Along with the resource that the rivers and river basins provide, it is important to point out as well that they provide a somewhat low tech highway for travel as well.Lakes and large waterways are for the most part dammed and have some obstacles, but the requirement for a vehicle requires very little effort of strength lifting to circumvent obstacles and continue travels.
At one point looking at Badin Lake in the Uwaharrie National Forest, we were able to track a path from that inland area by water all the way to the Carolina coast and in an emergency could well have made an escape had it been necessary without a great deal of trouble.
So the network of waterways provides a resource for survival that is water. It provides a resource for agriculture and growing food. It also provides a low tech highway that facilitates travel and allows for doing so with a minimum of physical strain and some ability to carry supplies.
The flow of water from the surface and seepage into the ground is illustrated in the graphics below. In the northern hemisphere water flow is from North to South above and below ground. Precipitation gathers as snow and water and runoffs saturate the ground allowing water to seep deep into the ground. A natural water table exists beneath the ground which moves water. These water tables are important to understand because they are the sources of water derived from wells that are punched or drilled into the Earth. Knowing where water is, the direction in which it flows, and mapping it is important for many reasons, not the least of which is to avoid polluting it when creating a septic system. It is important to locate the water and identify the depth before digging a well to avoid wasting time and labor on dry holes.
Wells are very often dug with a wider pipe than the one that will draw the water up for use. Whatever pumping mechanism is used, be sure to have a manual device available as well as any kind of power failure should have a reasonable means available for drawing water. As a staple it is necessary and must be available.