Giant tadpoles. LOL
Those current lines on the topo are 5-10 feet deep, and I assume, (bad word) the width is approx the same. It may have been more than a little ditch.
The walls around the Pyramids, served some function. Personally, I don't think they went to that much effort, for a decorative purpose. It has been estimated, they were 29-30 feet tale. Water could have flowed in all night long, and then be used, for the days work, and freshwater. Do not drink out of the Nile. It may make you sick. That is present day, it likely was much cleaned 4,000 years ago?
Are the fires over?