Everyone likes to point fingers in the opposite direction but there are few reasons for this and I personally don't believe climate change has been a factor long enough to be a major player....yet.
The aquifers are supplied by rainwater that permeates through the soil. Overall, the 48 contiguous states have seen the average annual rainfall increase over the past 120 years. One area that has seen less is in the southwest however not considered significant at this point. This information is available
here. I've pasted the synopsis below.
- On average, total annual precipitation has increased over land areas in the United States and worldwide (see Figures 1 and 2). Since 1901, global precipitation has increased at an average rate of 0.08 inches per decade, while precipitation in the contiguous 48 states has increased at a rate of 0.17 inches per decade.
- Some parts of the United States have experienced greater increases in precipitation than others. A few areas, such as the Southwest, have seen a decrease in precipitation (see Figure 3). Not all of these regional trends are statistically significant, however.
So why are the aquifers drying up? Because we are drawing more water out than what is capable of replacing through the soil. And why is that? Couple reasons.
- Population growth puts higher demand on ground water because we don't use surface water for our supply systems.
- Farming practices. More and more farmers are installing irrigation systems and pattern tiling in order to gain more control of the amount of water saturation on crop lands. This is a double-whammy because first, the tiling redirects water that would normally filter through the soil to replenish the aquifer to ditches and eventually to river systems which carry it to the oceans and second irrigation draws water from the aquifers.
- Our lifestyle. Every home, business, structure, and paved area such as parking lots, highways, sporting complexes, etc. take land that is normally collecting and absorbing rain water to replenish the aquifers and redirecting it over ground to ditches, rivers, and storm systems where it eventually ends up in our lakes and oceans.
- Our demand. Compared to the 1970s the average home in the US today is about twice the size while the average family size is almost half the size. What this means is that along with our population growth each person today demands about four times the roof area which impacts item 3 above.
These are just a few quick examples that I could come up with off the top of my head.