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The use of modern digital technologies in water management is an important driver for obtaining better data for assessing the status of water bodies and their development. These data can be beneficially implemented for the monitoring and management of rivers and especially waterways.In the BMDV-funded project RiverCloud, an autonomous tandem system consisting of an Unmanned Aerial Vehicle (UAV) and an Unmanned Surface Vehicle (USV) is being developed under the coordination of the gia of RWTH Aachen University, which will provide spatially and temporally high-resolution data for the development and maintenance of waterways as well as for river management. The contribution introduces the developed coupled UAV/USV tandem system with its mounted sensors for high resolution data acquisition and continuously accurate georeferencing and presents some significant results using the example of a study area on the Rhine River (Tomateninsel).The data presented are, among others, camera-based flow measurements using an image processing method, discharge data of a precise ADCP (Acoustic Doppler Current Profiler) with 2000 kHz frequency and ten water quality parameters using a multi-parameter probe. All data mentioned were simultaneously collected in two locations of the study area on the Rhine River in September 2022. The 4 seconds videos collected by the UAV-camera were processed using an image processing method based on the surface velocity after implementing a new developed stabilisation tool. The cross-section data collected by ADCP were used for the configuration of the two sites. The agreement between ADCP and camera-based flow and discharge data was very good on both sites with less than 5% deviation for a discharge value of approx. 600 m3/s and 1.63 m/s mean velocity. The water quality parameters collected during the measuring campaign were temperature, conductivity, salinity, pH value, oxygen concentration, oxygen saturation, ammonium, turbidity, Total suspended solids (TSS) and total dissolved solids (TDS). The water quality data were in the expected ranges for river water (e.g. average values: pH 7.8, T 21.8°C, EC 0.35 mS/cm, Sal 0.71%, O2 7.5 mg/l, NH4+ 0.3 mg/l).The results, specific requirements of the developed solution and challenges under the measuring conditions of the study area are presented in this paper. The data collected are used as the input of an overview report for river or waterway water flow and quality monitoring.

Maintenance of waterways is often a challenging task with conflicting interests between different parties. They are subject to economical stresses through the industry and transportation sector on the one hand, on the other the European Water Framework Directive dictates to ensure (or lead them back to) a chemically and ecologically “good status” (which benefits the balance between regulating, supporting, providing and cultural ecosystem services).To have a good decision base for ecological measures, local-scale high resolution temporal and spatial data is needed to make sound decisions for a sustainable river management, which extends to assess and monitor the succession of restoration areas and to document change.The objective of the project RiverCloud is the development of a data acquisition platform which enables synchronous data collection with unmanned aerial vehicles (UAV) and unmanned surface vehicles (USV). On the base of this platform different sensors can be used for a holistic data base in semiterrestrial areas of streams: e.g. acoustic doppler current profilers, multi-parameter sensors, multibeam-echosounders and a 360° camera for the USV; Sensors on the UAV consist of a bathymetric range finder and an industrial grade camera for structure from motion application to derive high-resolution point clouds and orthomosaics.Building upon this data base, a further objective is the detection of vegetation structures such as a canopy height, single trees and the balancing of aboveground biomass, as a regulating ecosystem service for carbon sequestration, from high-resolution point clouds by using open source software. The results from remote sensing data are tested against comparative data collected in the field. Workflow, results and benefits for river management will be presented. All data was collected in September 2022 along the river Rhine near Karlsruhe, Germany.

Monitoring volumetric flow in arid and semi-arid regions is a major challenge due to their harsh and continuously changing environment (e.g. extreme temperature, severe sand storms). In these regions, hydrological events such as rainfall storms and flash flood events occur intermittently, time between major events may take years. Drainage water courses in these areas are often referred as Wadis, which are ephemeral drainage courses. Wadis are normally dry except after a rain event, often resulting in flash floods events with flood peak values occurring in the first few minutes of the event.Monitoring the volumetric flow under these environments requires robust devices which record continuously at relatively short recording intervals, e.g. minutes or less, to be able to capture the steep ramp of the flood peak.On April 2021 a DischargeKeeper, an image-based system for flow monitoring, with a PTZ camera was installed at the Wadi Naqab located in northern United Arab Emirates. The Wadi is approximately 50m wide and has been dry for most of the time. One event occurred at the beginning of January 2022, reaching a peak discharge of 78 m3/s just 15min after water started flowing. In this session we will show the system, its challenges and the results of the event.