Design and Field Implementation of a Low-Cost, Open-Hardware Platform for Hydrological Monitoring

Hydrologic processes acting on catchments are complex and variable, especially in mountain basins due to their topography and specific characteristics, so runoff simulation models and water management are also complex. Nevertheless, model parameters are usually estimated on the basis of guidelines from user manuals and literature because they are not usually monitored, due to the high cost of conventional monitoring systems. Within this framework, a new and promising generation of low-cost sensors for hydrologic monitoring, logging, and transition has been developed. We aimed to design a low-cost, open-hardware platform, based on a Raspberry Pi and software written in Python 3, for measuring, recording, and wireless data transmission in hydrological monitoring contexts. Moreover, the data are linked to a runoff model, in real time, for flood prevention. Complementarily, it emphasizes the role of the calibration and validation of soil moisture, rain gauges, and water depth sensors in laboratories. It was installed in a small mountain basin. The results showed mean absolute errors of ±2.2% in soil moisture, ±1 mm in rainfall, and ±0.51 cm in water depth measurements; they highlight the potential of this platform for hydrological monitoring and flood risk management.

Study on Construction of Hydrological Monitoring System of the Yangtze River and Application of New Technologies on Flood Monitoring

The flood of the Yangtze River has the characteristics of high peak, large quantity and long duration. The Yangtze River Hydrology Bureau summarizes and combs the complete business process chain of flood hydrological monitoring, and gradually constructs the Yangtze River flood hydrological monitoring system. Including station network layout, early warning response, monitoring technology, information processing, results output and other dimensions. The hydrological monitoring system of the Yangtze River flood has been gradually constructed and has been successfully applied in many flood basins. Especially under the special situation of COVID-19 epidemic situation in 2020 and the severe flood situation in the Yangtze River Basin, the scientific and practical nature and practicability of the hydrological monitoring system of the Yangtze River flood are further verified. In view of the shortcomings existing in the existing monitoring system, this paper looks forward to the frontier technologies involved in flood monitoring, and has a certain reference function for flood hydrological emergency monitoring.

Response of Multi-Incidence Angle Polarimetric RADARSAT-2 Data to Herbaceous Vegetation Features in the Lower Paraná River Floodplain, Argentina

Wetland ecosystems play a key role in hydrological and biogeochemical cycles. In emergent vegetation targets, the occurrence of double-bounce scatter is indicative of the presence of water and can be valuable for hydrological monitoring. Double-bounce scatter would lead to an increase of σ0HH over σ0VV and a non-zero co-polarized phase difference (CPD). In the Lower Paraná River floodplain, a total of 11 full polarimetric RADARSAT-2 scenes from a wide range of incidence angles were acquired during a month. Flooded targets dominated by two herbaceous species were sampled: Schoenoplectus californicus (four sites, Bulrush marshes) and Ludwigia peruviana (three sites, Broadleaf marshes). As a general trend, σ0HH was higher than σ0VV, especially at the steeper incidence angles. By modeling CPD with maximum likelihood estimations, we found results consistent with double-bounce scatter in two Ludwigia plots, at certain scene incidence angles. Incidence angle accounted for most of the variation on σ0HH, whereas emergent green biomass was the main feature influencing σ0HV. Multivariate models explaining backscattering variation included the incidence angle and at least two of these variables: emergent plant height, stem diameter, number of green stems, and emergent green biomass. This study provides an example of using CPD to decide on the contribution of double-bounce scatter and highlights the influence of vegetation biomass on radar response. Even with the presence of water below vegetation, the contribution of double-bounce scatter to C-band backscattering depends on scene incidence angles and may be negligible in dense herbaceous targets.

Performing Hydrological Monitoring at a National Scale by Exploiting Rain-Gauge and Radar Networks: The Italian Case

Hydrological monitoring systems relying on radar data and distributed hydrological models are now feasible at large-scale and represent effective early warning systems for flash floods. Here we describe a system that allows hydrological occurrences in terms of streamflow at a national scale to be monitored. We then evaluate its operational application in Italy, a country characterized by various climatic conditions and topographic features. The proposed system exploits a modified conditional merging (MCM) algorithm to generate rainfall estimates by blending data from national radar and rain-gauge networks. Then, we use the merged rainfall fields as input for the distributed and continuous hydrological model, Continuum, to obtain real-time streamflow predictions. We assess its performance in terms of rainfall estimates from MCM, using cross-validation and comparison with a conditional merging technique at an event-scale. We also assess its performance against rainfall fields from ground-based data at catchment-scale. We further evaluate the performance of the hydrological system in terms of streamflow against observed data (relative error on high flows less than 25% and Nash–Sutcliffe Efficiency greater than 0.5 for 72% and 46% of the calibrated study sections, respectively). These results, therefore, confirm the suitability of such an approach, even at national scale, over a wide range of catchment types, climates, and hydrometeorological regimes, and for operational purposes.

Monitoring of Suspended Sediments in a Tropical Forested Landscape With Citizen Science

Catchments are complex systems, which require regular monitoring of hydro-chemical parameters in space and time to provide comprehensive datasets. These are needed to characterize catchment behavior on a local level, make future projections based on models, implement mitigation measures and meet policy targets. However, many developing countries lack a good infrastructure for hydrological monitoring since its establishment is costly and the required resources are often not available. To overcome such challenges in data scarce regions like Kenya, a participatory citizen science approach can be a promising strategy for monitoring water resources. This study evaluates the potential of using a contributory citizen science approach to explore spatiotemporal turbidity and suspended sediment dynamics in the Sondu-Miriu river basin, western Kenya. A group of 19 citizen scientists was trained to monitor turbidity using turbidity tubes and water levels with water level gauges in six nested subcatchments of the Sondu-Miriu river basin. Over the course of the project, a total of 37 citizen scientists participated and contributed to the overall dataset of turbidity. The sampling effort and data contribution varied from year to year and among participants with the majority of the data (72%) originating from 8 (22%) citizen scientists. Comparison between citizen-scientist collected suspended sediment data and measurements from automated stations showed high correlation (R2 > 0.9) which demonstrates that data collected by citizen scientists can be comparable to data collected using expensive monitoring equipment. However, there was reduced precision of the measurements of suspended sediment concentrations at low and high levels attributed largely to the detection limitations of the turbidity tubes and citizen scientists not capturing major sediment export events. Suspended sediment concentrations were significantly higher downstream (109 ± 94 mg L−1), a subcatchment dominated by agriculture and rangeland with low forest vegetation cover, as compared to a subcatchment with high forest cover (50 ± 24.7 mg L−1). This finding indicates that forest cover is a key landscape feature to control suspended sediment concentrations in the region. Future citizen science projects should focus on motivation and engagement strategies and the application of robust methods with improved detection limits and resolution to advance hydrological monitoring.

The Mini Buoy: a novel hydrodynamics sensor for long-term deployments in coastal wetlands

<p>Hydrological monitoring is crucial for management and research in coastal wetlands. However, long-term monitoring is scarce due to the high cost of conventional hydrological equipment. The development of open-source and low-power sensors over the past decade presents an opportunity for enabling long-term, high spatial resolution monitoring of hydrodynamics in the intertidal zone. Here, we present the design, calibration, and application of one such sensor: the Mini Buoy. The Mini Buoy is a battery-powered accelerometer and data logger, contained in a standard centrifuge tube. The Mini Buoy floats upright when inundated, and moves freely about a tether anchored to the substrate. Acceleration is measured along a single axis of the buoy, and motion along the axis is used to measure inundation, currents, and waves. Deployments of up to 6 months are possible, and the buoy can measure current and wave orbital velocities as low as 0.05 m/s. Mini Buoys cost less than €350 to assemble, and the materials are globally available. We present the successful application of Mini Buoys in four contrasting scenarios: (1) characterising waves under calm and stormy conditions; (2) linking saltmarsh erosion-expansion patterns with hydrological exposure; (3) identifying high-resolution spatial variability of waves and currents along a saltmarsh edge; and (4) assessing the suitability of former aquaculture ponds for mangrove restoration. Mini Buoys are also being deployed along mangrove fringes across Vietnam, India, and Bangladesh, in order to detect thresholds in hydrodynamic forcing responsible for triggering erosion or progradation events. Mini Buoys offer an exciting and novel tool for coastal management worldwide.</p>

Low-Cost, Low-Energy, Wireless Hydrological Monitoring Platform: Design, Deployment, and Evaluation

Climate change has increasingly been considered responsible for irregular weather patterns leading to many environmental hazards and catastrophes. Coping with these conditions and providing effective solutions require monitoring and collecting data of various hydrological parameters and events in high spatial and temporal resolutions, which is generally limited by the cost and energy requirements of the monitoring devices. In this work, we push the limit of the current low-cost data acquisition capabilities by developing the HydroMon3: a hydrological monitoring platform that collects, stores, and transmits high temporal resolution data reliably and accurately, and capable of interfacing different types of sensors. The modular design is driven by utilizing the recent burst in commercially available IoT-related electronics modules to minimize the cost and maximize flexibility, while applying various hardware and software techniques to ensure reliability and energy performance. Stream stage and tipping bucket monitoring units based on the HydroMon3 platform were deployed to more than 20 locations in two different watersheds, and their performance over a 6-month season was evaluated. Collected data for a number of storms provided important insights for linking hydrological events and showed substantial variability in the monitored parameters both spatially and temporally, which were compared with local data records and confirmed that conventional hydrological data acquisition methods are under representative of the actual events. Field-proven results demonstrate the units’ ability to maintain autonomous operation from several months for the stream stage monitors to years for the rainfall gauges using of-the-shelf AA batteries.

Validation of TRMM data in the geographical regions of Brazil

ABSTRACT The low density of precipitation gauges, the areas of difficult access and the high number of missing values hinder a rapid and effective hydrological monitoring. Thus, the present study aims to statistically validate the precipitation estimates by the data Tropical Rainfall Measuring Mission (TRMM) in relation to the data observed in the Conventional Meteorological Stations (CMSs) in the geographic regions of Brazil. The statistical indicators used were: Correlation Coefficient (r), Mean Absolute Error (MAE), Percentage of Bias (Pbias), T-Test and Mann-Witiney Test. It is concluded that the precipitation data estimated via TRMM are effective and reliable alternatives for hydrological studies in areas that do not have in-situ gauges and/or need to fill missing values in the five regions of the country, especially in the driest months and in larger time scales.