Without water, there is no farm.
Happily I'm in an area that historically gets enough rain on average. Some years are quite wet (like now!) Some years are quite droughty. The wet vs dry is cyclic, so surviving one versus the other is not all that difficult. It's just a matter of waiting for the next year.
This farm relies upon rainwater. There are no streams. There is a inactive dry river bed cutting across the farm that in the past carried excess rainwater during heavy rain storms. It was not a continuous stream. But bulldozing up the mountainside has diverted the water. ☹️ There are no natural ponds nor bogs here either. The majority of the farm lies atop an old a-a lava flow, so that excess rain rapidly drains down into the lava. A few acres lies atop a pahoehoe flow which has numerous small lava tubes below it. Again, heavy rain rapidly drains away in most places but there are spots where drainage is slow or delayed. Thus the farm does not create its own ponds. The only visual evidence of rain runoff is in the driveway. Therefore swales to capture rain runoff would be on no use on this land.
Rainwater is harvested via roof tops and directed to large storage tanks called catchment tanks. Roof tops include the house, barn, various sheds and livestock shelters. The farm had three large, round, corrugated steel tanks capable of holding a total of 23,000 gallons. Additional water is stored in numerous small man-made ponds, one larger 16' round diameter 3' deep (4500 gallons), and the others varying from 25 gallons to 150 gallons. These smaller ponds are for mosquito control.
During droughts, my current water storage is not sufficient. So I haul water by the half ton load twice a week. That's not a lot of water, but if I do it continuously, it's enough to get the farm through the drought years. I just don't put off hauling water until the tanks gets low. It would be too late then to make a difference. So I haul year around whenever the tanks are less than full. And since I pass by the water spigots several times a week anyway, it's not a hassle getting water.
Another source of water for farm use is reusing the greywater. My take is.....why drain greywater into a hole in the ground when water is so precious a resource? Greywater is diverted to orchard trees and some fodder crops. Bananas and pipinolas thrive on the constant water. By not allowing the ground to become waterlogged and by adding manure & mulch from time to time, I have no odor problems when using the greywater.
I don't try to store greywater. Storing it mean that it would need to be treated in some fashion. Even if it just means dribbling it through a series of plant filled ponds, I don't have the set up for it. Aaaaaaah, perhaps a future project. So currently I just run it directly to the plants that I am targeting.