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Abstract Wildfires have increased in size, frequency, and intensity in arid regions of the western United States because of human activity, changing land use, and rising temperature. Fire can degrade water quality, reshape aquatic habitat, and increase the risk of high discharge and erosion. Drawing from patterns in montane dry forest, chaparral, and desert ecosystems, we developed a conceptual framework describing how interactions and feedbacks among material accumulation, combustion of fuels, and hydrologic transport influence the effects of fire on streams. Accumulation and flammability of fuels shift in opposition along gradients of aridity, influencing the materials available for transport. Hydrologic transport of combustion products and materials accumulated after fire can propagate the effects of fire to unburned stream–riparian corridors, and episodic precipitation characteristic of arid lands can cause lags, spatial heterogeneity, and feedbacks in response. Resolving uncertainty in fire effects on arid catchments will require monitoring across hydroclimatic gradients and episodic precipitation. 

Automated detection of vulnerabilities and weaknesses in binary code is a critical need at the frontier of cybersecurity research. Cybersecurity static-analysis tools aim to detect and enumerate vulnerabilities and weaknesses. Two popular tools are CVE Binary Tool (cve-bin-tool) and cwechecker. Cve-bin-tool reports vulnerabilities using Common Vulnerabilities and Exposures (CVE) whereas cwe-checker reports weaknesses using Common Weakness Enumeration (CWE). Despite widespread use, the consistency with which these tools report vulnerabilities and weaknesses (herein, “findings”) was unaddressed. We conducted a systematic investigation of 660 unique binaries taken from a Kali Linux distribution, evaluated each binary with multiple versions of the static-analysis tools, and investigated how the findings changed according to the version of the static-analysis tool used. We expected some variation in findings commensurate with the software-development life cycle. However, we were surprised by the number and magnitude of the changes in findings reported across versions. New versions gave new answers. 

Abstract In streams where water temperatures stress native biota, management of riparian shade or hyporheic exchange are both considered viable management strategies for reducing the peaks of daily and seasonal stream channel temperature cycles. Although shade and hyporheic exchange may have similar effects on stream temperatures, their mechanisms differ. Improved understanding of the heat‐exchange mechanisms influenced by shade and hyporheic exchange will aid in the appropriate application of either stream temperature management strategy. To illustrate a conceptual model highlighting shade as ‘thermal insulation’ and hyporheic exchange imparting ‘thermal capacitance’ to a stream reach, we conducted an in‐silico simulation modelling experiment increasing shade or hyporheic exchange parameters on an idealized, hypothetical stream. We assessed the potential effects of increasing shade or hyporheic exchange on a stream reach using an established process‐based heat‐energy budget model of stream‐atmosphere heat exchange and incorporated an advection‐driven hyporheic heat exchange routine. The model tracked heat transport through the hyporheic zone and exchange with the stream channel, while including the effects of hyporheic water age distribution on upwelling hyporheic temperatures. Results showed that shade and hyporheic exchange similarly damped diurnal temperature cycles and differentially altered seasonal cycles of our theoretical stream. In winter, hyporheic exchange warmed simulated channel temperatures whereas shade had little effect. In summer, both shade and hyporheic exchange cooled channel temperatures, though the effects of shade were more pronounced. Our simple‐to‐grasp analogies of ‘thermal insulation’ for shade effects and ‘thermal capacitance’ for hyporheic exchange effects on stream temperature encourage more accurate conceptualization of complex, dynamic heat exchange processes among the atmosphere, stream channel, and alluvial aquifer. 

Abstract Relative to their limited areal extent, riparian ecosystems are disproportionately important in regulating inorganic solute export from agricultural landscapes. We investigated spatial patterns of solute concentrations in surface and ground waters of stream corridors to infer the dominant hydrologic transport and biogeochemical pathways that influence riparian nitrate and sulfate processing from uplands to streams. We selected three reaches of stream corridors draining an agricultural landscape that vary in hydrologic connection with upland aquifers. Non‐irrigated crop production dominates land use in the study area and influences the quality of upland groundwater draining to the stream corridors. We interpret patterns in solute concentrations of riparian groundwater and stream water relative to upland groundwater to infer the influences of biogeochemical processing and hydrologic connectivity. Excess nitrate from cultivated soils is evident in upland groundwater concentrations that consistently exceed the U.S. Environmental Protection Agency public drinking water standard. Nitrate and oxygen concentrations in riparian groundwaters were consistently lower than in terrace groundwater and adjacent stream waters, suggesting rapid consumption of oxygen and influence of anaerobic metabolic reduction processes in subsurface flow. Sulfate concentrations in streams were higher than in terrace groundwater, likely due to weathering of shale‐derived substrate in riparian aquifers. The degree of solute mitigation or augmentation by riparian biogeochemical processes depended on the geomorphic context that controlled the fraction of upland water passing through the riparian substrate. Observed net nitrate losses with net sulfate gains from uplands to stream channels reflect flow paths through a complex distribution of redox conditions throughout the riparian areas, emphasizing the importance of considering riparian area heterogeneity in predicting solute export in streams. This research contributes to understanding how stream corridor substrate and geomorphic context controls the biogeochemical and hydrologic processes influencing the quality of water exported from agricultural landscapes. 

Instrument fidelity in message testing research hinges upon how precisely messages operationalize treatment conditions. However, numerous message testing studies have unmitigated threats to validity and reliability because no established procedures exist to guide construction of message treatments. Their construction typically occurs in a black box, resulting in suspect inferential conclusions about treatment effects. Because a mixed methods approach is needed to enhance instrument fidelity in message testing research, this article contributes to the field of mixed methods research by presenting an integrated multistage procedure for constructing precise message treatments using an exploratory sequential mixed methods design. This work harnesses the power of integration through crossover analysis to improve instrument fidelity in message testing research through the use of natural language processing (NLP). 

Hyporheic exchange is now widely acknowledged as a key driver of ecosystem processes in many streams. Yet stream ecologists have been slow to adopt nuanced hydrologic frameworks developed and applied by engineers and hydrologists to describe the relationship between water storage, water age, and water balance in finite hydrosystems such as hyporheic zones. Here, in the context of hyporheic hydrology, we summarize a well-established mathematical framework useful for describing hyporheic hydrology, while also applying the framework heuristically to visualize the relationships between water age, rates of hyporheic exchange, and water volume within hyporheic zones. Building on this heuristic application, we discuss how improved accuracy in the conceptualization of hyporheic exchange can yield a deeper understanding of the role of the hyporheic zone in stream ecosystems. Although the equations presented here have been well-described for decades, our aim is to make the mathematical basis as accessible as possible and to encourage broader understanding among aquatic ecologists of the implications of tailed age distributions commonly observed in water discharged from and stored within hyporheic zones. Our quantitative description of “hyporheic hydraulic geometry,” associated visualizations, and discussion offer a nuanced and realistic understanding of hyporheic hydrology to aid in considering hyporheic exchange in the context of river and stream ecosystem science and management. 

Hyporheic exchange is a key driver of ecosystem processes in streams, yet stream ecologists often fail to leverage detailed conceptual models developed by engineers and hydrologists describing the relationship between water storage, water balance, and water age (time elapsed since a conceptual parcel of water entered the hyporheic zone) in hyporheic zones.  In a companion paper (G.C. Poole et al. Hyporheic Hydraulic Geometry: Conceptualizing relationships among hyporheic exchange, storage, and water age, published in PLoS ONE; doi:10.1371/journal.pone.0262080), we provide visualizations of these relationships in an effort to allow non-hydrologists to grasp four primary concepts along with associated research and management implications: 1) the rate of hyporheic exchange, size of the hyporheic zone, and hyporheic water age are inexorably linked; 2) such linkages can be leveraged to build understanding of hyporheic processes; 3) the age distribution of hyporheic water and hyporheic discharge is heavily skewed toward young water ages -- at any temporal scale of observation (minutes, hours, days, or months) older hyporheic water is rare relative to younger water; 4) the age distribution of water discharged from any hyporheic zone is not the same as the age distribution of water stored within that hyporheic zone. The data set presented here represents the numerical values represented by the figures published in the companion paper.