Comment by danans
12 hours ago
> In other arid areas, people use terracing on hills so the water runoff is slowed and the water can soak into the aquifers. Also, dikes are built around fields to hold the water and also let it soak into the ground.
> Are these done in California?
People terrace where the only arable land is in hills or mountains. The vast majority of California's farmland is flat as a board.
California's central valley also has one of the most massive systems of water control (aqueducts, levees, etc) in the world.
The problem with water and Ag in California is caused by the massive disparities in water rights that make it extremely cheap for some and expensive for others, depending on their water rights.
I infer they aren't bulldozing a dike around the flat farmland to prevent runoff and allow the water to soak into the ground.
This will also reduce flooding from overloading the rivers with water.
You need some outflow to carry away salts. Otherwise, the water just evaporates and leaves the salt there, and eventually the land becomes unable to grow crops. This has historically been a serious problem in Mesopotamia, for example.