Location: Watershed Physical Processes Research
2023 Annual Report
Objectives
1. Develop and implement acoustic based methods for measurement and interpretation of sediment transport in streams.
1.A. Develop novel methods for data analysis and visualization to aid interpretation of acoustic sedimentation data while continuing to develop sediment transport measurement technologies.
1.B. Engage in CEAP/LTAR research by implementing existing acoustic sediment monitoring technology in CEAP/LTAR watershed.
2. Develop and adapt acoustic and geophysical methods for characterizing soils and monitoring processes within the agricultural watershed.
2.A. Develop an acoustic based soil water status assessment tool for improving water management and irrigation and rain fed decision support systems.
2.B. Develop rapid and noninvasive agrogeophysical methods for mapping and monitoring erosional processes (e.g., soil pipes in relation to gully erosion) in agricultural landscapes.
2.C. Application of geophysical measurements for estimating groundwater flow, aquifer parameters, and aquifer thickness.
2.D. Development of relationships between soil properties and geophysical attributes using machine learning.
Approach
Development of acoustic and geophysics technology addressing gaps in the USDA's suite of tools to map and monitor hydraulic processes over a range of time and space scales will consist of: theoretical and modeling efforts, controlled laboratory experiments, and field measurements using the newly developed hardware and techniques. Theoretical and modeling efforts establish the feasibility and sensitive of acoustic attributes to soil processes and sediment transport. Laboratory measurements help to better understand the physics of soils and its interaction with water and determine optimal sensor configurations, data quality requirements, and data processing schemes. Field measurements provide the final proof of concept design and incorporation into USDA applications. The first objective relates to the development of novel methods for data analysis and visualization to aid interpretation of acoustic sedimentation data while continuing to develop sediment transport measurement technologies. The second objective relates to acoustic and geophysical methods that can monitor and evaluate the performance of agricultural irrigation, drainage, and rain-fed systems, improve technology for studying soil pipe development, and to assess suitable sites and monitor the efficacy of surface water to groundwater interaction. Both parties are actively engaged in independent research projects related to the development and use of acoustic/ seismic technology for water resources applications. The parties agree that meeting the objectives of this project will expand the suite of tools, technology, and sensors for acquiring data to support science-based decision support systems.
Progress Report
Progress on Objective 1A. Experiments were conducted at the University of Mississippi Biological Field Station during the summer of 2022 using the Single Frequency Acoustic Attenuation System in environments with varying algal concentrations. Data relating to the measured algal concentrations has not yet been made available. However, analysis of the acoustic data and ancillary data indicated parameters that may affect acoustic signal, primarily light intensity, temperature, and dissolved oxygen. Laboratory experiments were conducted to investigate light intensity and temperature and yielded a correction for temperature. After applying the correction, it was shown that light intensity does not have an independent influence on the acoustic signal. Applying the temperature correction to the field data did not account for all of the observed attenuation, thus leading researchers to believe that algae may have an independent effect on the acoustic signal. A laboratory experiment to isolate the effect of dissolved oxygen is currently being designed. With the algal concentration data still unavailable, no conclusion can be made regarding the effect of algae on the acoustic signal.
Progress on Objective 1B. The deployment of the Single Frequency Acoustic Attenuation System at Goodwin Creek Station 1 continued throughout the year. During Fiscal Year 2023 the system collected acoustic data from four high flow events spanning approximately twenty-two days. Researchers are awaiting the data from the physical samples collected by partners at the National Sedimentation Laboratory in Oxford, Mississippi. The raw acoustic data has been processed, timestamped and uploaded to a database so that it can be compared to parameters such as flow discharge, stage height and measured sediment concentration as those data become available. Discussion with research partners at the National Sedimentation Laboratory have indicated that Station 2 on Goodwin Creek is an ideal location for a deployment. This site is instrumented with numerous measurement systems and will provide more parameters with which the acoustic signal can be compared.
Progress on Objective 2A. It is desirable to develop a subsurface soil water status sensing system that can noninvasively generate soil water profile map and to monitor and evaluate the performance of agriculture irrigation, drainage, and rain-fed system. A high-frequency multi-channel analysis of surface waves method has been improved with several enhanced techniques. A functional prototype of a mobile/portable system has been developed, which consists of a portable geophone array, a small shaker, and a data acquisition board that can measure surface vibrations along a straight line. An electrodynamic shaker was used as a vibration source. The measurement system is automated, and can be used at a predefined time interval (for example, once per minute) to capture soil responses to irrigation and rainfall. The system can measure soil profiles up to 2.0 meters below the surface. The testing site was located on the campus of The University of Mississippi, near the National Center for Physical Acoustics building, in Oxford, Mississippi. Five time-domain reflectometers were also installed to measure moisture contents at different depths. Three sprinklers were installed at the site for controlled irrigation. The measurements were conducted continuously before, during, and after irrigation under different initial soil conditions. Temporal variations of shear wave velocity profiles were used for assessing the initial soil conditions, on-going soil responses to irrigation and drainage processes. The study demonstrated that the method can capture temporal variations of soil profile caused by irrigation. A database of the HF-MASW (the high-frequency multichannel analysis of surface wave) test results of irrigation has been established.
Progress on Objective 2B. Accurately mapping and quantifying the amount of total soil loss from agricultural fields is vital in implementing adequate mitigation measures. While internal soil pipe formations contribute to the total soil loss from agricultural fields, quantifying their contribution is a challenge due to their small size and subsurface occurrence. This project aims to conduct agrogeophysical surveys on agricultural fields and map the field's susceptibility to soil pipe formations. Progress towards this objective is made by conducting small-scale electromagnetic induction and ground penetrating radar grid surveys at Goodwin Creek Watershed on a 3230 square foot area with documented soil pipe formations. After identifying the attributes of internal soil pipes on the agrogeophysical measurement results, additional electromagnetic induction and ground penetrating radar grid surveys on a larger area (15,250 square feet) within the same watershed are conducted to generate soil pipe susceptibility maps. Ground truth geotechnical measurements are also conducted at multiple locations to confirm the findings of the agrogeophysical methods. Results from the small-scale study showed that electromagnetic induction surveys can be used to generate zoning maps with varying degrees of internal soil pipe susceptibility. Ground penetrating radar depth slices can be used to determine the depth and pathway of soil pipes. Results of the electromagnetic induction survey on the larger area showed regions of low apparent electrical conductivities similar to what was observed for the small-scale study, indicating locations that might be affected by soil pipe formations. A plan is underway to collect additional geophysical measurements on a larger area and to collect drone elevation data to incorporate topographic information for generating improved internal soil pipe zoning maps.
Progress on Objective 2C. Ground-based geophysical measurements are used for aquifer characterization at a groundwater extraction site near a river and identify evidence of surface water to groundwater interaction in the geophysical data. Progress was made in conducting self-potential (SP) and electrical resistivity tomography (ERT) surveys, at the Shellmound, Mississippi groundwater extraction site. Self-potential measurements were carried out for three months and compared with observation well data from eight locations. Three lines of electrical resistivity tomography data were collected. The self-potential signal produced by pumping near a river is influenced by groundwater, water flow into the aquifer, and mixing of waters with different chemical compositions and temperatures. Results from the self-potential data showed that they could be used to quantify time scales associated with these processes. The data showed that the river interacts with the groundwater after one hour of pumping at an extraction rate of approximately 1500 gallons per minute. The electrical resistivity profile collected from the Tallahatchie River riverbank going across the extraction well (located about 40 meters from the river) shows that the Mississippi River Valley Alluvial Aquifer (MRVA) transitions from confined to unconfined at 380 meters away from the river. The electrical resistivity profile that runs parallel to the river at 65 meters from the riverbank shows that the aquifer is confined along the profile and thicker on the northern side than the extraction well's south side. This profile also shows four higher resistivity anomaly zones ranging from 20 to 32 m that may be attributed to preferential groundwater flow paths or loosely packed sand and gravel zones. The parallel profile at 370 meters from the riverbank shows that the aquifer varies from confined to unconfined at multiple places. Progress is underway to construct a three-dimensional conceptual model of the aquifer from the electrical resistivity profiles that can precisely model groundwater flow at the extraction site. The three-dimensional distribution of electrical conductivity from the electrical resistivity profiles will be calculated to inform self-potential coupled modeling for this site.
Progress on Objective 2D. The objective of this project is to conduct ground-based rapid geophysical measurements at multiple Long-Term Agroecosystem Research (LTAR) sites and correlate the geophysical results to soil parameters obtained from laboratory tests on soil samples. Establishing correlations will enable the prediction of soil parameters using geophysical methods, which will reduce time-consuming laboratory measurements and improve spatial resolution. Progress towards this objective is made by conducting ground-based electromagnetic surveys at three Long Term Agro-ecosystem Research sites in Mississippi covering 258 acres at Schmidt farm (Coahoma County) and 57 acres at Scott farm (Bolivar County). Fifteen lines of electromagnetic (Geonics EM38) surveys totaling more than 7550 meters are conducted at Arant farm (Sunflower County). Electromagnetic methods are sensitive to the distribution of soil moisture, salinity, and clay content. The measurements included vertical and horizontal dipole apparent electrical conductivity (ECa) and in-phase measurements collected by pulling a Geonics EM38 electromagnetic system behind an all-terrain vehicle. In addition, USDA-ARS-NSL personnel collected soil samples for correlation with geophysical measurements. Results from the electromagnetic surveys at Schmidt farm revealed old drainage ditches and varying land cover. High electrical conductivity regions were associated with higher clay content or more soil moisture. The results agreed with soil classifications from the USDA web soil survey website.
Accomplishments
1. Determination of the effects of temperature and light intensity on the Single Frequency Acoustic Attenuation System. The goal of this project is to create a system that provides an accurate estimate of suspended sediment transport with high temporal resolution. While suspended sediment is typically the dominant factor in the Single Frequency Acoustic Attenuation System’s estimate, there are other parameters that can have secondary effects on the acoustic signal. To address these effects and further improve the sediment concentration measurements, experiments were designed and conducted in clear still water with varying light intensity and controlled temperature. From these experiments, ARS researchers in Oxford, Mississippi, determined a correction for water temperature that has been incorporated into the data processing routine. Researchers also showed that light intensity does not have an independent effect on the Single Frequency Acoustic Attenuation System. It is likely that these fundamental results pertain to other acoustic systems. Calibrating an estimation system for as many secondary parameters as possible provides an improved estimation which allows stakeholders such as researchers, scientists and government agencies to make more accurate assessments of suspended sediment transport.
2. Continued deployment of Single Frequency Acoustic Attenuation System at Goodwin Creek for long-term operation. Monitoring the suspended sediment that is transported in rivers and streams can be difficult and expensive and results in very temporally-coarse measurements. The Single Frequency Acoustic Attenuation System collects near-continuous acoustic data that can be used to estimate the concentration of suspended sediment. Continued deployment of this system, by ARS researchers in Oxford, Mississippi, provides data to help improve the predictive capabilities which in turn provides a more accurate estimate of suspended sediment transportation. The high temporal resolution of this deployment has provided data that indicates significant sediment transport that the pump sampler underrepresented because of longer times between each measurement. This improved estimation allows stakeholders such as researchers, scientists and government agencies to make more accurate assessments of sediment transport rates in stream channels.
3. A portable soil profiler for near surface soil exploration. In agricultural applications and farmland soil management, it is important to have a non-invasive tool to measure soil mechanical and hydrologic properties, map, and monitor their temporal and spatial variations. An acoustic surface wave technique, the high-frequency multichannel analysis of surface wave method has been developed to noninvasively measure soil profiles, in other words, the shear wave velocity as a function of depth, up to 2 meters below the surface. This technique is based on the well-established relationship among the acoustic velocity and soil mechanical and hydrologic properties. This technique has been applied by ARS researchers in Oxford, Mississippi, to many agricultural applications, including (1) near surface soil profiling, (2) studying weather and seasonal effects, (3) monitoring of rainfall events, (4) detecting fragipan layers, (5) studying surface sealing/crusting, (6) a farmland compaction study, and (7) irrigation performance evaluation. These studies demonstrated that the technique is an effective non-invasive tool to measure soil subsurface mechanical and hydrological properties. Recently this technique was further improved by building a portable device that can be employed in the field for rapid survey. With the translation and commercialization of the device, the potential users could be soil scientists, famers, environment/civil engineering researchers, and military personnel.
4. Estimation of soil parameters from spatial agrogeophysical surveys. Differences in soil parameters such as moisture content, nutrient level, electrical conductivity, pH, and grain size distribution within a field can result in variable crop water and nutrient needs. Understanding site-specific irrigation and nutrient application needs can reduce irrigation water use and improve crop production. Conventional methods of determining soil parameters require collecting multiple soil samples by ARS researchers in Oxford, Mississippi, from agricultural fields and involve time-consuming laboratory measurements. The results obtained from conventional methods are accurate but discrete to the locations where the samples are collected. This research applies rapid agrogeophysical methods for generating spatially and temporally variable maps of soil parameters on agricultural fields. Developing correlations between soil parameters obtained from laboratory measurements and agrogeophysical attributes will significantly reduce the soil samples required from vast agricultural fields. To date, rapid agrogeophysical surveys at multiple agricultural fields have been collected, and spatial maps of geophysical attributes have been generated. Scientists from the United States Department of Agriculture have collected soil samples from the agricultural fields for laboratory processing. The results from the laboratory measurements will be correlated to the geophysical attributes to convert the geophysical maps to spatial maps of soil parameters. Preliminary results showed that the geophysical results agree with historical land coverage and soil classifications obtained from the United States Department of Agriculture web soil survey website. Results from this study are important to farmers and landowners in providing site-specific dynamic prescription maps to inform and/or control water and nutrient management.
5. Application of geophysical information for determining surface-to-groundwater interaction. Understanding water movement between the watershed, stream, and groundwater is needed to estimate and forecast future water availability conditions. Understanding and quantifying the exchanges at the surface water to groundwater interface is also crucial in forecasting how the chemical quality of water will change in response to changes in climate, land use, or management practices. The traditional approach of determining groundwater flow direction and velocity fields requires the installation of multiple observation wells, which is laborious and provides only point measurements through extensive data logging. However, geophysical methods such as self-potential and electrical resistivity can provide the subsurface's geological, hydrological, and biogeochemical spatial properties. These data assist in the determination of sub-surface's water content, subsurface composition, clay content, permeability, conductivity, and stratigraphy. This research is advancing geophysical information for the hydrogeological characterization of aquifers and determining the surface-to-groundwater interaction. Using an 80-electrode remote self-potential system developed at the University of Mississippi National Center for Physical Acoustics, readings across spatio-temporal (varying in space and time) have been collected continuously for three months at the Shellmound, Mississippi, groundwater extraction site in Leflore County, Mississippi. In addition, electrical resistivity data have been collected on three profiles for a total survey length of 1780 meters. Time-series and spatial distribution of self-potential data have shown that the river interacts with the groundwater after one hour of pumping at 1500 gallons per minute, and the electrical resistivity results have shown locations of preferential groundwater flow paths in the subsurface. Findings from these studies are essential to hydrologists and engineers developing and monitoring aquifer storage and recovery (ASR) and managed aqu
6. Generation of zoning maps with varying degrees of internal soil pipe susceptibility. Understanding and mitigating the different mechanisms of soil loss from agricultural fields is important in ensuring fertile soil preservation and increasing agricultural output. Soil loss from forming ephemeral gullies can account for as much as 100% of soil loss from agricultural fields. Unmitigated internal soil pipes can lead to the development of mature gullies adding to the soil loss problem. Internal soil pipes are commonly undetected in agricultural fields because they occur below the surface. Current characterization of internal soil pipes is most commonly inferred from surface features such as flute holes, depressions, and sinkholes which is challenging due to crop cover. This research by ARS researchers in Oxford, Mississippi, is advancing rapid agrogeophysical methods for generating zoning maps with varying degrees of internal soil pipe susceptibility. Surveys conducted at Goodwin Creek Watershed in Panola County, Mississippi, east of the Mississippi River valley demonstrated that electromagnetic induction surveys can quickly cover agricultural fields and generate spatial information on locations most likely affected by internal soil pipe formations. Identifying internal soil pipe susceptible locations on vast agricultural fields helps focus the application of other high-resolution geophysical surveys or invasive geotechnical surveys to confirm the existence of these features. Results from this study are important to farmers and land owners in identifying soil pipe affected locations and implementing preemptive measures. A paper that was previously under review titled 'Integrated Agrogeophysical Approach for Investigating Soil Pipes in Agricultural Fields' has been published in the Journal of Environmental and Engineering Geophysics (JEEG).
Review Publications
Johora, F.T., Hickey, C.J., Yasarer, H. 2022. Predicting geotechnical parameters from seismic wave velocity using artificial neural networks. Applied Sciences. 12:12815. https://doi.org/10.3390/app122412815.
Carpenter, B., Goodwiller, B., Wren, D.G., Taylor, J.M., Aubuchon, J., Brown, J., Posner, A. 2022. Field testing a high-frequency acoustic attenuation system for measuring fine suspended sediments and algal movements. Applied Acoustics. 198: 2022. 108980. https://doi.org/10.1016/j.apacoust.2022.108980.
