Hydrogeophysical Characterization of Agricultural Soils in Western Newfoundland using Integrated GPR-EMI
Increasing local food availability, and thus minimising the dependence on imported food, has become a major challenge for the Government of NL in the quest to enhance food security. Extraction of natural resources and accelerated conversion of natural systems into agricultural management will affect lands and waters threatening the sustainability of boreal ecosystems of the Province. The knowledge of near-surface hydrology is extremely important in agriculture and forestry since controls plant growth, climate and quality of surface and subsurface waters. Additionally, changes in soil properties and contamination of both soil and water resources directly affect agricultural sustainability as well as the sustainability of adjacent managed or natural (eco) systems. Due to the natural heterogeneity of the subsurface, accurate characterization is essential in understanding groundwater recharge, solute transport, and the movement and storage of water in the unsaturated zone. The conventional methods used in such characterizations are invasive, time-consuming, costly, and provide only point measurements resulting in large scale uncertainty of field measurements. Recent advances in digital technology, computing and geophysical instrumentation provide opportunities to efficiently map the heterogeneity of soil properties at both spatial and temporal scales. Among these near surface geophysical methods, ground penetrating radar (GPR) and electromagnetic induction (EMI) methods have been tested and are being used extensively. However, the integrated GPR-EMI has not been tested and evaluated under different agricultural management systems especially under boreal climates and soils.
Description of the work to be done
Five main activities will be carried out in this research project. (i) Calibration of GPR-EMI equipment and baseline geophysical surveys at the field site, (ii) Geophysical surveys using GPR-EMI throughout the growing season and measuring soil properties using standard methods in the field as well as through laboratory analysis of soil samples. Spatiotemporal variability of apparent electrical conductivity (ECa), volumetric soil moisture content (VSMC) and water table depth (WTD) will be measured using GPR-EMI method. Piezometers will be installed to monitor WTD and validate GPR-EMI results. The main soil physical properties that will be measured: soil texture, bulk density, porosity, saturated hydraulic conductivity, electric conductivity of soil solution (ECw), gravimetric soil moisture, soil saturation percentage and organic matter content, (iii) evaluate the accuracy of estimated soil physical and hydraulic properties using GPR-EMI methods. (iv) develop soil hydraulic functions for soils of the research farm, (v) data analysis, interpretation, reporting and dissemination.
Challenges that this project will address
If one considers the highly sensitive ecological equilibrium of boreal ecosystems, conversion of forest lands to agriculture as well as intensive agricultural practices will strongly affect the soil physical and hydraulic properties. These changes in soil properties might affect the efficiency of agriculture and forestry production systems as well as the sustainability of these sectors. Those changes and their potential impacts on near surface hydrology, crop water and agricultural production, contaminant transport, groundwater recharge potentials, and climate are yet not well understood for western Newfoundland. To fill this gap, we propose protocol development and implementation of an integrated GPR-EMI as a non-invasive geophysical approach for remotely sensing the spatiotemporal variability of soil physical and hydraulic properties to support precision agricultural and environmental management under both managed (agricultural) and natural landscapes in western Newfoundland.
The goal or anticipated outcomes
The main goal of this proposed research project is to evaluate the accuracy of integrated GPR-EMI method for non-invasive mapping of the spatiotemporal variability of soil physical and hydraulic properties in boreal soils. Additional goal is to develop hydraulic function of soils at Pynn’s Brook Research Station and estimate crop water availability. The results and knowledge generated through this project will be useful in sustainable management of soil and water resources in increasing agricultural and crop productivity while protecting valuable ecosystems. Once the integrated GPR-EMI method is evaluated, the method can be used for rapid characterization of different soils in NL, which will be useful in sectors naming; agriculture and forestry, water pollution control and water supply, mining and site rehabilitation and natural resources management.