Hydrogeology, often called ground water which is water in the materials of the earth's crust, is important to all of us as it is the life source for growing anything. Research has shown that ground water reserves rise and fall with the amount of moisture which falls and soaks into the earth. California, which is a source of much of the food within the US, actually was mostly dry, desert land until the arrival of irrigation on a large scale. Water to irrigate and maintain crops is a huge issue in California. Also, ground water is the source used for much of the drinking water for cities. If the ground water is polluted by chemicals, or decimated by the demands of irrigation, California will not have enough water to both irrigate and maintain urban water for drinking. That means that food grown in California is put at risk which will affect supply and price for the rest of us. My belief is that the next conflict or war will be over water rights.