Month

August 2020
05
Aug

Two recent exercises in modeling the hydrological effects of forest thinning and wildfire are yielding intriguing insights.

Hydrogeologist Fadji Maina and colleague Erica Siirila-Woodburn of the Lawrence Berkeley National Laboratory ran simulations of wildfire effects in the Cosumnes River watershed (see map). “We chose the Cosumnes because it’s one of the largest rivers that has no dam in California,” explains Maina. The most significant findings concerned the way wildfire affects groundwater recharge and storage. “It depends on where the wildfire occurs,” says Maina. The underlying rocks—foothill volcanics or High Sierra granites—make a difference. Consistent with earlier studies, the model also showed more snow accumulation after wildfire, but unexpected results include a post-fire increase in evapotranspiration in some downslope areas. Another study focused on the effects of forest thinning on snowpack on the west side of Lake Tahoe. A team led by...
Read More
05
Aug

A team of scientists is close to chasing down every last thing that happens to nitrogen in wastewater as it passes through the soils and plants of a horizontal levee.

Not only is 97% of the nitrogen removed, but also trace pharmaceuticals. “You just have to focus on where the water is going,” says environmental engineer Aidan Cecchetti, referring to the UC Berkeley-Stanford-ReNUWIt team’s experimentation with three components of flow through the levee system—under the surface, over the surface, or into the air (through evapotranspiration). “In the wastewater pumped to the subsurface, you see full removal of every contaminant except phosphorous.” What’s most astonishing is how much of the work occurs in that subsurface drainage through the first 10% of levee slope. What happened further along the slope mattered less, the team found; plants only absorbed 8-12% of the nitrogen, with willows being the highest performing species. “Predicting performance is...
Read More
05
Aug

Although the Covid-19 pandemic and attendant economic cataclysm have tripped up some ambitious plans for funding climate resilience in California, other measures to integrate adaptation and planning are still on track.

In July, the Metropolitan Transportation Commission and the Association of Bay Area Governments released the draft of Plan Bay Area 2050, a 30-year plan to guide growth in the nine-county region. “The biggest new integration in the plan is a set of investments to protect our Bay and ocean shorelines from rising sea levels,” says MTC’s Dave Vautin. The plan calls for just under $20 billion in investments ranging from seawalls and traditional levees to horizontal levees and wetland restoration to protect communities and infrastructure. “The draft showcases how that system of infrastructure improvements could protect 98% of all homes at risk over the next 30-years, as well as all major highways, railways and the vast majority of offices and...
Read More
05
Aug

Great whales, the largest creatures in the sea, can help mitigate climate change by locking up carbon in their massive bodies and boosting phytoplankton with their waste products.

A preliminary study by researchers with the International Monetary Fund’s Institute for Capacity Development, the University of Notre Dame, and Duke University found that each great whale sequesters an average of 33 tons of CO2 over its lifetime, taking that carbon out of the atmosphere for centuries: when a whale dies and sinks to the sea floor, it takes that carbon with it, says Joe Roman, conservation biologist and author of Whale. (Compare that to a tree, which sequesters about 48 pounds of CO2 per year.) Whales act as nutrient pumps in the ocean as they dive and feed and then surface, nourishing phytoplankton growth with their waste products, which contain the iron and nitrogen the marine algae need to...
Read More
05
Aug

More than half the water diverted from Central Valley rivers is used to irrigate cattle-feed crops, implicating beef and dairy as top drivers of recent fish declines.

Recent findings, published in Nature Sustainability in March, strengthen the environmental arguments for going vegan while rewriting the familiar narrative that almonds and other high-value tree crops are the top hogs of Central Valley water resources. The study’s authors, led by Brian Richter of Virginia-based Sustainable Waters, focused on the arid West and found that irrigated crops like alfalfa and hay, more than any others, are drying out rivers. The reduced flows are pushing dozens of fish species toward extinction. “We estimate that 60 fish species in the western US are at elevated risk of imperilment or extinction due to flow depletion, and that 53 (88%) of these are primarily due to irrigation of cattle-feed crops,” the scientists wrote in...
Read More