research Dude, research
Here is what I do when researching.
I used to work at the USGS, so I have many many topographical maps. Now you can get the images online, but sometimes its hard to take them with you. I am old school and like to look at paper maps so I can think and see a lot of the territory instead of using my phone and only seeing a small area.
I look for secondary streams, even small which could only be considered a ditch. Remember thousands of years ago the water table was higher and what may be a small ditch with little water back then likely had more water.
Then I log into the GIS web site for the county to find the land owner. I also purchase plat books from the county.
From that information I contact the land owner - normally by knocking on the front door. Its too easy for them to say no or simply hang up on the phone.
If they are like me, in today's world of spam robo-calls, I don't even answer the phone if they are not in my contact list.
I have met some nice folks this way, and they normally remember me.
I spoke to a guy a few weeks ago I had not spoken to in almost 20 years, and he remembered me. I also remind them of the truck I had then, and the new truck I have now so that may jog their memory. And it helps them associate me when they see my truck parked by their barn.