The Soil and Water Assessment Tool:Historical Development, Applications, and Future Research Directions, 2007

The Soil and Water Assessment Tool (SWAT) model is a continuation of nearly 30 years of modeling efforts conducted by the U.S. Department of Agriculture (USDA), Agricultural Research Service. SWAT has gained international acceptance as a robust interdisciplinary watershed modeling tool, as evidenced by international SWAT conferences, hundreds of SWAT-related papers presented at numerous scientific meetings, and dozens of articles published in peer-reviewed journals. The model has also been adopted as part of the U.S. Environmental Protection Agency’s BASINS (Better Assessment Science Integrating Point & Nonpoint Sources) software package and is being used by many U.S. federal and state agencies, including the USDA within the Conservation Effects Assessment Project. At present, over 250 peer-reviewed, published articles have been identified that report SWAT applications, reviews of SWAT components, or other research that includes SWAT. Many of these peer-reviewed articles are summarized here according to relevant application categories such as streamflow calibration and related hydrologic analyses, climate change impacts on hydrology, pollutant load assessments, comparisons with other models, and sensitivity analyses and calibration techniques. Strengths and weaknesses of the model are presented, and recommended research needs for SWAT are provided.

Safety Assessment Tool for Construction Zone Work Phasing Plans, 2016

The Highway Safety Manual (HSM) is the compilation of national safety research that provides quantitative methods for analyzing highway safety. The HSM presents crash modification functions related to freeway work zone characteristics such as work zone duration and length. These crash modification functions were based on freeway work zones with high traffic volumes in California. When the HSM-referenced model was calibrated for Missouri, the value was 3.78, which is not ideal since it is significantly larger than 1. Therefore, new models were developed in this study using Missouri data to capture geographical, driver behavior, and other factors in the Midwest. Also, new models for expressway and rural two-lane work zones that barely were studied in the literature were developed. A large sample of 20,837 freeway, 8,993 expressway, and 64,476 rural two-lane work zones in Missouri was analyzed to derive 15 work zone crash prediction models. The most appropriate samples of 1,546 freeway, 1,189 expressway, and 6,095 rural two-lane work zones longer than 0.1 mile and with a duration of greater than 10 days were used to make eight, four, and three models, respectively. A challenging question for practitioners is always how to use crash prediction models to make the best estimation of work zone crash count. To solve this problem, a user-friendly software tool was developed in a spreadsheet format to predict work zone crashes based on work zone characteristics. This software selects the best model, estimates the work zone crashes by severity, and converts them to monetary values using standard crash estimates. This study also included a survey of departments of transportation (DOTs), Federal Highway Administration (FHWA) representatives, and contractors to assess the current state of the practice regarding work zone safety. The survey results indicate that many agencies look at work zone safety informally using engineering judgment. Respondents indicated that they would like a tool that could help them to balance work zone safety across projects by looking at crashes and user costs.

The Iowa Sex Offender Registry and Recidivism, 2000

The Iowa Division of Criminal and Juvenile Justice Planning (CJJP) received funding through the Bureau of Justice Statistics’ (BJS) State Justice Statistics (SJS) Program for the purpose of collection and analysis of data related to implementation of the Iowa Sex Offender Registry. The research had two specific goals: · To enhance understanding of the State’s Sex Offender Registry through collection and analysis of data on sex offenders before and after the Registry’s implementation. · To develop and validate a unique Iowa Sex Offender Risk Assessment tool to assist in identifying those offenders who constitute the highest risk to re-offend. Few studies have addressed the impact of a Sex Offender Registry program on recidivism rates or other variables. It was the purpose of this first study to examine and compare two groups of individuals to determine what effect, if any, the requirement to register as a sex offender had on recidivism rates over a 3-4 year period.

Calibration and Validation of SWAT for the Upper Maquoketa River Watershed, June 2005

A validation study has been performed using the Soil and Water Assessment Tool (SWAT) model with data collected for the Upper Maquoketa River Watershed (UMRW), which drains over 16,000 ha in northeast Iowa. This validation assessment builds on a previous study with nested modeling for the UMRW that required both the Agricultural Policy EXtender (APEX) model and SWAT. In the nested modeling approach, edge-offield flows and pollutant load estimates were generated for manure application fields with APEX and were then subsequently routed to the watershed outlet in SWAT, along with flows and pollutant loadings estimated for the rest of the watershed routed to the watershed outlet. In the current study, the entire UMRW cropland area was simulated in SWAT, which required translating the APEX subareas into SWAT hydrologic response units (HRUs). Calibration and validation of the SWAT output was performed by comparing predicted flow and NO3-N loadings with corresponding in-stream measurements at the watershed outlet from 1999 to 2001. Annual stream flows measured at the watershed outlet were greatly under-predicted when precipitation data collected within the watershed during the 1999-2001 period were used to drive SWAT. Selection of alternative climate data resulted in greatly improved average annual stream predictions, and also relatively strong r2 values of 0.73 and 0.72 for the predicted average monthly flows and NO3-N loads, respectively. The impact of alternative precipitation data shows that as average annual precipitation increases 19%, the relative change in average annual streamflow is about 55%. In summary, the results of this study show that SWAT can replicate measured trends for this watershed and that climate inputs are very important for validating SWAT and other water quality models.

Adoption Subsidies and Environmental Impacts of Alternative Energy Crops, March 2007

We provide estimates of the costs associated with inducing substantial conversion of land from production of traditional crops to switchgrass. Higher traditional crop prices due to increased demand for corn from the ethanol industry has increased the relative advantage that row crops have over switchgrass. Results indicate that farmers will convert to switchgrass production only with significant conversion subsidies. To examine potential environmental consequences of conversion, we investigate three stylized landscape usage scenarios, one with an entire conversion of a watershed to switchgrass production, a second with the entire watershed planted to continuous corn under a 50% removal rate of the biomass, and a third scenario that places switchgrass on the most erodible land in the watershed and places continuous corn on the least erodible. For each of these illustrative scenarios, the watershed-scale Soil and Water Assessment Tool (SWAT) hydrological model (Arnold et al., 1998; Arnold and Forher, 2005) is used to evaluate the effect of these landscape uses on sediment and nutrient loadings in the Maquoketa Watershed in eastern Iowa.

Hydrologic Simulations of the Maquoketa River Watershed Using SWAT Working Paper 09-WP 49,June 2009

This paper describes the application of the Soil and Water Assessment Tool (SWAT) model to the Maquoketa River watershed, located in northeast Iowa. The inputs to the model were obtained from the Environmental Protection Agency’s geographic information/database system called Better Assessment Science Integrating Point and Nonpoint Sources (BASINS). Climatic data from six weather stations located in and around the watershed, and measured streamflow data from a U.S. Geological Survey gage station at the watershed outlet were used in the sensitivity analysis of SWAT model parameters as well as its calibration and validation for watershed hydrology and streamflow. A sensitivity analysis was performed using an influence coefficient method to evaluate surface runoff and base flow variations in response to changes in model input hydrologic parameters. The curve number, evaporation compensation factor, and soil available water capacity were found to be the most sensitive parameters among eight selected parameters when applying SWAT to the Maquoketa River watershed. Model calibration, facilitated by the sensitivity analysis, was performed for the period 1988 through 1993, and validation was performed for 1982 through 1987. The model performance was evaluated by well-established statistical methods and was found to explain at least 86% and 69% of the variability in the measured stream flow data for the calibration and validation periods, respectively. This initial hydrologic modeling analysis will facilitate future applications of SWAT to the Maquoketa River watershed for various watershed analysis, including water quality.

Disorders Among Iowa Inmates Higher Than Previously Assessed, Data Download, Iowa Department of Corrections, May 2008

A newly released study shows that the prevalence of mental health and substance abuse disorders among Iowa’s inmate population is even higher than earlier findings indicated. Using the MINI-Plus assessment tool, University of Iowa researchers screened a randomly selected group of 320 incoming nonviolent offenders at IMCC from 2005 to 2007. DOC’s Director of Mental Health Services, Dr. Bruce Sieleni, participated in the study.

LSI-R Scores: Change Matters, Data Download, Iowa Department of Corrections, April 2009

Past studies have shown the LSI-R risk assessment tool to be accurate in assessing the risk level of Iowa offenders. A more recent study, conducted by the University of Cincinnati, showed that a reduction in the LSI-R score over time results in a lower risk that an Iowa offender will reoffend.

LSI-R Scores: Change Matters - Part III, Data Download, Iowa Department of Corrections, June 2009

In this issue, we take a closer look at the individual risk factors measured by the LSI-R. There are several risk factors that the LSI-R assessment tool measures: Criminal History; Education/Employment; Financial; Family/Marital; Accommodations (Living Situation); Leisure/Recreation; Companions; Alcohol/Drug Problem; Emotional/Personal; and Attitudes/Orientation.

GED Completion Reduces Recidivism, Data Download, Iowa Department of Corrections, January 2013, Corrections, Department of

During 2011, the Iowa Department of Corrections analyzed the impact that attaining a GED has on recidivism – specifically, three-year return-to-prison rate. For those inmates who have a low or moderate risk level (as measured by the LSI-R assessment tool), attaining a GED does not tend to reduce the return-to-prison rate. However, attaining a GED does tend to reduce the rate for higher risk offenders.

Iowa's Renewable Energy and Infrastructure Impacts, TR-593, 2010

The federal government is aggressively promoting biofuels as an answer to global climate change and dependence on imported sources of energy. Iowa has quickly become a leader in the bioeconomy and wind energy production, but meeting the United States Department of Energy’s goal having 20% of U.S. transportation fuels come from biologically based sources by 2030 will require a dramatic increase in ethanol and biodiesel production and distribution. At the same time, much of Iowa’s rural transportation infrastructure is near or beyond its original design life. As Iowa’s rural roadway structures, pavements, and unpaved roadways become structurally deficient or functionally obsolete, public sector maintenance and rehabilitation costs rapidly increase. More importantly, costs to move all farm products will rapidly increase if infrastructure components are allowed to fail; longer hauls, slower turnaround times, and smaller loads result. When these results occur on a large scale, Iowa will start to lose its economic competitive edge in the rapidly developing bioeconomy. The primary objective of this study was to document the current physical and fiscal impacts of Iowa’s existing biofuels and wind power industries. A four-county cluster in north-central Iowa and a two-county cluster in southeast Iowa were identified through a local agency survey as having a large number of diverse facilities and were selected for the traffic and physical impact analysis. The research team investigated the large truck traffic patterns on Iowa’s secondary and local roads from 2002 to 2008 and associated those with the pavement condition and county maintenance expenditures. The impacts were quantified to the extent possible and visualized using geographic information system (GIS) tools. In addition, a traffic and fiscal assessment tool was developed to understand the impact of the development of the biofuels on Iowa’s secondary road system. Recommended changes in public policies relating to the local government and to the administration of those policies included standardizing the reporting and format of all county expenditures, conducting regular pavement evaluations on a county’s system, cooperating and communicating with cities (adjacent to a plant site), considering utilization of tax increment financing (TIF) districts as a short-term tool to produce revenues, and considering alternative ways to tax the industry.

Iowa State Profile Tool: An Assessment of Iowa's Long-Term Support System, March 31, 2009

The Iowa State Profile Tool is a comprehensive, high-level assessment of Iowa’s progress toward a balanced long-term care system – a system that relies less on institutional services and provides greater opportunities for the in-home and community-based services that most people prefer. This report includes long-term support for people of all ages and disability types and is based on a variety of state and federal data sources and interviews with public and private leaders in Iowa’s long-term care system.

A Transportation Safety Planning Tool for the City of Ames, August 2011

The historically-reactive approach to identifying safety problems and mitigating them involves selecting black spots or hot spots by ranking locations based on crash frequency and severity. The approach focuses mainly on the corridor level without taking the exposure rate (vehicle miles traveled) and socio-demographics information of the study area, which are very important in the transportation planning process, into consideration. A larger study analysis unit at the Transportation Analysis Zone (TAZ) level or the network planning level should be used to address the needs of development of the community in the future and incorporate safety into the long-range transportation planning process. In this study, existing planning tools (such as the PLANSAFE models presented in NCHRP Report 546) were evaluated for forecasting safety in small and medium-sized communities, particularly as related to changes in socio-demographics characteristics, traffic demand, road network, and countermeasures. The research also evaluated the applicability of the Empirical Bayes (EB) method to network-level analysis. In addition, application of the United States Road Assessment Program (usRAP) protocols at the local urban road network level was investigated. This research evaluated the applicability of these three methods for the City of Ames, Iowa. The outcome of this research is a systematic process and framework for considering road safety issues explicitly in the small and medium-sized community transportation planning process and for quantifying the safety impacts of new developments and policy programs. More specifically, quantitative safety may be incorporated into the planning process, through effective visualization and increased awareness of safety issues (usRAP), the identification of high-risk locations with potential for improvement, (usRAP maps and EB), countermeasures for high-risk locations (EB before and after study and PLANSAFE), and socio-economic and demographic induced changes at the planning-level (PLANSAFE).

Asset Management Program Enhancement Plan: Baseline Assessment Phases I and II, 2015

This project resulted in the development of a framework for making asset management decisions on low-volume bridges. The research focused on low-volume bridges located in the agricultural counties of Iowa because recent research has shown that these counties have the greatest percentage of structurally deficient bridges in the nation. Many of the same counties also have the highest crop yields in the state, creating a situation where detours caused by deficient bridges on farm-to-market roads increase the cost to transport the crops. Thus, the research proposed the use of social return on investment (SROI), a tool used by international institutions such as the World Bank, as an asset management metric to gauge to the socioeconomic impact of structurally deficient bridges on the state in an effort to provide quantified justification to fund improvements on low-volume assets such as these rural bridges. The study found that combining SROI with current asset management metrics like average daily traffic (ADT) made it possible to prioritize the bridges in such a way that the limited resources available are allocated in a manner that promotes a more equitable distribution and that directly benefits the user, in this case Iowa farmers. The result is a system that more closely aligns itself with the spirit of MAP-21, in that infrastructure investments are used to facilitate economic growth for Iowa’s agricultural economy.

Iowa Pavement Asset Management Decision-Making Framework & Pavement Treatment Selection Tool for Local Agencies, TR-651, 2015

Most local agencies in Iowa currently make their pavement treatment decisions based on their limited experience due primarily to lack of a systematic decision-making framework and a decision-aid tool. The lack of objective condition assessment data of agency pavements also contributes to this problem. This study developed a systematic pavement treatment selection framework for local agencies to assist them in selecting the most appropriate treatment and to help justify their maintenance and rehabilitation decisions. The framework is based on an extensive literature review of the various pavement treatment techniques in terms of their technical applicability and limitations, meaningful practices of neighboring states, and the results of a survey of local agencies. The treatment selection framework involves three different steps: pavement condition assessment, selection of technically feasible treatments using decision trees, and selection of the most appropriate treatment considering the return-on-investment (ROI) and other non-economic factors. An Excel-based spreadsheet tool that automates the treatment selection framework was also developed, along with a standalone user guide for the tool. The Pavement Treatment Selection Tool (PTST) for Local Agencies allows users to enter the severity and extent levels of existing distresses and then, recommends a set of technically feasible treatments. The tool also evaluates the ROI of each feasible treatment and, if necessary, it can also evaluate the non-economic value of each treatment option to help determine the most appropriate treatment for the pavement. It is expected that the framework and tool will help local agencies improve their pavement asset management practices significantly and make better economic and defensible decisions on pavement treatment selection.