Propagation of future climate conditions into hydrologic response from coastal southern California watersheds
As a biodiverse region under a Mediterranean climate with a mix of highly developed and natural watersheds, coastal Santa Barbara County (SB), located in southern California, is susceptible to the hydrologic impacts of climate change. This study investigates the potential changes in hydro-meteorological variables in this region as well as their societal and ecological implications for projected climate conditions during the twenty-first century. Daily streamflow ensembles from 135 coastal watersheds for the period 2021–2100 are developed using the Hillslope River Routing (HRR) model forced with downscaled precipitation and temperature projections derived from 10 climate models in the Coupled Model Inter-Comparison Project, Phase 5, and two emission scenarios (Representative Concentration Pathways, RCP, 4.5 and 8.5). Analysis of the projected ensemble precipitation and streamflow series relative to historical conditions (1961–2000) shows (i) minimal change in annual precipitation (median change within ±3%); (ii) an altered seasonal rainfall distribution with a decrease in rainfall at the beginning of the rainy season (Oct–Dec), an increase during the Jan–Mar period, and a decrease at the end of the season (Apr–Jun); (iii) increases in the magnitude and frequency of large storms (> 36 mm/day) which combined with a shorter rainy season, lead to increases in annual peak flows; and (iv) the propagation of the altered precipitation characteristics resulting in nonlinear changes in the magnitude and variability of annual maximum discharges (i.e., mean, standard deviation, skew) impacting estimated return period discharges (e.g., estimated 100-year flood discharges for the period 2061–2100 under 8.5 increase by up to 185%). While these results are specific to southern coastal California, the nature of nonlinear hydrologic response to altered precipitation characteristics underscores the value of regional studies investigating potential impacts of climate projections on streamflow dynamics.
We thank Dr. David Pierce for the climate model downscaling datasets, support for which was provided by the California Energy Commission (CEC-500-10-041) and the US Geological Survey through the Southwest Climate Science Center and from NOAA through the California Nevada Climate Applications Project (CNAP) Regional Integrated Science Applications (RISA) program.
D.F., E.B., J.M. and D.C. designed the framework of this study. D.F. and E.B. wrote the paper with support from J.M. R.R. developed PET data, Y.Z. contributed to the HRR model setup, S.I. performed the precipitation and temperature downscaling. D.F. performed the model calibration, future simulations, and results analyses.
This research was supported by the Santa Barbara Area Coastal Ecosystem Vulnerability Assessment (SBA CEVA) with funding from the NOAA Climate Program Office Coastal and Ocean Climate Applications (COCA) and Sea Grant Community Climate Adaptation Initiative (CCAI), NASA’s Terrestrial Hydrology (NNX12AQ36G, NNX14AD82G) and SWOT (NNX16AQ39G) Programs, and the National Science Foundation’s Long-Term Ecological Research (LTER) program (Santa Barbara Coastal LTER—OCE9982105, OCE-0620276, and OCE-123277).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no competing interests.
- Beighley R, Moglen G (2002) Trend assessment in rainfall-runoff behavior in urbanizing watersheds. J Hydrol Eng 7(1):27–34. https://doi.org/10.1061/(ASCE)1084-0699(2002)7:1(27) CrossRefGoogle Scholar
- Beighley RE, Melack JM, Dunne T (2003) Impacts of California’s climatic regimes and coastal land use change on streamflow characteristics. JAWRA J Am Water Res Assoc 39(6):1419–1433. https://doi.org/10.1111/j.1752-1688.2003.tb04428.x CrossRefGoogle Scholar
- Beighley RE, Dunne T, Melack JM (2008) Impacts of climate variability and land use alterations on frequency distributions of terrestrial runoff loading to coastal waters in Southern California. JAWRA Journal of the American Water Resources Association 44(1):62–74. https://doi.org/10.1111/j.1752-1688.2007.00138.x CrossRefGoogle Scholar
- Cayan D, Tyree M, Kunkel KE, Castro C, Gershunov A, Barsugli J, Ray AJ, Overpeck J, Anderson M, Russell J et al (2013) Future climate: Projected average. In: Garfin G, Jardine A, Merideth R, Black M, LeRoy S (eds) In assessment of climate change in the southwest United States: A report prepared for the national climate assessment. A report by the Southwest Climate Alliance, Washington, DC, pp 101–125CrossRefGoogle Scholar
- Hoerling MP, Dettinger M, Wolter K, Lukas J, Eischeid J, Nemani R, Liebmann B and Kunkel KE (2013). “Present weather and climate: Evolving conditions.” In assessment of climate change in the southwest united states: A report prepared for the national climate assessment. A report by the Southwest Climate Alliance. G. Garfin, A. Jardine, R. Merideth, M. Black and S. LeRoy. Washington, DC: 74–100Google Scholar
- Homer CG, Dewitz JA, Yang L, Jin S, Danielson P, Xian G, Coulston J, Herold ND, Wickham JD, Megown K (2015) Completion of the 2011 national land cover database for the conterminous United States-representing a decade of land cover change information. Photogramm Eng Remote Sens 81(5):345–354Google Scholar
- Hossain F, Arnold J, Beighley E, Brown C, Burian S, Chen J, Mitra A, Niyogi D, Pielke R Sr, Tidwell V et al (2015) What do experienced water managers think of water resources of our nation and its management infrastructure? PLoS One 10(11):e0142073. https://doi.org/10.1371/journal.pone.0142073 CrossRefGoogle Scholar
- Johnson T, Butcher J, Deb D, Faizullabhoy M, Hummel P, Kittle J, McGinnis S, Mearns LO, Nover D, Parker A et al (2015) Modeling streamflow and water quality sensitivity to climate change and urban development in 20 U.S. watersheds. JAWRA J Am Water Resour Assoc 51(5):1321–1341. https://doi.org/10.1111/1752-1688.12308 CrossRefGoogle Scholar
- Kunkel KE, Stevens LE, Stevens SE, Sun L, Janssen E, Wuebbles D, Redmond KT and Dobson JG (2013). Regional climate trends and scenarios for the U.S. National Climate Assessment: part 5. Climate of the Southwest U.S. NOAA Technical Report. Washington, D.C., National Oceanic and Atmospheric Administration 87Google Scholar
- Livneh B, Rosenberg EA, Lin C, Nijssen B, Mishra V, Andreadis KM, Maurer EP, Lettenmaier DP (2013) A long-term hydrologically based dataset of land surface fluxes and states for the conterminous United States: update and extensions. J Clim 26:9384–9392. https://doi.org/10.1175/jcli-d-12-00508.1 CrossRefGoogle Scholar
- Mishra V and Lettenmaier DP (2011). Climatic trends in major US urban areas, 1950–2009. Geophys Res Lett 38(16)Google Scholar
- Myers MR, Cayan DR, Iacobellis SF, Melack JM, Beighley RE, Barnard PL, Dugan JE and Page HM (2017). Santa Barbara area coastal ecosystem vulnerability assessmentGoogle Scholar
- O’Neill JAI (2010) Climate change’s impact on the design of water, wastewater, and stormwater infrastructure. Hydrol Days 2010:79–88Google Scholar
- Pierce DW, Kalansky JF and Cayan DR (2018). Climate, drought, and sea level rise scenarios for the fourth California climate assessment. California’s Fourth Climate Change Assessment, California Energy Commission. Publication number: CNRA-CEC-2018-006Google Scholar
- Priestley CHB, Taylor RJ (1972) On the assessment of surface heat flux and evaporation using large-scale parameters. Mon Weather Rev 100(2):81–92. https://doi.org/10.1175/1520-0493(1972)100<0081:OTAOSH>2.3.CO;2 CrossRefGoogle Scholar
- Ray RL, Beighley RE, Yoon Y (2016) Integrating runoff generation and flow routing in Susquehanna River basin to characterize key hydrologic processes contributing to maximum annual flood events. J Hydrol Eng 21(9):04016026. https://doi.org/10.1061/(ASCE)HE.1943-5584.0001389 CrossRefGoogle Scholar
- Thomas C. Peterson, Richard R. Heim, Robert Hirsch, Dale P. Kaiser, Harold Brooks, Noah S. Diffenbaugh, Randall M. Dole, Jason P. Giovannettone, Kristen Guirguis, Thomas R. Karl, Richard W. Katz, Kenneth Kunkel, Dennis Lettenmaier, Gregory J. McCabe, Christopher J. Paciorek, Karen R. Ryberg, Siegfried Schubert, Viviane B. S. Silva, Brooke C. Stewart, Aldo V. Vecchia, Gabriele Villarini, Russell S. Vose, John Walsh, Michael Wehner, David Wolock, Klaus Wolter, Connie A. Woodhouse, Donald Wuebbles, (2013) Monitoring and Understanding Changes in Heat Waves, Cold Waves, Floods, and Droughts in the United States: State of Knowledge. Bulletin of the American Meteorological Society 94(6):821–834Google Scholar
- Warrick JA, Melack JM, Goodridge BM (2015) Sediment yields from small, steep coastal watersheds of California. J Hydrol: Regional Studies 4:516–534Google Scholar