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John Wesley Powell Center for Analysis and Synthesis

Current Powell Center Working Groups

Climate elasticity of streamflow for virgin basins over the continental United States  (Sankarasubramanian and Vogel, 2003) with the inset showing the modified Budyko's framework (Wang and Hejazi , 2011) for decom.jpg from ScienceBase Item
A global synthesis of land-surface fluxes under natural and human-altered watersheds using the Budyko framework
Global hydroclimatic conditions have been significantly altered, over the past century, by anthropogenic influences that arise from warming global climate and also from local/regional anthropogenic disturbances. There has been never been an effort that has systematically analyzed how the spatio-temporal variability of land-surface fluxes vary in natural and human-altered watersheds globally. This synthesis study will adapt and extend the classical Budyko framework to quantify the role of drivers - changing climate and local human disturbances - in altering flow regimes and in creating urban heat island episodes over the globe. An allied goal is to develop parsimonious hydroclimatic models that explain the spatio-temporal variability [...] (Read More)
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Accounting for U.S. ecosystem services at national and subnational scales
Ecosystem services - the benefits that nature provides to society and the economy - are gaining increasing traction worldwide as governments and the private sector use them to monitor integrated environmental and economic trends. When they are well understood and managed, ecosystems can provide these long-term benefits to people - such as clean air and water, flood control, crop pollination, and recreational, cultural, and aesthetic benefits. Within the U.S. government, a memo issued by the White House Council on Environmental Quality in October 2015 charged agencies with incorporating these values in planning, investment, and regulatory processes. Natural capital accounting - a tool being used in dozens of countries globally and by [...] (Read More)
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Advancing understanding of ecosystem responses to climate change with warming experiments: what we have learned and what is unknown?
Advancing our mechanistic understanding of ecosystem responses to climate change is critical to improve ecological theories, develop predictive models to simulate ecosystem processes, and inform sound policies to manage ecosystems and human activities. Manipulation of temperature in the field, or the “ecosystem warming experiment,” has proved to be a powerful tool to understand ecosystem responses to changes in temperature. No comprehensive synthesis has been conducted since the last one more than 10 years ago. A new synthetic analysis is critically needed to advance our understanding of ecosystem responses to warming, to highlight experimental artifacts and appropriate interpretations, and to guide development of the next generation [...] (Read More)
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Broader view of North American climate over the past two millennia: Synthesizing paleoclimate records from diverse archives
Regional- to continental-scale paleoclimate syntheses of temperature and hydroclimate in North America are essential for understanding long-term spatiotemporal variability in climate, and for properly assessing risk on decadal and longer timescales. However, existing syntheses rely almost exclusively on tree-ring records, which are known to underestimate low-frequency variability and rarely extend beyond the last millennium. Meanwhile, many additional records from a variety of archives are available and hold the potential of broadening and enhancing our understanding of past climate in North America over the past two thousand years. We propose to bring together a diverse group of with expertise that spans the relevant natural archives [...] (Read More)
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Characterizing landscape genomics and reconstructing pathways to plant ecological specialization and speciation
This proposal brings together biologists and geoscientists to evaluate the evolution of stress tolerance and adaptation to extreme environments in plants. Stress tolerance has been studied mainly from a physiological perspective using laboratory and field experiments. In contrast, this project will take a combined environmental and evolutionary perspective using national public databases and a “big data” approach. Thus the proposal will illustrate an application of spatially integrated big datasets for basic research, a synthesis goal of the Powell Center. We will use the geochemical and mineralogical data from the USGS Soil Geochemical Landscapes of the Conterminous United States Project, digital elevation and terrain data, Biodiversity [...] (Read More)
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Climate change and ecohydrology in temperate dryland ecosystems: a global assessment
Water cycling and availability exert dominant control over ecological processes and the sustainability of ecosystem services in water - limited ecosystems. Consequently, dryland ecosystems have the potential to be dramatically impacted by hydrologic alterations emerging from global change, notably increasing temperature and altered precipitation patterns. In addition, the possibility of directly manipulating global solar radiation by augmenting stratospheric SO2 is receiving increasing attention as CO2 emissions continue to increase - these manipulations are anticipated to decrease precipitation, a change that may be as influential as temperature increases in dryland ecosystems. We propose to integrate a proven soil water model with [...] (Read More)
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Completing the dryland puzzle: creating a predictive framework for biological soil crust function and response to climate change
Drylands are integral to the Earth system and the present and future of human society. Drylands encompass more than 40% of the terrestrial landmass and support 34% of the world’s human population. Biocrusts are the “living skin” of Earth’s drylands, sometimes dominating the ground cover and figuring prominently in ecosystem structure and function. Biocrusts are a biological aggregate of cyanobacteria, fungi, algae, lichens and mosses in the surface millimeters of soil. By aggregating soil, biocrusts make sediment less erodible. They also strongly influence the water runoff-infiltration balance. In some ecosystems they generate runoff, whereas in other systems they enhance water capture. Vascular plant germination, establishment, [...] (Read More)
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Continental-scale overview of stream primary productivity, its links to water quality, and consequences for aquatic carbon biogeochemistry
Streams and rivers have a limited spatial extent, but are increasingly recognized as key components of regional biogeochemical cycles. The collective metabolic processing of organisms, known as ecosystem metabolism, is centrally important to nutrient cycling and carbon fluxes in these environments, but is poorly integrated into emerging biogeochemical concepts. This line of inquiry lags behind other aspects of regional biogeochemistry because of the lack of long-term, regionally-diverse studies of stream metabolism. With a few exceptions, metabolism studies have focused on small headwater catchments using short-term (days to weeks) observation. As a consequence, basic patterns and controls of this fundamental process, such as seasonality, [...] (Read More)
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Dam removal: synthesis of ecological and physical responses
Dam decommissioning is rapidly emerging as an important river restoration strategy in the U.S., with several major removals recently completed or in progress. But few studies have evaluated the far-reaching consequences of these significant environmental perturbations, especially those resulting from removals of large (>10-15 m tall) structures during the last decade. In particular, interactions between physical and ecological aspects of dam removal are poorly known. From recent work, however, observations are now available from several diverse settings nationwide to allow synthesis of key physical and ecological processes associated with dam removals, including fish and benthic community response, reservoir erosion, downstream sedimentation, [...] (Read More)
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Elucidating mechanisms underlying amphibian declines in North America using hierarchical spatial models
Amphibian populations are declining globally at unprecedented rates but statistically rigorous identification of mechanisms is lacking. Identification of reasons underlying large-scale declines is imperative to plan and implement effective conservation efforts. Most research on amphibian population decline has focused on local populations and local factors. However, the ubiquity of declines across species and landscapes suggests that causal factors at a broader scale are also important. Elucidation of the mechanisms driving population change has lagged, mainly because data have been unavailable at continental scales. We propose to address this need by assembling data to answer questions about broad-scale drivers of amphibian decline. [...] (Read More)
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Evidence for shifts in plant species diversity along N deposition gradients: a first synthesis for the United States
The impacts of nitrogen (N) deposition on plant diversity loss have been well documented across N deposition gradients in Europe, but much less so in the U.S. Published N fertilizer studies suggest losses will occur in the US, but many of these were done at levels of N input that were higher than modeled and measured N deposition, and higher than presumed N critical loads. The recent availability of modeled N deposition across the U.S. (e.g. using CMAQ) has provided a high‐resolution tool to identify regions where steep N deposition gradients facilitate detection of ecological shifts. A number of plant diversity (richness plus abundance) data sets across the U.S. have explained diversity shifts based on anthropogenic drivers such as [...] (Read More)
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Exploiting high-resolution topography for advancing the understanding of mass and energy transfer across landscapes: Opportunities, challenges, and needs
One of the grand challenges of Earth Surface Science and Natural Resource Management lies in the prediction of mass and energy transfer for large watersheds and landscapes. High resolution topography (lidar) datasets show potential to significantly advance our understanding of hydrologic and geomorphic processes controlling mass and energy transfer because they represent features at the appropriate fine scale on which surface processes operate. While lidar datasets have become readily available across the United States, challenges remain in extracting accurate and objective information relevant for hydrologic and geomorphic research, modeling, and prediction, as well as watershed management. We primarily focus our efforts on river [...] (Read More)
Lawrence_forest_response_to_N.jpg from ScienceBase Item
Forecasting forest response to N deposition: integrating data from individual plant responses to soil chemistry with a continental-scale gradient analysis
Nitrogen deposition is altering forest dynamics, terrestrial carbon storage, and biodiversity. However, our ability to forecast how different tree species will respond to N deposition, especially key response thresholds, is limited by a lack of synthesis across spatial scales and research approaches. To develop our best understanding of N deposition impact on tree growth and survival, we will integrate plot-­‐ level studies describing plant growth and survival responses to N inputs and plant-­‐ available soil nutrients with a continental scale analysis across a N deposition gradient. Our primary outcome will be estimates of tree response to N deposition with explicit representation of uncertainty and the identification of thresholds [...] (Read More)
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Global Croplands and Their Water Use for Food Security in the Twenty-first Century
Global climate change is putting unprecedented pressure on global croplands and their water use, vital for ensuring future food security for the world's rapidly expanding human population. The end of the green green revolution (productivity per unit of land) era has meant declining global per capita agricultural production requiring immediate policy responses to safeguard food security amidst global climate change and economic turbulence. Above all, global croplands are water guzzlers, consuming between 60-90% of all human water use. With increasing urbanization, industrialization, and other demands (e.g., bio-fuels) on water there is increasing pressure to reduce agricultural water use by producing more food from existing or even [...] (Read More)
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Global Evaluation of the Impacts of Storms on freshwater Habitat and Structure of phytoplankton Assemblages (GEISHA)
Climate change is expected to cause more intense and frequent extreme weather events, but we only have a basic understanding of how these events might alter freshwater systems. Storms are likely to impact lake systems through delivery of sediments from watersheds and mixing of the water column, both of which could have important consequences for phytoplankton. Phytoplankton are the base of the food web; their community configuration and how the community changes across seasons have large impacts on ecosystem processes such as energy flow, nutrient cycling, and carbon cycling. External disturbances may abruptly alter phytoplankton community dynamics and thus impact ecosystem function. The effects of storms on the physical structure [...] (Read More)
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Integrating GRACE Satellite and Ground-based Estimates of Groundwater Storage Changes
Groundwater storage depletion is a critical issue for many of the major aquifers in the U.S., particularly during intense droughts. The GRACE (Gravity Recovery and Climate Experiment) satellites launched in 2002, with sensors designed to measure changes in the Earth’s gravitational field at large spatial scales (≥ ~200,000 km2). These changes are primarily driven by changes in water storage on the Earth’s surface. Estimates of groundwater storage changes based on these gravity measurements have attracted considerable media attention in the U.S. and globally. However, groundwater storage changes are computed indirectly by subtracting snow, surface water, and soil moisture storage from the total water storage monitored by GRACE, and [...] (Read More)
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Integrating modeling and empirical approaches to improve predictions of tropical forest responses to global warming
Tropical forests contain > 50% of the world’s known species (Heywood 1995), 55% of global forest biomass (Pan et al. 2011), and exchange more carbon (C), water and energy with the atmosphere than any other ecosystem type (e.g., Saugier et al. 2001). Despite their importance, there is more uncertainty associated with predictions of how tropical forests will respond to warming than for any other biome (Randerson et al. 2009). This uncertainty is of global concern due to the large quantity of C cycled by these forests and the high potential for biodiversity loss. Given the importance of tropical forests, decision makers and land managers around the globe need increased predictive capacity regarding how tropical forests will respond to [...] (Read More)
Estimated probability of arsenic greater than 10 micrograms per liter in domestic wells in the conterminous United States.JPG from ScienceBase Item
Linking environmental and public health data to evaluate health effects of arsenic exposure from domestic and public supply wells
Everyone needs clean drinking water in order to thrive. The US EPA and public water purveyors in the US work together in adherence with the Safe Drinking Water Act to make water safe for public consumption. The recent media coverage of lead in public drinking water supplies in Flint, Michigan, and schools in many cities with aging infrastructure throughout the US has raised public awareness of drinking water as a potential pathway of exposure to toxic chemicals. Epidemiologists and other researchers have conclusively shown that high arsenic levels in drinking water in Bangladesh, Taiwan, and South America cause adverse human health outcomes. However, research in study populations with levels of arsenic exposure relevant to communities [...] (Read More)
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Local-scale ecosystem resilience amid global-scale ocean change: the coral reef example
Coral reefs are massive, wave resistant structures found throughout the tropics, where they have long attracted attention for their beauty, ecological importance, and rich biological diversity. However, in recent years attention to these systems has focused on their downturn in health and the potential that they effectively could disappear within a century. Yet while many coral reefs have deteriorated, a small number have flourished and now represent “oases” with the potential to drive repopulation of the denuded areas that surround them. This working group focuses on the geographic, biological, ecological, and physical features that characterize oases in coral reef communities, and evaluates the potential of these oases to catalyze [...] (Read More)
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Mercury cycling, bioaccumulation, and risk across western North America: a landscape scale synthesis linking long-term datasets
Mercury (Hg) is a serious environmental problem that is impacting ecological and human health on a global scale. However, local and regional processes are largely responsible for producing methylmercury, which drives ecological risk. This is particularly true in western North America where the combination of diverse landscapes, habitat types, climates, and Hg sources may disproportionally impact the region relative to other areas in North America. Even with decades of regional Hg research and monitoring, there is still no holistic synthesis of the spatiotemporal patterns of Hg in abiotic and biotic resources across the region, nor has there been a formal, simultaneous analysis of the landscape, ecological and climatological factors [...] (Read More)
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NEON Workshop: Harmonizing eco-informatics approaches to facilitate data integration
There is a wealth of biodiversity and environmental data that can provide the basis for addressing global scale questions of societal concern. However, our ability to access and integrate this data is hampered by the lack of standardized languages and systems to make this information accessible through the Internet. New tools (e.g. ontologies, standards, integration tools, unique identifiers) are being developed that will move this process closer to establishing a framework for linked open data, but these tools are still nascent and require efforts in the biodiversity and environmental realm to bring to fruition, as has occurred in other domains (e.g. biomedicine). With the right data modeling and tools, data assembly for ecological [...] (Read More)
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NEON Workshop: Operationalizing Ecological Forecasts
Ecosystems are changing worldwide and critical decisions that affect ecosystem health and sustainability are being made every day. As ecologists, we have a responsibility to ensure that these decisions are made with access to the best available science. However, to bring this idea into practice, ecology needs to make a substantial leap forward towards becoming a more predictive science. Furthermore, even for basic, conceptual questions there is a lot to be gained by addressing problems from a forecasting perspective, with more frequent data-model comparisons helping to highlight misunderstandings and reframe long-standing questions. Ecological forecasting is occurring across a wide range of ecological sub-disciplines, but there [...] (Read More)
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Next Generation of Ecological Indicators: Defining Which Microbial Properties Matter Most to Ecosystem Function and How to Measure Them
While it is widely recognized that microorganisms are intimately linked with every biogeochemical cycle in all ecosystems, it is not clear how and when microbial dynamics constrain ecosystem processes. As a result, it is know clear how to apply the value of increasingly detailed characterization of microbial properties to our understanding of ecosystem ecology. Several recent papers have demonstrated how information about microbial dynamics can be incorporated into ecosystem models (Allison et al. 2010, McGuire and Treseder 2010, Todd - Brown et al. 2011a), but it is generally not clear what types of microbial data are most useful in explaining variation in biogeochemical processes and ecosystem functioning, especially in the face [...] (Read More)
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North American Analysis and Synthesis on the Connectivity of "Geographically Isolated Wetlands" to Downstream Waters
Geographically Isolated Wetlands (GIWs) occur along gradients of hydrologic and ecological connectivity and isolation, even within wetland types (e.g., forested, emergent marshes) and functional classes (e.g., ephemeral systems, permanent systems, etc.). Within a given watershed, the relative positions of wetlands and open-waters along these gradients influence the type and magnitude of their chemical, physical, and biological effects on downgradient waters. In addition, the ways in which GIWs connect to the broader hydrological landscape, and the effects of such connectivity on downgradient waters, depends largely upon climate, geology, and relief, the heterogeneity of which expands with increasing scale. Developing an understanding [...] (Read More)
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Operational Earthquake Forecasting – Implementing a Real-Time System for California
It is well know that every earthquake can spawn others (e.g., as aftershocks), and that such triggered events can be large and damaging, as recently demonstrated by L’Aquila, Italy and Christchurch, New Zealand earthquakes. In spite of being an explicit USGS strategic-action priority (; page 32), the USGS currently lacks an automated system with which to forecast such events and official protocols for disseminating the potential implications. This capability, known as Operational Earthquake Forecasting (OEF), could provide valuable situational awareness to emergency managers, the public, and other entities interested in preparing for potentially damaging earthquakes. With the various ingredients in [...] (Read More)
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Optimizing satellite resources for the global assessment and mitigation of volcanic hazards
A vast number of the world’s volcanoes are unmonitored by ground-based sensors, yet constitute an important hazard to nearby residents and infrastructure, as well as air travel and the global economy. Satellite data provide a cost-effective means of tracking activity at such volcanoes. Unfortunately, satellite acquisitions are not optimized for application to volcano hazards, in part because clear relations between satellite-monitored unrest and eruptive activity are lacking. We aim to bridge this gap by developing linked global databases of satellite observations of volcanic activity, with the goal of relating surface change and volcanic emissions to eruption style and impact. This database (or databases) will be used to design [...] (Read More)
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Potential Impacts of Prospective Climate Change on Groundwater Recharge in the Western United States
Groundwater withdrawals in the western US are a critical component of the water resources strategy for the region. Climate change already may be substantially altering recharge into groundwater systems; however, the quantity and direction (increase or decrease) of changes are relatively unknown as most climate change assessments have focused on surface water systems. We propose to conduct a broad scale literature review followed by a synthesis of available data, analysis and simulations with available downscaled climate scenarios to understand how recharge in the western US might respond to plausible climatic shifts during the rest of the 21st Century. We will produce an estimated range of impacts on groundwater recharge across the [...] (Read More)
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Predicting the next high-impact insect invasion: Elucidating traits and factors determining the risk of introduced herbivorous insects on North American native plants
Non-native insect invasions increasingly cause widespread ecological and economic damage in natural and agricultural ecosystems. Non-native insects specialized for feeding on specific plant groups are particularly problematic as they can potentially eliminate an entire genus of native plant species across a wide area. For example, emerald ash borer has killed hundreds of millions of ash trees in North America since its accidental introduction from Asia, including more than 99% of all trees in forests near the epicenter of the invasion. However, most introduced insects do not become high-impact pests. Our goal is to develop a framework that allows us to predict whether non-native herbivorous insects in natural ecosystems will cause [...] (Read More)
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River Corridor hot spots for biogeochemical processing: a continental scale synthesis
Rivers are the veins of the landscape, providing environmental benefits that are disproportionately high relative to their aerial extent; shedding flood waters, hosting aquatic ecosystems, transporting solutes and energy-rich materials, and storing and transforming pollutants into less harmful forms. From uplands to the coasts, rivers facilitate key biogeochemical reactions that cumulatively influence water quality. Many of the reactions are optimized outside the main channel, in hyporheic zones, riparian zones, and floodplain areas, where riverine water is in close contact with geochemically and microbially-active sediments. However, little is known about the distribution, intermittency, and overall effectiveness of biogeochemical [...] (Read More)
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Transport of dissolved organic matter by river networks from mountains to the sea: a re-examination of the role of flow across temporal and spatial scales
The transport of dissolved organic matter (DOM) by rivers is an important component of the global carbon cycle, affects ecosystems and water quality, and reflects biogeochemical and hydrological processes in watersheds. Understanding the fundamental relationships between discharge and DOM concentration and composition reveals important information about watershed flow paths, soil flushing, connectivity to riparian zones, organic matter leaching, soil moisture, and climatic influences. Data to describe these processes - both magnitude and timing - is critical for modeling and predicting watershed DOM dynamics, particularly in light of land use and climate change . Despite several decades of data collection, a synthesis of how hydrology [...] (Read More)
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Tsunami Source Standardization for Hazards Mitigation in the United States
The goal of this Powell Center Working Group is to produce a collection of vetted and standardized earthquake and landslide tsunami sources that can be used to produce the meaningful hazard assessment products required for effective tsunami hazard mitigation and risk reduction. The need for a set of realistic and consistent tsunami sources was identified as a high priority at a 2016 workshop between USGS scientists and the National Tsunami Hazards Mitigation Program (NTHMP). The Powell Center Working Group will include scientists from the USGS, NOAA, the NTHMP, academia, and consulting companies. Tsunamis are extreme events that have caused devastation worldwide over the past several decades. The tsunami from the 2004 Indonesian [...] (Read More)
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Understanding and managing for resilience in the face of global change
Resilience science provides a conceptual framework and methodology for quantitatively assessing the ability of a system to remain in a particular state. Probable non-linear ecological responses to global change, including climate change, require a clear framework for understanding and managing resilience. However, much of the resilience research to date has been qualitative in nature, and frameworks developed for the implementation of resilience science have been either vague or focused on the social component of social-ecological systems. Attempts to quantify resilience and operationalize the concept include the cross-scale resilience model, discontinuity theory and the early detection of leading indicators of regime shifts. More [...] (Read More)
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Understanding Fluid Injection Induced Seismicity
Fluid injection induced seismicity has been reported since the 1960s. There are currently more than 150,000 injection wells associated with oil and gas production in 34 states in the conterminous US. Pore pressure disturbance caused by injection is generally considered the culprit for injection induced seismicity, but, not all injection causes seismicity. It is not well understood what mechanical and hydrologic conditions cause some sites to be more prone than others to seismicity. The objectives of this proposed research are to utilize existing data on fluid injection and seismicity to (1) identify spatial and temporal correlations between fluid injection and induced seismicity; (2) conduct a hydro-mechanical modeling study to better [...] (Read More)
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Water availability for ungauged rivers: an integrative, multi-model approach to estimate water availability at ungauged rivers across the United States
There has been increasing attention placed on the need for water availability information at ungauged locations, particularly related to balancing human and ecological needs for water. Critical to assessing water availability is the necessity for daily streamflow time series; however, most of the rivers in the United States are ungauged. This proposal leverages over $1M currently allocated to the USGS National Water Census Program towards developing an integrated modeling approach to estimate daily streamflow at ungauged locations, with the ultimate goal of providing daily streamflow estimates at 160,000 ungauged catchments across the United States. By assembling a diverse and prolific group of international scientists, this proposal [...] (Read More)
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What lies below? Improving quantification and prediction of soil carbon storage, stability, and susceptibility to disturbance.
Soils are a vast reservoir of organic carbon (C), rendering the fate of soil C an important control on the global climate system. Widespread changes in soil C storage capacity present a potentially strong feedback to global change. Yet, a comprehensive understanding of how soil C will respond to climate and/or land use disturbance remains illusive, resulting in major uncertainties in global climate models. Our working group will synthesize information on the processes controlling soil C storage across different spatial scales and develop new procedures to translate local measurements to the regional and global scale datasets used by models. These activities will improve our ability to map the vulnerability of soil C and constrain [...] (Read More)

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