Colorado River

Ocean submesoscale fronts induce diabatic heating and convective precipitation within storms

Nature Portfolio (Springer Nature) | January 30th, 2025

The intensity of atmospheric storms is influenced by ocean temperature contrasts. While mesoscale sea surface temperature anomalies ( ~ 200 km-size) are known to inte

The intensity of atmospheric storms is influenced by ocean temperature contrasts. While mesoscale sea surface temperature anomalies ( ~ 200 km-size) are known to intensify storms via latent heat release, the role of finer oceanic scales remains unknown. Using a global coupled ocean-atmosphere simulation at a km-scale resolution, we show that half of latent heat flux variability is driven by oceanic motions at the meso- ( ~ 40%) and submesoscale ( ~ 10-20 km-size,  < 10%) in the Kuroshio Extension during winter. Additionally, ocean submesoscale fronts, with temperature gradients of 5 °C per 10 km, induce a secondary circulation reaching 4 km within the troposphere, which enhances diabatic processes and convective precipitations within storms. In the warm sector of storms, ocean submesoscale fronts locally account for half the total precipitations, averaging 14 mm day−1 over five days. As such, ocean submesoscale fronts pump moisture from the ocean to the atmosphere and have the potential to affect storm intensification.

Optimal Selection and Placement of Green Infrastructure in Urban Watersheds for PCB Control

American Society of Civil Engineers (ASCE) | May 1st, 2019

San Francisco Bay and its watersheds are polluted by legacy polychlorinated biphenyls (PCBs), resulting in the establishment of a total maximum daily load (TDML) that req

San Francisco Bay and its watersheds are polluted by legacy polychlorinated biphenyls (PCBs), resulting in the establishment of a total maximum daily load (TDML) that requires a 90% PCB load reduction from municipal stormwater. Green infrastructure (GI) is a multibenefit solution for stormwater management, potentially addressing the TMDL objectives, but planning and implementing GI cost-effectively to achieve management goals remains a challenge and requires an integrated watershed approach. This study used the nondominated sorting genetic algorithm (NSGA-II) coupled with the Stormwater Management Model (SWMM) to find near-optimal combinations of GIs that maximize PCB load reduction and minimize total relative cost at a watershed scale. The selection and placement of three locally favored GI types (bioretention, infiltration trench, and permeable pavement) were analyzed based on their cost and effectiveness. The results show that between optimal solutions and nonoptimal solutions, the effectiveness in load reduction could vary as much as 30% and the difference in total relative cost could be well over $100 million. Sensitivity analysis of both GI costs and sizing criteria suggest that the assumptions made regarding these parameters greatly influenced the optimal solutions.

Ordinary High Flows and the Stage–Discharge Relationship in the Arid West Region

U.S. Army Corps of Engineers (USACE) | July 14th, 2011

The Ordinary High Water Mark (OHWM) defines the lateral extent of non-wetland waters and is regulated as “Waters of the United States” under Sec. 404 of the Clean Wat

The Ordinary High Water Mark (OHWM) defines the lateral extent of non-wetland waters and is regulated as “Waters of the United States” under Sec. 404 of the Clean Water Act. Previous research has developed a reliable and repeatable methodology for identifying the OHWM on ephemeral and intermittent streams in the Arid West using the physical features of the channel (Lichvar and McColley 2008, Curtis and Lichvar 2010). This study expands upon the previous reports by providing an analysis of how gage data may be utilized in OHW determinations. We clarify the methodology for using gage data, review the potential errors encountered in developing a stage–discharge relationship, compare the position of the gage-predicted OHWM to the field OHW signature, and determine the recurrence interval and flow duration of OHW events. The field OHW signature often is not associated with a 2-year flood event like many assume, but ranges from <1- to 15.5-year flood event. This large variation in recurrence intervals for the field OHWMs makes it impossible to define the frequency of the ordinary high flow from gage data because the OHW event is unique to each channel.

Origins of Extreme Climate States during the 1982–83 ENSO Winter

American Meteorological Society (AMS) | November 1st, 1997

Overview of Management and Restoration Activities in the Salton Sea

Congressional Research Service (CRS) | November 24th, 2013

Efforts to restore the Salton Sea ecosystem have been discussed and initiated through state and federal actions. Several studies by state and federal agencies have provid

Efforts to restore the Salton Sea ecosystem have been discussed and initiated through state and federal actions. Several studies by state and federal agencies have provided baseline data about the Sea, and some restoration plans have been proposed. The State of California, the Salton Sea Authority, and the federal government through the Bureau of Reclamation have devised plans for restoring the Sea. However, none of these plans are being fully implemented. Federal authorities that address restoration of the Salton Sea are generally based on creating and evaluating proposals for restoration, rather than implementing restoration activities in a comprehensive manner similar to other initiatives in the Everglades and Great Lakes. California is pursuing restoration options, but funding for implementing them is lacking. Whether or not to restore the Salton Sea remains controversial. Proponents of restoration contend that the Salton Sea ecosystem is valuable from an ecological standpoint because it is one of the few remaining large-scale wetland habitats in California for migratory birds and fish. Further, some argue that keeping the Salton Sea intact will stimulate economic development, recreation, and tourism in the region. They note that losing the Sea could cause economic and environmental decline, and could lead to air quality problems from exposed seabeds. Others contend that the Sea should not be restored. They argue that the Salton Sea is naturally declining, as it has throughout its geological history. Further, they note that countering this process will be costly and ultimately not worth the expense. They state that limited restoration funds should be used to restore other natural wetlands in California, such as the Sacramento-San Joaquin Bay Delta. The decline of the Salton Sea ecosystem is accelerating due to water transfers from agricultural lands to municipal water districts in San Diego under the terms of the Quantification Settlement Agreement, an agreement on how to share California’s apportionment of Colorado River water. The water transfers have resulted in less water flowing into the Salton Sea and accelerated increases in salinity and shoreline recession. According to some scientists, salinity levels may reach lethal levels for most fish and wildlife as soon as 2018. These predictions, along with the steadily declining ecosystem might provoke Congress to consider a larger role in restoration for the federal government. Congress may decide to address restoration by increasing the federal role in restoration efforts.  This could be done by funding existing federal authorities that address, or could address, restoring the ecosystem; authorizing federal participation and appropriations for implementing existing restoration plans; or authorizing a new comprehensive plan to be created that might involve participation from federal and non-federal stakeholders, similar to other restoration initiatives around the country. Congress might also decide not to address restoration of the Salton Sea ecosystem, or simply maintain the status quo of federal participation.

Passage and Flow Considered Anew: Wild Salmon Restoration Via Hyrdo Relicensing

University of Montana | May 24th, 2016

Paying for California's Water System

Public Policy Institute of California (PPIC) | May 31st, 2021

Paying it Forward: The Path Toward Climate-Safe Infrastructure in California

Climate-Safe Infrastructure Working Group | September 1st, 2018

Performance of Fire Danger Indices and Their Utility in Predicting Future Wildfire Danger Over the Conterminous United States

American Geophysical Union (AGU) | November 20th, 2023

Piloting a Water Rights Information System for California

Center for Law, Energy, and the Environment (CLEE) | July 15th, 2021

California’s complex water management challenges are growing and intensifying. Systemic stressors like the more frequent and severe droughts and floods driven by climat

California’s complex water management challenges are growing and intensifying. Systemic stressors like the more frequent and severe droughts and floods driven by climate change are only making it harder to respond. Accordingly, California needs to dramatically improve the ability of local, regional, and State entities to make agile and effective water management decisions. We believe doing so will require enhanced understanding of our water resources and how they align with the needs of a range of agencies and stakeholders. Water rights data provide a crucial opportunity for advancing this understanding. We find that modernizing water rights data is feasible, affordable, and can increase transparency and clarity for better decision-making.