Rapid progression of ocean acidification in the California current system

American Association for the Advancement of Science (AAAS) | June 14th, 2012

Nearshore waters of the California Current System (California CS) already today have a low carbonate saturation state, making them particularly susceptible to o

Nearshore waters of the California Current System (California CS) already today have a low carbonate saturation state, making them particularly susceptible to ocean acidification. Here, we use eddy-resolving model simulations to study the potential development of ocean acidification in this system up to 2050 under the SRES A2 and B1 scenarios. In both scenarios, the saturation state of aragonite Ωaragis projected to drop rapidly, with much of the nearshore regions developing summer-long undersaturation in the top 60 m within the next 30 years. By the year 2050, waters with Ωarag above 1.5 have largely disappeared and more than half of the waters are undersaturated year-round. Habitats along the seafloor become exposed to year-round undersaturation within the next 20 to 30 years. This has potentially major implications for the rich and diverse ecosystem that characterizes the California CS.

Recommendations for a Modeling Framework to Answer Nutrient Management Questions in the Sacramento-San Joaquin Delta

San Francisco Estuary Institute (SFEI) | March 1st, 2016

Management actions in the Delta related to nutrients could cost billions of dollars to implement in the coming decades depending on decisions that will come before the Ce

Management actions in the Delta related to nutrients could cost billions of dollars to implement in the coming decades depending on decisions that will come before the Central Valley Regional Water Quality Control Board (Water Board). The complexity of the Delta ecosystem and the range of questions to be addressed demand that numerical, processed-based water quality modeling be part of Delta management efforts. In light of this fact, the Water Board convened the Modeling Science Workgroup in 2015, and tasked it with advising on the development and use of water quality models as one component of the Water Board’s Nutrient Research Plan. The Charge to the Modeling Science Workgroup (included in Appendix B) was to provide advice to the Water Board on:  · The types of models would be needed to answer the nutrient management questions raised by stakeholders,  · Organizational arrangements to support and maximize the benefits of models, and  · Cost estimates for the modeling task and how such work might be phased over time. 

Reconstructing the Mediaeval low stands of Mono Lake, Sierra Nevada, California, USA

Holocene (Sage Journals) | December 1st, 2019

Palaeosimulations of Mono Lake covering the past 2 kyr have been conducted using a water balance model forced with tree-ring derived inflow estimates. The results show tw

Palaeosimulations of Mono Lake covering the past 2 kyr have been conducted using a water balance model forced with tree-ring derived inflow estimates. The results show two low stands, during the ninth to tenth and twelfth to thirteenth centuries, that agree well in timing and magnitude with those described by Stine (1987, 1990, 1994) on the basis of geomorphic evidence and relict trees and shrubs exposed on Mono Lake's artificially exposed shorelands. The lake simulation provides independent corroboration of the timing and magnitude of Stine's drought-induced low stands and supports the accuracy of tree-ring-derived estimates of Mediaeval precipitation and runoff reductions in the central Sierra Nevada. Specifically, we estimate that during the two Mediaeval droughts, centennial average precipitation and river runoff in the central Sierra Nevada reached as low as 75% of the twentieth century values, with multidecade averages as low as 60—65%. In both magnitude and duration, these droughts far exceed anything experienced in the region during modern times. An analysis of the spatial patterns of reconstructed drought indices shows that the particular `two drought' Mono Lake low stand signal was focused over central and southern California, indicating the dominant role of boreal winter precipitation deficits. In this respect, the `Great Sierra Nevada droughts' were somewhat distinct from the more general Great Basin/far western Plains pattern of Mediaeval aridity over the western USA.

Refinement of Rice Water Consumptive Use During the Growing Season — Sacramento Valley Phase II — Cal-SIMETAW Model Study

California Department of Water Resources (DWR) | June 6th, 2018

The purpose of this study is to evaluate crop water use for the most commonly grown paddy rice variety grown in the Sacramento Valley, M206, based on field data collected

The purpose of this study is to evaluate crop water use for the most commonly grown paddy rice variety grown in the Sacramento Valley, M206, based on field data collected from 2007 through 2009, and from 2011 through 2013. M206 was identified by the University of California (UC) Cooperative Extension Farm Advisors as the most commonly grown rice variety in the study area. Phase I of this study was conducted by the University of California, Davis (UC Davis), under contract with DWR. A brief description of both Phase I and Phase II have been included here to provide orientation as the progression of the work and linkages between each phase regarding the study results. 

Regional Monitoring Program (RMP) Small Tributaries Loading Strategy: Modeling and Trends Strategy 2018

San Francisco Estuary Institute (SFEI) | September 3rd, 2018

The Small Tributaries Loading Strategy (STLS) (SFEI, 2009) is a collaboration between the RMP, the Water Board, and Bay Area stormwater programs to address information n

The Small Tributaries Loading Strategy (STLS) (SFEI, 2009) is a collaboration between the RMP, the Water Board, and Bay Area stormwater programs to address information needs associated with improving understanding about the sources, pathways, loads, trends, and management opportunities in relation to watershed-derived pollutants of concern (POCs). Elements contained in this Strategy may be conducted via RMP collaborative efforts, or independently by the Water Board or Bay Area stormwater programs outside of, but in coordination with the RMP. The current priority POCs are mercury (Hg) and polychlorinated biphenyls (PCBs), for which there are identified impairments and cleanup plans in place. The San Francisco Bay Hg and PCBs total maximum daily loads (TMDLs) reports (SFRWQCB, 2006; SFRWQCB, 2007) call for a reduction in tributary loads by 50% and 90%, respectively. In response, from 2010-2015, during the first term of the Municipal Regional Stormwater Permit (MRP 1.0) (SFRWQCB, 2009; 2011), a number of pilot efforts were initiated, focusing mainly on PCBs, to better understand the potential cost-effectiveness for a range of management options and the level of opportunity (the number of polluted sites or the amount of mass associated with polluted sites, property ownership and other factors). During the second term of the MRP (MRP 2.0) (SFRWQCB, 2015), efforts have been made to move from pilot testing to a greater amount of focused implementation. All of these past, current, and future efforts also aim to address (but at a lesser level) multiple benefits for other POCs including current-use pesticides and emerging contaminants, for which there is interest in monitoring the potential for biological impact. These are lower priority at the present, but in the longer term, the STLS Trends Strategy could address these and other POCs in a more focused manner.

Regional patterns and proximal causes of the recent snowpack decline in the Rocky Mountains, U.S.

American Geophysical Union (AGU) | March 30th, 2013

Climatologies of Rocky Mountain snowpack are shown to be seasonally and regionally complex, with Pacific decadal variability positively reinforcing the anthropogenic warm

Climatologies of Rocky Mountain snowpack are shown to be seasonally and regionally complex, with Pacific decadal variability positively reinforcing the anthropogenic warming trend.

Regional Watershed Modeling and Trends Implementation Plan

San Francisco Estuary Institute (SFEI) | July 1st, 2019

Regional Watershed Spreadsheet Model (RWSM) Year 5 Progress Report

San Francisco Estuary Institute (SFEI) | March 1st, 2016

The Regional Watershed Spreadsheet Model (RWSM) is a regional-scale planning tool developed primarily to estimate long-term average annual loads from the small tributari

The Regional Watershed Spreadsheet Model (RWSM) is a regional-scale planning tool developed primarily to estimate long-term average annual loads from the small tributaries surrounding San Francisco Bay, and secondarily to provide supporting information for prioritizing watersheds or areas within watersheds for management actions. The RWSM has been in development since 2010. In previous years, obstacles to calibrating the PCB and Hg models included issues associated with GIS data underlying the Model, a simplistic model structure and parameterization, lack of available empirical data for calibrating concentrations associated with specific land uses and source areas, and the high uncertainty with the empirical calibration dataset. The modeling effort in Years 2014 and 2015 (Year 4 and 5 of the model development) focused on improving the model calibration to attempt to resolve these issues. The major changes included switching from a sediment-based model to a water-based model, elimination of double counting of source areas on top of general land uses, changes in the model calibration approach, and changes to the land use grouping.

Relationship between wetland condition, stress, and buffer

San Francisco Estuary Institute (SFEI) | April 25th, 2016

Relationship between wetland size and CRAM condition scores for depressional wetlands

San Francisco Estuary Institute (SFEI) | March 28th, 2016