==> What I think is unethical, (not necessarily limited to engineers ethics) is to put poor people with no ability to flee a natural disaster in such areas.
I absolutely agree with that. However, there are a three questions/comments that arise from that, but may not be applicable for this forum. First, many of the people who lived in flooded areas were not 'put' there, but chose to live there. Second, many of the people who lived in those areas choose not to flee, and finally, many of those in those areas are not poor. Although one person is not sufficient grounds for broad generalizations, Fats Domino is probably the most well-known example of one who lived in the lower ninth ward and lost everything, but doesn't meat any of those three criteria.
Again, I completely agree with your premise, and yes, it is true that many who suffered and died were poor and to varying degrees immobile, I hope that no-one believes that all who suffered or died, were poor, put there, and had no chance to flee. Some had no choice, but many were just plain foolish.
Good Luck
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As a circle of light increases so does the circumference of darkness around it. - Albert Einstein