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Publications (217)
Societal risks from flooding are evident at a range of spatial scales and climate change will exacerbate these risks in the future. Assessing flood risks across broad geographical regions is a challenge, and often done using streamflow time-series records or hydrologic models. In this study, we used a national-scale hydrological model to identify,...
The Upper Mississippi Information System (UMIS) is a cyberinfrastructure framework designed to support large-scale real-time water-quality data integration, analysis, and visualization for the Upper Mississippi River Basin (UMRB). UMIS is intended to directly address three of the Grand Challenges for Engineering including (1) understanding access t...
Agricultural nutrient runoff has been a major contributor to hypoxia in many downstream coastal ecosystems. Although programs have been designed to reduce nutrient loading in individual coastal waters, cross watershed interdependencies of nutrient runoff have not been quantified due to a lack of suitable modeling tools. Cross-watershed pollution le...
Tile drainage is a common practice to increase agricultural productivity in regions with high water tables. Ecohydrological models, such as the Soil and Water Assessment Tool (SWAT), are key tools used to simulate these subsurface drainage structures and their corresponding management effects on water balance. This study is an investigation of the...
The Upper Mississippi Information System (UMIS) is a cyberinfrastructure framework designed to support large-scale real-time water quality data integration, analysis, and visualization for the Upper Mississippi River Basin (UMRB). UMIS is intended to directly address three of the Grand Challenges for Engineering including: 1) understanding access t...
Gassman, P., Y. Ji, and T.M. Brighenti. 2023. "Linking Water Quality Improvement with Economic Benefits to the Iowa Population." Agricultural Policy Review
Fall 2023. Center for Agricultural and Rural Development, Iowa State University. Available at: https://agpolicyreview.card.iastate.edu/fall-2023/linking-water-quality-improvement-economic-benef...
CONTEXT
Despite a steady increase in staple crop yields over the past ten years, current agricultural production must escalate even more to keep pace with the expected world population growth, which in turn will require improved agricultural methods that are adapted to many environmental pressures. Comprehensive models that can simulate crop produc...
While the ecological benefits of no-till are largely indisputable, the economic impacts are less certain, and the latter may be partly to blame for lower-than-expected adoption of no-till. In this study, we contribute to a better understanding of the ecosystem and farm-level economic impacts of no-till, with Buchanan County in the northeastern regi...
Nonpoint source pollution from cultivated croplands has often been associated with downstream water quality impairment in various watersheds. Given projected changes in global climate patterns, this study contributes to the existing literature by elucidating the impacts of climate projections on edge-of-field surface runoff and sediment and nutrien...
Climate Change and Soil Viability
In this study, we evaluate the implications of a bias correction method on a combination of Global/Regional Climate Models (GCM and RCM) for simulating precipitation and, subsequently, streamflow, surface runoff, and water yield in the Soil and Water Assessment Tool (SWAT). The study area is the Des Moines River Basin, U.S.A. The climate projection...
Using a survey of 430 farmer respondents in the Boone and North Raccoon River watersheds in Iowa, we examine the impacts of three program innovations—reverse auctions, spatially targeted payments, and higher offered payments—on agricultural conservation program cost effectiveness and participation by farmers. We combine farmer responses to a discre...
Projections of climate patterns through the end of the 21st century indicate varying impacts across the U.S. However, a common thread of these projections calls for increasing atmospheric temperatures in every region, some more pronounced than others. The significance of these projections for corn and soybean production cannot be overestimated. Thi...
Risks from flooding and poor water quality are evident at a range of spatial scales and climate change will exacerbate these risks in the future. Natural infrastructure (NI), consisting of structural or perennial vegetation, measures that provide multiple ecosystem benefits have the potential to reduce flood and water quality risks. In this study,...
Several factors, including science, markets, and policies influence decisions regarding agricultural systems (e.g., crop type and farming practices). This study indicates potential strengths and weaknesses of different crop production scenarios and how they affect agricultural sustainability. A shift in land use to increase table food production in...
Nitrogen (N) fertilizer use in agricultural production is a significant determinant of surface water quality. As climate changes, agricultural producers are likely to adapt at extensive and intensive margins in terms of land and per acre input use, including fertilizers. These changes can affect downstream water quality. We investigate the effect o...
Improving food systems to address food insecurity and minimize environmental impacts is still a challenge in the 21st century. Ecohydrological models are a key tool for accurate system representation and impact measurement. We used a multi-phase testing approach to represent baseline hydrologic conditions across three agricultural basins that drain...
The Soil and Water Assessment Tool (SWAT) is an ecohydrological watershed-scale model which was initially developed in the early 1990s to simulate the impacts of land use, management systems, and climate on hydrology and/or water quality. First adopted in the U.S., the use of the model then spread to Europe and then later to Asia and other regions....
The Iowa Urban FEWS project is focused on developing sustainable food production systems in the Des Moines–West Des Moines Metropolitan Statistical Area (DM-MSA). Multiple models are being integrated within the project to evaluate the impact of converting cropland, peri-urban and/or urban landscapes to fruit and vegetable production in DM-MSA trans...
An integrated hydro-economic agricultural land use model was developed with endogenous and spatially explicit crop planting, nitrogen (N) fertilizer use and irrigation in the Mississippi River Basin (MRB). We used the model to quantify the effects of energy and N fertilizer prices on N runoff to the Gulf of Mexico. Results show a modest effect of e...
Alternative climate products, such as gauge-based gridded data, ground-based weather radar, satellite precipitation and climate reanalysis products, are being increasingly applied for hydrological modelling. This review aims to summarize the studies that have evaluated alternative climate products within Soil and Water Assessment Tool (SWAT) applic...
Most people in the world live in urban areas, and their high population densities, heavy reliance on external sources of food, energy, and water, and disproportionately large waste production result in severe and cumulative negative environmental effects. Integrated study of urban areas requires a system-of-systems analytical framework that include...
The quality of input data and the process of watershed delineation can affect the accuracy of runoff predictions in watershed modeling. The Upper Mississippi River Basin was selected to evaluate the effects of subbasin and/or hydrologic response unit (HRU) delineations and the density of climate dataset on the simulated streamflow and water balance...
Most semi-distributed and distributed hydrological models can potentially be applied for comprehensive catchment simulations, but these models may require modifications to capture dominant hydrological processes. The Soil and Water Assessment Tool (SWAT) ecohydrological model, an open source program, provides flexibility for modification to capture...
There is a critical need for a national agroecosystem model for conservation policy and environmental planning, driven by issues including harmful algal blooms, water scarcity, flooding, and other weather‐related extremes. In this study, we illustrate the feasibility of a national agroecosystem model that will downscale processes to individual fiel...
Hydrologic modeling was used to estimate potential changes in nutrients, suspended sediment, and streamflow in various biomass production scenarios with conservation practices under different landscape designs. Two major corn and soybean croplands were selected for study: the South Fork of the Iowa River watershed and the headwater of the Raccoon R...
Hydro-climatic extremes, such as droughts and floods, have most likely increased due to climatic change and could lead to severe impacts on socio-economic, structural and environmental sectors. With nearly 4,000 publications, the Soil and Water Assessment Tool (SWAT) is clearly one of the most extensively used ecohydrological models worldwide. The...
This study reports the application of Soil and Water Assessment Tool (SWAT) within the Hydrologic and Water Quality System (HAWQS) on-line platform, for the Upper Mississippi River Basin (UMRB). The UMRB is an important ecosystem located in the north central U.S. that is experiencing a range of ecological stresses. Specifically, testing of SWAT was...
Although multiple pollution sources could discharge significant nutrient loads within a river basin, few studies have attempted to analyze the spatiotemporal distribution patterns of nutrient pollution source compositions across a basin. Using the Xiaohong River Basin as a case example, this study aims to establish a feasible framework for characte...
Harvesting corn stover removes N from the fields, but its effect on subsurface drainage and other N losses is uncertain. We used the Root Zone Water Quality Model (RZWQM) to examine N losses with 0 (NRR) or 50% (RR) corn residue removal within a corn and soybean rotation over a 10-yr period. In general, all simulations used the same pre-plant or po...
The Soil and Water Assessment Tool (SWAT) model is recognized as one of the top hydrological models applied for addressing hydrologic and environmental issues. This is the first review on the SWAT model studies in Southeast Asia, with an emphasis on its applications, current challenges and future research directions. A total of 126 articles were id...
This study is a part of the Conservation Effects Assessment Project (CEAP) aimed to quantify the environmental and economic benefits of conservation practices implemented in the cultivated cropland throughout the United States. The Soil and Water Assessment Tool (SWAT) model under the Hydrologic United Modeling of the United States (HUMUS) framewor...
The Des Moines Lobe (DML) of north-central Iowa has been artificially drained by subsurface drains and surface ditches to provide some of the most productive agricultural land in the world. Herein we report on the use of end-member mixing analysis (EMMA) models and the numerical model Soil and Water Assessment Tool (SWAT) to quantify the contributi...
The Clarivate Analytics Journal Citation Reports (JCR) and Web of Science (WoS) platforms are arguably the most
influential journal citation/metric databases worldwide. Journals must first be indexed in the WoS Core Collection (CC)
before being indexed in the JCR. The JCR and WoS platform are separate Clarivate Analytics products, but the JCR is
in...
The Clarivate Analytics Journal Citation Reports (JCR) and Web of Science (WoS) platforms are arguably the most influential journal citation/metric databases worldwide. Journals must first be indexed in the WoS Core Collection (CC) before being indexed in the JCR. The JCR and WoS platform are separate Clarivate Analytics products, but the JCR is in...
Limited field studies have been performed to evaluate the impacts of conservation agriculture (CA) on crop yields and soil organic carbon sequestration in tropical conditions. In this study, we used the Environmental Policy Integrated Climate (EPIC) model to evaluate the impact of CA and conservation tillage (CT) on crop yields in tropical conditio...
Will soil organic carbon (SOC) and yields increase for conservation management systems
in tropical zones in response to the next 100 years? To answer the question, the Environmental Policy
Integrated Climate (EPIC) model was used to study the effects of climate change, cropping systems,
conservation agriculture (CA) and conservation tillage managem...
Free download full paper until Nov 17, 2017 at https://authors.elsevier.com/a/1VoI1cA-ISCCX
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Soil organic carbon (SOC) sequestration was evaluated for several long-term rain-fed cropping systems for conservation agriculture (CA) and conservation tillage (CT) in Cambodia using the Environmental Polic...
About 50% of U.S. water pollution problems are caused by non-point source (NPS) pollution, primarily sediment and nutrients from agricultural areas, despite the widespread implementation of agricultural Best Management Practices (BMPs). However, the effectiveness of implementation strategies and type of BMPs at watershed scale are still not well un...
The Upper Mississippi River Basin and Ohio-Tennessee River Basin comprise the majority of the United States Corn Belt region, resulting in degraded Mississippi River and Gulf of Mexico water quality. To address the water quality implications of increased biofuel production, biofuel scenarios were tested with a Soil and Water Assessment Tool (SWAT)...
Land use change can significantly affect the provision of ecosystem services and the effects could be exacerbated by projected climate change. We quantify ecosystem services of bioenergy-based land use change and estimate the potential changes of ecosystem services due to climate change projections. We considered 17 bioenergy-based scenarios with M...
The implications and value of Soil and Water Assessment Tool (SWAT)-based simulations of the productive potential and water quality impacts associated with switchgrass, Miscanthus, or corn stover removal biofuel cropping systems are discussed. Specifically, the three accompanying studies describe the water quality implications of adopting the three...
Several biofuel cropping scenarios were evaluated with an improved version of Soil and Water Assessment Tool (SWAT) as part of the CenUSA Bioenergy consortium for the Boone River Watershed (BRW), which drains about 2,370 km² in north central Iowa. The adoption of corn stover removal, switchgrass, and/or Miscanthus biofuel cropping systems was simul...
The ability to accurately simulate flow and nutrient removal in treatment wetlands within an agricultural, watershed-scale model is needed to develop effective plans for meeting nutrient reduction goals associated with protection of drinking water supplies and reduction of the Gulf of Mexico hypoxic zone. The objectives of this study were to incorp...
Tile drainage significantly alters flow and nutrient pathways and reliable simulation at this scale is needed for effective planning of nutrient reduction strategies. The Soil and Water Assessment Tool (SWAT) has been widely utilized for prediction of flow and nutrient loads, but few applications have evaluated the model's ability to simulate pathw...
The Intergovernmental Panel on Climate Change (IPCC) has predicted that changes in climate patterns (higher temperatures, changes in extreme precipitation events, and higher level of humidity) will adversely impact water quality. Given the implications of climate change on water and soil quality, it is important for watershed managers, stakeholders...
It is critical, given an increasingly variable climate and occurrence of extreme weather events, to develop and test management approaches that increase the adaptive capacity of corn-based agriculture, and equip farmers and land managers to be functionally resilient.The findings, implications and recommendations in this report represent research co...
Gridded climate products (GCPs) provide a potential source for representing weather
in remote, poor quality or short-term observation regions. The accuracy of three long-term GCPs
(Asian Precipitation—Highly-Resolved Observational Data Integration towards Evaluation of Water
Resources: APHRODITE, Precipitation Estimation from Remotely Sensed Inform...
At present, Para rubber is an economical crop which provides a high priced product and is in demand by global markets. Consequently, the government of Thailand is promoting the expansion of Para rubber plantations throughout the country. Traditionally, Para rubber was planted and grown only in the southern areas of the country. However, due to the...
Corn is the major cereal crop of the United States, with two-thirds of national corn and soybean acreage concentrated in the upper Midwest. Farmers in the region have highly specialized knowledge and experience with these crops and considerable capital and infrastructure investments. It is critical, given an increasingly variable climate and occurr...
Modeling impacts of agricultural scenarios and climate change on surface
water quantity and quality provides useful information for planning effective
water, environmental and land use policies. Despite the significant impacts
of agriculture on water quantity and quality, limited literature exists that
describes the combined impacts of agricultural...
We assess empirically how agricultural lands should be used to produce the highest valued outputs, which include food, energy, and environmental goods and services. We explore efficiency tradeoffs associated with allocating land between food and bioenergy and use a set of market prices and nonmarket environmental values to value the outputs produce...
Applications of the Soil and Water Assessment Tool (SWAT) model typically involve delineation of a watershed into subwatersheds/subbasins that are then further subdivided into hydrologic response units (HRUs) which are homogeneous areas of aggregated soil, landuse, and slope and are the smallest modeling units used within the model. In a given stan...
Modeling impacts of agricultural scenarios and climate change on surface water quantity and quality provides useful information for planning effective water, environmental, and land use policies. Despite the significant impacts of agriculture on water quantity and quality, limited literature exists that describes the combined impacts of agricultura...
Plant water availability is a key factor that determines maize yield response to excess heat. Lack of available data has limited researchers' ability to estimate this relationship at regional and global scales. Using a new soil moisture data set developed by running a crop growth simulator over historical data we demonstrate how current estimates o...
The Soil and Water Assessment Tool (SWAT) ecohydrological model was used to assess a suite of adaptive nutrient management, alternative cropping system and combination scenarios in support of a Master Plan that was developed to help guide policy makers, land owners and other stakeholders in improving water quality for the 9,400 km2 Raccoon River wa...
The Soil and Water Assessment Tool (SWAT) model was used to assess the impacts of different land use scenarios on hydrological processes in the Fuhe watershed in Poyang Lake Basin, East China. A total of 12 model parameters were calibrated with observed monthly runoff data for 1982-1988 and validated for 1991-1998 for baseline conditions. The basel...
The geographical extent of Brazil exceeds 8.5 million km 2 and encompasses a complex mix of biomes and other environmental conditions. Multipe decision support tools are needed to help support management of these diverse Brazilian natural resources including ecohydrological models. The use of the Soil and Water Assessment Tool (SWAT) ecohydrologica...
Nonpoint source pollution from agriculture is the main source of nitrogen and phosphorus in the stream systems of the Corn Belt region in the Midwestern US. The eastern part of this region is comprised of the Ohio-Tennessee River Basin (OTRB), which is considered a key contributing area for water pollution and the Northern Gulf of Mexico hypoxic zo...
The Soil and Water Assessment Tool (SWAT) ecohydrological model is used worldwide to evaluate hydrological and water quality concerns across a plethora of watershed scales and environmental conditions. The ten studies featured in this special issue confirm the global utility of SWAT, which include applications of the model in Brazil, China, Ethiopi...
We assess empirically how agricultural lands should be used to produce the highest valued outputs, which include food, energy, and environmental goods and services. We explore efficiency tradeoffs associated with allocating land between food and bioenergy and use a set of market prices and nonmarket environmental values to value the outputs produce...
Significance
Hypoxic (low-oxygen) zones threaten an increasing number of marine ecosystems. Hypoxia in the Gulf of Mexico is the second largest in the world. The United States has a policy goal of reducing the average zone to 5,000 km ² . Reductions in nutrients from cropland in the Mississippi-Atchafalaya River Basin are needed to achieve this goa...