For any region, country, culture, civilization to succeed and grow and support substantial populations it must have a stable supply and flow of water. Weather and weather cycles play a huge issue with these needs and can create very difficult challenges to over come. EL Nino and La Nina are very well known in the United States. These factors of the Pacific Ocean cycles affect nearly two-thirds of the populations of the World. Causes floods and droughts here in the US.

Large population bases have the need for storage and recharging aquifers during times of excess water. Once it flows to the ocean, it may not return for several years. As populations grow there are increasing frequency and severity of these droughts. Without adequate water supply, common decency goes out the window, with water rights fights leading to court battles in the US and actual wars where countries share a river