What’s the largest waterfall in the world? If you’re talking by flow rate, it’s Inga Falls. If you mean the tallest, it’s Angel Falls. The widest? Khone Falls. But if you want to know the very largest waterfall in the world, you’ll have to look beneath the ocean. That’s where you’ll find the Denmark Strait Cataract, an underwater waterfall with measurements that make the others look laughable.

The Denmark Strait sits between Greenland and Iceland.

Don’t Go Chasing This Waterfall

Buried far underneath the water’s surface in the Denmark Strait between Greenland and Iceland hides the largest waterfall known to man. Underwater waterfalls, known as cascades—or, when they’re really big, cataracts—exist when cold and warm water meet. The molecules in cold water don’t move around much, so they stay close together and make the water denser than warm water, whose molecules tend to buzz around and leave more space between them. That makes cold water sink straight down through warm water, creating a steady and consistent flow. Read more

Rising temperatures and declining snowpack in the mountains mean that the drought across the western U.S. is about to get even worse.

Sparse snowpack in California’s mountains in late winter 2014 is being repeated in 2015 (above, Mount Lassen in northern California). Snowmelt helps recharge the reservoirs that supply water to the Central Valley. 

Snowpack—which essentially serves as a water tower for the western United States—produces vital meltwater that flows off the mountains each spring. Like a time-release capsule, snowpack refills streams and reservoirs and waters crops and cities through the dry summer in this largely semiarid region.

But the snowpack is becoming more like a snow gap, as temperatures in the Cascades and Sierra Nevadabecome too warm for the snow that replenishes the ecosystem each winter.

Temperatures in the West are rising, and winter storms—which have been in infrequent for years—are bringing more rain and less snow. Read more

We do not often think about what happens after it rains, after we run the dishwasher, after we flush the toilet, or after a business uses water for production. For most of us, bulky and unattractive water infrastructure, such as storm sewers and storage tanks, are conveniently buried underground—out of sight and out of mind.

Congress should advance legislation that will address the nation’s neglected water infrastructure. Our economy, our environment, and public health will benefit.

Yet our policy and investment decisions regarding how we manage and treat polluted runoff—also referred to as stormwater—and wastewater deeply affect our environment, health, and economy. Clean water supports a $50 billion per year recreation industry, $225 billion in coastal tourism, and $29 billion in commercial fishing, as well as billions of dollars in manufacturing and support services. For every $1 billion invested in clean water infrastructure, we create between 10,000 and 15,000 jobs. Read more

Ensuring water security is seen by many as an urgent challenge that could threaten the lives and livelihoods of billions of people if not addressed. Loucks (2011) projects that the population in water-stressed countries will increase from less than one billion people in the mid-1990s to four billion people in 2050. 

Mekonnen and Hoekstra (2016) estimate that four billion already face extreme water scarcity when seasonal and inter-annual variations in water availability are taken into account, implying that more than half the world’s population may currently face water insecurity driven by resource scarcity. In addition to the direct impact of scarcity on security, water shortages and disruptions may also contribute to traditional security threats (Hartley et al., 2017; UN Water, 2013). Concern with water security is reinforced by the appreciation that the impacts of climate change on people will be felt first and most strongly though the water cycle (Stern, 2007).

Water security was first articulated as a policy challenge at the World Water Forum in 2000 in the United Nations Ministerial Declaration of The Hague on Water Security in the Twenty-first Century and it has remained on the agenda of international organisations since then. Extreme weather events such as Hurricanes Harvey and Sandy, and Australia’s Millennium drought have brought water security for large urban populations onto the front page and up the policy agenda at the national and local levels (Dijk et al., 2013; Rosenzweig and Solecki, 2014). Water risk, the corollary of water security, has also become an established boardroom subject: it has been consistently cited by the World Economic Forum as a critical risk for businesses and in 2015 it was identified as the global risk likely to have the greatest impact on economies, environments and people (World Economic Forum, 2015). Read more

This study specifically looked at total water supply in China, water withdrawal from various sources and various usage of water. From the analysis, it was realized that water supply from the underground source contributes greatly to the total water supply in China, a cubic unit withdrawal in underground water results in about 45% increase in the total water supply. Water from other sources also contributes to the total water supply in China.

Water from other sources includes supplies from wastewater treatment, rain collection, seawater desalinization and other water projects. The result shows that a cubic unit increase in withdrawals from other sources results in about 3% change in gross water supply in China. A cubic unit withdrawal of water for industrial use results in about 29% increase in water use in China.

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