The modelling process

In an IWRM modelling project the EIA IWRM Modelling tool acts as

  • Data integrator for all project data
  • Spatial scenario assessment tool to explore benefits, costs and impacts of basin management options
  • Planning tool for designing sustainable social, economic and environmental outcomes of basin management, infrastructure and operations measures
  • Communication tool to illustrate basin functions and management option impacts on them

The modelling process consists of five steps. Initially, a baseline model is being build. The baseline model documents the current hydrological status in the basin of interest. Scenario analysis is a cyclic process. 

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Build baseline model


A baseline model is build as the initial step in a modelling project. The outcome of this task is a calibrated base model ready for scenario analysis. The base model consist of basic spatial and temporal data and model controls representing the hydrological system of the basin of interest.

Setup scenarios


Scenario analysis is the core process in an IWRM modelling project. Once the management options have been identified, the model is used to gain an understanding of the hydrological processes in the basin, and determine how the proposed management action will affect these processes.

The management option scenarios are built by altering the base line model and/or modelled scenarios. For this there’s a multitude of options.

Simulate scenarios


The EIA IWRM Modelling Tool consists of the distributed hydrological base model and several coupled components. Each component is flexible so that management alternatives can be incorporated into the model and assessed.

  • Hydrology which enables analysis of the impact of land use changes, water conservation measures and climate change;
  • River flow which enables analysis of water availability, hydropower operations, flooding and flood management;
  • Sediments and erosion which enables analysis of soil conservation measures and reservoir sediment trapping;
  • Reservoir operations which enables analysis of the impact of construction and operation of reservoirs and other water storage infrastructure; and
  • Irrigation and crop yield which enables analysis of altering irrigation and crop planting regimes.

To read more about the key computation methods for each model component of the model, see the Download section.

Impact assessment


Impact assessment is based on scenario results visualization and interpretation. There are three methods for visualisation and analysis of results:

  • Time series illustrate the temporal change of an indicator through time for a point location. Visual representation is in form of charts;
  • Indicator maps illustrate the spatial change of a n indicator for a set time or statistic (e.g. average, max or min) for a set time period. Visual representation is in form of geo-referenced maps; and
  • Animations illustrate the spatial and temporal change of an indicator, the visual representation is in form of georeferenced animations, which can be presented on a map background.