Swales on contour confusion

i have a question: i built a swale on contour (that is with the berm downhill along the contour line, so the bottom side of the trench)
there are two sides at the swale though, the trench has an upper side too (uphill)
this one is not level at all on my piece of land, does that matter?
I hope you get my question
I think i know the answer but just checking if someone could give me a light bulb?

Oh yes and yet another question: does the bottom side or the upper side of the trench (or both sides) have to be at an angle of 45 degrees to prevent erosion?

THANKS

Hi Murielle,

The MOST important is that the top of the berm be on contour, AND that you have a compacted sill for overflow in case of a major rain event. It is not as important that the upslope side be exactly level, but it does help to prevent some gully wash erosion of water going into the swale.

You are also correct in assuming that the 45 degree angle slope is for the down-hill side.

Nathanael is spot on. One thing I do as extra protection is load some rocks into the emergency overflow. It’s extra protection plus I can scoop any clay or or silt that has built up behind the rocks.