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Water temperature is one of the key factors controlling aquatic ecosystems and influencing physical, chemical and biological processes. Detailed observations of spatial and temporal patterns in water temperature are important for assessing e.g. variations in thermal refugia, impacts of climate change and for developing appropriate management strategies. Freshwater  temperatures are still mostly analysed based on single point measurements, but these do not reflect the spatial thermal variability within waterbodies (i.e. stream and lake) and therefore could lack information on thermal refugia. 2-D images of freshwater temperature in varying spatial resolution are increasingly obtained by space- and airborne methods such as UAV (unmanned aircraft vehicles). While these UAV methods offer the necessary spatial resolution at the surface, they require in situ measurements to obtain absolute temperature values and don’t provide information on vertical thermal variability. Approaches that bridge this gap do exist (e.g. fibreoptic cables), but high demand on resources and high costs limit widespread use.

The aim of this work was to develop a low-cost, custom-build, fully flexible 3-D temperature sensor system that can be used for calibration and validation of thermal UAV observations, but also adds information on water temperature with depth. The design of our floating sensor system (with a maximum of 72 sensors) offers high flexibility in horizontal/vertical spacing and logging time intervals (ms to h). Here we present the first results of our prototype, which was calibrated using Solinst Leveloggers (accuracy ± 0.05ºC) and tested under various ambient conditions, both in the laboratory and in a lab-in-field experiment in a relatively shallow lake (maximum measurement depth of 1.50 m) in NE Scotland. We also evaluated the use of this system with UAV imagery at the lake.

The results show a quick response of the individual sensors to temperature changes and indicate suitability of the system for validating and calibrating thermal UAV images. For a set-up with 12 vertical arrays (6 sensors at different depths for each array) and arranged as a grid, preliminary data indicated the value for a 3-D approach as not all thermal patterns at depth were captured by surface measurements. Next, the transferability of the sensor system to a stream will be tested and applied to a stream water management case. Together with UAV thermal imagery, the new sensor system could have the potential for a wide range of research and management applications (e.g. thermal habitats, groundwater upwelling, infiltration of cooling water).

How to cite: Loerke, E., Wilkinson, M. E., Pohle, I., Drummond, D., and Geris, J.: A new low-cost approach to 3-D water temperature monitoring, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1120, https://doi.org/10.5194/egusphere-egu21-1120, 2021.

International attempts to limit greenhouse gas (GHG) concentrations, aimed at stabilizing human induced climate change, require a detailed understanding of the current and potential future role of forests to sequester carbon. Accurate, high frequency and reliable measurements are therefore vital in developing effective mitigation strategies and help to improve understanding of the other ecosystem services provided by forests which are valued by society. However, forests are typically located in remote, rural environments which can make regular access for surveyors and other forest scientists challenging and logistically difficult. In 2020, Forest Research worked in partnership with the UK government’s Department for Environment, Food and Rural Affairs (Defra) and Vodafone to explore how Internet of things (IoT) technology can be used to improve environmental and forest monitoring and to test its suitability at remote rural locations in the UK. A pilot study which ran at Forest Research’s two contrasting long-term carbon flux sites, Alice Holt (Hampshire) and Harwood (Northumberland) used IoT technology to measure and transmit high frequency growth and environmental data over the course on an entire growing season. Tree growth sensors (automated dendrometers) and a range of other environmental sensors (e.g. air temperature and  humidity, soil moisture) attached to the trees and in the soil (nine replicates per site), were connected to the Vodafone Narrowband-IoT (NB-IoT) network. Data was uploaded every 15 minutes to a Grafana based online web portal, providing researchers with near real time access to the data.  Here we present results from these two sites, details of the hardware used in these new devices and evaluation of their performance during this pilot study.

How to cite: Wilkinson, M., Bell, M., Baer, T., and Xenakis, G.: Measuring and monitoring trees and forests using a novel IoT approach, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-887, https://doi.org/10.5194/egusphere-egu21-887, 2021.

Over the past years, simple acoustic drop detectors have been developed for different objectives. The core of these detectors were standard piezoelectric elements. For some applications, such as simply counting drops, not much signal processing is needed. For other applications, however, such as measurement of drop energy, which would allow for estimation of drop sizes as well, careful signal processing is needed. For this purpose, we have developed a shield, or “Wing” that can be plugged into an Adafruit Feather (https://www.adafruit.com/feather), which we call DisdroWing. This board includes a high-end operational amplifier and a fast analogue to digital converter. With this board, the user can experiment and implement specific applications, such as rain/no rain detection, hail detection, or drop energy. The design of the DisdroWing is publicly available and can also be purchased fully assembled.

How to cite: van de Giesen, N., Hut, R., and van der Lubbe - Sanjuan, D.: Open source hardware for counting and measuring raindrops, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2289, https://doi.org/10.5194/egusphere-egu21-2289, 2021.

Off-the-shelf portable automatic water samplers, such as the 6712 full-size portable sampler (Teledyne ISCO, Lincoln, USA), are often used in remote locations to collect precipitation or streamwater for subsequent analysis of deuterium and oxygen-18.  The bottles inside these automatic samplers remain open during the full duration of sampler deployment and the collected water samples can thus be subjected to evaporation and vapor exchange.  Both processes are known to alter the isotope composition of the water sample, and thus the questions arise as to 1) how credible the isotope measurements from automatically collected water samples are and 2) how can these isotope effects in the automatic water sampler be reduced?

We evaluated these questions through laboratory and field experiments in which we quantified the change in isotope composition in the water samples with respect to ambient conditions (air temperature and relative humidity), storage duration, and sample volume.  We found that isotope fractionation in the water samples was substantial under very warm and dry condition, when sample volumes are small or when sample storage exceeded 10 days.  To address these problems, we have designed an evaporation protection method which modifies autosampler bottles using a syringe housing and silicone tube.  We performed paired experiments with open vs. evaporation-protected bottles in Teledyne ISCO 6712 full-size portable samplers to evaluate our design.  We could show that the evaporation protection successfully reduced isotope fractionation in the water samples for storage durations of up to 24 days and for a wide range of ambient conditions; e.g., while deuterium concentrations in the water samples in open bottles changed by ca. 3‰ under very warm and dry conditions, no isotope effect was measured in the bottles equipped with the evaporation protection. Because our design is very cost efficient it can easily be implemented to upgrade Teledyne ISCO’s 6712 full-size portable samplers or other similar devices for collecting more reliable isotope data.

How to cite: von Freyberg, J., Knapp, J. L. A., Rücker, A., Studer, B., Zappa, M., and Kirchner, J. W.: An easy-to-use, low-cost evaporation protection to collect more reliable stable water isotope data with Teledyne ISCO portable samplers, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2764, https://doi.org/10.5194/egusphere-egu21-2764, 2021.

Sewage overflows in headwater catchments are critical, mostly not well monitored point sources for many pollutants such as oxygen depleting substances, pharmaceuticals or heavy metals. The outlets are often located at places where no connection to the power grid is available, hence it is often necessary to provide deployed sensors or sampling devices with mobile power sources like car-batteries. In addition, autosamplers or on-line sensors are expensive devices. For these reasons, a proper monitoring strategy, including water quality parameters in these structures is often complicated to implement and from an economical point of view not reasonable. Therefore, we combined two low-budget DIY devices, a modified Zurich sequential sampler for time-discrete rainfall samples and Stream Temperature, Intermittency, and Conductivity loggers (STIC), to build a low-budget monitoring system being able to take time-discrete samples from sewage overflow. Our modified sampler collects 12 samples in a row, with variable volumes from 0.25 to 0.5 L. In each bottle a STIC was implemented. The STICs start to measure a conductivity higher than zero as soon as water starts to flow into the bottle. This allows for a clear assignment between sample and time. We called this sampler the Sewage Overflow Monitoring Sampler (SOMS).

Though the probe volume and the time period for sampling is strongly limited, concentration variations, including peak concentrations, in sewage overflows are expected to be measured right at the beginning of an event (first flush) and should be therefore covered by the sampler. First laboratory tests were successful. In the next step the monitoring system will be implemented on a field side.

Depending on the scientific question of the study, the SOMS can be complemented in the field by either another STIC logger or a pressure probe. The STIC logger is located at the bottom of the canal. This allows the detection of the duration of the overflow event. By installing a pressure probe the discharge can be approximated as long as gradient and the geometry of the canal is known.

How to cite: Spill, C., Ditzel, L., Brumm, N., Böhm, J., and Gassmann, M.: Low-Budget Sewage Overflow Monitoring, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8325, https://doi.org/10.5194/egusphere-egu21-8325, 2021.

Water vapour observations represent an important input e.g. for predicting mesoscale initiation of convective precipitation or estimating evapotranspiration. E-band commercial microwave links (CMLs), which are increasingly used in cellular backhaul, might be used as unintentional water vapour sensors accessible remotely from a network operation centre. E-band CMLs operate at frequencies between 71 and 86 GHz where water vapour causes substantial attenuation of electromagnetic waves. This attenuation can be related to water vapour density along a CML path, nevertheless, it has to be properly separated from other sources of attenuation, especially rainfall-induced attenuation, and wet antenna attenuation caused by wet surface of antenna radomes. Moreover, the relation between attenuation and water vapour density is also dependent on temperature (Fencl et al., 2020).

This contribution evaluates capability to estimate water vapour density on a 4.86 km long full-duplex CML being operated within cellular backhaul at frequencies 73.5 GHz and 83.5 GHz. Three rain gauges are deployed along its path, two of them being equipped with an air humidity sensor. The evaluation period is between August to December 2018. The results show that estimation of water vapour density is feasible when there is now rain and antenna radomes are dry, which is only about 50% of time. Estimated water vapour density during dry weather is highly correlated with humidity observations (r = 0.7). The highest correlations are observed during summer season (r = 0.9) and lowest during December (r = 0.3) when amplitude of water vapour fluctuations are small. In contrast, mean absolute error is highest during August (approx. 1 g/m³) and lowest in December (0.2 g/m³). Most of the outliers were encountered during October, probably due to multipath inferences occurring during clear-sky conditions.

Unintentional sensing of water vapour density with E-band CMLs is feasible by sufficiently (several kilometres) long CMLs. Currently, 20 % of new CML deployments are operated E-band. E-band CMLs might thus greatly increase continental coverage of water vapour ground observations.

Fencl, M., Dohnal, M., Valtr, P., Grabner, M. and Bareš, V.: Atmospheric observations with E-band microwave links – challenges and opportunities, Atmospheric Measurement Techniques, 13(12), 6559–6578, https://doi.org/10.5194/amt-13-6559-2020, 2020.

How to cite: Fencl, M. and Bares, V.: Water vapour monitoring with E-band microwave links of cellular backhaul, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8384, https://doi.org/10.5194/egusphere-egu21-8384, 2021.

Compared to horizontal components, the vertical components of ocean currents are generally very weak (a few mm/s) in all oceanic regions of the world. Due to their major role in the vertical distribution of physical and biogeochemical properties of sea water, their extended knowledge is of utmost importance for oceanographers. However, their in-situ measurement represents a real technical challenge, even using sophisticated instruments such as ADCPs.

As a complement to the ADCP method presented in another session (Comby et al.), we have developed an original alternative instrument, called the VVP (Vertical Velocity Profiler). It was inspired by several published works which exploit the difference between the real vertical speed Wr of a submarine glider (~dP/dt, from the onboard pressure sensor) and its theoretical vertical speed Wth extracted from a flight model. The oceanic vertical speed Woc is thus expressed by the simple difference Woc = Wr - Wth at any  point in the water column.

The very first prototype of the VVP consisted of a float and a friction disc, ballasted to sink at a very low speed (~ 0.1 m / s) and dragged down to the desired depth by a dead-weight which was automatically released after a suitable delay. The release system was developped in-house (patent filled in March 2020), based on a textured insert trapped in a volume of ice melting at controlled speed. Since then, the concept of the profiler has evolved considerably. The last design uses an electric thruster that drives the profiler down to a predefined setpoint depth. Once the depth is reached, the thruster is stopped and the profiler then rises slowly (~0.1 m/s) to the surface under the sole effect of its slightly positive buoyancy. The mechanical balance between buoyancy and hydrodynamic drag results in a constant vertical speed of ascent in water at rest. Any deviation from this constant speed is then interpreted as an oceanic  vertical velocity signal. This new design allows a very large number of consecutive profiles to be collected, the number of descent-ascent cycles and the setpoint depth being programmed and controlled using an ARDUINO microcontroller board. The selected Li-Io battery allows for several hours of continuous profiling.  When on surface, the profiler is currently located by a commercial GPS tracker integrated into the electronic case. The vertical velocity of the profiler is accurately measured at  high frequency (2Hz) thanks to the fast-response pressure sensor of the onboard RBR-CONCERTO autonomous CTD, which also measures the sea water density involved in  drag and buoyancy.

Trials both in deep pool and in the field are scheduled in spring 2021 in order to refine the prototype design and to definitely set the flight model parameters. This development benefits from CNES (Centre National d'Etudes Spatiales) financial support in the framework of the BIOSWOT international program.

How to cite: Fuda, J.-L., Barrillon, S., Doglioli, A., Petrenko, A., Gregori, G., Tzortzis, R., Comby, C., Thyssen, M., Lafont, M., Bhairy, N., Malengros, D., Guillemain, D., and Grenz, C.: A new approch for measuring ocean vertical velocities, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9371, https://doi.org/10.5194/egusphere-egu21-9371, 2021.

Measuring water transparency allows us to monitor the water body's environmental status. One parameter to estimate water transparency is the light diffuse attenuation coefficient (Kd). This coefficient is of particular interest in water quality monitoring programs.

The Kd describes the light extinction as function as the depth of downwelling irradiance, Ed. However, self-shading by the instrument itself can cause errors in Ed estimations. To avoid this effect, relative complex structures must be required to install the sensors that limit the vertical resolution of Ed measurements. Here we propose to use optical sensors in an annular-shape distribution to mitigate these limitations. For this, we introduce a new concept: the annular irradiance, Ea. We first compute the optimal angle to avoid self-shading while maximizing the light captured by the sensor. Second, we assess the robustness of the corresponding diffuse attenuation coefficient, Ka, in different scenarios of water types, solar angle and cloud coverage. Finally, we correlate Ka measurements with Kd at PAR region, and we derive empirical functions from translating Ka to Kd measurements.      

This new coefficient is the basis of the new generation of the KdUINO instrument  (Bardaji et al., 2016) as a KduSTICK, which estimates the near-surface light extinction coefficient based on Ka measurements. Since the design of the instrument avoids self-shading, the device is expected to be particularly useful in those underwater environments where high vertical Ed resolution is required.

Furthermore, instruments based on this light-sensing approach are much simpler to deploy and maintain, and it is possible to design low-cost and Do-It-Yourself (DIY) versions. All these features facilitate its use for non-academic users, making the KduSTICK an optimal instrument to be used in Citizen Science water quality monitoring programs.

How to cite: Rodero, C., Bardaji, R., Salvador, J., Olmedo, E., and Piera, J.: Underwater annular irradiance: New concept to measure the light diffuse attenuation coefficient through the KduSTICK, a Do-It-Yourself device, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9421, https://doi.org/10.5194/egusphere-egu21-9421, 2021.

Monitoring ephemeral and intermittent streams is a major challenge in hydrology. While direct field observations are best to detect spatial patterns of flow persistence, on site inspections are time and labor intensive and may be impractical in difficult-to-access environments. Motivated by latest advancements of digital cameras and computer vision techniques, in this work, we describe the development and application of a stage-camera system to monitor the water level in ungauged headwater streams. The system encompasses a consumer grade wildlife camera with near infrared (NIR) night vision capabilities and a white pole that serves as reference object in the collected images. Time-lapse imagery is processed through a computationally inexpensive algorithm featuring image quantization and binarization, and water level time series are filtered through a simple statistical scheme. The feasibility of the approach is demonstrated through a set of benchmark experiments performed in controlled and natural settings, characterized by an increased level of complexity. Maximum mean absolute errors between stage-camera and reference data are approximately equal to 2 cm in the worst scenario that corresponds to severe hydrometeorological conditions. Our preliminary results are encouraging and support the scalability of the stage camera in future implementations in a wide range of natural settings.

How to cite: Noto, S., Tauro, F., Petroselli, A., Apollonio, C., Botter, G., and Grimaldi, S.: Continuous water level monitoring using time-lapse imagery, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10906, https://doi.org/10.5194/egusphere-egu21-10906, 2021.

Fine sediment supply to floodplains and coastal areas is extremely important for nutrient transport, global biogeochemical cycles, water quality and pollution in riverine, coastal and marine ecosystems. Monitoring of suspended sediment in rivers with current sensors is challenging and expensive, and most monitoring setups are restricted to few single point measurements. To better understand the spatial heterogeneity of fine sediment production and transport in river systems there is a need for new smart water turbidity sensing that is multisite and at the same time accurate and affordable.

We developed an affordable but reasonably accurate turbidity sensor, that is suitable for distributed sensing with a multitude of sensors across catchments. Our turbidity sensor is much cheaper than existing options of comparable quality. It works by illuminating a sediment-laden water sample with an 860nm IR LED and detects the amount of light scattered at two different angles (with respect to the LED) using light-to-frequency converters. It also incudes an internal temperature sensor and data storage on an SD card. We are also planning to include a water pressure sensor, a GPS module, a more compact and durable design with a printed circuit board, and the option of remote data transmission via LoRa.

Here, we present the results of two experiments with the developed new sensor: (1) a calibration test using formazin (4000 NTU) dilutions to evaluate which detector angles work best in the 0-4000 NTU range, how ambient light affects the results, and if focusing lenses and high-pass filters increase the sensor’s accuracy; (2) a laboratory test with various sediment types and concentrations mixed in a large water tank to compare replicates of our sensors (six in total) to different commercially available turbidity probes. Our results show that a high accuracy in the 0-4000 NTU range can be achieved with our low cost, low power sensor.

The new turbidity sensor will allow us to localise sediment sources and sinks in catchments, i.e. where and when fine sediment is produced, transported and deposited across entire catchments. We will be able to observe the variability in suspended sediment fluxes in glacial streams (the development, expansion and collapse of subglacial channels), along river networks with different local sources (effect of tributary inputs and hillslope landslides), concentration variability due to flow-bed interactions (influence of river bed morphology and grain size), and asses the activation of erosion by rainfall across the multiple potential sediment sources of a catchment. The developed sensor will enable the development of distributed measurement setups, which hopefully can address many other complex challenges related to the spatially heterogeneous processes of sediment activation and transport. This project lays a foundation to explore water turbidity sensing in other global environmental applications in the future, such as soil erosion, sediment trapping behind dams, lake monitoring, and ecological studies.

How to cite: Molnar, P., Droujko, J., and Floriancic, M.: A Low-Cost Turbidity Sensor for Deployment in Rivers, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13337, https://doi.org/10.5194/egusphere-egu21-13337, 2021.

Streamflow measurement and prediction are important for proper water resources management. In this case, the water resources problem is drought in the Coastal Mountains of British Columbia, Canada, where a village is drawing drinking water from a mountain stream. Because of challenges with other flow measurement methods in streep turbulent streams, salt dilution gauging is the best way to measure streamflow, but it is labour intensive.

To advance progress towards the singularity, an intelligent automated salt dilution gauging system was deployed, and provides good results, but some disturbances occur due to the presence of a tributary and a drinking water intake. We show how this noise can be turned into signals and discuss a range of other signals that together provide input for the discharge record.

How to cite: Weijs, S. and Eugeni, S.: Bring the noise: Piecing together a discharge record from an automated salt dilution gauging setup and various other information sources, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14324, https://doi.org/10.5194/egusphere-egu21-14324, 2021.