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A comparison of the taxonomic and trait structure of macroinvertebrate communities between the riffles and pools of montane headwater streams
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A comparison of the taxonomic and trait structure of macroinvertebrate communities between the riffles and pools of montane headwater streams
Hydrobiologica, Springer International Publishing | May 30, 2018...
Summary
Macroinvertebrate community taxonomic and trait structure showed consistent differences between riffles and pools across 12 headwater streams in the Sierra Nevada (California) even...

Macroinvertebrate community taxonomic and trait structure showed consistent differences between riffles and pools across 12 headwater streams in the Sierra Nevada (California) even as flows varied from wet to dry years and between seasons. Densities of Ephemeroptera, Plecoptera, Trichoptera, Elmidae, Orthocladiinae and Diamesinae midges, and mites were greater in riffles, whereas Tanypodinae, Chironominae, Sialis, and Pisidium were more abundant in pools. Pools had higher densities but estimated biomass was greater in riffles. Collector-gatherer and micropredator abundances were greater in pools whereas grazers, collector-filterers, and macropredators were more abundant in riffles. Stonefly shredders were most abundant in riffles but some caddis shredders were more abundant in pools. Trait state patterns were related to food resource and physical habitat differences between riffles and pools. Of the distinct pool–riffle differences we found among taxa, only about half conformed to expectations from the literature. Pool and riffle assemblages were most dissimilar at intermediate discharge and converged at low and high flows when one or the other habitat dominated. Bioassessment sampling will need to account for these flow-related differences. Benthic invertebrate communities in these mountain streams clearly differ between pools and riffles, but the relative extent of habitats and biological similarity shift with flow regime.

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A conceptual model for floodplains in the Sacramento-San Joaquin Delta

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A conceptual model for floodplains in the Sacramento-San Joaquin Delta
San Francisco Estuary and Watershed Science | October 3, 2012...
Summary
Floodplains are among the most biologically productive and diverse ecosystems on Earth and they provide significant benefits to society such as attenuation of...
Floodplains are among the most biologically productive and diverse ecosystems on Earth and they provide significant benefits to society such as attenuation of floodwaters, groundwater recharge, filtration of nutrients and sediments, carbon sequestration, fisheries productivity and recreation. However, floodplains are also among the most converted and threatened ecosystems. Floodplain habitats in the Sacramento-San Joaquin Delta, and throughout California’s Central Valley, have been greatly reduced from their historic extent and key processes that create and maintain floodplains, such as flood flows and meander migration, have been greatly altered. These widespread alterations to habitats and processes have lead to declines in many species’ populations in California’s Central Valley and Delta, creating challenges for both environmental and water management. To address these challenges numerous entities and programs are now focused on restoring floodplains and other Delta habitats. This paper provides a conceptual model for floodplains that characterizes the key features and identifies the critical processes, drivers, and linkages that allow floodplains to produce a variety of functional outputs of management importance. These outputs include: (1) the floodplain habitat mosaic, including riparian vegetation and its associated wildlife; (2) spawning and rearing habitat for native fish; and (3) food-web productivity that can support native fish on the floodplain as well as be exported to downstream ecosystems. The model emphasizes that the production of these outputs from floodplains requires vertical and lateral hydrological connectivity across a broad range of flow conditions. For example, long-duration flooding in the spring promotes native fish spawning and food-web productivity that benefits native species.

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A freshwater conservation blueprint for California: prioritizing watersheds for freshwater biodiversity

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A freshwater conservation blueprint for California: prioritizing watersheds for freshwater biodiversity
Freshwater Science, University of Chicago Press Journals | April 18, 2018...
Summary
Conservation scientists have adapted conservation planning principles designed for protection of habi- tats ranging from terrestrial to freshwater ecosystems. We applied current approaches...

Conservation scientists have adapted conservation planning principles designed for protection of habi- tats ranging from terrestrial to freshwater ecosystems. We applied current approaches in conservation planning to prioritize California watersheds for management of biodiversity. For all watersheds, we compiled data on the pre- sence/absence of herpetofauna and fishes; observations of freshwater-dependent mammals, selected invertebrates, and plants; maps of freshwater habitat types; measures of habitat condition and vulnerability; and current manage- ment status. We analyzed species-distribution data to identify areas of high freshwater conservation value that op- timized representation of target taxa on the landscape and leveraged existing protected areas. The resulting priority network encompasses 34% of the area of California and includes ≥10% of the geographic range for all target taxa. High-value watersheds supported nontarget freshwater taxa and habitats, and focusing on target taxa may provide broad conservation value. Most of the priority conservation network occurs on public lands (69% by area), and 46% overlaps with protected areas already managed for biodiversity. A significant proportion of the network area is on private land and underscores the value of programs that incentivize landowners to manage freshwater species and habitats. The priority conservation areas encompass more freshwater habitats/ha than existing protected areas. Land use (agriculture and urbanization), altered fire regimes, nonnative fish communities, and flow impairment are the most important threats to freshwater habitat in the priority network, whereas factors associated with changing climate are the key drivers of habitat vulnerability. Our study is a guide to a comprehensive approach to freshwater conservation currently lacking in California. Conservation resources are often limited, so prioritiza- tion tools are valuable assets to land and water managers.

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A rationale for effective post-fire debris flow mitigation within forested terrain

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A rationale for effective post-fire debris flow mitigation within forested terrain
Geoenvironmental Disasters, Springer | May 25, 2018...
Summary
Watersheds recently burned by wildfires are recognized as having an increased susceptibility to debris flow occurrence. The great majority occur within the first 2...
Watersheds recently burned by wildfires are recognized as having an increased susceptibility to debris flow occurrence. The great majority occur within the first 2 years following wildfires. These debris flows are generated primarily through the process of progressive entrainment of material eroded from hillslopes and channels by surface runoff and appears independent of the vegetative community burned. The decreased likelihood of debris flows over time is linked to the restoration of hydrologic function as vegetative cover and soil infiltration functioning return to pre-fire conditions. An exception to this pattern of post-wildfire debris flow susceptibility occurs in burned drainage basins with forest cover. A second, later period of increased debris flow susceptibility due to infiltration-triggered landslides can occur in burned forested basins. This later period of debris flow susceptibility is largely attributable to the fire-induced tree mortality and subsequent decay of tree root networks decreasing soil strength on steep hillslopes which produces an increased likelihood of debris flow occurrence 3 to 10 or more years after the wildfire. Consequently, post-fire mitigation measures in forested terrain must address the risk posed by debris flows caused by progressive entrainment during the 2 years following the wildfire and debris flows due to infiltration-induced debris slides three or more years later. Mitigation for the later debris flows in forested terrain involves identification of areas with infiltration-induced debris slides coincident with concentrations of fire-killed trees. Timely reforestation of these areas after a wildfire limits the loss of soil strength from decaying roots.

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A Research Guide to California Water Law
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A Research Guide to California Water Law
Loyola Law School | February 21, 2017...
Summary
California water law is a complex subject. It is governed by both state and federal law, and is part property law and part...
California water law is a complex subject. It is governed by both state and federal law, and is part property law and part environmental law. This topic has important historical roots, based in common law concepts of private rights to water, but is now dominated by federal legislation aimed at achieving environmental purposes. Adding to this complexity is the existence of a large number of federal, state and local agencies which play a role in the allocation and management of the state’s water resources.

This research guide explains the basic concepts a researcher needs in order to begin understanding the current legal regime that controls the water of California. The guide covers a wide variety of resources, both print and online, some of which are freely available but others only through paid subscriptions. The greater emphasis is on California statutes, cases and regulations, but the secondary sources discussed will provide the necessary explanation of how federal law applies.

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A shift from drought to extreme rainfall drives a stable landslide to catastrophic failure

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A shift from drought to extreme rainfall drives a stable landslide to catastrophic failure
Nature | February 7, 2019...
Summary
The addition of water on or below the earth’s surface generates changes in stress that can trigger both stable and unstable sliding of...

The addition of water on or below the earth’s surface generates changes in stress that can trigger both stable and unstable sliding of landslides and faults. While these sliding behaviours are well-described by commonly used mechanical models developed from laboratory testing (e.g., critical-state soilmechanics and rate-and-state friction), less is known about the field-scale environmental conditions orkinematic behaviours that occur during the transition from stable to unstable sliding. Here we use radarinterferometry (InSAR) and a simple 1D hydrological model to characterize 8 years of stable sliding of the Mud Creek landslide, California, UsA, prior to its rapid acceleration and catastrophic failure on May 20, 2017. Our results suggest a large increase in pore-fluid pressure occurred during a shift from historic drought to record rainfall that triggered a large increase in velocity and drove slip localization, overcoming the stabilizing mechanisms that had previously inhibited landslide acceleration. Given thepredicted increase in precipitation extremes with a warming climate, we expect it to become more common for landslides to transition from stable to unstable motion, and therefore a better assessmentof this destabilization process is required to prevent loss of life and infrastructure.

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A Simulation-Optimization Model for Water-Resources Management, Santa Barbara, California
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A Simulation-Optimization Model for Water-Resources Management, Santa Barbara, California
U.S. Geological Survey (USGS) | September 1, 1998...
Summary
A simulation-optimization model has been developed for the optimal management of the city of Santa Barbara's water resources during a drought. The model,...
A simulation-optimization model has been developed for the optimal management of the city of Santa Barbara's water resources during a drought. The model, which links ground-water simulation with linear programming, has a planning horizon of 5 years. The objective is to minimize the cost of water supply subject to: water demand constraints, hydraulic head constraints to control seawater intrusion, and water capacity constraints. The decision variables are monthly water deliveries from surface water and ground water. The state variables are hydraulic heads. The drought of 1947–51 is the city's worst drought on record, and simulated surface-water supplies for this period were used as a basis for testing optimal management of current water resources under drought conditions. The simulation-optimization model was applied using three reservoir operation rules. In addition, the model's sensitivity to demand, carryover [the storage of water in one year for use in a later year(s)], head constraints, and capacity constraints was tested.

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A spatially comprehensive, hydrometeorological data set for Mexico, the U.S., and Southern Canada 1950–2013

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A spatially comprehensive, hydrometeorological data set for Mexico, the U.S., and Southern Canada 1950–2013
Nature | August 18, 2015...
Summary
A data set of observed daily precipitation, maximum and minimum temperature, gridded to a 1/16° (~6 km) resolution, is described that spans the...

A data set of observed daily precipitation, maximum and minimum temperature, gridded to a 1/16° (~6 km) resolution, is described that spans the entire country of Mexico, the conterminous U.S. (CONUS), and regions of Canada south of 53° N for the period 1950–2013. The dataset improves previous products in spatial extent, orographic precipitation adjustment over Mexico and parts of Canada, and reduction of transboundary discontinuities. The impacts of adjusting gridded precipitation for orographic effects are quantified by scaling precipitation to an elevation-aware 1981–2010 precipitation climatology in Mexico and Canada. Differences are evaluated in terms of total precipitation as well as by hydrologic quantities simulated with a land surface model. Overall, orographic correction impacts total precipitation by up to 50% in mountainous regions outside CONUS. Hydrologic fluxes show sensitivities of similar magnitude, with discharge more sensitive than evapotranspiration and soil moisture. Because of the consistent gridding methodology, the current product reduces transboundary discontinuities as compared with a commonly used reanalysis product, making it suitable for estimating large-scale hydrometeorologic phenomena.

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A study of methods to estimate debris flow velocity

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A study of methods to estimate debris flow velocity
Landslides, Springer | September 16, 2019...
Summary
Debris flow velocities are commonly back-calculated from superelevation events which require subjective estimates of radii of curvature of bends in the debris flow...
Debris flow velocities are commonly back-calculated from superelevation events which require subjective estimates of radii of curvature of bends in the debris flow channel or predicted using flow equations that require the selection of appropriate rheological models and material property inputs. This research investigated difficulties associated with the use of these conventional velocity estimation methods. Radii of curvature estimates were found to vary with the extent of the channel investigated and with the scale of the media used, and back-calculated velocities varied among different investigated locations along a channel. Distinct populations of Bingham properties were found to exist between those measured by laboratory tests and those back-calculated from field data; thus, laboratory-obtained values would not be representative of field-scale debris flow behavior. To avoid these difficulties with conventional methods, a new preliminary velocity estimation method is presented that statistically relates flow velocity to the channel slope and the flow depth. This method presents ranges of reasonable velocity predictions based on 30 previously measured velocities.

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A Twenty-First-Century California Observing Network for Monitoring Extreme Weather Events

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A Twenty-First-Century California Observing Network for Monitoring Extreme Weather Events
Journal of Atmospheric and Oceanic Technology, American Meteorological Society | August 27, 2013...
Summary
During Northern Hemisphere winters, the West Coast of North America is battered by extratropical storms. The impact of these storms is of paramount...
During Northern Hemisphere winters, the West Coast of North America is battered by extratropical storms. The impact of these storms is of paramount concern to California, where aging water supply and flood protection infrastructures are challenged by increased standards for urban flood protection, an unusually variable weather regime, and projections of climate change. Additionally, there are inherent conflicts between releasing water to provide flood protection and storing water to meet requirements for the water supply, water quality, hydropower generation, water temperature and flow for at-risk species, and recreation. To improve reservoir management and meet the increasing demands on water, improved forecasts of precipitation, especially during extreme events, are required. Here, the authors describe how California is addressing their most important and costliest environmental issue-water management-in part, by installing a state-of-the-art observing system to better track the area's most severe wintertime storms.

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A comparison of the taxonomic and trait structure of macroinvertebrate communities between the riffles and pools of montane headwater streams

A comparison of the taxonomic and trait structure of macroinvertebrate communities between the riffles and pools of montane headwater streams

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A conceptual model for floodplains in the Sacramento-San Joaquin Delta

A conceptual model for floodplains in the Sacramento-San Joaquin Delta

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A freshwater conservation blueprint for California: prioritizing watersheds for freshwater biodiversity

A freshwater conservation blueprint for California: prioritizing watersheds for freshwater biodiversity

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A rationale for effective post-fire debris flow mitigation within forested terrain

A rationale for effective post-fire debris flow mitigation within forested terrain

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A Research Guide to California Water Law

A Research Guide to California Water Law

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A shift from drought to extreme rainfall drives a stable landslide to catastrophic failure

A shift from drought to extreme rainfall drives a stable landslide to catastrophic failure

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A Simulation-Optimization Model for Water-Resources Management, Santa Barbara, California

A Simulation-Optimization Model for Water-Resources Management, Santa Barbara, California

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A spatially comprehensive, hydrometeorological data set for Mexico, the U.S., and Southern Canada 1950–2013

A spatially comprehensive, hydrometeorological data set for Mexico, the U.S., and Southern Canada 1950–2013

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A study of methods to estimate debris flow velocity

A study of methods to estimate debris flow velocity

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A Twenty-First-Century California Observing Network for Monitoring Extreme Weather Events

A Twenty-First-Century California Observing Network for Monitoring Extreme Weather Events

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