Where to place rock wall for potential dew collection?

As we have been planting our citrus trees I noticed I have a nice natural depression in a mostly flat part of the yard. Call it a rain garden or a crater garden or just a mostly round depression swale thing. Anyway, it is prime for a project so I am trying to figure out how best to use it. It will naturally collect water when it rains, so that's good but I want to up my game. We get some nice fog here in the summer so I thought I would make a rock wall/bench and see if the fog and dew to collect and add to the crater. But I am not sure what side  I should place the rocks - upslope or downslope? Or does that matter?

See very rock picture not to scale.

Thanks in advance.

I would do a test by getting some scrap sheet metal and place it around and observe the results with it facing in different directions.   Scrap metal is much easier to move around than a stone wall, and you can know for sure what direction is best prior to putting up the wall.

Nancy, what a great idea. Thank you!