Noah Knowles


My research involves the application of climate science, numerical modeling, and analysis of large datasets to natural systems. I work mainly on investigations of systems in which climate change in various manifestations could have an important influence. I have worked at multiple spatial scales, from local to national. Much of my work has focused on California and the San Francisco Bay-Delta estuary and watershed, a system in which the USGS has a long history of cross-disciplinary study. I am currently part of a large, multidisciplinary project aimed at assessing the impacts of projected climate change on the Bay-Delta and its watershed. Our goal is to provide useful information to resource managers in this system.

My work also has relevance beyond this region. The San Francisco Bay-Delta estuary is an urbanized estuary with a highly managed upstream watershed. In these aspects, this system is representative of many watershed-estuary systems throughout the world. The various influences of climate change depicted in my work in California and the U.S. represent a common future for similar systems around the world. 

I received a BS and MS in Physics from the University of Illinois, Urbana-Champaign in 1991 and 1993, respectively. I received a PhD in Oceanography from Scripps Institution of Oceanography (SIO) at the University of California, San Diego in 2000. I subsequently served as a postdoctoral researcher at SIO, then as a National Research Council Research Associate with the U.S. Geological Survey in Menlo Park, California. My research topics have included historical trends in precipitation form in the western U.S. and the influence of projected climate change in California, including changes in snowpack, runoff timing, and San Francisco Bay-Delta water quality. I am currently a Research Hydrologist with the USGS, and my research interests include analysis of regional and national hydrometorological trends and variability, continued hydrologic and estuarine model development, development of hydroclimate scenarios for use in evaluating ecological impacts, and changes in estuarine water quality and shoreline risks due to sea level rise.



Knowles, N., Cronkite‐Ratcliff, C., Pierce, D. W., & Cayan, D. R. 2018. Responses of unimpaired flows, storage, and managed flows to scenarios of climate change in the San Francisco Bay‐Delta watershed.  Water Resources Research, 54. [Link]

Knowles, Noah, and Cronkite-Ratcliff, Collin, 2018. Modeling managed flows in the Sacramento/San Joaquin watershed under scenarios of future change for CASCaDE2: U.S. Geological Survey Open-File Report 2018–1101. [Link]

Knowles, N., Cronkite-Ratcliff, C., Pierce, D.W., and Cayan, D.R. 2018. Data and Associated Code for Projections of Unimpaired Flows, Storage, and Managed Flows for Climate Change Scenarios in the San Francisco Bay-Delta Watershed, California: U.S. Geological Survey data release. [Link]

Knowles, N. 2015. Trends in Snow Cover and Related Quantities at Weather Stations in the Conterminous United States. J. Climate28, 7518–7528. [Link]

Cloern J.E., Knowles N., Brown L.R., Cayan D.R., Dettinger M.D., Morgan T.L., Schoellhamer D.H., Stacey M., van der Wegen M., Wagner R.W., Jassby A.D. 2011. Projected evolution of California’s San Francisco Bay-Delta-River system in a century of climate change. PLoS ONE,6(9). [Link]

Brown, L.R., W.A. Bennett, R.W. Wagner, T. Morgan-King, N. Knowles, F. Feyrer, D. Schoellhamer, M. Stacey, M. Dettinger. 2011. Implications for Future Survival of Delta Smelt from Four Climate Change Scenarios for the Sacramento-San Joaquin Delta, California. Estuaries and Coasts36(4). [Link]

Knowles, N., 2010. Potential inundation due to rising sea levels in the San Francisco Bay region. San Francisco Estuary and Watershed Science,8(1). [Link]

Dettinger, M.D., H. Hidalgo, T. Das, Cayan, D.R., and Knowles, N., 2009. Projections of potential flood regime changes in California. California Climate Change Center publication CEC-500-2009-050-F, 68 pages. [Link]

Ganju, N.K., Knowles, N., and Schoellhamer, D.H., 2008. Temporal downscaling of decadal sediment load estimates to a daily interval for use in hindcast simulations. Journal of Hydrology 349(3-4): 512-523. [Link]

Knowles, N., Dettinger, M.D., and Cayan, D.R., 2006. Trends in snowfall versus rainfall in the western United States. Journal of Climate,19(18), 4545–4559. [Link]

Cloern, J. E., Schraga, T.S., Lopez, C.B., Knowles, N., Labiosa, R.G., and Dugdale, R., 2005. Climate anomalies generate an exceptional dinoflagellate bloom in San Francisco Bay. Geophysical Research Letters32, L14608. [Link]

Knowles, N. and Cayan, D.R., 2004. Elevational dependence of projected hydrologic changes in the San Francisco Estuary and watershed.Climatic Change62, 319-336. [Link]

Cayan, D.R., Dettinger, M.D., Redmond, K., McCabe, G., Knowles, N., and Peterson, D.H., 2003. "The transboundary setting of California's water and hydropower systems—linkages between the Sierra Nevada, Columbia, and Colorado hydroclimates", book chapter. [Link]

Dettinger, M.D., Bennett, W.A., Cayan, D.R., Florsheim, J., Hughes, M., Ingram, B.L., Jassby, A., Knowles, N., Malamud, F., Peterson, D.H., Redmond, K., and Smith, L., 2003. Climate science issues and needs of the CALFED Bay-Delta Program. American Meteorological Society, 83rd Annual Meeting, Impacts of Water Variability Symposium, Long Beach, California, 7.11-1 to 7.11-4. [Link]

Knowles, N., 2002. Natural and human influences on freshwater inflows and salinity in the San Francisco Estuary at monthly to interannual scales. Water Resources Research38, 25-1-25-11. [Link]

Knowles, N. and Cayan, D.R., 2002. Potential effects of global warming on the Sacramento/San Joaquin watershed and the San Francisco Estuary. Geophysical Research Letters29, 38-1-38-4. [Link]

Stahle, D., Therrell, M., Cleaveland, M.K., Cayan, D.R., Dettinger, M.D., and Knowles, N., 2001. Ancient blue oaks reveal human impact on San Francisco Bay salinity. EOS: Transactions, American Geophysical Union, 82(12). [Link]

Knowles, N. 2000. Modeling the hydroclimate of the San Francisco Bay-Delta Estuary and watershed. Doctoral Dissertation, Scripps Institution of Oceanography. La Jolla, California, University of California, San Diego. [Link]