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Article

Bioeconomic Models  

Ihtiyor Bobojonov

Bioeconomic models are analytical tools that integrate biophysical and economic models. These models allow for analysis of the biological and economic changes caused by human activities. The biophysical and economic components of these models are developed based on historical observations or theoretical relations. Technically these models may have various levels of complexity in terms of equation systems considered in the model, modeling activities, and programming languages. Often, biophysical components of the models include crop or hydrological models. The core economic components of these models are optimization or simulation models established according to neoclassical economic theories. The models are often developed at farm, country, and global scales, and are used in various fields, including agriculture, fisheries, forestry, and environmental sectors. Bioeconomic models are commonly used in research on environmental externalities associated with policy reforms and technological modernization, including climate change impact analysis, and also explore the negative consequences of global warming. A large number of studies and reports on bioeconomic models exist, yet there is a lack of studies describing the multiple uses of these models across different disciplines.

Article

Economics of Climate Change Adaptation  

Babatunde O. Abidoye

To view climate change adaptation from an economic perspective requires a definition of adaptation, an economic framework in which to view adaptation, and a review of the literature on specific adaptations (especially in agriculture). A focus on tools for applying adaptation to developing countries highlights the difference between mitigation and the adaptation decision-making process. Mitigation decisions take a long-term perspective because carbon dioxide lasts for a very long time in the atmosphere. Adaptation decisions typically last the lifespan of the investments, so the time frame depends on the specific adaptation investment, but it is invariably short compared to mitigation choices, which have implications for centuries. The short time frame means that adaptation decisions are not plagued by the same uncertainty that plagues mitigation choices. Finally, most adaptation decisions are local and private, whereas mitigation is a global public decision. Private adaptation will occur even without large government programs. Public adaptations that require government assistance can mainly be made by existing government agencies. Adaptation does not require a global agreement.

Article

The Family of HYDRUS Models  

Jiří Šimůnek, Giuseppe Brunetti, Martinus Th. van Genuchten, and Miroslav Šejna

HYDRUS is a Windows-based modeling software package that can be used to analyze water flow and heat and solute transport in variably saturated porous media (e.g., soils or the vadose zone). The HYDRUS software includes an interactive graphics-based interface for data preprocessing, soil profile discretization, and graphic presentation of the results. Historically, HYDRUS consisted of two independent software packages. While HYDRUS-1D simulated flow and transport processes in one dimension and was a public domain software, HYDRUS (2D/3D; and earlier HYDRUS-2D) extended the simulation capabilities to the second and third dimensions and was distributed commercially. These two previously independent software packages were merged in 2023 into a single software package called HYDRUS. The capabilities of the HYDRUS software packages have been significantly expanded by various standard and nonstandard specialized add-on modules. The standard add-on modules are fully incorporated and supported by the HYDRUS graphical user-friendly interfaces (GUIs) and documented in detail in the technical and user manuals. This is not the case for several additional nonstandard modules, which require additional work outside the GUI. A commonality of all HYDRUS add-on modules is that they simulate variably saturated water flow and heat and solute transport in porous media. The specialized add-on modules provide additional capabilities, such as considering general reactive transport (in the HPx models) or reactive transport with specific chemistry (notably the Wetland and UNSATCHEM modules). Other modules provide additional flow and/or transport modeling processes, such as to account for preferential flow (the DualPerm module), colloid-facilitated solute transport (the C-Ride module), or the transport of polyfluoroalkyl substances (PFAS; the PFAS module) or fumigant (the Fumigant module) compounds. The HYDRUS models are among the most widely used numerical models for simulating processes in the subsurface. There are many thousands of HYDRUS users worldwide, with many applications (also several thousand) appearing in peer-reviewed international literature and many technical reports.