Developing Hydrogeophysical Tools to Study Hydro-bio-geo-chemical Processes in Dryland Agricultural Fields at the Nexus of Food, Water and Soils
Combining hydrological, geochemical and hydrogeophysical tools (e.g., resistivity, GPR) to study these managed agricultural systems has great implications for soil sustainability and water resources management. Irrigation alters surface and subsurface hydrologic regimes and impacts the regional water balance and quality of the adjacent aquifers. Indeed, pathways and residence time of water within the heterogeneous soil substrates are critical for identifying efficient and effective irrigation strategies, assessing the water connection among Rio Grande, groundwater and agricultural return flows, and examining the variations in the groundwater level by pumping and recharge during intensive irrigation. Furthermore, solute transport is controlled by water flow. High evapotranspiration rates in these systems lead to water loss and salt accumulation, especially in fine-textured soils, significantly degrading soil quality. In addition, soils are typically amended with fertilizers and pesticides, and irrigation moves nutrients and toxic trace metals from soils to other water reservoirs along its flow paths, impacting drinking water quality.
In summary, dryland agricultural fields represent an important Critical Zone end-member that are highly modified by human activities. They are biologically and chemically active, driven by alternating wet and dry soil conditions, but challenging to study at regional scales due to layered geological structure and heterogeneity in their hydrological properties.