near future.

Dear Dr. Nizar, Thank you very much for your nice comments. I fully agree with your views on government's responsibility for managing the problem of seawater intrusion. But the main hurdle in the implementation of these techniques is the heavy expenditure which is associated with the osmosis plants and sewage treatment plants etc. This is particularly a very big challenge for the poor countries. Don't you agree with me?

Dear Dr. Ajay, I agree with you that reverse osmosis & sewage treatment plants are costly for poor countries. But they are not costly  ,e.g., for many countries which are located around the Mediterranean Sea ( A sea undergoing continuous damage). The problem, which you thankfully presented, has occurred in our country "in Gaza Strip" where the people there drink salty water with bad quality & the production of crops has decreased. Of course, that part of our country is poor & needs help. A cost paid today may be better than a heavier cost paid tomorrow.

Dear Dr. Nizar, You have made a very good point here that 'A cost paid today may be better than a heavier cost paid tomorrow.'. But in practice, to follow this very simple principle needs a vision from the policymakers side in the poor countries, because they are going to put money on these measures.

Dear Kamal,

Thanks for your response. Yes,controlled usage of ground waters and coast land protection by building rock fences in the see shores will definitely helpful in combating the seawater intrusion problem in theses areas.

I think the control of usage of ground water is the main option can be followed for manging the environmental problem of seawater intrusion in coastal areas.

Yes Mahfuz, I agree with you because over-exploitation of groundwater is the main cause of seawater intrusion problem in coastal areas.

What is the best option for managing the environmental problem of seawater intrusion in coastal areas?

Sea (salt) water intrusion is a problem for coastal regions around the world and is expected to become a more serious issue in climate changes scenario. Sea-level rise, extreme weather events, coastal erosion, changing precipitation patterns, warmer temperatures, and the potential for increased freshwater demand could all increase the risks of saltwater intrusion. Greater knowledge vulnerability to saltwater intrusion, particularly under conditions of a changing climate is needed in order to plan adequately for the future. Scientific monitoring and assessment form an essential starting point for effective management of saltwater intrusion. As particular aquifer dynamics can vary greatly from location to location, these tools give decision makers an in-depth, localized understanding of their coastal freshwater resources and enable them to make sound and informed decisions. In addition to both supply and demand-related policies, regulatory action may be capable of solving problem related to water quality and quantity in coastal aquifers. Engineering techniques including artificial recharge, aquifer storage and recovery systems, barrier systems, desalination, and blending employed as a way to adapt in the event of saltwater intrusion may also work in coastal aquifer management strategies. However, the effectiveness of engineering techniques will depend a lot on local conditions.

I am very surprised to see answers that actually are literature reviews. I really believe that we need answers from people who have worked on the subject,

Dear George,

Thank you very much for your close and positive observations. I fully agree with you that the answers of RG questions should be original.  However, if it is necessary to quote a published work in support of a particular aspect of a response then a reference/link should be provided.

Dear Ajay,

I agree 100% with you!! 

With a significant rise in sea level there will be an acceleration of beach erosion in areas already eroding and possibly a start of erosion in areas not previously subject to erosion. There are several reasons for this.

1. The main reason for increased erosion is simply that the higher water level allows wave and current erosion processes to act farther up on the beach profile and cause a readjustment of that profile, which results in a net erosion of the beach and deposition on the nearshore bottom.

2.Beach profiles are concave, increasing in steepness nearer to shore. At higher sea levels, waves can get closer to shore before breaking and cause increased erosion.

3. Deeper water also decreases wave refraction and thus increases the capacity for alongshore transport.

4. Higher sea level could change the source of sediments, for example, by decreasing river transport to the sea as the mouth is flooded. However, higher sea level can also act to diminish erosion by making more material available to alongshore transport by allowing wave attack on previously untouched erodable cliffs.

http://papers.risingsea.net/downloads/Challenge_for_this_generation_Barth_and_Titus_chapter6.pdf

Is this an answer to the present question????

Actually do not know but need to know my dears.

Dear RG Fellows,

Thank you very much for your valuable time.

Happy New Year 2015 with hope that you will have many blessings in it.

É um problema complexo, mas sem dúvida que o planejamento, conscientização e fiscalização quanto a retirada excessiva da água no local é um alternativa viável.