Journal Article

Search Results

Browse All Documents

“Good Luck Fixing the Problem”: Small Low-Income Community Participation in Collaborative Groundwater Governance and Implications for Drinking Water Source Protection

Bulk Download

“Good Luck Fixing the Problem”: Small Low-Income Community Participation in Collaborative Groundwater Governance and Implications for Drinking Water Source Protection
Society and Natural Resources, Routledge | June 10, 2020...
Summary
There is increasing interest in the potential of source water protection to address chronic challenges with small systems and rural drinking water provision....
There is increasing interest in the potential of source water protection to address chronic challenges with small systems and rural drinking water provision. Such a planning and management approach to increasing safe drinking water access, however, will likely require leveraging multi-stakeholder collaborative governance venues to this effect. This paper investigates the prospects of doing so using the case of California’s groundwater reform process known as the Sustainable Groundwater Management Act or SGMA. Interviews with drinking water stakeholders from small low-income communities in the San Joaquin Valley show how existing power and resource disparities limit the prospects of integrating rural drinking water priorities into regional planning. Long-term, more fundamental changes will be needed to meaningfully transform water management in this direction. Short-term state intervention is needed to protect equity and public good goals, raising potential contradictions between devolved water management and improved drinking water access that need to be addressed.

View Document
Become a member to access this feature
Download NowEmail Details
A 1,200-year perspective of 21st century drought in southwestern North America

Bulk Download

A 1,200-year perspective of 21st century drought in southwestern North America
Proceedings of the National Academy of Sciences (PNAS) | December 11, 2009...
Summary
A key feature of anticipated 21st century droughts in Southwest North America is the concurrence of elevated temperatures and increased aridity. Instrumental records...
A key feature of anticipated 21st century droughts in Southwest North America is the concurrence of elevated temperatures and increased aridity. Instrumental records and paleoclimatic evidence for past prolonged drought in the Southwest that coincide with elevated temperatures can be assessed to provide insights on temperature-drought relations and to develop worst-case scenarios for the future. In particular, during the medieval period, ∼AD 900–1300, the Northern Hemisphere experienced temperatures warmer than all but the most recent decades. Paleoclimatic and model data indicate increased temperatures in western North America of approximately 1 °C over the long-term mean. This was a period of extensive and persistent aridity over western North America. Paleoclimatic evidence suggests drought in the mid-12th century far exceeded the severity, duration, and extent of subsequent droughts. The driest decade of this drought was anomalously warm, though not as warm as the late 20th and early 21st centuries. The convergence of prolonged warming and arid conditions suggests the mid-12th century may serve as a conservative analogue for severe droughts that might occur in the future. The severity, extent, and persistence of the 12th century drought that occurred under natural climate variability, have important implications for water resource management. The causes of past and future drought will not be identical but warm droughts, inferred from paleoclimatic records, demonstrate the plausibility of extensive, severe droughts, provide a long-term perspective on the ongoing drought conditions in the Southwest, and suggest the need for regional sustainability planning for the future.

View Document
Become a member to access this feature
Download NowEmail Details
A 20,000-year record of ocean circulation and climate change from the Santa Barbara basin

Bulk Download

A 20,000-year record of ocean circulation and climate change from the Santa Barbara basin
Nature | October 12, 1995...
Summary
MUCH of the evidence for climate-driven fluctuations in ocean circulation during the past 20,000 years has come from studies of the North Atlantic...
MUCH of the evidence for climate-driven fluctuations in ocean circulation during the past 20,000 years has come from studies of the North Atlantic region. The extent to which such interactions have occurred in other ocean basins, and any associated teleconnec-tions between basins, is poorly understood. Here we present high-resolution palaeoclimate and palaeoceanographic records from a 20,000-year sedimentary sequence from the Santa Barbara basin, on the eastern margin of the North Pacific Ocean. The sequence shows oscillations of the benthic environment between low-oxygen conditions (laminated sediments) during periods of warm climate, and higher-oxygen conditions (non-laminated, bioturbated sediments) during cool intervals. Age differences between coexisting benthic and planktonic foraminifers indicate climate-related changes in the age and source-and, hence, oxygen content-of basin bottom waters. Relatively young bottom waters are associated with the cooler intervals and are considered to reflect high proportions of intermediate waters derived from proximal sources. Conversely, older bottom waters are associated with the warmer intervals and were derived from more distal sources. These climate-driven variations in ocean circulation appear to be synchronous with the main ocean-climate fluctuations in the North Atlantic region, suggesting that a tight coupling mechanism operates between the two basins.

View Document
Become a member to access this feature
Download NowEmail Details
A 450-year record of environmental change from Castle Lake, California (USA), inferred from diatoms and organic geochemistry

Bulk Download

A 450-year record of environmental change from Castle Lake, California (USA), inferred from diatoms and organic geochemistry
Journal of Paleolimnology | November 11, 2020...
Summary
A 39-cm sediment core from Castle Lake, California (USA) spans the last ~ 450 years and was analyzed for diatoms and organic geochemistry (δ15N, δ13C, and...
A 39-cm sediment core from Castle Lake, California (USA) spans the last ~ 450 years and was analyzed for diatoms and organic geochemistry (δ¹⁵N, δ¹³C, and C:N), with the goal of determining sensitivity to natural climate variation and twentieth century anthropogenic effects. Castle Lake is a subalpine, nitrogen-limited lake with ~ 5 months of annual ice cover. Human impacts include light recreational use, past fish stocking, and experimental use by the Castle Lake Research Station. The base of the core (below 32 cm; pre mid-1700s) represents the period of maximum ice cover. In contrast, the end of the Little Ice Age (mid 1700s–early 1800s) is dominated by cyclotelloids (mostly Discostella stelligera), indicating significant open-water periods, a condition that persisted into the early 1900s. Cyclotelloids began to decline in the 1960s and were replaced by the Fragilaria tenera grp. (peak in 1970s), succeeded by Asterionella formosa (peak ~ 2010), and accompanied by a reduction in δ¹⁵N values and a decrease in C:N that may represent increased atmospheric nitrogen deposition. Another anthropogenic signal was discerned in the core and was interpreted to be the result of an ammonium nitrate fertilization experiment of the epilimnion that was conducted in 1980 and 1981. This signal was manifested in the core largely by a negative excursion in δ¹⁵N, possibly caused by fractionation during denitrification in surface sediment. A phytoplankton monitoring dataset collected by the Castle Lake Research Station from 1967 to 1984 corroborates the timing of increased araphid euplanktonic species in the 1970s, and increases in two benthic diatoms (Staurosirella pinnata and Tabellaria fenestrata), entrained in the phytoplankton tows during the experimentation years. Both ice cover and nitrogen addition appear to be strong drivers that affected the lake diatoms, although additional drivers, such as fish stocking and associated cascade effects need further exploration. These data will be helpful for interpreting longer core records from Castle Lake, should the opportunity arise, as well as cores from similar systems in the region.

View Document
Become a member to access this feature
Download NowEmail Details
A Bayesian approach to infer nitrogen loading rates from crop and land-use types surrounding private wells in the Central Valley, California

Bulk Download

A Bayesian approach to infer nitrogen loading rates from crop and land-use types surrounding private wells in the Central Valley, California
European Geosciences Union | May 7, 2018...
Summary
This study is focused on nitrogen loading from a wide variety of crop and land-use types in the Central Valley, California, USA, an intensively farmed...
This study is focused on nitrogen loading from a wide variety of crop and land-use types in the Central Valley, California, USA, an intensively farmed region with high agricultural crop diversity. Nitrogen loading rates for several crop types have been measured based on field-scale experiments, and recent research has calculated nitrogen loading rates for crops throughout the Central Valley based on a mass balance approach. However, research is lacking to infer nitrogen loading rates for the broad diversity of crop and land use types directly from groundwater nitrate measurements.

Relating groundwater nitrate measurements to specific crops must account for the uncertainty about and multiplicity in contributing crops (and other land uses) to individual well measurements, and for the variability of nitrogen loading within farms and from farm to farm for the same crop type. In this study, we developed a Bayesian regression model that allowed us to estimate land-use-specific groundwater nitrogen loading rate probability distributions for 15 crop and land-use groups based on a database of recent nitrate measurements from 2149 private wells in the Central Valley.

The water and natural, rice, and alfalfa and pasture groups had the lowest median estimated nitrogen loading rates, each with a median estimate below 5 kg N ha -1 yr -1. Confined animal feeding operations (dairies) and citrus and subtropical crops had the greatest median estimated nitrogen loading rates at approximately 269 and 65 kg N ha -1 yr-1, respectively. In general, our probability-based estimates compare favorably with previous direct measurements and with mass-balance-based estimates of nitrogen loading. Nitrogen mass-balance-based estimates are larger than our groundwater nitrate derived estimates for manured and non-manured forage, nuts, cotton, tree fruit, and rice crops. These discrepancies are thought to be due to groundwater age mixing, dilution from infiltrating river water, or denitrification between the time when nitrogen leaves the root zone (point of reference for mass-balance derived loading) and the time and location of groundwater measurement.

View Document
Become a member to access this feature
Download NowEmail Details
A changing framework for urban water systems

Bulk Download

A changing framework for urban water systems
American Chemical Society (ACS) | May 8, 2013...
Summary
Urban water infrastructure and the institutions responsible for its management have gradually evolved over the past two centuries. Today, they are under increasing...

Urban water infrastructure and the institutions responsible for its management have gradually evolved over the past two centuries. Today, they are under increasing stress as water scarcity and a growing recognition of the importance of factors other than the cost of service provision are forcing a reexamination of long-held ideas. Research and development that supports new technological approaches and more effective management strategies are needed to ensure that the emerging framework for urban water systems will meet future societal needs

View Document
Become a member to access this feature
Download NowEmail Details
A comparison of the taxonomic and trait structure of macroinvertebrate communities between the riffles and pools of montane headwater streams
$0.00
Bulk Download

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.

View Document
Become a member to access this feature
Download NowEmail Details
A conceptual model for floodplains in the Sacramento-San Joaquin Delta

Bulk Download

A conceptual model for floodplains in the Sacramento-San Joaquin Delta
San Francisco Estuary & Watershed Science (UC Davis) | 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.

View Document
Become a member to access this feature
Download NowEmail Details
A freshwater conservation blueprint for California: prioritizing watersheds for freshwater biodiversity

Bulk Download

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.

View Document
Become a member to access this feature
Download NowEmail Details
A General Framework for Analyzing Sustainability of Social-Ecological Systems

Bulk Download

A General Framework for Analyzing Sustainability of Social-Ecological Systems
Science Magazine, American Association for the Advancement of Science | July 24, 2009...
Summary
A major problem worldwide is the potential loss of fisheries, forests, and water resources. Understanding of the processes that lead to improvements in...
A major problem worldwide is the potential loss of fisheries, forests, and water resources. Understanding of the processes that lead to improvements in or deterioration of natural resources is limited, because scientific disciplines use different concepts and languages to describe and explain complex social-ecological systems (SESs). Without a common framework to organize findings, isolated knowledge does not cumulate. Until recently, accepted theory has assumed that resource users will never self-organize to maintain their resources and that governments must impose solutions. Research in multiple disciplines, however, has found that some government policies accelerate resource destruction, whereas some resource users have invested their time and energy to achieve sustainability. A general framework is used to identify 10 subsystem variables that affect the likelihood of self-organization in efforts to achieve a sustainable SES.

View Document
Become a member to access this feature
Download NowEmail Details

Search

Journal Article

Search

Browse All Documents

Type

Topic

Keywords

Publisher

Publication Year

Hydrologic Region

Index By

“Good Luck Fixing the Problem”: Small Low-Income Community Participation in Collaborative Groundwater Governance and Implications for Drinking Water Source Protection

“Good Luck Fixing the Problem”: Small Low-Income Community Participation in Collaborative Groundwater Governance and Implications for Drinking Water Source Protection

Become a member to access this feature

A 1,200-year perspective of 21st century drought in southwestern North America

A 1,200-year perspective of 21st century drought in southwestern North America

Become a member to access this feature

A 20,000-year record of ocean circulation and climate change from the Santa Barbara basin

A 20,000-year record of ocean circulation and climate change from the Santa Barbara basin

Become a member to access this feature

A 450-year record of environmental change from Castle Lake, California (USA), inferred from diatoms and organic geochemistry

A 450-year record of environmental change from Castle Lake, California (USA), inferred from diatoms and organic geochemistry

Become a member to access this feature

A Bayesian approach to infer nitrogen loading rates from crop and land-use types surrounding private wells in the Central Valley, California

A Bayesian approach to infer nitrogen loading rates from crop and land-use types surrounding private wells in the Central Valley, California

Become a member to access this feature

A changing framework for urban water systems

A changing framework for urban water systems

Become a member to access this feature

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

Become a member to access this feature

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

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

Become a member to access this feature

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

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

Become a member to access this feature

A General Framework for Analyzing Sustainability of Social-Ecological Systems

A General Framework for Analyzing Sustainability of Social-Ecological Systems

Become a member to access this feature