Sinkholes and Saturated solutions
Question:

In 2009 a man fell into a sinkhole 20 meters deep near the Dead Sea in Israel during a trip in that area.

A sinkhole is a hole in the ground caused by the collapse of the ground surface layer as a result of certain natural processes.


It is known that in the Dead Sea area, salt layers buried underneath the ground surface are covered by salty groundwater that is in a saturated solution state. It is also known that the sinkholes' phenomenon is related to the fact that every year the Dead Sea water level declines. Water level decline causes the salt layers to be flooded by fresh groundwater.




The animation shared under Creative Commons Licenses: http://www.haaretz.co.il/st/c/static/media/2016/deadsea/how2.gif





The following animation about Saturated and non-saturated Solutions will help you to refresh your memory. 




What might be then the connection between the Dead Sea water level decline and the sinkholes' phenomenon?




0 People tried to answer this question

When sea level declines the water above the salt layers is no longer a saturated solution, then the salt dissolves causing the sinkhole to form.

When sea level declines salty groundwater floods the salt layers, the water above is no longer a saturated solution, then the salt dissolves causing the sinkhole to form.

When sea level declines the salt layers dry out and break causing the sinkhole to form.

When sea level declines the water above the salt layers is a saturated solution, then the salt dissolves causing the sinkhole to form.



Comments:
1.  . Lior (2020-05-20 16:00:00)
Good job!

Excellent question, guys and gals!

The question is closely related to the picture, the video and the geographic location.

Solving the question involves deep understanding of the topic and thorough thinking. The picture and the video add much info and help answering the question. A picture is worth a thousand words. For example, we can see that the fresh water appears above the salt layer, so we can imagine how it dissolves the salt.

You’ve used an actual occurrence from local news.

Minor items for improvement:

  • Try keeping the answer variants of a similar length.

  • Try keeping the map points as close to your location as possible, e.g. sinkholes in Mexico.

  • I would add a relevant video clip:


ABC Breaking News | Latest News Videos Credit: ABC news.


  • I would add a more detailed sketch and a photo of a sinkhole to the question, like these: sketch, photo.


2.  (2021-05-20 16:00:00)
Good Job: Question and Topic

First and foremost, I want to say that the question is great and is relevant both to student's from abroad and especially to student's here in Israel where the phenomena has become widespread in recent years.

Although, I would like to raise a few points to think about:

    1. A wise and educated student who is aware of the fact that the dead sea is located in a desert zone with no replenishing  water sources, would find it hard to understand the sudden source of fresh water that dissolve the salt layer in the ground creating the sinkholes.

    2. The diagrams presented to the student as part of the material  the question is built upon, does not supply the dimension of time in which the fresh water appears. A short explanation about floods phenomena in the area is needed to explain to the student why and how fresh water gets in contact with the salty ground. In addition, there needs to be an explanation about the retreatment of the sea and the exposure of the salty ground to the sudden flush of the fresh water coming from the floods. This ultimately break's the natural circle that one's was present in the area. The dissolving of the salt by the fresh water coming from the floods is fairly quick due to the fact they are not saturated with salt almost at all. The sea however cannot replenish the salt in the rock anymore because it is no longer in contact with it, thus endorsing the formation of sinkholes in the area.

         Regards

          Ohad Menaker

3.  Shay Meni (2021-05-20 16:00:00)
something to think about
This question is interesting. It makes use of  sientific knowledge and connects it to our day to day lives, espcially, if you are fond of trips in the desert, like I do.


4.  farran olfat (29.05.2016 pm 01.57.09)
Personal point

A very interesting question and is related to our daily lives, not only scientific knowledge but also everyday life and in addition to that this question is relevant for students in Israel and to students from the rest of the world ,that the above phenomenon is very common phenomenon and could occur in our lives  every day.

• Try to keep the points close to your location on map as far as possible sinkhole, for example, sinkholes in Mexico.

• I think that a student does not have to think much in order to answer, immediately after he read the paragraph, you showed the relationship between the water level and the phenomenon of formation sinkholes in the paragraph and explanation of the chemical side in the animation, so I would use the image alone without an explanation of each phase, and begin the paragraph with an accident that occurred in a particular place were roads closed due to a sinkhole, and so the simulation will be enough.

• I would further add a video of sinkholes occurrence because some students do not even know what a sinkhole is and how it looks like.

5.  Levy Yardena (02.06.2016 pm 11.22.33)
Thank you all

I would like to thank all who commented. It is very nice to get such supporting comments. Thank you all also for the suggestions. However, we preferred to keep the question simple and not too long, so we added information through the points on the map, such as a sample of a sinkhole, though in Mexico. It would have been better in the Dead Sea, we accept that.

It was important for us that the students will make the right connection between the scientific knowledge of saturated and un-saturated solutions and what is happening under the ground of the Dead Sea. This connection is the heart of the question. I can accept Olfat suggestion to take out the chemical explanation in the animation to make the question more difficult but the animation is not the answer so the student still has to figure out the right connection that explain the sinkhole formation. 

6.  Levy Yardena (02.06.2016 pm 11.42.56)
Fresh groundwater

I would like to add something to Ohad about the fresh groundwater. We did not explain their presence since this is not essential information to the question and did not want to prolong the question unnecessarily. Actually we assumed they are originated from rains. Although the Dead Sea area is a relatively dry area, it gets rain, and heavy rain brings floods. 

Thank you Ohad for your comment. 

7.  Dagash Wael (05.06.2016 am 10.52.53)
response
Thank you all for your comments,
Because there is another point about the sinkholes in dead sea, I decided to add another point that explains the difference between saltwater and freshwater .you can see this point in the map (wael's home).


History of edits
Edited BY: Yardena Levy Edit Date: 2016-05-15 23:00:15
Edited BY: Yardena Levy Edit Date: 2016-05-15 22:41:06
Edited BY: Yardena Levy Edit Date: 2016-05-15 22:37:44
Edited BY: Yardena Levy Edit Date: 2016-05-15 22:35:20
Edited BY: Yardena Levy Edit Date: 2016-05-15 22:31:48
Edited BY: Yardena Levy Edit Date: 2016-05-15 22:27:07