Water reservoir-straight vs zigzag wall

[waterpipe]

Dear all,
I am a mechanical engineer but it doesn't stop me of nailing some civil concepts!
Dealing with a 50000 m3 concrete water reservoir, due to land limitation, consultant civil department has submitted the reservoir plan like the following schematic sketch (blue color is the proposed plan):

Here's my question: why not using a straight wall (such as alternative 1 or 2) instead of the zigzag south walls? Any design or construction consideration? wall height is around 6 meter.
Thank you all in advance.

 

[plasgears]

The zigzag reminds me of the semicircular shell designs that were used to save material in large dams. The circ shells were in compression, and the downstream appearance was a series of vertial columns. KISS.

 

[waterpipe]

Thank you all for your comments. For updating and closing the post:

I had a meeting with the designer firm at the construction site. As soon as I shot the question, the senior structural engineer said: "It is a valid concern and there is no explanation for the inclined wall. Few custom panels are nothing compared to the added complexity and materials. I had the same question when I came in ... blah blah blah. BUT the wall pouring has started!".

Well, I take it as an example where there's no "thinking" brain behind a project and planning. A "desk engineer" designer plus no supervisory control definitely lead to these kind of blunders.

I am sorry, but this time it was you structural colleagues!

Best regards
waterpipe
Mechanical Eng.