Search Results (12)

The major challenges in designing a Hybrid Renewable Energy System (HRES) include selecting appropriate renewable energy sources and storage systems, accurately sizing each component, and defining suitable optimization criteria. This study addresses these challenges by employing Particle Swarm Optimization (PSO) within a multi-criteria optimization framework to design an HRES in Kern County, USA. The proposed system integrates wind turbines (WTS), photovoltaic (PV) panels, Biomass Gasifiers (BMGs), batteries, electrolyzers (ELs), and fuel cells (FCs), aiming to minimize Annual System Cost (ASC), minimize Loss of Power Supply Probability (LPSP), and maximize renewable energy fraction (REF). Results demonstrate that the PSO-optimized system achieves an ASC of USD6,336,303, an LPSP of 0.01%, and a REF of 90.01%, all of which are reached after 25 iterations. When compared to the Genetic Algorithm (GA) and hybrid GA-PSO, PSO improved cost-effectiveness by 3.4% over GA and reduced ASC by 1.09% compared to GAPSO. In terms of REF, PSO outperformed GA by 1.22% and GAPSO by 0.99%. The PSO-optimized configuration includes WT (4669 kW), solar PV (10,623 kW), BMG (2174 kW), battery (8000 kWh), FC (2305 kW), and EL (6806 kW). Sensitivity analysis highlights the flexibility of the optimization framework under varying weight distributions. These results highlight the dependability, cost-effectiveness, and sustainability for the proposed system, offering valuable insights for policymakers and practitioners transitioning to renewable energy systems. Full article

The endangered San Joaquin kit fox (SJKF) (Vulpes macrotis mutica), which is endemic to the San Joaquin Valley in California, has lost most of its natural habitat due to urban sprawl and change in land use over time. Many studies have been conducted to restore and protect the remaining habitat, involving presence/absence surveys prior to urban development using camera monitoring, tracking dogs, tracking plates, spotlighting, and trapping. While these traditional methods work well, they can be invasive, expensive, labor-intensive, and require permits to perform. In our study, we used a non-invasive method based on DNA extraction from scat collected in the environment, followed by a diagnostic Polymerase Chain Reaction (PCR)-based approach on mitochondrial DNA fragments and investigated the presence of the SJKF on four case study sites that shared a high SJKF habitat suitability index but are under the threat of development. We found that the diagnostic PCR was able to accurately differentiate between different canids present at the sites, in a time- and cost-effective manner. Including this non-invasive method in the Department of Fish and Wildlife’s standardized recommendations for survey methods would help to improve future environmental assessments for SJKF populations in the Central Valley of California. Full article

Kern County is one of the most valuable agricultural counties in the nation. This, however, is being put in jeopardy with the recently implemented Sustainable Groundwater Management Act (SGMA) in response to the ongoing California drought and extensive groundwater pumping for irrigation. The Groundwater Sustainability Agencies (GSAs) are responsible for developing Groundwater Sustainability Plans to address the new SGMA policies. The objective of this paper is to examine the Kern Groundwater Sustainability Plan (KGSP), determine its strengths and weaknesses, and provide recommendations for the updated plan released in 2025. The plan performs well in defining criteria that must be met, but fails to address how these goals will be implemented. Based on our policy analysis, our recommendations include standardizing groundwater management terms across sub-basins, defining clear measurements of undesirable results, utilizing financial (dis)incentives to encourage groundwater users to manage water sustainably, and increasing interconnections between local and state organizations. Importantly, improving this policy process for the SGMA may be an example for critically overdrafted groundwater basins globally on how to more sustainably manage their groundwater. Full article

The genus Edwardsiella, previously residing in the family Enterobacteriaceae and now a member of the family Hafniaceae, is currently composed of five species, although the taxonomy of this genus is still unsettled. The genus can primarily be divided into two pathogenic groups: E. tarda strains are responsible for almost all human infections, and two other species (E. ictaluri, E. piscicida) cause diseases in fish. Human infections predominate in subtropical habitats of the world and in specific geospatial regions with gastrointestinal disease, bloodborne infections, and wound infections, the most common clinical presentations in decreasing order. Gastroenteritis can present in many different forms and mimic other intestinal disturbances. Chronic gastroenteritis is not uncommon. Septicemia is primarily found in persons with comorbid conditions including malignancies and liver disease. Mortality rates range from 9% to 28%. Most human infections are linked to one of several risk factors associated with freshwater or marine environments such as seafood consumption. In contrast, edwardsiellosis in fish is caused by two other species, in particular E. ictaluri. Both E. ictaluri and E. piscicida can cause massive outbreaks of disease in aquaculture systems worldwide, including enteric septicemia in channel catfish and tilapia. Collectively, these species are increasingly being recognized as important pathogens in clinical and veterinary medicine. This article highlights and provides a current perspective on the taxonomy, microbiology, epidemiology, and pathogenicity of this increasingly important group. Full article

California’s San Joaquin Valley is both drought-prone and water-scarce but relies on high-intensity agriculture as its primary economy. Climate change adaptation strategies for high-intensity agriculture require reliable and highly resolved land use classification data to accurately account for changes in crop water demand, greenhouse gas (GHG) emissions, and farmgate revenue. Understanding direct and indirect economic impacts from potential changes to high-intensity agriculture to reduce groundwater overdrafts, such as reductions in the cultivated area or switching to less water-intensive crops, is unachievable if land use data are too coarse and inconsistent or misclassified. This study quantified the revenue, crop water requirement, and GHG emission discrepancies resulting from land use misclassification in the United States’ most complex agricultural region, California’s San Joaquin Valley. By comparing three commonly used land use classification datasets—CropScape, Land IQ, and Kern County Agriculture—this study found that CropScape led to considerable revenue and crop water requirement discrepancies compared to other sources. Crop misclassification across all datasets resulted in an underestimation of GHG emissions. The total revenue discrepancies of misclassified crops by area for the 2016 dataset comparisons result in underestimations by CropScape of around USD 3 billion and overestimation by LIQ and Kern Ag of USD 72 million. Reducing crop misclassification discrepancies is essential for crafting climate resilience strategies, especially for California, which generates USD 50 billion in annual agricultural revenue, faces increasing water scarcity, and aims to reach carbon neutrality by 2045. Additional investments are needed to produce spatial land use data that are highly resolved and locally validated, especially in high-intensity agriculture regions dominated by specialty crops with unique characteristics not well suited to national mapping efforts. Full article

The Temblor Mountain Special Recreation Area (SRMA) on the western flank of the San Joaquin Valley, CA, is located in the endemic area of Coccidioides, a fungal pathogen responsible for the increasing incidence of coccidioidomycosis (Valley fever). Recreationists in the SRMA, such as off-highway vehicle (OHV) drivers and mountain bikers who disturb the soils, are at risk of being exposed to airborne arthroconidia (asexual spores) of the pathogen. To reduce the risk of pathogen exposure for visitors, the Bureau of Land Management (BLM) plans to limit recreational activities to areas with a reduced pathogen presence. They envision an official OHV park in the future, by also restricting access to areas with ongoing restoration efforts and by limiting soil erosion in sensitive areas. To investigate which soils in the Temblor SRMA are most likely to support the growth of Coccidioides spp., soil samples were collected over a 3-year period from dominant soil types in a northern and a southern sampling area and analyzed for the pathogen using a culture-independent PCR-based method. In addition, soil pH and electrical conductivity were determined. The results of this study revealed slight genetic variance in the Coccidioides sequences obtained from the soils of the Temblor SRMA. An analysis of variance (ANOVA) could not confirm differences in soil pH and electrical conductivity (EC) between the different soil types investigated and between sites where the pathogen was detected compared to sites where it could not be found. However, the year of sampling appeared to have an influence on observed soil pH and EC, and the presence of the pathogen. Of all dominant soil types investigated, those belonging to the Littlesignal–Cochora association were the least likely to contain the pathogen, whereas soils of the Beam–Panoza–Hillbrick association appeared more supportive. In addition to pointing out OHV areas with lower pathogen exposure risk in the Temblor SRMA, recommendations were made to educate visitors and BLM workers about the risk of contracting Valley fever. Full article

During California’s severe drought from 2011 to 2017, a significant shift in irrigated area from annual to perennial crops occurred. Due to the time requirements associated with bringing perennial crops to maturity, more perennial acreage likely increases the opportunity costs of fallowing, a common drought mitigation strategy. Increases in the costs of fallowing may put additional pressure on another common “go-to” drought mitigation strategy—groundwater pumping. Yet, overdrafted groundwater systems worldwide are increasingly becoming the norm. In response to depleting aquifers, as evidenced in California, sustainable groundwater management policies are being implemented. There has been little modeling of the potential effect of increased perennial crop production on groundwater use and the implications for public policy. A dynamic, integrated deterministic model of agricultural production in Kern County, CA, is developed here with both groundwater and perennial area by vintage treated as stock variables. Model scenarios investigate the impacts of surface water reductions and perennial prices on land and groundwater use. The results generally indicate that perennial production may lead to slower aquifer draw-down compared with deterministic models lacking perennial crop dynamics, highlighting the importance of accounting for the dynamic nature of perennial crops in understanding the co-evolution of agricultural and groundwater systems under climate change. Full article

In this study, declining pistachio rootstocks were detected in newly planted commercial pistachio orchards in Kern County, California. Symptoms were characterized by wilted foliage combined with crown rot in the rootstock. From diseased trees, 42 isolates were obtained, and all had similar cultural and morphological characteristics of Macrophomina phaseolina. Analyses of nucleotide sequences of three gene fragments, the internal transcribed spacer region (ITS1–5.8S–ITS2), partial sequences of β-tubulin, and translation elongation factor 1-α (TEF1) confirmed this identification, and 20 representative isolates are presented in the phylogenetic study. Testing of Koch’s postulates showed that M. phaseolina, when inoculated to stems and roots of the pistachio rootstocks using mycelial plugs or a microsclerotial suspension, is indeed pathogenic to this host. The widely used clonal University of California Berkeley I (UCBI) rootstock appeared highly susceptible to M. phaseolina, suggesting that this pathogen is an emerging threat to the production of pistachio in California. This study confirmed the association of M. phaseolina with the decline of pistachio trees and represents the first description of this fungus as a crown rot-causing agent of pistachio in California. Full article

Valley Fever, or Coccidioidomycosis, a fungal respiratory disease, is prevalent with increasing incidence in the Southwestern United States, especially in the central region of California. Public health agencies in the region do not have a consistent strategy for communication and health promotion targeting vulnerable communities about this climate-sensitive disease. We used the behavior adaptation communication model to design and conduct semi-structured interviews with representatives of public health agencies in five California counties: Fresno, Kern, Kings, San Luis Obispo, and Tulare County. While none of the agencies currently include climate change information into their Valley Fever risk messaging, the agencies discuss future communication methods similar to other health risk factors such as poor air quality days and influenza virus season. For political reasons, some public health agencies deliberately avoided the use of climate change language in communicating health risk factors to farmers who are particularly vulnerable to soil and dust-borne fungal spores. The effectiveness of health communication activities of the public health agencies has not been measured in reducing the prevalence of Valley Fever in impacted communities. Given the transboundary nature of climate influence on Valley Fever risk, a concerted and consistent health communication strategy is expected to be more effective than current practices. Full article

Understanding how different crops use water over time is essential for planning and managing water allocation, water rights, and agricultural production. The main objective of this paper is to characterize the spatiotemporal dynamics of crop water use in the Central Valley of California using Landsat-based annual actual evapotranspiration (ETa) from 2008 to 2018 derived from the Operational Simplified Surface Energy Balance (SSEBop) model. Crop water use for 10 crops is characterized at multiple scales. The Mann–Kendall trend analysis revealed a significant increase in area cultivated with almonds and their water use, with an annual rate of change of 16,327 ha in area and 13,488 ha-m in water use. Conversely, alfalfa showed a significant decline with 12,429 ha in area and 13,901 ha-m in water use per year during the same period. A pixel-based Mann–Kendall trend analysis showed the changing crop type and water use at the level of individual fields for all of Kern County in the Central Valley. This study demonstrates the useful application of historical Landsat ET to produce relevant water management information. Similar studies can be conducted at regional and global scales to understand and quantify the relationships between land cover change and its impact on water use. Full article

In California, a significant percentage of the pistachio acreage is in the San Joaquin Valley on saline and saline-sodic soils. However, irrigation management practices in commercial pistachio production are based on water-use information developed nearly two decades ago from experiments conducted in non-saline orchards sprinkler-irrigated with good quality water. No information is currently available that quantify the effect of salinity or combined salinity and sodicity on water use of micro-irrigated pistachio orchards, even though such information would help growers schedule irrigations and control soil salinity through leaching. To fill this gap, a field research study was conducted in 2016 and 2017 to measure the actual evapotranspiration (ETa) from commercial pistachio orchards grown on non-saline and saline-sodic soils in the southern portion of the San Joaquin Valley of California. The study aimed at investigating the functional relations between soil salinity/sodicity and tree performance, and understanding the mechanisms regulating water-use reduction under saline and saline-sodic conditions. Pistachio ETa was measured with the residual of energy balance method using a combination of surface renewal and eddy covariance equipment. Saline and saline-sodic conditions in the soil adversely affected tree performance with different intensity. The analysis of field data showed that ETa, light interception by the tree canopy, and nut yield were highly and linearly related (r² > 0.9). Moving from non-saline to saline and saline-sodic conditions, the canopy light interception decreased from 75% (non-saline) to around 50% (saline) and 30% (saline-sodic), and ETa decreased by 32% to 46% relative to the non-saline orchard. In saline-sodic soils, the nut yield resulted around 50% lower than that of non-saline orchard. A statistical analysis performed on the correlations between soil physical-chemical parameters and selected tree performance indicators (ETa, light interception, and nut yield) revealed that the sodium adsorption ratio (SAR) adversely affected tree performance more than the soil electrical conductivity (ECe). Results suggest that secondary effects of sodicity (i.e., degradation of soil structure, possibly leading to poor soil aeration and root hypoxia) might have had a stronger impact on pistachio performance than did salinity in the long term. The information presented in this paper can help pistachio growers and farm managers better tailor irrigation water allocation and management to site-specific orchard conditions (e.g., canopy features and soil-water salinity/sodicity), and potentially lead to water and energy savings through improved irrigation management practices. Full article

Information on residential pesticide usage and behaviors that may influence pesticide exposure was collected in three population-based studies of older adults residing in the three Central California counties of Fresno, Kern, and Tulare. We present data from participants in the Study of Use of Products and Exposure Related Behaviors (SUPERB) study (N = 153) and from community controls ascertained in two Parkinson’s disease studies, the Parkinson’s Environment and Gene (PEG) study (N = 359) and The Center for Gene-Environment Studies in Parkinson’s Disease (CGEP; N = 297). All participants were interviewed by telephone to obtain information on recent and lifetime indoor and outdoor residential pesticide use. Interviews ascertained type of product used, frequency of use, and behaviors that may influence exposure to pesticides during and after application. Well over half of all participants reported ever using indoor and outdoor pesticides; yet frequency of pesticide use was relatively low, and appeared to increase slightly with age. Few participants engaged in behaviors to protect themselves or family members and limit exposure to pesticides during and after treatment, such as ventilating and cleaning treated areas, or using protective equipment during application. Our findings on frequency of use over lifetime and exposure related behaviors will inform future efforts to develop population pesticide exposure models and risk assessment. Full article