Water management in permaculture
All organisms require water to survive, so to feed a designed ecosystem, you need to harvest water from the environment. Look at the land you are working with, and observe, in fine detail, how water moves on it. Where does the water come from and where does it go to? Is there a river or stream? Is there a lot of rain? Is precipitation regular, or does it only occur at certain times of year? Is there a spring or a well? Are there dry patches of land and wet patches of land? For example, you will sometimes see an area beside a wall that is sheltered from the rain. Sometimes a field has a depressed patch that water runs down into. Buildings, roads and other built things tend to catch rain from a broad area and concentrate it. You will often notice that a paved road has a point at the edge that is slightly lower, and all the rain that falls on the road drains out there.
When you know how much water every little spot on the farm gets, you will be able to position plants and other elements tactically. Water-hungry plants can be put in the wettest places, and other plants in drier areas.
You may be lucky enough to be able to build the farm you want around the natural flow of water. But sometimes, you will want to modify the water-flow patterns on the farm. One way of doing this is digging swales, which are indentations in the earth that catch water and soak it into the ground, where it can be tapped by the roots of plants. Another option is to build a rainwater catchment tank.