goodhors said:
I just keep my ditches well mowed, then spray with Round-up when they dry out in summer. Spraying keeps the grass and weeds down for faster drainage times. Ditches with dirt bottoms stay slick, don't catch leaves to make more dirt.
I use a weedwhacker for the same purpose. Wait til ditch is dry, then scalp the bottom real good, down to bare earth. Two thumbs up

It is amazing how very much faster water flows over smooth bare earth than over short grass, and how much faster over *short* grass than a ditch choked with weeds and tall fallen-over stuff.
Shovel work is for lifting the lid over where underground tube turns, so it gets air to drain better and faster.
Unfortunately we have a very flat property with minimal slope to the ditches, so mine are continually silting in. Once a year, or at most every year and a half, they just need to have a few inches of dirt removed (which is easiest to shovel when it's wet dirt, but easiest to get correctly level/sloped when it's actually carrying a bit of water, so I usually end up doing the 'shoveling underwater' thing although ideally only under an inch or three of water)
We get the water about 3 hours after torrential storms, since we are the bottom of the drainage runoff system where all the water collects to enter the ditch tubes.
In our midwinter thaws, the tide starts to rise *very suddenly* in our backyard at usually about 3 or 4 p.m., hits high water mark around 9 p.m. and then goes back down due to the source watershed being once-again frozen. It's really funny. You look out the window at 3 and see nothing; at 3:15 there is a small patch of water-saturated snow in the "uphill-most" low spots; at 3:30 it's made it all the way across the backyard and by 4 p.m. it has expanded tenfold or more and the driveway culvert is entirely submerged, surf's up!
The main horse paddock does the same thing. 90% of it is too high to ever flood, but there is a strip across one edge that gets runoff from our back fields and beyond, with a meltwater stream at least 30' across and 16" deep in parts going across it. Yet I have very very seldom actually SEEN this running (only when there is a lot of rain on top of a big meltoff) because it does not typically start till after dark, and is shut off and drained/frozen by morning.
Surface-water hydrology is fun, as long as nothing important is in the way of it
(For one thing it's why we could afford this place

The house and barn were originally built by Standardbred people who went to great expense to create a 1/2 mile training track, raised up above mud level in the low part of the property. The raised track of course COMPLETELY cuts off the natural flow of water in all directions, which then ponds and floods really badly behind it. The STB people moved on after just a few years, but the property had another 25+ yrs of owners after that, NONE OF WHOM thought to CUT DITCHES THROUGH the long-since-gone-back-to-grass track berm. Instead they ran gas-powered pumps to pump the water OVER the berms, very slowly. So that was one of the first things we did here (especially after discovering the barn was regularly flooding to at least 12"). Amazingly, when you let the water GO somewhere, not nearly as much ACCUMULATES. People amaze me.)
Pat