| 16 Apr 2026
Technical note: A Water Analysis Trailer for Environmental Research (WATER)
Abstract. In complex hydrological systems, flow path dynamics, water storage and mixing, and biogeochemical processing vary in space and may change rapidly during events. Understanding source areas, connectivity and short-term dynamics in stream water quality therefore requires high-temporal-frequency, multi-source observations both within and across catchments. Revolutions in field-deployable analysers and sensors, together with advancement in automation techniques, now make such observations feasible via true “labs-in-the-field”. This paper details the technical realisation and proof-of-concept for the Water Analysis Trailer for Environmental Research (WATER). The WATER is a mobile, trailer-based platform for environmental sensing and automated, high-temporal-frequency sampling and analysis of water from multiple (currently up to 11) sources. It is currently equipped to measure stable water isotopes, nitrate, electrical conductivity, pH and temperature, though its modular design supports the integration of additional measurement devices in the future. A field test in the 1.03 km2 Schwingbach Environmental Observatory, Germany, demonstrated the ability of the WATER to successfully and autonomously collect and analyse samples from six water sources (2 × stream water, 3 × groundwater, 1 × precipitation) over a period of six months, with collected data offering potential for new understanding of catchment functioning. Insights were also gained into the practical considerations necessary when deploying the WATER for an extended period of time, such as ensuring an adequate self-sufficient power supply and scheduling routine maintenance visits. Simulation of the reduced sampling frequency that would result from extending the WATER to sample at its full capacity of 11 sources also indicated that, over multi-month periods, key distributional characteristics of the collected data would likely be maintained. Overall, the WATER provides a mobile and scalable solution for high-temporal-frequency, multi-source hydrological and hydrochemical monitoring that can be (re-)deployed in different locations or targeted to specific events.
Important advances have been made in the development of field-deployable analysers and sensors that enables in-situ, high-temporal-resolution measurements at a reasonable cost without the requirement involving sample collection, transport and analysis to and in the lab. Such continuous measurements using either deployable sensors to look at for example nutrients and/or dissolved organic matter, or semi-continuous measurements using devises that pump water to the analytical instrument for biogeochemical, physical and stable water isotopes analysis are increasing our ability to provide process-based understanding. Hence, the further development of such lab-in-the-field devices will be important in the years to come.
The manuscript provides another dimension of this such a lab-in-the-field approach, namely being mobile. While this is a rather obvious development, it has to my knowledge not previously been formalized into a paper. This is an advantage since others can more easily follow by using the detailed instructions or coming up with new ideas on how to improve it further.
The mobile laboratory allows for relatively advanced measurement, while the authors also are honest with not only the pros, but also the cons for others to develop alternative solutions.
While I generally applaud this, I think that the data presentation could be improved. It is difficult to make much sense of the data. Perhaps use better colour scheme, try to help the reader with some lines between points and make clear what data is what. But these are minor issues.