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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Economic and environmental bottlenecks in the industrial‐scale production of lipid‐derived biofuels from oleaginous yeasts: A review of the current trends and future prospects

Abstract Concerns about climate change and the reliance on fossil fuel reserves have motivated researchers to identify new renewable sources of energy. Biomass holds the potential to replace fossil‐derived products with biofuels and bio‐based chemicals. Plant‐derived lipids are promising sources of biofuels; however, the production of plant oil often leads to the release of massive amounts of carbon dioxide due to deforestation and land‐use change. The production of biofuels via plant oils (such as soybean) also competes with food production and in turn, impacts biodiversity. To mitigate these issues, the production of lipids from oleaginous yeasts could be an excellent alternative by incorporating these microbes into biorefineries utilizing agricultural or forest residues. Eventually, these microbial lipids could be potential sources for producing lipid‐derived biofuels. However, the current conventional methods for the production and recovery of lipids from oleaginous microbes suffer from economic and ecological challenges that affect its industrial‐scale expansion. This review highlights the major economic and environmental bottlenecks for the production of lipid‐derived biofuels from oleaginous yeasts. It also provides perspectives on the strategies that could be adapted on economic and ecological fronts to assist the expansion of the production of microbial lipid‐derived biofuels at an industrial scale.

Agriculture↗
DOE OSTI2017

Novel tropical forests: response to global change

Warming climates in the twenty-first century are expected to push tropical ecosystems, which currently reside at the warm and wet edge of bioclimatic life zones, into novel states that have no analog on Earth today (Fig. 1). Shifting precipitation patterns will expose some tropical forest regions to more frequent drought conditions that may reduce carbon (C) assimilation and lead to vegetation dieback, and all regions will experience higher temperatures never encountered by extant taxa. At the same time, direct anthropogenic disturbances, such as the hunting of large seed dispersers, use of fire for land management, deforestation, and agricultural land abandonment, are affecting the capacity of forests to mitigate climate change.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Future bioenergy expansion could alter carbon sequestration potential and exacerbate water stress in the United States

The maximum future projected bioenergy expansion potential, in scenarios limiting warming to 2°C or below, is equivalent to half of present-day croplands. We quantify the impacts of large-scale bioenergy expansion against re/afforestation, which remain elusive, using an integrated human-natural system modeling framework with explicit representation of perennial bioenergy crops. The end-of-century net carbon sequestration due to bioenergy deployment coupled with carbon capture and storage largely depends on fossil fuel displacement types, ranging from 11.4 to 31.2 PgC over the conterminous United States. These net carbon sequestration benefits are inclusive of a 10 PgC carbon release due to land use conversions and a 2.4 PgC loss of additional carbon sink capacity associated with bioenergy-driven deforestation. Moreover, nearly one-fourth of U.S. land areas will suffer severe water stress by 2100 due to either reduced availability or deteriorated quality. These broader impacts of bioenergy expansion should be weighed against the costs and benefits of re/afforestation-based strategies.

09 BIOMASS FUELS↗
DOE OSTI2016

The Amazon Dense GNSS Meteorological Network: A New Approach for Examining Water Vapor and Deep Convection Interactions in the Tropics

The Amazon Dense Global Navigational Satellite System (GNSS) Meteorological Network ((ADGMN) provides high spatiotemporal resolution, all-weather precipitable water vapor for studying the evolution of continental tropical and sea-breeze convective regimes of Amazonia. The ADGMN campaign consisted of two experiments: a 6-week campaign in and around Belem, which coincided with the Cloud Processes of the Main Precipitation Systems in Brazil: A Contribution to Cloud-Resolving Modeling and to the Global Precipitation Measurement (CHUVA) and a 1-yr campaign in and around Manaus. The Belem network was composed of 15 GNSS/meteorological stations that provided high-frequency (5 min) PWV data as well as surface meteorological variables For the 6-week duration of the Belem experiment, days were categorized as convective (22 days) or nonconvective (19 days) based solely on a minimum cloud-top temperature of 240 K or below over the central portion of the network and a report of precipitation at at least one site during the afternoon or evening. Here, the Manaus network commenced in April 2011 with 12 GNSS meteorological stations. Local circulations in Manaus driven by anthropogenic deforestation have, in particular, received attention.

58 GEOSCIENCES↗
DOE OSTI2012

Simulating the biogeochemical and biogeophysical impacts of transient land cover change and wood harvest in the Community Climate System Model (CCSM4) from 1850 to 2100

To assess the climate impacts of historical and projected land cover change and land use in the Community Climate System Model (CCSM4) we have developed new time series of transient Community Land Model (CLM4) Plant Functional Type (PFT) parameters and wood harvest parameters. The new parameters capture the dynamics of the Coupled Model Inter-comparison Project phase 5 (CMIP5) land cover change and wood harvest trajectories for the historical period from 1850 to 2005, and for the four Representative Concentration Pathways (RCP) periods from 2006 to 2100. Analysis of the biogeochemical impacts of land cover change in CCSM4 with the parameters found the model produced an historical cumulative land use flux of 148.4 PgC from 1850 to 2005, which was in good agreement with other global estimates of around 156 PgC for the same period. The biogeophysical impacts of only applying the transient land cover change parameters in CCSM4 were cooling of the near surface atmospheric over land by -0.1OC, through increased surface albedo and reduced shortwave radiation absorption. When combined with other transient climate forcings, the higher albedo from land cover change was overwhelmed at global scales by decreases in snow albedo from black carbon deposition and from high latitude warming. At regional scales however the land cover change forcing persisted resulting in reduced warming, with the biggest impacts in eastern North America. The future CCSM4 RCP simulations showed that the CLM4 transient PFT and wood harvest parameters could be used to represent a wide range of human land cover change and land use scenarios. Furthermore, these simulations ranged from the RCP 4.5 reforestation scenario that was able to draw down 82.6 PgC from the atmosphere, to the RCP 8.5 wide scale deforestation scenario that released 171.6 PgC to the atmosphere.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2013

Greenhouse gas policy influences climate via direct effects of land-use change

Proposed climate mitigation measures do not account for direct biophysical climate impacts of land-use change (LUC), nor do the stabilization targets modeled for the 5th Climate Model Intercomparison Project (CMIP5) Representative Concentration Pathways (RCPs). To examine the significance of such effects on global and regional patterns of climate change, a baseline and alternative scenario of future anthropogenic activity are simulated within the Integrated Earth System Model, which couples the Global Change Assessment Model, Global Land-use Model, and Community Earth System Model. The alternative scenario has high biofuel utilization and approximately 50% less global forest cover compared to the baseline, standard RCP4.5 scenario. Both scenarios stabilize radiative forcing from atmospheric constituents at 4.5 W/m2 by 2100. Thus, differences between their climate predictions quantify the biophysical effects of LUC. Offline radiative transfer and land model simulations are also utilized to identify forcing and feedback mechanisms driving the coupled response. Boreal deforestation is found to strongly influence climate due to increased albedo coupled with a regional-scale water vapor feedback. Globally, the alternative scenario yields a 21st century warming trend that is 0.5 °C cooler than baseline, driven by a 1 W/m2 mean decrease in radiative forcing that is distributed unevenly around the globe. Some regions are cooler in the alternative scenario than in 2005. These results demonstrate that neither climate change nor actual radiative forcing are uniquely related to atmospheric forcing targets such as those found in the RCP’s, but rather depend on particulars of the socioeconomic pathways followed to meet each target.

Jones, Andrew D.↗
DOE OSTI2023

Biophysical Impact of Land-Use and Land-Cover Change on Subgrid Temperature in CMIP6 Models

In this study, we investigate the air temperature response to land-use and land-cover change (LULCC; cropland expansion and deforestation) using subgrid land model output generated by a set of CMIP6 model simulations. Our study is motivated by the fact that ongoing land-use activities are occurring at local scales, typically significantly smaller than the resolvable scale of a grid cell in Earth system models. It aims to explore the potential for a multimodel approach to better characterize LULCC local climatic effects. On an annual scale, the CMIP6 models are in general agreement that croplands are warmer than primary and secondary land (psl; mainly forests, grasslands, and bare ground) in the tropics and cooler in the mid–high latitudes, except for one model. The transition from warming to cooling occurs at approximately 40°N. Although the surface heating potential, which combines albedo and latent heat flux effects, can explain reasonably well the zonal mean latitudinal subgrid temperature variations between crop and psl tiles in the historical simulations, it does not provide a good prediction on subgrid temperature for other land tile configurations (crop vs forest; grass vs forest) under Shared Socioeconomic Pathway 5–8.5 (SSP5–8.5) forcing scenarios. A subset of simulations with the CESM2 model reveals that latitudinal subgrid temperature variation is positively related to variation in net surface shortwave radiation and negatively related to variation in the surface energy redistribution factor, with a dominant role from the latter south of 30°N. We suggest that this emergent relationship can be used to benchmark the performance of land surface parameterizations and for prediction of local temperature response to LULCC.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Effects of forest degradation classification on the uncertainty of aboveground carbon estimates in the Amazon

Tropical forests are critical for the global carbon budget, yet they have been threatened by deforestation and forest degradation by fire, selective logging, and fragmentation. Existing uncertainties on land cover classification and in biomass estimates hinder accurate attribution of carbon emissions to specific forest classes. In this study, we used textural metrics derived from PlanetScope images to implement a probabilistic classification framework to identify intact, logged and burned forests in three Amazonian sites. We also estimated biomass for these forest classes using airborne lidar and compared biomass uncertainties using the lidar-derived estimates only to biomass uncertainties considering the forest degradation classification as well. Our classification approach reached overall accuracy of 0.86, with accuracy at individual sites varying from 0.69 to 0.93. Logged forests showed variable biomass changes, while burned forests showed an average carbon loss of 35%. We found that including uncertainty in forest degradation classification significantly increased uncertainty and decreased estimates of mean carbon density in two of the three test sites. Our findings indicate that the attribution of biomass changes to forest degradation classes needs to account for the uncertainty in forest degradation classification. By combining very high-resolution images with lidar data, we could attribute carbon stock changes to specific pathways of forest degradation. This approach also allows quantifying uncertainties of carbon emissions associated with forest degradation through logging and fire. Both the attribution and uncertainty quantification provide critical information for national greenhouse gas inventories.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Data for Evaluation of 1,2-Diacyl-3-Acetyl Triacylglycerol Production in Yarrowia lipolytica

Plants produce many high-value oleochemical molecules. While oil-crop agriculture is performed at industrial scales, suitable land is not available to meet global oleochemical demand. Worse, establishing new oil-crop farms often comes with the environmental cost of tropical deforestation. The field of metabolic engineering offers tools to transplant oleochemical metabolism into tractable hosts while simultaneously providing access to molecules produced by non-agricultural plants. Here, we evaluate strategies for rewiring metabolism in the oleaginous yeast Yarrowia lipolytica to synthesize a foreign lipid, 3-acetyl-1,2-diacyl-sn-glycerol (acTAG). Oils made up of acTAG have a reduced viscosity and melting point relative to traditional triacylglycerol oils making them attractive as low-grade diesels, lubricants, and emulsifiers. This manuscript describes a metabolic engineering study that established acTAG production at g/L scale, exploration of the impact of lipid bodies on acTAG titer, and a techno-economic analysis that establishes the performance benchmarks required for microbial acTAG production to be economically feasible.

Biomass Analytics↗
DOE OSTI2016

Synergistic Ecoclimate Teleconnections from Forest Loss in Different Regions Structure Global Ecological Responses

Forest loss in hotspots around the world impacts not only local climate where loss occurs, but also influences climate and vegetation in remote parts of the globe through ecoclimate teleconnections. The magnitude and mechanism of remote impacts likely depends on the location and distribution of forest loss hotspots, but the nature of these dependencies has not been investigated. We use global climate model simulations to estimate the distribution of ecologically-relevant climate changes resulting from forest loss in two hotspot regions: western North America (wNA), which is experiencing accelerated dieoff, and the Amazon basin, which is subject to high rates of deforestation. The remote climatic and ecological net effects of simultaneous forest loss in both regions differed from the combined effects of loss from the two regions simulated separately, as evident in three impacted areas. Eastern South American Gross Primary Productivity (GPP) increased due to changes in seasonal rainfall associated with Amazon forest loss and changes in temperature related to wNA forest loss. Eurasia's GPP declined with wNA forest loss due to cooling temperatures increasing soil ice volume. Southeastern North American productivity increased with simultaneous forest loss, but declined with only wNA forest loss due to changes in VPD. In conclusion, our results illustrate the need for a new generation of local-to-global scale analyses to identify potential ecoclimate teleconnections, their underlying mechanisms, and most importantly, their synergistic interactions, to predict the responses to increasing forest loss under future land use change and climate change.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2012

North America carbon dioxide sources and sinks: magnitude, attribution, and uncertainty

North America is both a source and sink of atmospheric CO2. Sources, predominately fossil-fuel combustion in the United States along with contributions from deforestation in Mexico, add CO2 to the atmosphere. Most North America ecosystems, particularly regrowing forests in the United States, are sinks for atmospheric CO2. CO2 is removed from the atmosphere in photosynthesis, converted into biomass and stored as carbon in vegetation, soil and wood products. Fossil-fuel emissions dominate the North American source-sink balance. North America is a net source of atmospheric CO2 with ecosystem sinks balancing approximately 35% of fossil-fuel CO2 emissions from North America.

King, Anthony W↗
DOE OSTI2013

Improved Biomass Cooking Stoves and Improved Stove Emission Equipment

In developing countries, there is an urgent need for access to safe, efficient, and more affordable cooking technologies. Nearly 2.5 billion people currently use an open fire or traditional cookstove to prepare their meals, and recent models predict that use of biomass for cooking will continue to be the dominant energy use in rural, resource-poor households through 2030. For these families, cooking poses serious risks to health, safety, and income. An alarming 4 million people, primarily women and children, die prematurely each year from indoor and outdoor exposure to the harmful emissions released by solid fuel combustion. Use of traditional stoves can also have a significant impact on deforestation and climate change. This dire situation creates a critical need for cookstoves that significantly and verifiably reduce fuel use and emissions in order to reach protective levels for human health and the environment. Additionally, advances in the scientific equipment needed to measure and monitor stove fuel use and emissions have not kept pace with the significant need within the industry. While several testing centers in the developed world may have hundred thousand-dollar emissions testing systems, organizations in the field have had little more than a thermometer, a scale, and subjective observations to quantify the performance of stove designs. There is an urgent need for easy-to-use, inexpensive, accurate, and robust stove testing equipment for use by laboratory and field researchers around the world. ASAT and their research partner, Aprovecho Research Center (ARC), have over thirty years of experience addressing these two needs, improved cookstoves and emissions monitoring equipment, with expertise spanning the full spectrum of development from conceptual design to product manufacturing and dissemination. This includes: 1) research, design, and verification of clean biomass cookstove technology and emissions monitoring equipment; 2) mass production of quality-controlled stove and emissions equipment at levels scalable to meet global demand; and 3) global distribution through a variety of channels and partners. ARC has been instrumental in designing and improving more than 100 stove designs over the past thirty years. In the last four years, ASAT and ARC have played a key role in the production and sales of over 200,000 improved stoves in the developed and developing world. The ARC-designed emissions equipment is currently used by researchers in laboratories and field studies on five continents. During Phase I of the DOE STTR grant, ASAT and ARC worked together to apply their wealth of product development experience towards creating the next generation of improved cookstoves and emissions monitoring equipment. Highlights of Phase I for the biomass cookstove project include 1) the development of several new stove technologies that reached the DOE 50/90 benchmark; 2) fabrication of new stove prototypes by ASAT’s manufacturing partner, Shengzhou Stove Manufacturing (SSM); 3) field testing of prototype stoves with consumers in Puerto Rico and the US; and 4) the selection of three stove prototypes for further development and commercialization during Phase II. Highlights of Phase I for the emissions monitoring equipment project include: 1) creation of a new emissions monitoring equipment product, the Laboratory Emissions Monitoring System (LEMS 2) the addition of gravimetric PM measurements to the stove testing systems to meet International Standards Organization criteria; 3) the addition of a CO{sub 2} sensor and wireless 3G capability to the IAP Meter; and 4) and the improvement of sensors and signal quality on all systems. Twelve Regional Testing and Knowledge Centers purchased this equipment during the Phase I project period.

09 BIOMASS FUELS↗
DOE OSTI2012

Research Priorities for Tropical Ecosystems Under Climate Change Workshop Report, June 4-5, 2012

The Tropics, with approximately 40% of Earth’s land surface area, critically regulate many Earth system processes. Containing great stores of biomass, tropical ecosystems represent the largest reservoir of terrestrial carbon. The Tropics also cycle more carbon dioxide (CO 2 ) and water than any other biome and play important roles in determining Earth’s energy balance, which drives global systems of temperature and precipitation. Overall, wet tropical forests contain about 25% of the carbon in the terrestrial biosphere and account for 34% of Earth’s gross primary production. This vast area, which includes the world’s driest deserts and wettest forests, also harbors a large fraction of Earth’s biodiversity. Despite the negative impact of widespread deforestation, tropical ecosystems continue to benefit Earth’s atmosphere and climate system by mitigating climatic warming through carbon sequestration and evaporative cooling. Of great concern, however, is the vulnerability of tropical ecosystems to rapid shifts resulting from a changing climate. Significant potential thus exists for important feedbacks with CO 2 , water, and energy exchange from tropical ecosystems due to climatic change. Tropical forests are thought to be especially vulnerable to climate change compared to other regions of Earth. Unlike in temperate forests where temperatures fluctuate widely during the course of a year, temperatures in tropical forests (at a given elevation) vary little, with trees adapted to thrive in a relatively narrow thermal range. Hence, the relative impact of climatic warming likely will be greater in the Tropics because predicted changes in temperature are large compared to normal interannual variation. Moreover, increasing atmospheric temperatures may push tropical forests into climate regimes beyond those ever experienced by existing forests. Also, high biomass tropical forests require sufficient moisture to maintain a closed canopy, and changing precipitation patterns such as a shift toward more extreme events and extended droughts potentially could push forests beyond a moisture threshold, causing widespread tree mortality. Catastrophic loss of tropical forests may be a key feedback in tropical ecosystems because widespread tree mortality would release large quantities of CO2 back to the atmosphere, accelerating the influence of this primary driver of global warming. Major disruptions in hydrologic cycles affecting large tropical regions also would be expected.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Semi-automated Design of Artificial Intelligence Earth Systems Models

Prediction and observation of water cycles at various scales involve not only patterns isolated in space and time, but also modeling of complex spatio-temporal relationships across multiple domains. For instance, evapotranspiration (ET) and leaf area indexes (LAI) are two parameters that are needed to accurately model and understand land-atmosphere processes. Accurate assessments of ET and LAI are critical for understanding hydrological processes, deforestation, crop yield, and irrigation impacts. However, ET estimates for global simulations are available at very coarse spatial resolution. They are usually derived from satellite data based on broad plant functional types (PFTs), which fail to capture fine-scale variations because of changes in vegetation type across the globe. Similarly LAI estimates have typically been derived from vegetation indices at global scales or estimated locally using physical models, both of which suffer from a range of uncertainties that impact model sensitivity. The new era of AI model development for Earth systems (ES) calls for data-driven methods that provide domain scientists with uncertainty-aware estimations of biophysical parameters such as ET and LAI in a generalizable, interpretable, and discoverable manner.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Using machine learning to improve land use/cover characterization and projection for scenario-based global modeling

The characterization of the land surface in models is critical for robust estimation of the water cycle and associated extremes. Land use determines water demand, and land cover affects water availability. The interaction between water demand and availability is the key determinant of whether systems are resilient to variability in the overall water cycle. Furthermore, activities such as irrigation and deforestation or afforestation may influence regional to global precipitation patterns, depending on the extent of the activity. Thus this proposed work aims to address the following question: How does integrated land use/cover data and improved land use/cover projection, as informed by machine learning approaches, better resolve human-earth system resilience to water cycle variability and extremes?

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Interactions between land use, fires, and dust as drivers of global climate change (Final Technical Report)

This award to UC Irvine and Cornell University led to the publication of 18 papers, three of which are highly cited. According to ISI Web of Science, the body of work from this grant has been cited over 476 times by May 2025. Several additional publications remain in review. This grant contributed to several significant science advances, including an improved understanding of the influence of fire aerosols on global photosynthesis (Xu et al., 2021), dust-driven teleconnections between Africa and South America (Li et al., 2021), the role of fire aerosols in triggering phytoplankton blooms in the Arctic (Ardyna et al., 2022), and wildfire responses to heat waves (Li et al., in review). Several other studies are being written up for publication, and will acknowledge funding support. These efforts include an analysis in which the magnitude of tropical fire emissions from land use change is constrained by comparing E3SMv3 simulations with atmospheric observations. This work has revealed that carbon cycle model estimates of land use change may considerably overestimate the global tropical deforestation flux. The project also contributed to several technical advances, including a new process-based and scale-aware desert dust emission scheme for global climate models (Leung et al., 2023), an improved representation of dust and its influence on radiation in E3SM (Feng et al., 2022), an improved representation of the dust parameterization in the Community Earth System Model (Li et al., 2022), and an improved coupling of wildfires with atmospheric chemistry in E3SM v3.

58 GEOSCIENCES↗
DOE OSTI2023

Pathways to Carbon Neutrality 2050 in Malaysia and Kuala Lumpur

Malaysia has recently set an ambitious target of achieving carbon neutrality as early as 2050. To accomplish this, the country will need to strategically reduce its emissions across all sectors. In 2020, Malaysia emitted approximately 368 MtCO2e, with the largest sources of emissions including electricity (36% of total emissions), transportation (17%), and industry (15%)1. We find that the greatest reductions in emissions can therefore come from decarbonizing power generation and electrifying end-use sectors. Digitalization, smart technologies, and improved energy efficiency will significantly reduce economy-wide energy consumption. By leveraging efficient technologies, both Malaysia and Kuala Lumpur can address the challenges posed by rapid urbanization and climate change. Digitalization is a broad category that includes a variety of measures; for example, the wide adoption of high-efficiency appliances and lighting or improved building energy codes in the buildings sector. Similarly, technological improvements can advance industrial energy efficiency, and for transportation, smart technologies cover a shift from private to public transportation and the greater use of electric vehicles. While renewable energy (RE) will play a crucial role in decarbonization, achieving carbon neutrality in certain sectors will be difficult without emerging technologies like carbon capture and storage (CCS) and innovative fuel sources such as hydrogen. In order for Malaysia to rely on CCS as a mitigation option, early investment and incentives to the private sector will be critical. This holds for the use of hydrogen as well: investing in the necessary technology, infrastructure, and human capital will allow Malaysia to position itself as an innovator in the region and leverage these advanced technologies as a key part of its climate strategy. Another possible carbon removal option other than CCS would be a land-use sink; however, given that Malaysia is still developing and may deforest in the near-term, this report does not focus on the mitigation potential of land-use change. With its innovative and bold climate plans, Kuala Lumpur is primed to be a leader in regional climate change efforts. Kuala Lumpur is also engaged in several international collaborations to ensure sustainable city development such as the C40 network and the ASEAN Smart Cities Partnership. As such, the city will play a critical role in contributing to Malaysia’s overall climate goals and as a policy trendsetter through ambitious, scalable plans. One key factor in these emissions reductions is that Kuala Lumpur has full control over its building guidelines, allowing for ambitious policies resulting in significant emissions reductions. However, in other sectors, Kuala Lumpur has less direct control over regulations; for example, power generation and integration of RE are largely in the hands of the Malaysian government. With limited and primarily light industry, Kuala Lumpur’s contributions to emissions reductions here are curbed. And, while Kuala Lumpur has control over local transportation policies like increasing access to and quality of public transportation, broad shifts in transportation will stem from national-level policies. As such, multi-level governance is an integral component of Malaysia’s climate strategy and coordination between local and national governments will be essential in reducing emissions and achieving other climate goals. This report addresses these and other key challenges and opportunities Malaysia faces on the road to carbon neutrality.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2026

VIC-Global Parameter Dataset Sensitivity with the Variable Infiltration Capacity Model: Evaluating the importance of dynamic land surface parameters when using the VIC-Global parameter dataset

Accurate prediction of runoff is essential to water resources management, flood risk assessment, and ecosystem protection. However, many hydrological models still have relatively substantial limitations when representing the influence of land use and land cover (LULC) on runoff generation and routing. Changes in LULC, such as deforestation, urban expansion, agricultural intensification, and wetland loss, have been shown to alter the water balance at the land surface through fundamental hydrologic processes (e.g., interception, infiltration, evapotranspiration, and soil storage). However, it remains an open question what the exact magnitude and timing of these impacts are for the spatial and temporal scales commonly used in engineering applications. In this analysis we focus on one aspect of recent LULC change for assessing human impacts, which is urbanization. Specifically we seek to determine the impacts of urbanization on the magnitude and timing of surface runoff and baseflow in HUC-12 basins in Clark County, Nevada which has experienced rapid urbanization. We use the Variable Infiltration Capacity (VIC) hydrology model with a widely used off-the-shelf dataset of land surface parameters, VIC-Global, both of which have been commonly used in the past for water and energy balance modeling for large scale hydrologic studies. We examine two scenarios where the first scenario removes all urbanized land cover and parameterizes those areas of the basins as barren or open shrubland. The second scenario tests the opposite case where all areas of the basins are classified as urban regardless of their present classification. The results from the VIC model show there is a low sensitivity for daily surface runoff between scenarios. The daily baseflow values indicate similar low sensitivity to the classification change during specific periods, but then have substantial differences during other period when large precipitation events are occurring. This is likely due to the assumed parameter values for the urban land cover classification made by the VIC-Global dataset. Using a static land cover parameterization is reasonable for large domain hydrology models that are being used for near-term planning horizons (<30 years). However, longer planning horizons where feedbacks between the atmosphere and land surface are important, especially in transient climate situations, considerations for how to update land surface parameters should be incorporated.

42 ENGINEERING↗