EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Citizen observers in hydrology – experiences from CrowdWater

Jan Seibert1,2, Simon Etter1, Barbara Strobl1, and Ilja van Meerveld1
Jan Seibert et al.
  • 1University of Zurich, Department of Geography, Zürich, Switzerland (
  • 2Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden

One possibility to overcome the lack of data in hydrology is to engage the public in hydrological observations. Citizen science projects are potentially useful to complement existing observation networks to obtain spatially distributed streamflow data. Projects, such as CrowdHydrology, have demonstrated that it is possible to engage the public in contributing hydrological observations. However, hydrological citizen science projects have, so far, been based on the use of different kinds of instruments or installations. For stream level observations, this is usually a staff gauge. While it may be relatively easy to install a staff gauge at a few river sites, the need for a physical installation makes it difficult to scale this type of citizen science approach to a large number of sites because these gauges cannot be installed everywhere or by everyone. Here, we present the CrowdWater smartphone app that allows the collection of hydrological data everywhere without any physical installation or specialized instruments. The approach is similar to geocaching, with the difference that instead of finding treasures, hydrological measurement sites can be set up by anyone at any location and these sites can be found by the initiator or other citizen scientists to take additional measurements at a later time. This way time series of observations can be collected. For stream levels, a virtual staff gauge approach is used: a picture of a staff gauge is digitally inserted into a photo of a stream bank or a bridge pillar, and the stream level during a subsequent field visit to that site is compared to the staff gauge on the first picture. For intermittent streams, soil moisture and plastic pollution, qualitative scales are used to enable citizens to report their observations. Participants have already contributed more than 10 000 observations. In this pico-presentation, we report on our experiences after about four years with the CrowdWater project and discuss the use of the app by citizen observers, methods to ensure data quality, and illustrate how these data can be used in hydrological model calibration.

How to cite: Seibert, J., Etter, S., Strobl, B., and van Meerveld, I.: Citizen observers in hydrology – experiences from CrowdWater, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12793,, 2020


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  • CC1: Comment on EGU2020-12793, Sarah Garré, 01 May 2020

    Great work. I installed the app. ;-) I particularly like the creative approach for data quality. Can you also explain how the soil moisture recordings are being analyzed? This seems like something particularly difficult to standardize...

    • AC1: Reply to comment on soil moisture, Jan Seibert, 02 May 2020

      Thanks for you kind words and we are looking forward to your observations :-)

      The soil moisture observations could be used to contrain a hydrological model. For a bucket-type model, such as HBV, one could compare time series of crowd-based soil moisture observations (averaged for a catchment if observations from several sites are available) in a similar way as we have done this for water level classes (van Meerveld et al., 2017, HESS).

      Yes, there might be some variation between persons, but we found that the observations are surprisingly constistent among different persons, see studies by Michael Rinderer (2012, 2015).

      Rinderer, M., Kollegger. A., Fischer, B.M.C., Stähli, M., Seibert, J., 2012, Sensing with boots and trousers – qualitative field observations of shallow soil moisture patterns, Hydrological Processes, 26(26): 4112-4120, doi: 10.1002/hyp.9531 

      Rinderer, M., Komakech, H. C., Müller, D., Wiesenberg, G. L. B., and Seibert, J., 2015. Qualitative soil moisture assessment in semi-arid Africa – the role of experience and training on inter-rater reliability, Hydrol. Earth Syst. Sci., 19, 3505-3516, doi:10.5194/hess-19-3505-2015

      van Meerveld, H.J., Vis, M., and Seibert, J., 2017. Information content of stream level class data for hydrological model calibration, Hydrol. Earth Syst. Sci.., 21, 4895-4905, doi: 10.5194/hess-2017-72

      Best regards,


  • CC2: Comment on EGU2020-12793, Antara Dasgupta, 04 May 2020

    Fantastic presentation Jan! I installed the app now and I loved the virtual staff gauge approach. I was wondering if these data were also used to constrain hydraulic/hydrodynamic models already? If so, could you comment on the differences you observed between the value of virtual and physical staff gauge observations?

    • AC2: Reply to CC2, Jan Seibert, 04 May 2020

      Thanks for your kind words. So far we have mainly used synthetic data to test the potential value of data. We recently compared the citizen observations with 'real' observations. This study, lead by Simon Etter, is currently in review. Short summary: citizens are quite good in observing water level classes using the CrowdWater app.

      • CC3: Reply to AC2, Antara Dasgupta, 04 May 2020

        Nice to learn this, I look forward to reading the paper when its out. :)

        Good luck!

      • CC4: Reply to AC2, Antara Dasgupta, 04 May 2020

        Nice to learn this, I look forward to reading the paper when its out. :)

        Good luck!

      • CC5: Reply to AC2, Antara Dasgupta, 04 May 2020

        Nice to learn this, I look forward to reading the paper when its out. :)

        Good luck!

  • CC6: Comment on EGU2020-12793, Demetris Koutsoyiannis, 04 May 2020

    Hi everybody!

    I have a comment for Jan’s presentation.

    You use the term “citizen” in the title. Somewhere in the text you write “ 'crowd' (citizen scientists)”, from which I understand you use the term “citizen scientists” as an equivalent for “crowd”.

    I have high respect for “citizens” and “scientists”. The two terms have very important yet quite different content and I cannot understand how you combine them.

    In particular, the first term is political, related to citizenship. According to Wikipedia, “Citizenship is the status of a person recognized under the custom or law as being a legal member of a sovereign state or belonging to a nation.”

    So, what do you mean with “citizen scientists”? A crowd of scientists? A crowd of non-scientists? People wearing Citizen watches? :-) Or do you mean just people, or the general public?

    Sorry to be scholastic or pernickety with terminology but I believe we should be careful and also avoid to downgrade the notions of “citizenship” and “science” by hastily combining them.


    Demetris Koutsoyiannis


    • AC3: Reply to CC6, Jan Seibert, 04 May 2020

      Hi Demetris, I agree, wording can be important, but I guess any of the words we are using might be problematic. Citizen sounds better than crowd but then comes the issue of citizenship … i.e., can I be a citizen scientist in a country where I am not a citizen? What I, and I guess most of us mean with the terms 'crowd' or 'citizen scientist' are engaged members of the  ‘general public’ The type of engagement then, of course, can vary largely.

      • CC7: Reply to AC3, Demetris Koutsoyiannis, 04 May 2020

        I am afraid it is not just wording, it tends to become terminology.

        Do you/we really mean scientists? Or people who are not necessarily scientists?

        What about 'engauged people'?

      • AC4: Reply to AC3, Jan Seibert, 04 May 2020

        While the term citizen science might not be perfect, as pointed out by Tim van Emmerik in the chat,  "citizen science" is the most commonly used term to refer to the involvement of "non-professional" scientists. As there is a broad understanding of what this term means in principle (although there are many different variants of 'citizen science'), there is an advantage of using this established term.

    • AC5: Reply to CC6, Jan Seibert, 04 May 2020

      Here an interesting article on citizen science terminology:

      Unfortunately, there is no clear answer from that paper either ("In our collective experience with citizen science projects, no single term is appropriate for all contexts. ")


      • CC8: Reply to AC5, Demetris Koutsoyiannis, 04 May 2020

        This site is by "Citizen Science Association". Hence, it is innapropriate to consult them whether "Citizen Science" is an appropriate term.

        In my view it is a bad term.

        • AC6: Reply to CC8, Jan Seibert, 04 May 2020

          you have a point here ;-)

          Still, the paper is worth reading.

          What would be your suggestion for a better term?

          • CC9: Reply to AC6, Demetris Koutsoyiannis, 04 May 2020

            Thinking loudly...

            Crowdsourcing is much more accurate than citizen science.

            "Crowd" is not ideal, though; I would prefer "Community"

            Community sourcing?

            And when we refer to the science assisted by such sourcing: Community-assisted science?