Winter Inputs Buffer Streamflow Sensitivity to Snowpack Losses in the Salt River Watershed in the Lo
Marcos D. Robles, John C. Hammond, Stephanie K. Kampf, Joel A. Biederman and Eleonora M. C. Demaria
Arizona, Colorado River Basin
Recent streamflow declines in the Upper Colorado River Basin raise concerns about the sensitivity of water supply for 40 million people to rising temperatures. Yet, other studies in western US river basins present a paradox: streamflow has not consistently declined with warming and snow loss. A potential explanation for this lack of consistency is warming-induced production of winter runoff when potential evaporative losses are low. This mechanism is more likely in basins at lower elevations or latitudes with relatively warm winter temperatures and intermittent snowpacks. We test whether this accounts for streamflow patterns in the Salt River and its tributaries, which is a sub-basin in the Lower Colorado River Basin (LCRB). Despite significant warming from 1968–2011 and snow loss in many of the Salt basins, annual and seasonal streamflow did not decline. Between 25% and 50% of annual streamflow is generated in winter when runoff ratios are generally higher and potential evapotranspiration losses are one-third of potential losses in spring. Short term streamflow responses to winter inputs were larger and more efficient than spring and summer responses and their frequencies and magnitudes increased in 1968–2011 compared to 1929–1967. In total, 75% of the largest winter events were associated with atmospheric rivers, which can produce large cool-season streamflow peaks. We conclude that temperature-induced snow loss in this LCRB sub-basin was moderated by enhanced winter hydrological inputs and streamflow production.
Aerial view of the Parks West restoration site overseen by TNC. Taken March 16, 2020.
Conservancy staffers, Dale Turner and Amanda Rebore, helping to map the Sabn Pedro River in Arizona. They use a GPS unit to denote the end of the water flow on the LowerSan Pedro River. They hiked through the Conservancy’s San Pedro Preserve.
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The Nature Conservancy, in collaboration with the Western Water Assessment and the USDA-Agricultural Research Service, has produced a snowtography handbook to support resource managers, researchers, and practitioners seeking to understand how the arrangement and density of trees, or the size and sev[…]
John. B. Bradford, Robert K. Shriver, Marcos D. Robles, Lisa A. McCauley, Travis J. Woolley, Caitlin A. Andrews, Michael Crimmins, David M. Bell
Tree mortality response to drought-density interactions suggests opportunities to enhance drought resistance
A future of hotter temperatures and less precipitation under climate change could increase tree mortality under drought conditions in dry forests across the western U.S., causing large-scale tree die offs. Restoration projects that reduce densities of overgrown forests can result in lower competit[…]
San Pedro River
Dale Turner, Holly Richter, Brooke Bushman
Wet/Dry Mapping Instructions and Data Forms
Example wet/dry mapping instructions and data forms used for the San Pedro wet/dry mapping effort. For more information, see our wet/dry mapping page.[…]