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Folders: ROOT > ScienceBase Catalog > USGS National Research Program > USGS National Research Program Projects > Predict the Variability and Recent Changes in the Hydrologic Cycle to Natural and Human-Induced Climatic Influences ( Show direct descendants )

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Current projections of climate change present a number of challenges to scientists and decision-makers. The projections predict a twenty-first-century climate in which many climate variables are likely to trend across broad geographical areas and at rates that are rapid by historical standards. The projections of change are likely to remain uncertain for many years to come, and complete surprises are possible. Responses to these changes will have to span large areas and many variables, and impacts will interact in complex ways. In the face of these challenges, we offer recommendations as to strategic approaches that the CALFED Science Program—which serves here as an important and illustrative example from among...
Observed changes in the timing of snowmelt dominated streamflow in the western United States are often linked to anthropogenic or other external causes. We assess whether observed streamflow timing changes can be statistically attributed to external forcing, or whether they still lie within the bounds of natural (internal) variability for four large Sierra Nevada (CA) basins, at inflow points to major reservoirs. Streamflow timing is measured by “center timing” (CT), the day when half the annual flow has passed a given point. We use a physically based hydrology model driven by meteorological input from a global climate model to quantify the natural variability in CT trends. Estimated 50-year trends in CT due to...
Categories: Publication; Types: Citation; Tags: runoff, snowmelt, streamflow
Blue oak tree-ring chronologies correlate highly with winter–spring precipitation totals over California, with Sacramento and San Joaquin river stream flow, and with seasonal variations in the salinity gradient in San Francisco Bay. The convergence of fresh and saline currents can influence turbidity, sediment accumulation, and biological productivity in the estuary. Three selected blue oak chronologies were used to develop a 625-year-long reconstruction of the seasonal salinity gradient, or low salinity zone (LSZ), which provides a unique perspective on the interannual-to-decadal variability of this important estuarine habitat indicator. The reconstruction was calibrated with instrumental LSZ data for the winter–spring...
Recent studies find global climate variability in the upper ocean and lower atmosphere during the twentieth century dominated by quasi-biennial, interannual, quasi-decadal and interdecadal signals. The quasi-decadal signal in upper ocean temperature undergoes global warming/cooling of ∼0.1°C, similar to that occurring with the interannual signal (i.e., El Niño–Southern Oscillation), both signals dominated by global warming/cooling in the tropics. From the National Centers for Environmental Prediction troposphere reanalysis and Scripps Institution of Oceanography upper ocean temperature reanalysis we examine the quasi-decadal global tropical diabatic heat storage (DHS) budget from 1975 to 2000. We find the anomalous...
Cayan, D., Tyree, M., Dettinger, M., Hidalgo, H., Das, T., Maurer, E., Bromirski, P., Graham, N., and Flick, R., 2009, Climate change scenarios and sea level rise estimates for California 2009 Climate Change Scenarios Assessment: California Energy Commission Report CEC-500-2009-014-D, 50 p. (on-line report in pdf format, 1851 KB)
Categories: Publication; Types: Citation
National Research Council, 2004, Groundwater Fluxes Across Interfaces: : National Academy Press, Washington, D.C., 85 p. (on-line book)
Categories: Publication; Types: Citation
Healey, M., Dettinger, M., and Norgaard, R., eds., 2008, The state of Bay-Delta science, 2008: CALFED Science Program, 174 p. (on-line report information or on-line report in pdf format, 5775 KB)
Categories: Publication; Types: Citation
Knowles, N., Dettinger, M., and Cayan, D., 2007, Trends in Snowfall Versus Rainfall for the Western United States, 1949-2001: California Energy Commission CEC-500-2007-032, 39 p. (on-line abstract or on-line report in pdf format, 880 KB)
Categories: Publication; Types: Citation
In response to an Executive Order by California Governor Schwarzenegger, an evaluation of the implications to California of possible climate changes was undertaken using a scenario-based approach. The “Scenarios Project” investigated projected impacts of climate change on six sectors in the California region. The investigation considered the early, middle and later portions of the twenty-first century, guided by a set of IPCC Fourth Assessment global climate model runs forced by higher and lower greenhouse gas emission scenarios. Each of these climate simulations produce substantial impacts in California that would require adaptations from present practices or status. The most severe impacts could be avoided, however,...
Experimental observations collected during meteorological field studies conducted by the National Oceanic and Atmospheric Administration near the Russian River of coastal northern California are combined with SSM/I satellite observations offshore to examine the role of landfalling atmospheric rivers in the creation of flooding. While recent studies have documented the characteristics and importance of narrow regions of strong meridional water vapor transport over the eastern Pacific Ocean (recently referred to as atmospheric rivers), this study describes their impact when they strike the U.S. West Coast. A detailed case study is presented, along with an assessment of all 7 floods on the Russian River since the experimental...
Cayan, D., VanScoy, M., Dettinger, M.D., and Helly, J., 2003, The wireless watershed at the Santa Margarita Ecological Reserve: Southwest Hydrology, v. 2, no. 5, p. 18-19. (on-line article, in pdf format)
Categories: Publication; Types: Citation
Peterson, D., Smith, R., and Hager, S., 2004, A walk through the hydroclimate network in Yosemite National Park: River Chemistry, Sierra Nature Notes, v. 4. (on-line article in pdf format)
Categories: Publication; Types: Citation
The timing of the last maximum extent of the Antarctic ice sheets relative to those in the Northern Hemisphere remains poorly understood. We develop a chronology for the Weddell Sea sector of the East Antarctic Ice Sheet that, combined with ages from other Antarctic ice-sheet sectors, indicates that the advance to and retreat from their maximum extent was within dating uncertainties synchronous with most sectors of Northern Hemisphere ice sheets. Surface climate forcing of Antarctic mass balance would probably cause an opposite response, whereby a warming climate would increase accumulation but not surface melting. Our new data support teleconnections involving sea-level forcing from Northern Hemisphere ice sheets...
Categories: Publication; Types: Citation
The USGS Multihazards Project is working with numerous agencies to evaluate and plan for hazards and damages that could be caused by extreme winter storms impacting California. Atmospheric and hydrological aspects of a hypothetical storm scenario have been quantified as a basis for estimation of human, infrastructure, economic, and environmental impacts for emergency-preparedness and flood-planning exercises. In order to ensure scientific defensibility and necessary levels of detail in the scenario description, selected historical storm episodes were concatentated to describe a rapid arrival of several major storms over the state, yielding precipitation totals and runoff rates beyond those occurring during the individual...
The extent to which winter precipitation is orographically enhanced within the Sierra Nevada of California varies from storm to storm, and season to season, from occasions when precipitation rates at low and high altitudes are almost the same to instances when precipitation rates at middle elevations (considered here) can be as much as 30 times more than at the base of the range. Analyses of large-scale conditions associated with orographic precipitation variations during storms and seasons from 1954 to 1999 show that strongly orographic storms most commonly have winds that transport water vapor across the range from a more nearly westerly direction than during less orographic storms and than during the largest...
Categories: Publication; Types: Citation
Recharge into granitic bedrock under a melting snowpack is being investigated as part of a study designed to understand hydrologic processes involving snow at Yosemite National Park in the Sierra Nevada Mountains of California. Snowpack measurements, accompanied by water content and matric potential measurements of the soil under the snowpack, allowed for estimates of infiltration into the soil during snowmelt and percolation into the bedrock. During portions of the snowmelt period, infiltration rates into the soil exceeded the permeability of the bedrock and caused ponding to be sustained at the soil–bedrock interface. During a 5-d period with little measured snowmelt, drainage of the ponded water into the underlying...
Hydrologic time series of groundwater levels, streamflow, precipitation, and tree-ring indices from four alluvial basins in the southwestern United States were spectrally analyzed, and then frequency components were reconstructed to isolate variability due to climatic variations on four time scales. Reconstructed components (RCs), from each time series, were compared to climatic indices like the Pacific Decadal Oscillation (PDO), North American Monsoon (NAM), and El Niño-Southern Oscillation (ENSO), to reveal that as much as 80% of RC variation can be correlated with climate variations on corresponding time scales. In most cases, the hydrologic RCs lag behind the climate indices by 1–36 months. In all four basins,...
The variability (1990–2002) of potential evapotranspiration estimates (ETo) and related meteorological variables from a set of stations from the California Irrigation Management System (CIMIS) is studied. Data from the National Climatic Data Center (NCDC) and from the Department of Energy from 1950 to 2001 were used to validate the results. The objective is to determine the characteristics of climatological ETo and to identify factors controlling its variability (including associated atmospheric circulations). Daily ETo anomalies are strongly correlated with net radiation (Rn) anomalies, relative humidity (RH), and cloud cover, and less with average daily temperature (Tavg). The highest intraseasonal variability...
Categories: Publication; Types: Citation
A 1-dimensional surface energy balance model is applied to produce continuous simulations of daily lake evaporation of Upper Klamath Lake, Oregon (UKL) for the period 1950–2005. The model is implemented using observed data from land-based sites and rafts collected during 2005–2006. Progressively longer, temporally overlapping simulations are produced using observed forcing data sets from sites near UKL. Simulation of the entire 56 years is accomplished using forcing data derived from weather station data and a 1949–2007 regional climate simulation over western North America. Simulated mean annual evaporation for 1950–2005 is 1073 mm. The simulated evaporation estimates are an improvement over existing May–September...