Vegetation and water on the landscape are directly linked, with leaf area controlling the partitioning of evapotranspiration, a process which creates a microclimate in the atmosphere above the plants. Therefore, widespread alterations to land use has potentially large implications for the water balance at regional and global scales. Unfortunately, many challenges persist that limit our ability to model with high confidence the biophysical constraints on evapotranspiration. One of the largest unknowns in this complex system is the root distribution, which is highly heterogeneous and dependent on both internal factors like the species and age of the plant, as well as external factors such as the climate and soil conditions. The physical limitations to studying properties below Earth's surface demands innovative approaches to improve our understanding of the interplay between roots, water, and the soil. Geophysical tools, such as electrical resistivity, have been employed for decades to study the properties of the Earth at scales from tens to hundreds of meters. Advancements in observing features such as oil and gas reserves, aquifer properties, and contaminant plumes has led the way to more recent work monitoring shallow soil properties such as water content and salinity. In this dissertation, I advance the field of hydrogeophysics with the development of a novel modeling approach that utilizes electrical resistivity data directly to parameterize root properties of site-specific hydrological models. Building on prior research using coupled hydrogeophysical inversion methods to estimate soil hydrological properties, the model presented and applied here addresses the pressing need for new tools to study root properties at the field scale. Chapter 1 provides a high-level introduction of the background and motivation for this area of research. Chapter 2 establishes the feasibility of the proposed modeling framework at a biofuel research site. Using site-specific soil and climate forcing data, I generated synthetic hydrological and electrical resistivity datasets using fixed soil and root parameters for a plot of maize. I then tested how well the model estimated those parameters under increasing levels of uncertainty. I found that even in the most data-poor scenario, the coupled hydrogeophysical inversion estimated the synthetic parameters with a high degree of accuracy. Chapter 3 proceeds to use the now-established model approach to estimate the root properties of two contrasting biofuel treatments, an annual rotation and a perennial grass. We again found the model returned reasonable estimates of the root distribution and evapotranspiration estimates for both crop types. In Chapter 4 I take advantage of the unique ability afforded by this modeling approach to test whether a theoretical coarse root fraction crossing the plane of the electrode array could produce an amplified resistivity measurement akin to what has been observed in the field. Given those estimates were within reason, subsequent estimates of coarse root fraction in a forested ecosystem were then validated against an index of above ground biomass. A statistically significant relationship was found, providing evidence in the absence of excavated root data that resistivity data can be used to non-invasively estimate the extent and relative quantity of coarse roots. Chapter 5 concludes this work by exploring the statistical relationship between above ground vegetation indices and the spatial and temporal heterogeneity in the observed resistivity data, providing the groundwork for future work modeling coarse root mass in a wide array of forest ecosystems.

This book focuses on the the application of hydrogeophysical methods to the understanding of hydrological processes and environmental problems dealing with the flow of water and the transport of solutes and contaminants. Taking a process-driven approach, the book offers a series of process-driven chapters, each authored by leading experts. Areas covered include: infiltration and solute transport processes, biogeochemical functioning of soil-water systems, coastal groundwater interactions, cold region hydrology, engineered barriers and landfill processes.

This book constitutes the refereed post-conference proceedings of the 7th International Conference on Advancement of Science and Technology, ICAST 2019, which took place in Bahir Dar, Ethiopia, in August 2019. The 76 revised full papers were carefully reviewed and selected from more than 150 submissions. The papers present economic and technologic developments in modern societies in five tracks: agro-processing industries for sustainable development, water resources and environmental engineering, recent advances in electrical, electronics and computing technologies, product design, manufacturing and systems organization, and material science and engineering.

This book reports on developments in Proximal Soil Sensing (PSS) and high resolution digital soil mapping. PSS has become a multidisciplinary area of study that aims to develop field-based techniques for collecting information on the soil from close by, or within, the soil. Amongst others, PSS involves the use of optical, geophysical, electrochemical, mathematical and statistical methods. This volume, suitable for undergraduate course material and postgraduate research, brings together ideas and examples from those developing and using proximal sensors and high resolution digital soil maps for applications such as precision agriculture, soil contamination, archaeology, peri-urban design and high land-value applications, where there is a particular need for high spatial resolution information. The book in particular covers soil sensor sampling, proximal soil sensor development and use, sensor calibrations, prediction methods for large data sets, applications of proximal soil sensing, and high-resolution digital soil mapping. Key themes: soil sensor sampling – soil sensor calibrations – spatial prediction methods – reflectance spectroscopy – electromagnetic induction and electrical resistivity – radar and gamma radiometrics – multi-sensor platforms – high resolution digital soil mapping - applications Raphael A. Viscarra Rossel is a scientist at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) of Australia. Alex McBratney is Pro-Dean and Professor of Soil Science in the Faculty of Agriculture Food & Natural Resources at the University of Sydney in Australia. Budiman Minasny is a Senior Research Fellow in the Faculty of Agriculture Food & Natural Resources at the University of Sydney in Australia.

A comprehensive text on resistivity and induced polarization covering theory and practice for the near-surface Earth supported by modelling software.

Vadose Zone Processes provides a unified, up-to-date treatment on the movement of water through unsaturated media. In addition to covering the basic equations governing the flow and fate of water in unsaturated media, the text covers the biogeochemistry of vadose environments and the statistical description of vadose processes. The authors emphasize maintaining an intuitive understanding of how the results are derived and how they are appropriately applied. This comprehensive and important book will be useful not only to those in traditional fields such as civil engineering, geology, crop science, chemical engineering, agricultural engineering, and hydrology but also in the newer environmental engineering fields including containment transport, pollution remediation, and waste disposal.

Precision farming, site infrastructure assessment, hydrologic monitoring, and environmental investigations- these are just a few current and potential uses of near-surface geophysical methods in agriculture. Responding to the growing demand for this technology, the Handbook of Agricultural Geophysics supplies a clear, concise overview of nea

GlobalSoilMap: Basis of the global spatial soil information system contains contributions that were presented at the 1st GlobalSoilMap conference, held 7-9 October 2013 in Orléans, France. These contributions demonstrate the latest developments in the GlobalSoilMap project and digital soil mapping technology for which the ultimate aim is to produce a high resolution digital spatial soil information system of selected soil properties and their uncertainties for the entire world. GlobalSoilMap: Basis of the global spatial soil information system aims to stimulate capacity building and new incentives to develop full GlobalSoilMap products in all parts of the world.