Application of an Ultrasonic Sensor to Monitor Soil Erosion and Deposition

HighlightsA sediment monitoring system was developed to measure erosion and deposition.The system uses an ultrasonic sensor to take high-frequency measurements.Tests in controlled lab settings showed high accuracy.The system measured 43.5 cm of deposition from two storm events.Abstract. Monitoring erosion at high temporal resolution can provide researchers and managers the data necessary to manage erosion. Current erosion monitoring methods tend to be invasive to the area of interest, record low-frequency measurements, have a narrow spatial range of measurement, or are expensive. There is a need for an affordable system capable of monitoring erosion and deposition non-invasively at high temporal resolution. The objectives of this research were to (1) design and construct a non-invasive sediment monitoring system (SMS) using an ultrasonic sensor capable of monitoring erosion and deposition continuously, (2) test the system in the lab and field, and (3) determine the applications and limitations of the system. The SMS was tested in the lab to determine the extent to which the soil type, slope, surface topography, change in distance, and vegetation impacted the measurements of the ultrasonic sensor. Soil type, slope, and surface topography had little effect on the measurement, but distance and the introduction of vegetation impacted the measurement. In the field during high flows, as erosion and deposition occurred, the changes in distance were determined in near real-time, allowing calculation of erosion and deposition quantities. The SMS was deployed to monitor deposition on sandy streambanks in the Nebraska Sandhills and erosion on a streambank and field plot in Lincoln, Nebraska. The SMS proved successful in measuring sediment change during high-flow events but yielded some error: ±1.06 mm in controlled lab settings and ±10.79 mm when subjected to environmental factors such as temperature, relative humidity, and wind. Keywords: Deposition, Erosion, Monitoring, Ultrasonic sensor.

Comparative Assessment of Fluvial Suspended Sediment Concentration Analysis Methods

The monitoring of fluvial suspended sediment transport plays an important role in the assessment of morphological processes, river habitats, or many social activities associated with river management. However, establishing and operating a well-functioning sediment monitoring system requires the involvement of advanced indirect methods. This study investigates the advantages and limitations of optical and acoustic devices, to quantify the uncertainties and provide a comprehensive comparative assessment of the investigated indirect methods. The novelty of this study, compared to previous ones, is that four different indirect techniques are parallel tested, i.e., the laser diffraction based LISST-Portable|XR, an infrared based optical instrument, the VELP TB1 turbidimeter, the acoustic based LISST-ABS (Acoustical Backscatter Sensor) sensor, and a 1200 kHz Teledyne RD Instruments Acoustic Doppler Current Profiler (ADCP). The calibration of all the indirect methods was performed based on more than 1000 samples taken from the Hungarian section of the Danube River within a wide suspended sediment concentration range. Implementing a comparative assessment of the different sediment analysis methods, a qualitative and quantitative characterisation of the applicability is provided. Furthermore, a proposal for an optimised sediment monitoring methodology is also suggested.

Redesign of a water quantity, quality, and sediment-monitoring network in a tropical region

The CORNARE region, located in Antioquia (Colombia), required a redesign of its water quantity, quality, and sediment-monitoring network, in order to collect convincing data to help decision-makers to respond to different technical and environmental issues. This paper proposes a methodology which is based on secondary information and which employs Geographical Information System –GIS- tools and knowledge of the region, given that historical data are unavailable in most of the region. Although the main methodology, which applied physical, anthropic, and economic factors was the same for all networks, specific strategies were used for water quantity, quality, and sediment networks in the region. These used expert criteria and weight distance methods. The results were satisfactory. Macro-location was implemented for the sites monitored in the CORNARE region, and this indicated that the proposed methodology was adequate for tropical Andean watersheds, where historical data were insufficient and did not permit the use of more complex techniques. This methodology integrates water quantity, water quality and sediment in an integrated hydrological monitoring network.

OVERVIEW OF MULTI-YEAR SEDIMENT MONITORING OF BUILDINGS AND THEIR BEARING STRUCTURES

The article provides an overview of articles and analysis of the results of observations of the precipitation of various buildings erected in difficult geological conditions. Practical conclusions are made for the development of a methodology for monitoring the magnitude of crack opening in residential and industrial buildings.