Tag Archive for: Science Daily

How Rock Expands Near Soil Surface In Southern Sierra Nevada

A University of Wyoming researcher and his team discovered that weathering of subsurface rock in the Southern Sierra Nevada Mountains of California occurs due more to rocks expanding than from chemical decomposition, as previously thought.

Porosity, the void space in rock, was conventionally thought to be produced when water flows through the rock, thus resulting in minerals chemically dissolving. Because mountain watershed provides large reservoirs of water, the new findings are relevant to water resource management throughout the U.S.

A Drier Future Sets The Stage For More Wildfires

November 8, 2018 was a dry day in Butte County, California. The state was in its sixth consecutive year of drought, and the county had not had a rainfall event producing more than a half inch of rain for seven months. The dry summer had parched the spring vegetation, and the strong northeasterly winds of autumn were gusting at 35 miles per hour and rising, creating red flag conditions: Any planned or unplanned fires could quickly get out of control.

Snowmelt Causes Seismic Swarm Near California’s Long Valley Caldera

The unusual event prompted U.S. Geological Survey researcher Emily Montgomery-Brown and her colleagues to look back through 33 years of seismic and water records for the region. They found that rates of shallow seismicity were about 37 times higher during very wet periods versus dry periods. Although scientists have linked earthquakes to heavy rainfall or heavy runoff before this, the evidence connecting the two has been relatively weak or ambiguous, says Montgomery-Brown. In the Long Valley Caldera case, she says, “we’re seeing phenomenal correlation between the seismicity and the stream discharge, and we are seeing about 37 times the number of earthquakes during the wet season as during the dry season.”

Coastal Ecosystems Suffer From Upriver Hydroelectric Dams

The researchers analyzed downstream ecosystems from four rivers, two dammed and two unobstructed, in the Mexican Pacific states of Sinaloa and Nayarit. They found dramatic coastal recession along the mouths of the obstructed rivers, including in vital ecosystems like mangrove forests, which provide protection from storms, commercial fishery habitats, and belowground carbon storage. The rivers that the researchers studied run roughly parallel to each other through similarly-developed land, into large coastal lagoon systems. The Santiago and Fuerte rivers have dams that provide hydroelectric power for the region, but withhold 95% of the flow of these rivers. Meanwhile, the San Pedro and Acaponeta rivers are relatively free-flowing and undammed, with over 75% of the rivers remaining unobstructed.