We’re nearly 20 years into celebrating World Water Day, and the issues have only grown more complex — and in many locales, more serious.

The theme of the United Nation’s World Water Day this year is water and food security. Irrigation for agriculture accounts for 70 percent of the water withdrawn from aquifers, rivers, lakes and wetlands. It takes 1,500 liters of water to produce 1 kilogram of wheat, but it takes more than 10 times that amount to produce 1 kilogram of beef.

The need for investment in water-related technologies, and especially in agriculture, is great. The irrigation rates in many parts of the U.S., Mexico, India, China and Spain are already unsustainable, according to a 2008 World Resources Institute report.

Although water scarcity is already critical in many regions, the solutions are also readily available. The WRI report found that 85 percent of global irrigation is still done by flooding field or furrows. Sprinkler and drip irrigation can increase efficiency by 70 percent to 80 percent.

China and India combined will soon spend more than $450 billion in water infrastructure, which includes irrigation, as laid out in both countries’ current five-year plans. That’s nearly a 10-fold growth from a decade ago, when the combined spend for the two countries was just $50 billion.

via World Water Day: Trillions Needed in Investment : Greentech Media.