Redshifts and Velocity Dispersions of Galaxy Clusters in the Horologium-Reticulum Supercluster

We present 118 new optical redshifts for galaxies in 12 clusters in the Horologium-Reticulum supercluster (HRS) of galaxies. For 76 galaxies, the data were obtained with the Dual Beam Spectrograph on the 2.3m telescope of the Australian National University at Siding Spring Observatory. After combining 42 previously unpublished redshifts with our new sample, we determine mean redshifts and velocity dispersions for 13 clusters, in which previous observational data were sparse. In six of the 13 clusters, the newly determined mean redshifts differ by more than 750 km/s from the published values. In the case of three clusters, A3047, A3109, and A3120, the redshift data indicate the presence of multiple components along the line of sight. The new cluster redshifts, when combined with other reliable mean redshifts for clusters in the HRS, are found to be distinctly bi-modal. Furthermore, the two redshift components are consistent with the bi-modal redshift distribution found for the inter-cluster galaxies in the HRS by Fleenor et al. (2005).Comment: 13 pages, 3 figures, Accepted to A

Drought and the Sacramento-San Joaquin Delta, 2012–2016: Environmental Review and Lessons

This paper reviews environmental management and the use of science in the Sacramento–San Joaquin Delta during California’s 2012–2016 drought. The review is based on available reports and data, and guided by discussions with 27 agency staff, stake-holders, and researchers. Key management actions for the drought are discussed relative to four major drought water management priorities stated by water managers: support public health and safety, control saltwater intrusion, preserve cold water in Shasta Reservoir, and maintain minimum protections for endangered species. Despite some success in streamlining communication through interagency task forces, conflicting management mandates sometimes led to confusion about priorities and actions during the drought (i.e., water delivery, the environment, etc.). This report highlights several lessons and offers suggestions to improve management for future droughts. Recommendations include use of pre-drought warnings, timely drought declarations, improved transparency and useful documentation, better scientific preparation, development of a Delta drought management plan (including preparing for salinity barriers), and improved water accounting. Finally, better environmental outcomes occur when resources are applied to improving habitat and bolstering populations of native species during inter-drought periods, well before stressful conditions occur.

2nd Annual Computer & Technology Law Institute

Materials from the 2nd Annual Computer & Technology Law Institute held by UK/CLE in March 2000

Simplified 1-D Hydrodynamic and Salinity Transport Modeling of the Sacramento–San Joaquin Delta: Sea Level Rise and Water Diversion Effects

Long-term hydrodynamic and salinity transport modeling of the Sacramento–San Joaquin Delta is needed to evaluate the future Delta in terms of the California co-equal goals of ecosystem health and reliable water supply. While 2-D and 3-D hydrodynamic and water quality models are by definition better suited to modeling a complex network of tidally influenced flows under future conditions, a 1-D model is more computationally efficient in narrowing the large variety of multiple-year simulations required into a more manageable task. Still, a 1-D model of sea level rise in an estuary must account for the three-dimensional effects where increased depths will affect density driven (baroclinic) circulation and tidal dispersion of salt. In this paper, we use a simplified Delta network model with a tidally averaged computational approach to quickly perform multi-year simulations for sea level rise. The 1-D model uses tidal dispersion coefficients developed from 3-D hydrodynamic models. The resulting model is capable of performing very fast simulations over a wide range of conditions, providing guidance on what should be explored in depth with more detailed, but slower models.Comparisons of unimpaired Delta inflow with the historical case show that the south Delta and San Joaquin River would be much fresher without exports, while the Sacramento River would be fresher in spring and more saline in the fall. Sea level rise will increase salinity throughout the Delta over time. With peripheral conveyance of export, water salinity will intrude upstream in the Sacramento River, be slightly lower up the San Joaquin River and increase in the south Delta. With sea level rise, peripheral conveyance will have similar trends to changes to the historical case, but export salinity will be improved by the peripheral conveyance component. A larger peripheral conveyance can benefit both the ecosystem and exports if managed properly.

Simplified 1-D Hydrodynamic and Salinity Transport Modeling of the Sacramento–San Joaquin Delta: Sea Level Rise and Water Diversion Effects

Long-term hydrodynamic and salinity transport modeling of the Sacramento–San Joaquin Delta is needed to evaluate the future Delta in terms of the California co-equal goals of ecosystem health and reliable water supply. While 2-D and 3-D hydrodynamic and water quality models are by definition better suited to modeling a complex network of tidally influenced flows under future conditions, a 1-D model is more computationally efficient in narrowing the large variety of multiple-year simulations required into a more manageable task. Still, a 1-D model of sea level rise in an estuary must account for the three-dimensional effects where increased depths will affect density driven (baroclinic) circulation and tidal dispersion of salt. In this paper, we use a simplified Delta network model with a tidally averaged computational approach to quickly perform multi-year simulations for sea level rise. The 1-D model uses tidal dispersion coefficients developed from 3-D hydrodynamic models. The resulting model is capable of performing very fast simulations over a wide range of conditions, providing guidance on what should be explored in depth with more detailed, but slower models. Comparisons of unimpaired Delta inflow with the historical case show that the south Delta and San Joaquin River would be much fresher without exports, while the Sacramento River would be fresher in spring and more saline in the fall. Sea level rise will increase salinity throughout the Delta over time. With peripheral conveyance of export, water salinity will intrude upstream in the Sacramento River, be slightly lower up the San Joaquin River and increase in the south Delta. With sea level rise, peripheral conveyance will have similar trends to changes to the historical case, but export salinity will be improved by the peripheral conveyance component. A larger peripheral conveyance can benefit both the ecosystem and exports if managed properly. </p

Physically Based Modeling of Delta Island Consumptive Use: Fabian Tract and Staten Island, California

Water use estimation is central to managing most water problems. To better understand water use in California’s Sacramento–San Joaquin Delta, a collaborative, integrated approach was used to predict Delta island diversion, consumption, and return of water on a more detailed temporal and spatial resolution. Fabian Tract and Staten Island were selected for this pilot study based on available data and island accessibility. Historical diversion and return location data, water rights claims, LiDAR digital elevation model data, and Google Earth were used to predict island diversion and return locations, which were tested and improved through ground-truthing. Soil and land-use characteristics as well as weather data were incorporated with the Integrated Water Flow Model Demand Calculator to estimate water use and runoff returns from input agricultural lands. For modeling, the islands were divided into grid cells forming subregions, representing fields, levees, ditches, and roads. The subregions were joined hydrographically to form diversion and return watersheds related to return and diversion locations. Diversions and returns were limited by physical capacities. Differences between initial model and measured results point to the importance of seepage into deeply subsided islands. The capabilities of the models presented far exceeded current knowledge of agricultural practices within the Delta, demonstrating the need for more data collection to enable improvements upon current Delta Island Consumptive Use estimates

Physically Based Modeling of Delta Island Consumptive Use: Fabian Tract and Staten Island, California

Water use estimation is central to managing most water problems. To better understand water use in California’s Sacramento–San Joaquin Delta, a collaborative, integrated approach was used to predict Delta island diversion, consumption, and return of water on a more detailed temporal and spatial resolution. Fabian Tract and Staten Island were selected for this pilot study based on available data and island accessibility. Historical diversion and return location data, water rights claims, LiDAR digital elevation model data, and Google Earth were used to predict island diversion and return locations, which were tested and improved through ground-truthing. Soil and land-use characteristics as well as weather data were incorporated with the Integrated Water Flow Model Demand Calculator to estimate water use and runoff returns from input agricultural lands. For modeling, the islands were divided into grid cells forming subregions, representing fields, levees, ditches, and roads. The subregions were joined hydrographically to form diversion and return watersheds related to return and diversion locations. Diversions and returns were limited by physical capacities. Differences between initial model and measured results point to the importance of seepage into deeply subsided islands. The capabilities of the models presented far exceeded current knowledge of agricultural practices within the Delta, demonstrating the need for more data collection to enable improvements upon current Delta Island Consumptive Use estimates

Physically Based Modeling of Delta Island Consumptive Use: Fabian Tract and Staten Island, California

doi: http://dx.doi.org/10.15447/sfews.2014v12iss4art2Water use estimation is central to managing most water problems. To better understand water use in California’s Sacramento–San Joaquin Delta, a collaborative, integrated approach was used to predict Delta island diversion, consumption, and return of water on a more detailed temporal and spatial resolution. Fabian Tract and Staten Island were selected for this pilot study based on available data and island accessibility. Historical diversion and return location data, water rights claims, LiDAR digital elevation model data, and Google Earth were used to predict island diversion and return locations, which were tested and improved through ground-truthing. Soil and land-use characteristics as well as weather data were incorporated with the Integrated Water Flow Model Demand Calculator to estimate water use and runoff returns from input agricultural lands. For modeling, the islands were divided into grid cells forming subregions, representing fields, levees, ditches, and roads. The subregions were joined hydrographically to form diversion and return watersheds related to return and diversion locations. Diversions and returns were limited by physical capacities. Differences between initial model and measured results point to the importance of seepage into deeply subsided islands. The capabilities of the models presented far exceeded current knowledge of agricultural practices within the Delta, demonstrating the need for more data collection to enable improvements upon current Delta Island Consumptive Use estimates.</p

Habitat Variability and Complexity in the Upper San Francisco Estuary

High variability in environmental conditions in both space and time once made the upper San Francisco Estuary (the Estuary) highly productive for native biota. Present conditions often discourage native species, providing a rationale for restoring estuarine variability and habitat complexity. Achieving a variable, more complex Estuary requires policies which: (1) establish internal Sacramento–San Joaquin Delta (the Delta) flows that create a tidally mixed, upstream–downstream gradient in water quality, with minimal cross-Delta flows; (2) create slough networks with more natural channel geometry and less diked, riprapped channel habitat; (3) increase inflows from the Sacramento and San Joaquin rivers; (4) increase tidal marsh habitat, including shallow (1 to 2 m) subtidal areas, in both fresh and brackish zones of the Estuary; (5) create/allow large expanses of low salinity (1 to 4 ppt) open water habitat in the Delta; (6) create a hydrodynamic regime where salinities in the upper Estuary range from near-fresh to 8 to 10 ppt periodically, to discourage alien species and favor desirable species; (7) take species-specific actions that reduce abundance of non-native species and increase abundance of desirable species; (8) establish abundant annual floodplain habitat, with additional large areas that flood in less frequent wet years; (9) reduce inflow of agricultural and urban pollutants; and (10) improve the temperature regime in large areas of the Estuary so temperatures rarely exceed 20 °C during summer and fall months. These actions collectively provide a realistic if experimental approach to achieving flow and habitat objectives to benefit desirable species. Some of these goals are likely to be achieved without deliberate action as the result of sea level rise, climate change, and levee failures, but in the near term, habitat, flow restoration and export reduction projects can enhance a return to a more variable and more productive ecosystem

Habitat Variability and Complexity in the Upper San Francisco Estuary

High variability in environmental conditions in both space and time once made the upper San Francisco Estuary (the Estuary) highly productive for native biota. Present conditions often discourage native species, providing a rationale for restoring estuarine variability and habitat complexity. Achieving a variable, more complex Estuary requires policies which: (1) establish internal Sacramento–San Joaquin Delta (the Delta) flows that create a tidally mixed, upstream–downstream gradient in water quality, with minimal cross-Delta flows; (2) create slough networks with more natural channel geometry and less diked, riprapped channel habitat; (3) increase inflows from the Sacramento and San Joaquin rivers; (4) increase tidal marsh habitat, including shallow (1 to 2 m) subtidal areas, in both fresh and brackish zones of the Estuary; (5) create/allow large expanses of low salinity (1 to 4 ppt) open water habitat in the Delta; (6) create a hydrodynamic regime where salinities in the upper Estuary range from near-fresh to 8 to 10 ppt periodically, to discourage alien species and favor desirable species; (7) take species-specific actions that reduce abundance of non-native species and increase abundance of desirable species; (8) establish abundant annual floodplain habitat, with additional large areas that flood in less frequent wet years; (9) reduce inflow of agricultural and urban pollutants; and (10) improve the temperature regime in large areas of the Estuary so temperatures rarely exceed 20 °C during summer and fall months. These actions collectively provide a realistic if experimental approach to achieving flow and habitat objectives to benefit desirable species. Some of these goals are likely to be achieved without deliberate action as the result of sea level rise, climate change, and levee failures, but in the near term, habitat, flow restoration and export reduction projects can enhance a return to a more variable and more productive ecosystem