The first means of irrigation and base for most irrigation used by the egyptians. Along the Nile river there are several naturally formed indentions in the earth. During the annual flood these indentions would fill with water. The egyptians of that time came up with the idea to surround these indentions with mud dams so they would hold the water. Cannals were dug from these basins to the farmers fields. As the technology increased, the basins were surrounded by stone dams to keep more water and keep that water in the basin for longer periods. Later the basins were man made to move them to where they were needed. This method was replaced when the cannal system was devised.