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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 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 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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Adaptive Management and Science for the Delta Ecosystem
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Adaptive Management and Science for the Delta Ecosystem
San Francisco Estuary & Watershed Science | October 1, 2013...
Summary
Using science to adaptively guide management for the Sacramento-San Joaquin Delta is widely talked about as good public policy. Almost every agency, stakeholder,...
Using science to adaptively guide management for the Sacramento-San Joaquin Delta is widely talked about as good public policy. Almost every agency, stakeholder, and planning process professes support and has its own adaptive management and science efforts. But highly fragmented adaptive management and science cannot solve such urgent complex problems. California’s 2009 Delta Reform Act recognized that meeting the co-equal goals of a sustainable ecosystem and water supply reliability in the Delta required major changes in governance, planning, and management. Such changes also require major changes in how science is organized and employed in management. Here is a straw proposal for integrating the many parochial science and adaptive management programs for the Delta.

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Analysis and simulation of regional subsidence accompanying groundwater abstraction and compaction of susceptible aquifer systems in the USA

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Analysis and simulation of regional subsidence accompanying groundwater abstraction and compaction of susceptible aquifer systems in the USA
Boletín de la Sociedad Geológica Mexicana | January 17, 2013...
Summary
Regional aquifer-system compaction and land subsidence accompanying groundwater abstraction in susceptible aquifer systems in the USA is a challenge for managing groundwater resources...
Regional aquifer-system compaction and land subsidence accompanying groundwater abstraction in susceptible aquifer systems in the USA is a challenge for managing groundwater resources and mitigating associated hazards. Developments in the assessment of regional subsidence provide more information to constrain analyses and simulation of aquifer-system compaction. Current popular approaches to simulating vertical aquifer-system deformation (compaction), such as those embodied in the aquitard drainage model and the MODFLOW subsidence packages, have proven useful from the perspective of regional groundwater resources assessment. However, these approaches inadequately address related local-scale hazards—ground ruptures and damages to engineered structures on the land surface arising from tensional stresses and strains accompanying groundwater abstraction. This paper presents a brief overview of the general approaches taken by the U.S. Geological Survey toward understanding aquifer-system compaction and subsidence with regard to a) identifying the affected aquifer systems; b) making regional assessments; c) analyzing the governing processes; and d) simulating historical and future groundwater flow and subsidence conditions. Limitations and shortcomings of these approaches, as well as future challenges also are discussed

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Atmospheric Rivers as Drought Busters on the U.S. West Coast
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Atmospheric Rivers as Drought Busters on the U.S. West Coast
USGS | April 25, 2013...
Summary
Atmospheric rivers (ARs) have, in recent years, been recognized as the cause of the large majority of major floods in rivers all along...
Atmospheric rivers (ARs) have, in recent years, been recognized as the cause of the large majority of major floods in rivers all along the U.S. West Coast and as the source of 30%–50% of all precipitation in the same region. The present study surveys the frequency with which ARs have played a critical role as a common cause of the end of droughts on the West Coast. This question was based on the observation that, in most cases, droughts end abruptly as a result of the arrival of an especially wet month or, more exactly, a few very large storms. This observation is documented using both Palmer Drought Severity Index and 6-month Standardized Precipitation Index measures of drought occurrence for climate divisions across the conterminous United States from 1895 to 2010. When the individual storm sequences that contributed most to the wet months that broke historical West Coast droughts from 1950 to 2010 were evaluated, 33%–74% of droughts were broken by the arrival of landfalling AR storms. In the Pacific Northwest, 60%–74%of all persistent drought endings have been brought about by the arrival of AR storms. In California, about 33%–40% of all persistent drought endings have been brought about by landfalling AR storms, with more localized low pressure systems responsible for many of the remaining drought breaks.

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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 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 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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Adaptive Management and Science for the Delta Ecosystem

Adaptive Management and Science for the Delta Ecosystem

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Analysis and simulation of regional subsidence accompanying groundwater abstraction and compaction of susceptible aquifer systems in the USA

Analysis and simulation of regional subsidence accompanying groundwater abstraction and compaction of susceptible aquifer systems in the USA

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Atmospheric Rivers as Drought Busters on the U.S. West Coast

Atmospheric Rivers as Drought Busters on the U.S. West Coast

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