Researchers have found that the water supply of the Colorado River basin, one of the most important sources for water in the southwestern United States, is influenced more by wet-dry periods than by human use, which has been fairly stable during the past few decades. The team found that water storage decreased by 50 to 100 cubic kilometers (enough water to fill Lake Mead as much as three times) during droughts that occur about every decade. The big difference between recent and previous droughts is that there have been few wet years since 2000 to replenish the water. In contrast, multiple wet years followed drought years in the 1980s and 1990s.

In the American West, unprecedented droughts have caused extreme water shortages. The current drought in California and across the West is entering its fourth year, with precipitation and water storage reaching record low levels. Droughts are ranked second in the United States in terms of national weather-related economic impacts, with annual losses just shy of $9 billion. With water scarcity likely to increase due to advancing climate change, the economic and environmental impacts of drought are also likely to get worse. Alternative models of watershed protection that balance recreational use and land conservation must no longer be ignored to preserve water supplies against the effects of climate change, experts argue.

Engineers have found an energy-efficient material for removing salt from seawater. The material, a nanometer-thick sheet of molybdenum disulfide (MoS2) riddled with tiny holes called nanopores, is specially designed to let high volumes of water through but keep salt and other contaminates out, a process called desalination.

Wildfires, which are on the rise throughout the west as a result of prolonged drought and climate change, can alter soil properties and make it more vulnerable to erosion. A new study shows that the increase in wildfires may double soil erosion in some western United States by 2050, and all that dirt ends up in streams, clogging creeks and degrading water quality.

As meteorologists monitor the El Nino condition currently gaining strength in the Pacific Ocean, Californians look with hope to the much-needed rain and snow it could yield. But if Californians are going to make the most of the precipitation, they need to put a LID on it. LIDs, or low-impact development technologies, mimic pre-urban stream functions. Examples are green roofs that absorb and evapotranspire rainfall; rainwater tanks attached to homes and other buildings; and permeable pavement for roads, driveways and parking lots. Rainwater could even be used in the home for toilet flushing and laundry.

Summer, or southwest, monsoons are moisture-soaked seasonal winds that bring critical rainfall to the Indian subcontinent during the June-September wet season. An abundant season provides sustaining rainfall that replenishes water reservoirs and reaps bountiful crop harvests. By contrast, a weak season could lead to drought, soaring food prices and a battered economy. Better to understand global weather patterns and increase scientific collaboration between the United States and India, researchers have completed a month-long cruise studying summer monsoon conditions in the Bay of Bengal.

About half of the water supply in the southwestern United States is supplied by water conveyed from forests, which generally yield higher quality water than any other land use. However, forests are vulnerable to wildfire; more than twelve million acres of land, including important forested water-supply watersheds, have burned in the southwestern United States in the past thirty years. Wildfires increase susceptibility of watersheds to both flooding and erosion, and thus can impair water supplies.

To meet the requirements of Asian cities, researchers are adapting an idea they have already applied in Germany for comprehensive water management: They are developing a concept for reducing water use, treating wastewater and extracting fertilizer for a strip of coastline in the Vietnamese city of Da Nang.

Snowpack in California’s Sierra Nevada in 2015 was at the lowest level in the past 500 years, according to a new report. “Our study really points to the extreme character of the 2014-15 winter. This is not just unprecedented over 80 years — it’s unprecedented over 500 years,” said the lead author of the report. On 1 April of this year, California Governor Jerry Brown declared the first-ever mandatory water restrictions throughout the state while standing on dry ground at 6,800-foot elevation in the Sierra Nevada. The historical average snowpack on that site is more than five feet, according to the California Department of Water Resources.