Rainwater on raised beds

[Yorky1]

I've covered some raised beds in black plastic for the winter. The plastic is weighed down along the edges but on one of the beds the soil level is a couple of inches lower than the sides of the bed so it has filled with rainwater.

This isn't a particular problem but someone suggested it would go stagnant and start to smell .

Would this happen and if so could you suggest a simple solution?

Thanks in advance.

 

[freddiemercurystwin]

 

[big-all]

stones bricks sleepers bit off wood whatever it takes to make the hollow a high point
unless you are talking a few inches and a lot off litres stagnation is unlikely to be a problem as evaporation and more rain will cure the problem