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Filters: Tags: {"scheme":"https://www.sciencebase.gov/vocab/category/NCCWSC/DroughtFireandExtremeWeather","name":"drought"} (X) > partyWithName: Southwest CSC (X)

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Streamflow in the Colorado River is heavily influenced by high-elevation snowpack. Warming temperatures in spring can reduce snow-fed flows, with serious implications for the water supplies that support communities and wildlife. While it is already well-known that precipitation has a significant influence on river flow, recent observations suggest that temperature and the amount of water in soil may also influence streamflow. In the face of a changing climate, it is important that resource managers understand how factors such as changing temperatures and precipitation will affect this vital water source. To address this need, researchers are examining records of streamflow, temperature, soil moisture, and precipitation...
Abstract (from http://www.bioone.org/doi/abs/10.3417/2017006): The Earth system is undergoing rapid, profound anthropogenic change. The primary axes of change include not only the climate system, but also the spread of invasive species, altered biogeochemical and hydrological cycles, modified disturbance regimes, and land degradation and conversion. These factors are influencing the distribution of species and the structure and function of ecosystems worldwide, interacting with climatic stressors that may preclude the persistence of many current species distributions and communities. Ecological disturbances such as wildfires and insect outbreaks can interact with climate variability to precipitate abrupt change...
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Forests across the southwestern U.S. are crucial components of recreation and play an important role in state and local economies. Healthy forests also provide needed habitat for many wildlife species and contribute many other important services to our planet. “Hotter droughts” (otherwise normal droughts whose effects on ecosystems are exacerbated by higher temperatures) are an emerging climate change threat to forests with some of their earliest and strongest appearances happening in the Southwest. The Leaf to Landscape project uses California’s unusually hot drought as a potential preview of the future, allowing us to collect information that will help guide forest management in the face of a warming climate....
Abstract (from http://onlinelibrary.wiley.com/doi/10.1002/2015GL067613/full): This empirical study examines the influence of precipitation, temperature, and antecedent soil moisture on upper Colorado River basin (UCRB) water year streamflow over the past century. While cool season precipitation explains most of the variability in annual flows, temperature appears to be highly influential under certain conditions, with the role of antecedent fall soil moisture less clear. In both wet and dry years, when flow is substantially different than expected given precipitation, these factors can modulate the dominant precipitation influence on streamflow. Different combinations of temperature, precipitation, and soil moisture...
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California’s Central Valley is a nexus for water resources in the state, draining the Sacramento and San Joaquin River watersheds. Urban centers, agricultural operations, and the environment all compete for limited water, and demand is expected to only increase as the population grows and agriculture intensifies. At the same time, the water supply is projected to decrease as temperatures rise, precipitation patterns change, and the frequency of extreme droughts increases. The Central Valley also provides critical wetland habitats to migratory waterbirds, and wetland managers require information on how to best use water resources to support wildlife objectives, particularly during drought. This project seeks to...
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In the dry southwestern United States, snowmelt plays a crucial role as a water source for people, vegetation, and wildlife. However, snow droughts significantly lower snow accumulations, disrupting these critical water supplies for local communities and ecosystems. Despite its large influence on land- and water-resource management, snow drought has only recently been properly defined and its historical distribution and effects on key natural resources are essentially unknown. To remedy this serious knowledge gap, project researchers are examining the causes, effects, and forecastability of snow drought to provide needed scientific information and guidance to planners and decision makers. The central goals of...
A new satellite-derived low cloud retrieval reveals rich spatial texture and coherent space-time propagation in summertime California coastal low cloudiness (CLC). Throughout the region, CLC is greatest during May–September but has considerable monthly variability within this summer season. On average, June is cloudiest along the coast of southern California and northern Baja, Mexico, while July is cloudiest along northern California's coast. Over the course of the summer, the core of peak CLC migrates northward along coastal California, reaching its northernmost extent in late July/early August, then recedes while weakening. The timing and movement of the CLC climatological structure is related to the summer evolution...
Abstract (from Wiley): With increasing concerns about the impact of warming temperatures on water resources, more attention is being paid to the relationship between runoff and precipitation, or runoff efficiency. Temperature is a key influence on Colorado River runoff efficiency, and warming temperatures are projected to reduce runoff efficiency. Here, we investigate the nature of runoff efficiency in the upper Colorado River (UCRB) basin over the past 400 years, with a specific focus on major droughts and pluvials, and to contextualize the instrumental period. We first verify the feasibility of reconstructing runoff efficiency from tree‐ring data. The reconstruction is then used to evaluate variability in runoff...
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In 2017, California was experiencing its most severe drought in over a millennia. Low rainfall and record high temperatures resulted in increased tree mortality and complete forest diebacks across the West. Though land managers scrambled to respond, they lacked information needed to make informed decisions. Focusing on California’s central and southern Sierra Nevada Mountains, this project seeks to determine whether a key forest management practice – forest thinning via prescribed fire – can help forests better survive drought. Prescribed fire is commonly used in the western U.S. to remove potential wildfire fuel, such as small trees and shrubs. It is also thought that this act of selectively removing trees helps...
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The Colorado River is a crucial water source for millions of people in the Southwest. Warming temperatures, clearly documented in climate records for the Colorado River basin, are having an impact on the amount of annual streamflow yielded from rain and snow. Recent work has revealed that warming temperatures have played an increasingly important role over the past decades, both exacerbating droughts and dampening the effects of wet winters on high stream flows. Understanding and anticipating how warming temperatures will influence future water supply in the Colorado River basin is increasingly important for resource management, particularly in light of recent drought conditions. The overarching goals of this...
Abstract (from http://journals.ametsoc.org/doi/abs/10.1175/JAMC-D-15-0167.1): Annual precipitation in California is more variable than in any other state and is highly influenced by precipitation in winter months. A primary question among stakeholders is whether low precipitation in certain months is a harbinger of annual drought in California. Historical precipitation data from 1895 to 2013 are investigated to identify leading monthly indicators of annual drought in each of the seven climate divisions (CDs) as well as statewide. For this study, drought conditions are defined as monthly/annual (October–September) precipitation below the 20th/30th percentile, and a leading indicator is defined as a monthly drought...
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Estuaries are located at the interface where rivers meet the sea, creating unique ecosystems with complex physical and biological processes. Coastal wetlands provide essential ecosystem services to people, including flood protection from high tides and storm surges, commercial fisheries, carbon sequestration, improved water quality, and wildlife food and habitat. Coastal wetlands are also home to hundreds of migratory and resident wildlife species including threatened and endangered species of management concern. Wetlands also have the unique ability to increase their elevation relative to sea-level rise, therefore protecting nearby communities from flooding. In California, prolonged drought and extreme storm events...
Abstract (from https://www.sciencedirect.com/science/article/pii/S2405880717300924): Water managers are increasingly interested in better understanding and planning for projected resource impacts from climate change. In this management-guided study, we use a very large suite of synthetic climate scenarios in a statistical modeling framework to simultaneously evaluate how (1) average temperature and precipitation changes, (2) initial basin conditions, and (3) temporal characteristics of the input climate data influence water-year flow in the Upper Colorado River. The results here suggest that existing studies may underestimate the degree of uncertainty in future streamflow, particularly under moderate temperature...
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Drought is one of the biggest threats facing our forests today. In the western U.S., severe drought and rising temperatures have caused increased tree mortality and complete forest diebacks. Forests are changing rapidly, and while land managers are working to develop long-term climate change adaptation plans, they require tools that can enhance forest resistance to drought now. To address this immediate need, researchers are examining whether a common forest management tool, prescribed fire, can be implemented to help forests better survive drought. Prescribed fire is commonly used in the western U.S. to remove potential wildfire fuel, such as small trees and shrubs. It is also thought that this act of selectively...
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There is a growing realization that current warming trends may be associated with increases in the size, frequency, and severity of forest fires in the West. While rising temperatures can create drought conditions that favor severe fires, it is also possible that drought limits the ability of trees to survive a fire. During a drought, there is less water available for trees and more outbreaks of harmful insects and pathogens can occur, both of which can weaken trees. Tree mortality is one means of measuring the severity of a fire, and evidence shows that trees exposed to drought conditions for periods of 5-10 years are already more sensitive to the effects of fire – suggesting that drought could indeed increase...
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In the southwestern United States, droughts of 10 or more years are projected to become more frequent by 2100. It also is projected that there will be fewer wet days per year, with more precipitation falling on those wet days. Such climatic extremes can strongly affect wild animals and plants, ecosystems, and humans. In the Southwest, more frequent and intense storms may negatively affect protected species in coastal salt marshes; changes in the timing and amount of precipitation could lead to increases in fuel loads; and increasingly humid heat waves could lead to higher incidence of heat-related illness among visitors to national parks. This project will improve understanding of climate extremes and their potential...
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Invasive plants are a major land management problem in the Western U.S. Cheatgrass (Bromus tectorum) is the most prominent and problematic invader in cold deserts, with negative effects on rangeland fire patterns, wildlife habitats, and forage/vegetation. Red brome (B. madritensis) is an invader in the Mojave Desert, and can similarly introduce a new fire patterns to sensitive warm desert scrub. These invasions often cause management agencies to incur high costs for prevention, control, restoration, and fire responses. Control and prevention of invasive species is challenging because the risk of invasive plants becoming abundant depends on existing plant communities, climate and weather, land use, and fire history....
Abstract (from ScienceDirect): Improved coastal stratocumulus (Sc) cloud forecasts are needed because traditional satellite cloud motion vectors (CMV) do not accurately predict how Sc clouds move or dissipate in time, which often results in an underprediction of irradiance in the morning hours. CMV forecasts assume clouds move in the direction of the average regional wind field, which is not necessarily the case for Sc clouds. Sc clouds over the land form at night and typically reach their maximum coverage before sunrise. During the day, heating from solar radiation at the surface and entrainment of dry and warm air from above causes Sc clouds to dissipate. A Sc cloud edge forecast using Geostationary Operational...
    map background search result map search result map Examining the Influence of Temperature and Precipitation on Colorado River Water Resources: Reconstructing the Past to Understand the Future How Does Drought Influence Fire Severity in the Southwestern U.S.? Improving Understanding of Climate Extremes in the Southwestern United States Fighting Drought with Fire: A Comparison of Burned and Unburned Forests in Drought-Impacted Areas of the Southwest The Impact of Drought on Waterbirds and Their Wetland Habitats in California’s Central Valley Can Prescribed Fire Help Forests Survive Drought in the Sierra Nevada Mountains? Leaf to Landscape: Understanding and Mapping the Vulnerability of Forests to Hotter Droughts The Role of Climate in Shaping Invasive Plant Abundance across Different Spatial Locations Learning From Recent Snow Droughts to Improve Forecasting of Water Availability for People and Forests Anticipating Future Impacts of Temperature on Streamflow in the Colorado River Basin Climate Extremes and Ecological Impacts to California Estuaries Leaf to Landscape: Understanding and Mapping the Vulnerability of Forests to Hotter Droughts The Impact of Drought on Waterbirds and Their Wetland Habitats in California’s Central Valley Can Prescribed Fire Help Forests Survive Drought in the Sierra Nevada Mountains? Examining the Influence of Temperature and Precipitation on Colorado River Water Resources: Reconstructing the Past to Understand the Future Anticipating Future Impacts of Temperature on Streamflow in the Colorado River Basin Climate Extremes and Ecological Impacts to California Estuaries The Role of Climate in Shaping Invasive Plant Abundance across Different Spatial Locations Improving Understanding of Climate Extremes in the Southwestern United States Learning From Recent Snow Droughts to Improve Forecasting of Water Availability for People and Forests How Does Drought Influence Fire Severity in the Southwestern U.S.? Fighting Drought with Fire: A Comparison of Burned and Unburned Forests in Drought-Impacted Areas of the Southwest