Assessments of Impacts and Adaptations to Climate Change in Multiple Regions and Sectors: Data, Methods and Synthesis Activity
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This portion of the website provides brief descriptions of software and computer models that are useful in impacts, adaptation, and vulnerability assessments. Sections cover climate, agricultural, water resource, and ecosystem software tools. Note that this page does not include software tools such as geographic information systems, data management, data analysis and statistical software packages, which are being utilized across the AIACC projects.

Simple Climate Models and Data Analysis Tools

CLIMLAB 2000 was developed in conjunction with International Research Institute for Climate Prediction’s Training Courses. It is a tool that can be used to perform statistical analysis, data management (i.e. compute anomalies, seasonal values, etc.) display data and results (x-y plots, time series, histograms, contour plots, etc.), and compute more complex statistical analysis on climate data. A database of global sea surface temperatures is included with the software, along with instructions on how users can add their own datasets.

MAGICC – Model for the Assessment of Greenhouse-gas Induced Climate Change

MAGICC is a set of linked simple models that, collectively, fall in the genre of a simple climate model. MAGICC is not a General Circulation Model (GCM), but it uses a series of reduced-form models to emulate the behavior of fully three-dimensional, dynamic GCMs. MAGICC calculates the annual-mean global surface air temperature and global-mean sea-level implications of emissions scenarios for greenhouse gases and sulfur dioxide. Users are able to choose which emissions scenarios to use, or to define their own, and also to alter a number of model parameters to explore uncertainty. The model has been widely used by the IPCC in their various assessments.

SCENGEN – Global and Regional SCENario GENerator

SCENGEN, a global and regional scenario generator, is not a climate model; rather it is a simple database that contains the results of a large number of GCM experiments, as well as one observed global and four regional climate data sets. These various data fields are manipulated by SCENGEN, using the information about the rate and magnitude of global warming supplied by MAGICC and directed by the users choice of important climate scenario characteristics. SCENGEN has been developed over a number of years to operate in conjunction with MAGICC, but can be used on its own in a more limited function. SCENGEN has not been officially used by the IPCC, but nearly all of the data sets used by SCENGEN GCMs and observations have been used or assessed in different IPCC assessments including the Third Assessment Report due to be published in 2001.

Agricultural Models
Crop Production

APSIM – Agricultural Production Systems sIMulator.

APSIM is a model that simulates agricultural production systems. It has the ability to integrate models derived in fragmented research efforts. This enables research from one discipline or domain to be transported to the benefit of some other discipline or domain. It also facilitates comparison of models or sub-models on a common platform. This functionality has been achieved via the implementation of a "plug-in-pull-out" approach to APSIM design. APSIM has been developed in a way that allows the user to configure a model by choosing a set of sub-models from a suite of crop, soil and utility modules. Any logical combination of modules can be simply specified by the user "plugging-in" required modules and "pulling out" any modules no longer required.

DSSAT – Decision Support System for Agrotechnology Transfer

DSSAT (pronounced “DEEsat”) is a microcomputer software program combining crop soil and weather databases and programs to manage them, with crop models and application programs, to simulate multi-year outcomes of crop management strategies. As a software package integrating the effects of soil, crop phenotype, weather and management options, DSSAT allows users to ask "what if" questions and simulate results by conducting – in minutes on a desktop computer – experiments which would consume a significant part of an agronomist's career. DSSAT also provides for validation of crop model outputs; thus allowing users to compare simulated outcomes with observed results. Crop model validation is accomplished by inputting the user's minimum data set, running the model, and comparing outputs. By simulating probable outcomes of crop management strategies, DSSAT offers users information with which to rapidly appraise new crops, products, and practices for adoption.

EPIC – Erosion Productivity Impact Calculator

EPIC is designed to quantify the costs of soil erosion and benefits of soil erosion research and control. EPIC is designed to be: capable of simulating the relevant biophysical processes simultaneously, as well as realistically, using readily available inputs and, where possible, accepted methodologies; capable of simulating cropping systems for hundreds of years because erosion can be a relatively slow process; applicable to a wide range of soils, climates and crops; and efficient, convenient to use, and capable of simulating the particular effects of management on soil erosion and productivity in specific environments. The model uses a daily time step to simulate weather, hydrology, soil temperature, erosion-sedimentation, nutrient cycling, tillage, crop management and growth, pesticide and nutrient movement with water and sediment, and field-scale costs and returns.

WOFOST (click on “Products and Publications” à “Models” à “WOFOST”)

WOFOST simulates the daily growth of a specific crop, given the selected weather and soil data. For each simulation, you select specific boundary conditions, which comprise: the crop calendar and the soil's water and nutrient status. WOFOST follows the hierarchical distinction between potential and limited production. Light interception and CO2 assimilation are the growth driving processes, and crop phenological development the growth controlling process. WOFOST helps you: estimate crop production; indicate yield variability; evaluate effects of climate changes or soil fertility changes; and determine limiting biophysical factors.

Water Modeling for Crops

ACRU – Agrohydrological Model of the Agricultural Catchments Research Unit

The ACRU model has its hydrological origins in a distributed catchment evapotranspiration based study carried out in the Natal Drakensberg, South Africa, in the early 1970s. Multi-layer soil water budgeting is accomplished by partitioning and redistribution of soil water. Rainfall or irrigation not abstracted as interception or as stormflow (either rapid response or delayed), first enters through the surface layer and "resides" in the topsoil horizon. When that is "filled" to beyond its drained upper limit (field capacity) the "excess" water percolates into the subsoil horizon(s) as saturated drainage at a rate dependent on respective horizon soil textural characteristics, wetness and other drainage related properties. Should the soil water content of the bottom subsoil horizon of the plant root zone exceed the drained upper limit, saturated vertical drainage/recharge into the intermediate and eventually groundwater stores occurs, from which baseflow may be generated. Unsaturated soil water redistribution, both upwards and downwards, also occurs but at a rate considerably slower than the water movement under saturated conditions, and is dependent, inter alia, on the relative wetnesses of adjacent soil horizons in the root zone. Evaporation takes place from previously intercepted water as well as simultaneously from the various soil horizons, in which case it is either split into separate components of soil water evaporation (from the topsoil horizon only) and plant transpiration (from all horizons in the root zone), or combined, as total evaporation. Evaporative demand on the plant is estimated, inter alia, according to atmospheric demand (through a reference potential evaporation) and the plant's stage of growth. The roots absorb soil water in proportion to the distributions of root mass density of the respective horizons, except when conditions of low soil water content prevail, in which case the relatively wetter horizons provide higher proportions of soil water to the plant in order to obviate plant stress as long as possible.


CROPWAT is meant as a practical tool to help agro-meteorologists, agronomists and irrigation engineers to carry out standard calculations for evapotranspiration and crop water use studies, and more specifically the design and management of irrigation schemes. It allows the development of recommendations for improved irrigation practices, the planning of irrigation schedules under varying water supply conditions, and the assessment of production under rainfed conditions or deficit irrigation. Typical applications of the water balance include the development of irrigation schedules for various crops and various irrigation methods, the evaluation of irrigation practices, as well as rainfed production and drought effects. Calculations of crop water requirements and irrigation requirements are carried out with inputs of climatic and crop data.

PTF – Pedo-Transfer Function

PTF is a simple tool that converts easily obtainable soil data like texture and organic matter into the soil hydraulic functions (pF and Kh cuves) often required for modeling.

SWAP – Soil, Water, Atmosphere and Plant model (click on “Products and Publications” à “Models” à “SWAP”)

SWAP (Soil, Water, Atmosphere and Plant) simulates vertical transport of water, solutes and heat in unsaturated/saturated soils. The program is designed to simulate the transport processes at field scale level and during entire growing seasons. Basic, daily meteorological data are used to calculate daily, potential evaporation according to Penman-Monteith. If basic meteorological data are not available, potential evaporation or reference evaporation can be input. Precipitation may be provided either at a daily basis or at actual intensities. Short-term rainfall data allow the calculation of runoff and preferential flow. Crop growth is simulated by the code WOFOST 6.0 (see separate entry).

Water Resources Modeling
PODIUM – Policy Dialogue Model

PODIUM runs on a personal computer. Policy makers and planners can learn to use it in minutes, to explore vital questions such as: Can we feed ourselves in 2025? and Do we have enough water to irrigate the crops needed to ensure future national food supply and/or food security? The model maps the complex relationships between the numerous factors that affect water and food security, and displays information clearly, in both graphic and tabular formats. Projections for 2025 are determined in relation to 1995 data. Users can revise this data and change any of the variables used by the model.

SWAT – Soil & Water Assessment Tool

SWAT is a river basin scale model developed to quantify the impact of land management practices in large, complex watersheds. The model includes the following components: weather, surface runoff, return flow, percolation, ET, transmission losses, pond & reservoir storage, crop growth & irrigation, groundwater flow, reach routing, nutrient & pesticide loading, water transfer. It includes the following features: daily time step-long term simulations; basins subdivided to account for differences in soils, land use, crops, topography, weather, etc.; basins of several thousand square miles can be studied; soil profile can be divided into ten layers; basin subdivided into sub-basins or grid cells; reach routing command language to route and add flows; hundreds of cells/subbasins can be simulated in spatially displayed outputs; groundwater flow model; SWAT accepts measured data & point sources; and Windows interface.

Water Accounting for Integrated Water Management

The International Water Management Institute’s Water Accounting system provides a clear view of water resources in at the river basin scale – where water is going, how it's being used, and how much remains available for further use. Policy makers, planners and resource managers can use this information to: identify opportunities for saving water and/or increasing water productivity; conceptualize and test interventions in the context of multiple uses of water; develop effective strategies for allocating water among different users; and assess the scope for the development of additional water resources.

VIC – Variable Infiltration Capacity (VIC) Macroscale Hydrologic Model

VIC is a macroscale hydrologic model that solves full water and energy balances. It is a research model and in it's various forms it has been applied to many watersheds including the Columbia River, the Ohio River, the Arkansas-Red Rivers, and the Upper Mississippi Rivers, as well as being applied globally.

Ecosystem Models


The CENTURY model is a general model of plant-soil nutrient cycling which has been used to simulate carbon and nutrient dynamics for different types of ecosystems including grasslands, agricultural lands, forests and savannas. CENTURY is composed of a soil organic matter/decomposition sub-model, a water budget model, a grassland/crop sub-model, a forest production sub-model, and management and events scheduling functions. It computes the flow of carbon, nitrogen, phosphorus, and sulfur through the model's compartments. The minimum configuration of elements is C and N for all the model compartments. The organic matter structure for C, N, P and S are identical, the inorganic components are computed for the specific inorganic compound.

CLUE – Changing Land Use and Estuaries

CLUE is a tool to foster better understanding of the linkages between man's activities on land and the functioning of coastal ecosystems, and is not intended to provide hard and fast answers regarding the consequences of land-use decisions. All biological systems and their component parts are inherently variable and highly interactive. Science strives to see the patterns hidden within the profusion of detail that nature offers, recognizing that its conclusions must be approximations of the truth.

Funding for the AIACC Data, Methods & Synthesis Activity website is provided by the U.S. Agency for International Development (USAID). The opinions expressed are those of the author(s) and do not necessarily reflect the views of USAID. The site is designed and hosted by SEDAC. Copyright© 2004 The Trustees of Columbia University in the City of New York.
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