Robust & low-cost watersampler for rain samples

A watersampler for the sampling of rainwater was developed in the framework of the IATI-SGD project. The device was developed and built by an interdisciplinary team from UFZ (departments HDG and CATHYD) und TU Darmstadt.

Ansicht Autosampler Quelle: André Künzelmann, UFZ The watersampler is constructed to automatically, time-controlled, collect water samples for the analysis of stable isotopes and to store the samples as evaporation-free as possible until the laboratory analysis. As the first field application was Oman with its arid and semi-arid climate, great care was taken to ensure a robust and low-cost construction method.

Development team

Dr. Thomas Müller (UFZ, HDG), Dipl.-Ing. Nils Michelsen (TU Darmstadt), Gerrit Laube (UFZ), Dr. Jan Friesen (UFZ, CATHYD)


For a first in situ experiment the watersampler prototype was set up for several weeks in the Gondwananland of the Zoo Leipzig. The climateic conditions regarding temperature and humidity were comparable to those during the monsoon (Khareef) climate in Southern Oman, the actual study region.

The study region of the IATI-SGD project is situated in Southern Oman and extends from the Dhofar mountains into the Salaah coastal plain. Several watersampler units were set up along an elevational gradient to investigate the isotopic signatures of the monsoon precipitation, that recharges the groundwater resources of the costal plain.

Stable water isotopes are a powerful analysis tool for data driven modeling of flow and retention times of water. To monitor the event specific dynamics of retention time watersamplers will be deployed throughout the Bode catchment, where both rainfall as well as runoff samples for isotope analysis will be sampled at high temporal resolution. The watersampler is part of the flexible and mobile monitoring system for earth observation MOSES - Modular Observation Solutions for Earth Systems. Their use in the framework of MOSES aims at automated sampling for the investigation of transport processes of dynamic hydrological events (e.g. floods, high and low waters).

In addition to the first field experiments in the Gondwanaland (Zoo Leipzig) and in Southern Oman, the device was installed in a climate controlled cabinet to comparable numbers regarding the evaporation reduction. The climate controll test were conducted at the TU Darmstadt and are part of a proof-of-concept publication (in preparation).

In the framework of a project on green roofs, Prof. Dr. Andreas Zehnsdorf (UFZ, UBZ) currently has two watersamplers built by the UFZ workshop for the automatic sampling of rain- and runoffwater.

The watersampler has already been presented at conferences and project meetings. A publication that has been selected as a HESS highlight article includes a detailed description of the watersampler as well as laboratory results demonstrating the evaporation prevention mechanism. Interested colleagues that would like to fabricate their own watersamplers can find the required technical drawings, microcontroller code, manuals, as well as a detailed bill of materials below:

Bill of materials - the bill of materials provides all parts required to assemble the distribution and control units. Links to manufacturers that ship to Germany have been added but are only exemplary.

Technical drawings - based on these drawings you or workshops can manufactor the distribution unit and using the circuit digram the microcontroller can be assembled

Microcontroller code - the microcontroller is an off-the-shelf product that requires code to control the stepper motor withion the distribution unit.

Manuals - the manuals include an opertaion manual that details how to operate the watersampler in the field as well as a manual on how to upload the microcontroller code onto the device.


Michelsen, N., Laube, G., Friesen, J., Weise, S. M., Bait Said, A. B. A., and Müller, T.: Technical note: A microcontroller-based automatic rain sampler for stable isotope studies, Hydrol. Earth Syst. Sci., 23, 2637-2645,, 2019.

Michelsen, N., Laube, G., Friesen, J., Al Mashaikhi, K., Mueller, T. (2017) A microcontroller-based automatic rain sampler for stable isotope studies, EGU Leonardo Conference 2017. Michelsen_etal2017_EGU_Leonardo (1.3 MB)


The watersampler development  has received funding from the Institute for Advanced Technology Integration (IATI) under The Research Council (TRC) of the Sultanate of Oman. TRC Research Contract No. TRC/RCP/15/001


During the development we were suppported by the Zoo Leipzig, who enabled us to test a first proptotype in the Gondwanaland. We are very thankful to the UFZ workshop, who supported this project both during development as well as during construction. For the drawing of circuit schematics we would like to thank Guido Schramm.

In Oman we had tremendous support by the Ministry of Regional Municpalities & Water Resources who gave access to their monitoring stations and, next to storage and workspace, also provided logistical and staff support.