PODIUMSim provides a framework to develop scenarios of water and food supply at river basin, sub-national and national level. It is an interactive tool that runs on a personal computer, and has a Microsoft Excel interface which has been configured using Visual Basic programming language code. PODIUMSim-India is an example of the tool being applied to the major river basins in India.
PODIUMSim is a revised version of the Policy Dialogue Model (PODIUM). In 1999, the International Water Management Institute (IWMI) developed PODIUM as part of the Vision 2025 exercise (IWMI 2000); the model enabled users of different countries to develop scenarios of water and food supply and demand in relation to various policy options. The PODIUM model used cereal production and consumption as the leading indicators of water and food demand.
PODIUMSim expanded the analysis to cover other crop categories and capture the spatial variations, especially in large countries. The model was developed under the Country Policy Support Program (CPSP) of the International Commission on Irrigation and Drainage (ICID) (http://www.icid.org), and can generate scenarios at sub-national level, for example, at river-basin or administrative boundary level. The aggregated results provide the national situation. The model can be used by policy planners, researchers, students and others who are interested in developing water and food supply and demand scenarios under different policy options or hypotheses.
PODIUMSim can explore vital questions such as: Can river basins feed their populations in 2025? What is the food surplus or deficit at sub-national level and, subsequently, at national level? and Do we have enough water to irrigate the crops needed to ensure future national food requirements? It can also help to explore critical planning questions such as those shown below:
- How much improvement in irrigation efficiency would be needed to cover additional water requirements in the future?
- What level of increase in rainfed yield is required if additional food requirements were to be met by increases in rainfed agricultural productivity?
- How much food would a country have to import to feed its population in 2025, if there are no new investments in developing additional water resources?
The model maps the complex relationships between numerous factors (drivers in the model) that affect water and food demand and supply, and produces information in both graphical and tabular formats. Projections for future years are determined in relation to base-year data by the expected changes in the drivers over this period.
PODIUMSim enables users to set goals, such as food production for an adequate level of per capita consumption, and explores ways of reaching that goal: through expansion of the irrigated or rainfed area, increasing cropping intensity or importing more food. Likely scenarios can also be developed in terms of population growth, diets and developments in agriculture and water resources; and then determine the necessary steps that need to be taken to ensure food security and sustainable water use.
PODIUMSim consists of four main components
- Annual consumption-demand scenario development at national level.
- Seasonal production scenario development for irrigated and rainfed agriculture at sub-national or river-basin level.
- Seasonal water demand scenario development for the irrigated sector and annual water demand scenarios for domestic, industrial and environmental sectors at sub-national level.
- Annual water supply scenarios at sub-national level.
The publication, PODIUMSIM-CPSP Report 10, provides details of these components. Each of the components consists of several steps. These steps are embedded in one or several spreadsheets. The PODIUMSim-manual will help users to understand how to navigate between spreadsheets of different components or within components. The manual includes details on how to start the scenario building process for a target year; how to generate scenarios of national consumption; how to formulate scenarios at sub-national level; and get an aggregate picture at the country level.
The future scenarios depend largely on the base-year data and the assumptions made of changes in the drivers from the default scenario. Users are encouraged to adapt the model to suit different river basins and countries, and different base-year and default scenario. The default scenario generally reflects the changes under the “business-as-usual” scenario, where the default drivers are the trends in the recent past. Enquires on the model can be directed to Upali Amarasinghe, Senior Researcher, IWMI (firstname.lastname@example.org).
IWMI (International Water Management Institute). 2000. World water supply and demand: 1995-2025. Draft report. Colombo, Sri Lanka: International Water Management Institute (IWMI). 88p.