Water management in a wet hill with a high slope

Hi everyone! First post here

I am helping designing a water management system for a whole side of a hill in a tropical climate. This hill is heavily forested with very varied and interesting plants, so I want to keep the cutting down to a minimum.

The other problem is that in certain points the slope is too steep to make a proper channel (above 10°).

Lastly the hill ends in a meadow that is completely waterclogged.

1°: how do I drain this meadow? Would a deep ditch excavated at the base of the hill be enough?

2° there are for sure certain places were I can place canals to slow down erosion and slow the course of water, but I am not sure I can design a plan to bring these channels on the side of the hill down to the main ditch that it will be at the base of the hill, in the grassy meadow. Doing swales does not make much sense because the whole place is already soaking wet, so it doesn't need more water infiltration. Does it make sense to dig channels that end in fishponds with no outlet? Or for it to make sense I have to bring the water down to the main drainage ditch?

Sorry, I know my post is confused but I recieved a confusing assignment with no clear objective besides "drain this waterclogged meadow at the bottom of the hill".

Please let me know your ideas, this is the first time I am handling a problem like this on this scale and I need some ideas to bounce around.

Thank you!

Welcome to Permies!

Let me ask you a few questions, in hopes of being able to help you brainstorm!

Do you know what type of soil the area is? Heavy in clay?

How much rainfall do you tend to get in the area? Is it just standing water or do you have a lot of runoff events?

As Timothy has mentioned, we need a lot more information before commenting.
- where are you located
- Is the rainfall spread over the year or appear in a short time period?
- What area is being drained?
-  Where will the water be drained too?
- will any water run in bare earth or lined drains?
- what volumes are we looking at?

Welcome to the forum!

I agree that knowing what part of the world you are in will help folks answer your question.

Permaculture principle is that a problem is a resource that is not being utilized.  If the water is coming out of the hillside develop the spring to pipe the water to where it will be useful.  If the water is coming up in the meadow then make a pond lower than the meadow.

Does the hillside need to be drained or just the meadow? Is the meadow also really steep? I'm thinking leave the planting on the hill alone as much as possible to slow the water flow, and the trees will also suck up and reuse much of the rain. Maybe introduce some terracing if the soil type/rainfall permits. I've read that swales are not a good idea above certain gradients as the infiltratation of water can cause landslips. If the meadow is at the bottom with less slope then the options there for drainage ditches (for example) are various and less challenging.