Abstract. Spread across Twente and its neighbouring regions in the east of the
Netherlands, a network of 20 profile soil moisture and
temperature (5, 10, 20, 40, and 80 cm depths) monitoring stations
was established in 2009. Field campaigns have been conducted covering the
growing seasons of 2009, 2015, 2016, and 2017, during which soil sampling
rings and handheld probes were used to measure the top 5 cm volumetric soil
moisture content (VSM) of 28 fields near 12 monitoring stations. In this
paper, we describe the design of the monitoring network and the field
campaigns, adopted instrumentation, experimental setup, field sampling
strategies, and the development of sensor calibration functions. Maintenance
and quality control procedures and issues specific to the Twente network are
discussed. Moreover, we provide an overview of open third-party datasets
(i.e. land cover/use, soil information, elevation, groundwater, and
meteorological observations) that can support the use and analysis of the
Twente soil moisture and temperature datasets beyond the scope of this
contribution. An indication for the spatial representativeness of the permanent monitoring
stations is provided through comparisons of the 5 cm station measurements
with the top 5 cm field-averaged VSM derived from the field campaign
measurements. The results reveal in general reasonable agreements and root
mean squared errors that are dominated by underestimations of the
field-averaged VSM, which is particularly apparent for the grass fields and is
strong after heavy rain. Further, we discuss the prospects the datasets
offer to investigate (i) the reliability of soil moisture references that
serve the development and validation of soil moisture products, and (ii) the
water and energy exchanges across the groundwater–vadose-zone–atmosphere
continuum within a lowland environment in a changing climate. The datasets discussed are publicly available at
https://doi.org/10.17026/dans-znj-wyg5 (Van der Velde et al., 2022).