Hydrological Sciences

Listening to a bouquet of articles: review papers

Listening to a bouquet of articles: review papers

Let me guess from which city in the world you are reading this post: Lima, Lahore or Louisville? It might be that you are modelling one of these rivers: Nile, Rhine or Lena? Or studying the Caribbean Sea, the Arabian Sea or the Caspian Sea?

The country you live might be Uganda, Philippines or maybe Iceland and your home continent could well be Europe, Latin America or even Antarctica. I assume you are certainly from this world, not outer space! :), and the reason why I wanted to take you on a “world” tour is to highlight the importance of scales and context in how knowledge, thus perception, is shaped.

In the search for answers for known unknowns, and also unknown unknowns, a fresh and open mind is required to be able to take in all the inspiration offered by observations, data and theories. Moreover, scientific thinking is equally enriched by a bird’s-eye view.

Knowledge production and networking opportunities have improved significantly in the last century, and even more so since 1990s. There are thousands of research papers available in the literature, and the speed of both research and publishing is utterly increasing.

Most often than not, reading the literature can feel endless, like looking up into the night sky and wondering just how many stars are there in the universe! However, a greater challenge remains for scientists, especially when the pace of scientific publishing continues to rise.

Photo by Greg Rakozy (Unsplash License)

Review papers as tools for research integration and synthesis

One of the biggest concerns of a scientist might well be keeping up with the literature and maintaining a research vision. Questions like “what are the research gaps and priorities?”, “What are the research challenges and opportunities?” constantly pop up in the minds of many. A healthy option for researchers to keep up to date with the literature (without information overload), while maintaining a bird’s-eye view to be able to better understand research gaps and priorities, is reading review papers.

Research integration and synthesis is one of the core activities of the scientific process, and review papers are the perfect tools for it! They present “new conceptual frameworks, reveal inconsistencies in the extant body of research, synthesize diverse results, and generally give other scholars a ‘state-of-the-art’ snapshot of a domain” (Palmatier et al., 2018).

Original research articles typically cover background, hypothesis/objectives of the study, methods, interpretation of findings, and discussion of possible implications. Review papers, on the other hand, do not offer new methodologies or present new case studies. It is important that a review paper give an overall synthesis and perspective on a specific research topic and a particular context. A review paper’s objective (and its contributions) can significantly vary. However, some common objectives can be found (Palmatier et al., 2018):

  • Resolve definitional ambiguities and outline the scope of the topic,
  • Provide an integrated, synthesized overview of the current state of knowledge,
  • Identify inconsistencies in prior results and potential explanations,
  • Evaluate existing methodological approaches and unique insights,
  • Develop conceptual frameworks to reconcile and extend past research,
  • Describe research insights, existing gaps, and future research directions.

Reading a review paper is somewhat similar to getting a nice bouquet of flowers at a flower shop. The florist uses their floral design skill to create a magical beauty (a feast for the eyes!) that will inspire your soul. Likewise, the authors of a review paper put their best into this motivational and creative effort. Recently, I accepted the challenge for writing a review paper on clustering algorithms in hydrology and I realize that writing a review paper is not an easy task. It is a huge responsibility!

Photos by Gabriella Clare Marino and Kylie Paz (Unsplash License)

Recipes on how to write a review paper exist

Scholarly journals have various kinds of scientific publications – research articles that report on original research being the most common type. Besides, review papers and perspective/opinion pieces are considered as an article type by many journals, including those in hydrological sciences. There are also journals which are dedicated to publishing only review papers, e.g.: Wiley Interdisciplinary Reviews: Water (aka WIREs Water), Reviews of Geophysics or Environmental Research Reviews.

Each journal has its own policy on review papers, yet the common practice for many journals is that they are solicited by the editors (to experienced researchers). For unsolicited submissions, potential authors are required to contact the journal Editor-in-Chief where they justify the need for their review idea.

Specific guidelines on what should be in a review paper and the required methodology can be found on a journal’s website. One can also check the general guidelines provided by publishers like Taylor & Francis and Elsevier. The length of a review paper usually varies depending on the subject area, selected journal, and most importantly, the type of review paper. There are different types of review papers. A classification can be made with respect to (Mayer, 2009; Snyder, 2019; Palmatier et al., 2018):

  • the paper’s objective (status-quo, history, issue, theory/model),
  • the paper’s focus theme (domain-based, theory-based, method-based), or
  • the paper’s methodological approach (systematic, semi-systematic, integrative).

What are the review methodologies?

Conducting reviews include both narrative and/or quantitative (i.e., systematic, meta-analytic reviews) approaches. A narrative review is not as detailed and rigorous as a systematic review, and focuses on a particular field or topic rather than a well-defined research question. A systematic review, however, aims to offer comprehensive background for theory development and testing by adopting a transparent methodology for scientific reproducibility so that the bias in exhaustive literature searches is minimized (Linnenluecke et al., 2019).

Meta-analysis is a kind of systematic review where the quantitative findings across reviewed studies is statistically combined in order to obtain new insights. If you are planning on conducting a systematic review you might want to first read the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Existing guidelines for conducting a literature review is listed in Snyder (2019). I would also recommend the review paper by Grant et al. (2009) where 14 most common review types are compared and the need for an internationally agreed set of discrete, coherent and mutually exclusive review types is discussed.

Review papers are not a shortcut to have that literature review you are supposed to do on your own

Reading individual articles in your field with a focus on your research interests is absolutely necessary. Nothing can replace the unique benefits of this task. Review papers are rather valuable tools that enable readers to get an overview on a mature (or expanding) topic within a wider context while engaging in critical evaluation and reflective discussion.

Just like looking at these lovely photos of flower bouquets, reading review papers can help you find the inspiration that you have been longing for. There is a bouquet (oops! a review paper) for every taste, that’s for sure!

Review papers in Hydrology

In hydrological sciences, review papers are popular too. Both the authors and the readership appreciates the benefits of review papers. It is highly probable that everyone reading this post had read at least one review article on a hydrological topic. If so, you can share your most recent read in the comments!

The number and scope of review papers has increased substantially (personal observation). For example, just in Hydrology and Earth System Sciences alone 69 papers classified as review article are published since 2011; and 28 papers (7 opinion, 8 overview, 13 advanced review) are published only this year in WIREs Water (i.e. Volume 8). Note that both numbers are as of June 1st, 2021.

I have been collecting review (or overview) papers over the last seven years (since 2014 – when I started my PhD studies). I try my best to keep my collection as diverse as possible in terms of topics so that I can develop a basic level of understanding on each topic while embracing multi-/inter-/transdisciplinarity of hydrological sciences. At the end of this post I am sharing a list of review papers that gives a quite comprehensive overview of the hydrology literature (as of June 1st, 2021). The list is shaped mainly by my research interests and learning needs, and thus it is not exhaustive.

I consider these review papers as chapters of a hydrology book that would be my life-time bedside book – a wonderful book that one can refer to whenever I need to explore further an idea or to learn about a new topic to support my research vision with new insights. I can’t help but wonder how many of these review papers are actually open access. The overview and discussion presented in these papers can be of interest to non-academic hydrologists as well as policy makers. Overall, I believe that such review papers have great value for strengthening the science- policy-practice interface.

You can also share your favourite review paper(s), which helped expand your knowledge and inspired your research, by adding a comment under this post. It might be also that you authored a review article yourself and want to share that too!

Hydrology for generations Z and Alpha

It is interesting to note that there is a considerable boom in the number (and topical variety) of review papers in 2020 and (first half of) 2021. It seems that the hydrological sciences community is marking the end of the first 1/5th period of the 21st century by publishing review papers.

An exciting period is awaiting us for the next 100 years. New theories, new methods, innovative approaches, and new observational data… The babies of the last two decades (generation Z and generation Alpha) – mostly children of Millennials – are coming to transform the hydrological sciences landscape! Some of them have already joined the hydrology community, e.g. current BSc and MSc students in environmental and water sciences. In order for them to create new science, they will need to know enough about the current knowledge and practice.

Luckily some of the newbie hydrologists are already concerned by the power of water. Have you watched the water-inspired interval act by the host country, the Netherlands, during the first semi-final of the Eurovision Song Contest 2021? It was held in Rotterdam, May 18-22. The act is named ‘The Power of Water’. The song “Sweet Water” by Davina Michelle tells the story of the unique relationship between the Netherlands and water. If you haven’t, check it out (for lyrics click).

Generation Z and Alpha is born to a world of water extremes, so much that a musical show with the theme of hydrological extremes is staged at the Eurovision 2021! The world definitely needs more hydrologists!!! Hence, these review papers are the diamonds of academic publishing for their initiation in hydrological sciences!


Snyder, H. (2019). Literature review as a research methodology: An overview and guidelines. Journal of Business Research, 104, 333-339. https://doi.org/10.1016/j.jbusres.2019.07.039

Palmatier, R. W., Houston, M. B., & Hulland, J. (2018). Review articles: Purpose, process, and structure. Journal of the Academy of Marketing Science, 46, 1–5. https://doi.org/10.1007/s11747-017-0563-4

Linnenluecke, M. K., Marrone, M., & Singh, A. K. (2020). Conducting systematic literature reviews and bibliometric analyses. Australian Journal of Management, 45(2), 175-194. https://doi.org/10.1177%2F0312896219877678

Grant, M. J., & Booth, A. (2009). A typology of reviews: an analysis of 14 review types and associated methodologies. Health Information & Libraries Journal, 26(2), 91-108. https://doi.org/10.1111/j.1471-1842.2009.00848.x

https://www.editage.com/insights/a-young-researchers-guide-to-a-systematic-review (Accessed on 02 June 2021)

https://www.editage.com/insights/secondary-research-the-basics-of-narrative-reviews-systematic-reviews-and-meta-analysis (Accessed on 02 June 2021)

The list of 151 review papers collected can be downloaded here.

* In chronological order by year (and by topic within a year):

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Edited by Maria-Helena Ramos

Nilay Dogulu is a keen enthusiast for science-informed operational hydrology. Her research interests deal mainly with the applications of data-driven modelling techniques in hydrology. In her PhD research, Nilay explored the use of clustering methods for understanding catchment similarity and improving runoff predictions in ungauged basins. Nilay has acted as the Early Career Scientist Representative for the European Geosciences Union (EGU) HS Division (2017-19) and the International Association of Hydrological Sciences (IAHS) (2018-2022).

1 Comment

  1. How did I miss this one!!! >>> Wagener, T., & Pianosi, F. (2019). What has Global Sensitivity Analysis ever done for us? A systematic review to support scientific advancement and to inform policy-making in earth system modelling. Earth-science reviews, 194, 1-18. https://doi.org/10.1016/j.earscirev.2019.04.006


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