THE RIVERS MUST BE CONTROLLED
The real trick in both Egypt and Mesopotamia is to make the rivers work for you. In Egypt, this is a matter of building dikes and reservoirs that will catch and hold the Nile flood. In this way, the water is held and allowed to run off over the fields as it is needed. In Mesopotamia, it is a matter of taking advantage of natural river channels and branch channels, and of leading ditches from these onto the fields.
Obviously, we can no longer find the first dikes or reservoirs of the Nile Valley, or the first canals or ditches of Mesopotamia. The same land has been lived on far too long for any traces of the first attempts to be left; or, especially in Egypt, it has been covered by the yearly deposits of silt, dropped by the river floods. But we’re pretty sure the first food-producers of Egypt and southern Mesopotamia must have made such dikes, canals, and ditches. In the first place, there can’t have been enough rain for them to grow things otherwise. In the second place, the patterns for such projects seem to have been pretty well set by historic times.