Title: Anthropogenic Warming Impacts on Today's Sierra Nevada Snowpack and Flood Risk: WARMING IMPACTS ON SNOWPACK AND FLOOD RISK

Abstract

Abstract This study investigates temperature impacts to snowpack and runoff‐driven flood risk over the Sierra Nevada during the extremely wet year of 2016–2017, which followed the extraordinary California drought of 2011–2015. By perturbing near‐surface temperatures from a 9‐km dynamically downscaled simulation, a series of offline land surface model experiments explore how Sierra Nevada hydrology has already been impacted by historical anthropogenic warming and how these impacts evolve under future warming scenarios. Results show that historical warming reduced 2016–2017 Sierra Nevada snow water equivalent by 20% while increasing early‐season runoff by 30%. An additional one third to two thirds loss of snowpack is projected by the end of the century, depending on the emission scenario, with middle elevations experiencing the most significant declines. Notably, the number of days in the future with runoff exceeding 20 mm nearly doubles under a mitigation emission scenarios and triples under a business‐as‐usual scenario. A smaller snow‐to‐rain ratio, as opposed to increased snowmelt, is found to be the primary mechanism of temperature impacts to Sierra snowpack and runoff. These findings are consequential to the prevalence of early‐season floods in the Sierra Nevada. In the Feather River Watershed, historical warming increased runoff by over one third during themore » period of heaviest precipitation in February 2017. This suggests that historical anthropogenic warming may have exacerbated runoff conditions underlying the Oroville Dam spillway overflow that occurred in this month. As warming continues in the future, the potential for runoff‐based flood risk may rise even higher.« less

Authors:

Huang, Xingying  ^[1];

• Search DOE PAGES for author "Huang, Xingying"
• Search DOE PAGES for ORCID "0000-0003-2494-9897"

Hall, Alex D.  ^[1];

• Search DOE PAGES for author "Hall, Alex D."
• Search DOE PAGES for ORCID "0000-0003-4973-8500"

Berg, Neil  ^[1]

• Search DOE PAGES for author "Berg, Neil"
• Search DOE PAGES for ORCID "0000-0002-4939-2397"

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+ Show Author Affiliations

1. Univ. of California, Los Angeles, CA (United States)

Publication Date:

Fri Jun 15 00:00:00 EDT 2018

Research Org.:

Univ. of California, Davis, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1539739

Alternate Identifier(s):

OSTI ID: 1456253

Grant/Contract Number:  

SC0016605; 201603457-04

Resource Type:

Accepted Manuscript

Journal Name:

Geophysical Research Letters

Additional Journal Information:

Journal Volume: 45; Journal Issue: 12; Journal ID: ISSN 0094-8276

Publisher:

American Geophysical Union

Country of Publication:

United States

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; Geology