An EU-wide citizen science network to monitor hydrological conditions in intermittent rivers and ephemeral streams

What is the relationship between groundwater and rivers? What is the impact of climate change on water resources? These are questions that require regular observation of streamflow. Unfortunately small catchments – which are frequently intermittent – are poorly monitored and the development of this citizen science network aims to fill gaps in knowledge of the dynamics of intermittent streams through a collaborative approach. The challenge is to create a distributed network of observers who can perform visual observations over a large number of rivers over an extended period of time.

The first pilot study will investigate the spatial extent of Intermittent Rivers and Ephemeral Streams (IRES) at the European scale. Identifying IRES using gauging station data is biased due to the scarcity of flow records on IRES. The suggested strategy is to invite everyone to report the flow state for any stream in Europe during 2019 (no constraints on time, nor on the location of the IRES).

The second study will investigate the dynamics of flow intermittence in IRES. More specifically, we will examine if streams dry out or start to flow at approximately the same time and how they dry out (downstream or upstream progression of drying, or a more irregular pattern). This will require repeated observations along IRES. We aim for observations of the flow state at five or more locations along an IRES at least once a month during the summer and autumn of 2019, e.g., during the last 7 days of each month between April and October 2019 (but more frequent observations or over a longer period are also fine).

This citizen science network is an initiative of the SMIRES European project addressing the Science and Management of Intermittent Rivers & Ephemeral Streams ( These field observations will compensate for the scarcity of IRES hydrological information in Europe and complement the Intermittent Rivers Map based on gauging station data that is available here.

The CrowdWater app ( will be used for these observations. The app was developed by SPOTTERON for the University of Zurich and is available free for iOS and Android smartphones. Within the CrowdWater app, the state of any IRES can be recorded by selecting the Temporary Stream option from the first menu (in Figure 1). The GPS of the phone records the location of the observations (in Figure 1). It is very quick and easy to report the state of an IRES and to upload a photograph of the stream (in Figure 1). There are six states to choose from: dry streambed, damp or wet streambed, isolated pools, standing water, trickling water and flowing water (in Figure 1). The app can also be used to update the status of an already existing spot (by clicking on the plus sign) to obtain time series of the flow status of the IRES. The app can be used anywhere in the world. If no cell phone connection is available, the observations can be uploaded to the central database later. The data can be downloaded by anyone ( Citizens, who are very active in uploading observations via the CrowdWater app, will receive certificates of participation (signed by the University of Zurich and the Citizens’ Science Center Zurich). It takes less than a minute to report the observation of the status of an IRES with the app. So, if you pass by an IRES, please use the app to report the current status for this stream. If you, a colleague or friend pass by an IRES regularly (e.g., every month), then please contribute to the second study of this SMIRES initiative.

For more information on how to use the CrowdWater app,
please see
or watch the introduction video:

You can download the app here:


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