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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Urban water demand will increase by 80% by 2050, while climate change will alter the timing and distribution of water. Here we quantify the magnitude of these twin challenges to urban water security, combining a dataset of urban water sources of 482 of the world’s largest cities with estimates of future water demand, based on the Intergovernmental Panel on Climate Change (IPCC)’s Fifth Assessment scenarios, and predictions of future water availability, using the WaterGAP3 modelling framework.

We project an urban surface-water deficit of 1,386–6,764 million m³. More than 27% of cities studied, containing 233 million people, will have water demands that exceed surface-water availability. An additional 19% of cities, which are dependent on surface-water transfers, have a high potential for conflict between the urban and agricultural sectors, since both sectors cannot obtain their estimated future water demands. In 80% of these high-conflict watersheds, improvements in agricultural water-use efficiency could free up enough water for urban use. Investments in improving agricultural water use could thus serve as an important global change adaptation strategy.

Cities around the world are markedly expanding in size, as global urban growth (that is, increasing urban population) leads to more than two billion additional urban residents by 20301. Today, approximately 54% of the global population (that is, 3.9 billion people1) lives in cities, a fraction that is likely to grow to between 60% and 92% by the end of the twentyfirst century, according to the scenarios from shared socioeconomic pathways2 (SSPs). Domestic water use almost quadrupled over the last 60 years due to increasing population, wealth and access to drinking-water infrastructure3, and there was an even higher increase in water use in cities4. Read more