SWAT Literature Database for Peer-Reviewed Journal Articles

SWAT Literature Database Readme

Updated March 10, 2023

Welcome to the SWAT Literature Database for Peer-Reviewed Journal Articles. I urge anyone reading this document to also read the announcement of the passing of Curtis Balmer (if you have not read it already), who designed and maintained the database before his untimely death in February, 2023. The database is currently functioning well, including edits and updates to existing data, and incorporation of new data. However, any updates that require modifications to the database structure are currently not possible. I am hoping that a new CARD website manager will be able to continue Curtis’ efforts in the not-too-distant future (among many other duties).

Meanwhile, it would be a huge help for me if database users would upload citation data for studies they have co-authored that have been published in 2022 and 2023 (please search on author name or a portion of the title to make sure that the data for a study of interest is not already in the database). You may find it useful to review guidance regarding updating citation data in the document accessible at guidance. Thanks greatly to those who have uploaded citation data in the past and for those who provide citation data uploads in the future. Please note too that uploaded citation data are reviewed first before being released to the database.

The database is an outgrowth of the “SWAT review article” that was published in Trans. ASABE in 2007 (Gassman et al., 2007), that can be accessed via a link at https://swat.tamu.edu/publications/ (Comprehensive review of SWAT model article). Gassman et al (2014) provides a more in-depth description of the types of studies included, database structure, search options and other details (data provided in that article were based on a total of 1,700 articles recorded in the database at that time).

Dr. Raghavan Srinivasan (Spatial Sciences Lab., Texas A&M University, College Station, TX) provided the initial inspiration for the database. Mr. Curtis Balmer, Center for Agricultural and Rural Development (CARD), Iowa State University (ISU), created and maintained the on-line database from 2009 through the middle of 2022. The majority of the citation data uploaded to the database has been performed by a number of ISU undergraduate students. Others have contributed uploaded citation data including several dozen database users.

The citation data included in the SWAT Literature Database is limited to “peer-reviewed journal articles,” with the recognition that the peer review process is much stronger and legitimate for some publishers/journals versus others. Users are encouraged to review discussions that explore controversies related to alleged illegitimate publishing practices (e.g., Beall, 2013; 2017; Butler, 2013; Haug, 2013; Jalalian and Mahboobi. 2014; Baker, 2016; Ward, 2016; Wicherts, 2016; Chawla, 2017; Devraj, 2017; Wikipedia, 2023; Silver, 2017; Swauger, 2017; Vyawahare, 2017). Screening of studies for the database is performed primarily on whether an article is indexed in the Directory of Open Access Journals (DOAJ, 2019), Scopus (Elsevier, 2023a; 2023b) and/or Web of Science Core Collection (Clarivate Analytics, 2023). Studies that are not indexed in one of those three databases are rejected unless one of the following sub-criteria are met: (1) published in a non-English language (I have no way of evaluating such journals), or (2) the study was published in a journal hosted by a university, professional society or some other reputable organization. This screening criteria has resulted in rejecting a few hundred articles including one that I actually co-authored (Gassman, 2015); that journal was originally indexed in Scopus but then later dropped, so the study no longer meets the screening criteria.

Beyond journal articles, peer-reviewed book chapters and other articles are not included, even though some of those may be of equal or superior quality to some comparable journal articles (we can’t keep track of everything). Also, thousands of SWAT-related articles or reports exist in the so-called “grey literature” (Wikipedia, 2023) which are also excluded from the database. These documents encompass government reports, conference articles, etc., including hundreds of SWAT-related studies in SWAT conference proceedings alone (SWAT, 2023).

The majority of studies included in the SWAT Literature Database have been written in English although some are written in other languages; e.g., Chinese, Korean, Portuguese, Spanish, Farsi, German. In addition, most of the studies included in the database describe some type of specific application of the standard SWAT model. However, other types of studies have been entered in the database including: (1) applications of modified SWAT models, (2) review studies focused either on SWAT or comparisons of SWAT with other models, (3) studies that describe data and/or component development directly relevant to SWAT users, and (4) a limited set of studies which describe key predecessor or related models (Gassman et al., 2014).

The main information included in the database is the journal citation, model, abstract, watershed description, language, and broad, primary and secondary application categories. The application categories were originally applied to the 200+ SWAT-related articles reviewed in Table 2 of Gassman et al. (2007) and are subjectively determined; i.e., many of the articles could be categorized three or more ways. These categories have since been expanded and in some cases reflect emerging trends, such as studies focused on curve number modifications crop growth and yields, and wetland or GHG emission applications, and are an attempt to help database users to refine their searches for articles of interest (and I continue to refine these). You may find these useful or you may find them annoying; either way you can also use the general search tool which allows you to search on any word or phrase of interest.

The “models” designation is used to identify whether SWAT, a modified SWAT model, a predecessor or related model, or some combination of those is discussed in a specific study. In general, other types of models that are used in various studies are not reported in the database, such as interfaces or comparisons of SWAT with other models reported in the literature, due to the sheer volume of model names that would be involved (there are hundreds of such models, due especially to various review studies). However, SWAT-Daycent and SWAT-MODFLOW are two exceptions, because of the need to explicitly identify the modified versions of SWAT represented by these modeling approaches. Also, note that “BMP review or conceptual approach” is a broad category that is only used for studies that conceptually discuss the use of SWAT for BMP assessments but don’t actually present any SWAT BMP-related results.

Other information included for some entries in the database are the calibration summary, validation summary, general comments and keywords. The calibration summary, validation summary and general comments were used in support of writing Gassman et al. (2007) and are blank for the majority of the database entries, although general comments are added occasionally when additional clarification is warranted for a study. There are also three SWAT literature lists that are provided that organized as follows: (1) alphabetically, (2) model category, or (3) year of publication. These lists update automatically every time a new set of citation data is indexed in the literature database.

Finally, please also submit any comments or suggestions you have regarding the database using the “Contact Database Staff” option. We will try to quickly correct any errors, typos, etc. that anyone finds. We will also consider other requests but can’t promise for sure that we will be able to act on them, especially since we currently do not have an expert programmer to work on the different database functions, etc.

Phil Gassman


Baker, M. 2016. Open-access index delists thousands of journals: Many publications did not reapply after leading directory tightened its quality criteria. Nature. DOI: 10.1038/nature.2016.19871.

Beall, J. 2013. Medical publishing triage – Chronicling predatory open access publishers. Annals of Medicine and Surgery. 2(2): 47–49. DOI: 10.1016/S2049-0801(13)70035-9.

Beall, J. 2017. What I learned from predatory publishers. Biochemia Medica 27(2): 273–278. Doi: 10.11613/BM.2017.029.

Butler, D. 2013. Investigating journals: The dark side of publishing (The explosion in open-access publishing has fuelled the rise of questionable operators). Nature. 495: 433–435. DOI: 10.1038/495433a.

Chawla, D.S. 2017. Mystery as controversial list of predatory publishers disappears. Science. DOI: 10.1126/science.aal0625.

Clarivate Analytics. 2023. Web of Science Databases.

Devraj, R. 2017. Commission moves to block use of predatory publishers. University World News. Issue No.: 444.

DOAJ. 2023. Directory of Open Access Journals.

Elsevier. 2023a. Scopus.

Elsevier. 2023b. Scopus: Sources.

Gassman, P.W., Balmer, C., Siemers, M., and Srinivasan, R. 2014. The SWAT Literature Database: Overview of database structure and key SWAT literature trends. Proceedings of the 2014 International SWAT Conference, July 28–1 August, Pernambuco, Brazil, Texas Water Resources Institute Technical Report – TR-472.

Gassman, P.W., M.K. Jha, C.F. Wolter and K.E. Schilling. 2015. Application of the Soil and Water Assessment Tool (SWAT) Model for the Raccoon River Watershed Master Plan. American Journal of Environmental Sciences. 11(4): 227-244. Doi: 10.3844/ajessp.2015.227.244.

Gassman, P.W., M.R. Reyes, C.H. Green, and J.G. Arnold. 2007. The Soil and Water Assessment Tool: historical development, applications, and future research directions. Transactions of the ASABE. 50(4): 1211-1250. Doi: 10.13031/2013.23634.

Haug, C. 2013. The downside of open-access publishing. The New England Journal of Medicine. 368: 791-793. DOI: 10.1056/NEJMp1214750.

Jalalian, M. and H. Mahboobi. 2014. Hijacked journals and predatory publishers: Is there a need to re-think how to assess the quality of academic research? Walailak Journal of Science and Technology. 11(5): 389-394. DOI: 10.14456/WJST.2014.16.

Silver, A. 2017. Controversial website that lists ‘predatory’ publishers shuts down: Librarian Jeffrey Beall won’t say why he has unpublished his widely read blog. Nature. DOI: 10.1038/nature.2017.21328.

SWAT. 2023. Soil & Water Assessment Tool: Conferences.

Swauger, S. 2017. Open access, power, and privilege: A response to “What I learned from predatory publishing.” College and Research Libraries News. 78(11): 603-606.

Vyawahare, M. 2017. Bogus Journals weighing down research in India. Hindustan Times, New Delhi, India.

Ward, S. 2016. The rise of predatory publishing: How to avoid being scammed. Weed Science. 64: 772–778. DOI: 10.1614/WS-D-16-00080.1.

Wicherts, J.M. 2016. Peer review quality and transparency of the peer-review process in open access and subscription journals. PLoS ONE. 11(1): e0147913. DOI: 10.1371/journal.pone.0147913.

Wikipedia. 2023. Grey Literature.

Wikipedia. 2023. Predatory open access publishing.