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The first premise of this book is that farmers need access to options for improving their situation. In agricultural terms, these options might be manage ment alternatives or different crops to grow, that can stabilize or increase household income, that reduce soil degradation and dependence on off-farm inputs, or that exploit local market opportunities. Farmers need a facilitating environment, in which affordable credit is available if needed, in which policies are conducive to judicious management of natural resources, and in which costs and prices of production are stable. Another key ingredient of this facilitating environment is information: an understanding of which options are viable, how these operate at the farm level, and what their impact may be on the things that farmers perceive as being important. The second premise is that systems analysis and simulation have an impor tant role to play in fostering this understanding of options, traditional field experimentation being time-consuming and costly. This book summarizes the activities of the International Benchmark Sites Network for Agrotechnology Transfer (IBSNAT) project, an international initiative funded by the United States Agency for International Development (USAID). IBSNAT was an attempt to demonstrate the effectiveness of understanding options through systems analysis and simulation for the ultimate benefit of farm households in the tropics and subtropics. The idea for the book was first suggested at one of the last IBSNAT group meetings held at the University of Hawaii in 1993.
This book deals primarily with monitoring, prediction and understanding of Tropical Cyclones (TCs). It was envisioned to serve as a teaching and reference resource at universities and academic institutions for researchers and post-graduate students. It has been designed to provide a broad outlook on recent advances in observations, assimilation and modeling of TCs with detailed and advanced information on genesis, intensification, movement and storm surge prediction. Specifically, it focuses on (i) state-of-the-art observations for advancing TC research, (ii) advances in numerical weather prediction for TCs, (iii) advanced assimilation and vortex initialization techniques, (iv) ocean coupling, (v) current capabilities to predict TCs, and (vi) advanced research in physical and dynamical processes in TCs. The chapters in the book are authored by leading international experts from academic, research and operational environments. The book is also expected to stimulate critical thinking for cyclone forecasters and researchers, managers, policy makers, and graduate and post-graduate students to carry out future research in the field of TCs.
In arid and semi-arid areas, the main contributions to land surface processes are precipitation, surface evaporation and surface energy balancing. In the close-to-surface layer and root-zone layer, vapor flux is the dominant flux controlling these processes - process which, in turn, influence the local climate pattern and the local ecosystem. The work reported in this thesis attempts to understand how the soil airflow affects the vapor transport during evaporation processes, by using a two-phase heat and mass transfer model. The necessity of including the airflow mechanism in land surface process studies is discussed and highlighted.
In past decades, there were discussions explaining the mechanisms and factors that influence water flow through soil in unsaturated conditions. This phenomenon is of major importance to the mining industry as water is one of the trigger mechanisms for Acid Rock Generation (ARD) generation. In 1999, Newman evaluated water flow in unsaturated conditions for two column experiments using a vertical layer system of sandy materials and waste rock from the Golden Sunlight mine. Later in 2009, Andrina analyzed water flow using waste rock from the Grasberg Mine in three Meso-scale experiments to understand flow mechanisms for incline layers of waste rock. The current study focuses on modeling the two column experiments by Newman and the three Meso-scale panels by Andrina to analyze the mechanisms controlling water flow in unsaturated soils. Additionally, one of the models is evaluated under three additional materials to compare the effect of different hydraulic properties in an inclined layering system. With finite element methods, the experiments are modeled and calculated under equal boundary conditions. The use of climate boundaries recreates the precipitation flux and head pressure boundary to generate the suction from the discharge points. The models are run using SvFlux software, which runs an automatic mesh refinement algorithm and solves the Partial Differential Equations (PDEs) using FlexPDE. The models are validated based on the correlation of the discharge volume from each experiment. The results from the models describe the profile changes of head pressure (hp), flux, flow paths, and matric suction to describe the mechanism of flow in the unsaturated conditions. The validation of the models was achieved through back analyzing the different tests in the experiments, due to the low correlation of the model using the laboratory properties and the experimental results. The back analysis of the material is focused on the air entry value, and the saturated hydraulic conductivity as a means to change the unsaturated flow. The result from the research displays similarities and disagreements between the models and experiments. The models showed that the measured discharge from a particular material does not represent the preferential flow path of water, as a small gradient in the pressure distribution can generate breakthrough at the base of the system.
Natural Groundwater Flow is an important volume focused on providing a complete description of groundwater flow velocity field and the velocity oriented approach for conducting numerical simulations and other applications. The book presents background information regarding the causes leading to spatial variations of the water table, related concepts of phreatic and specific storage, artificial flow, and flow driven by differences in groundwater density. Block-scale permeability is discussed in detail, and numerical applications using the Galerkin finite element method and pre-modeling techniques for obtaining data required for numerical modeling are examined. The book also presents never-before-published information regarding the theoretical justification and elucidation of hydrological systems analysis to analyze the effects of different spatio-temporal scales. Natural Groundwater Flow is an important reference for environmental physicists, hydrogeologists, civil engineers, mathematical geologists, and petroleum reservoir engineers.
Data assimilation methods were largely developed for operational weather forecasting, but in recent years have been applied to an increasing range of earth science disciplines. This book will set out the theoretical basis of data assimilation with contributions by top international experts in the field. Various aspects of data assimilation are discussed including: theory; observations; models; numerical weather prediction; evaluation of observations and models; assessment of future satellite missions; application to components of the Earth System. References are made to recent developments in data assimilation theory (e.g. Ensemble Kalman filter), and to novel applications of the data assimilation method (e.g. ionosphere, Mars data assimilation).