Open Source

The quality and availability of open access/open source software has grown significantly over the past few years. For example, private entities such as Deltares now have an open source policy regarding some flood models. In addition, leaders in developing risk models in the public sector, such as Geoscience Australia (EQRM, TCRM, TsuDAT, ANUGA) and CAPRA (ERN-Flood, Hurricane, CRISIS2007), are launching and/or helping many other initiatives. As we achieve greater interoperability between modelling tools, we will also achieve a future in which open source and open access modelling tools are connected and adapted to unified multi-risk model platforms and highly customized solutions.

It is important to note the difference between open source and open access and to articulate some of the key reasons why open source provides a more transparent framework than open access software packages. Open source, as the name suggests, refers to a software package model whose source code (programming language) is available for access and viewing. There are various formats for open source, with some software code being directly editable, some viewable but not directly editable, and some requiring registration before viewing. Open access, on the other hand, means that the software package is directly downloadable, but that the source code is not editable or viewable. There are also different forms of open access, including full open access, partial open access (i.e., certain components are open), and partial source code.

“Open” also refers to the fact that payment is not required for using a software package, though for the technical and research community, open source provides a transparent, user-community driven solution beyond the free price. In addition to making access to the software code available free of charge, open source software packages have the following advantages:

• The models and calculations are transparent (not a black box), so the science and assumptions behind the models can be checked and sensitivity analyses undertaken.
• The software allows users to detect and correct errors and to make direct improvements.
• Collaborative development of some packages means that many experts work on improving, and solving problems within, the same models.
• All their processes can be easily replicated and checked, which is critical for validation of the outputs.

Photo credit: Teaser image, Abby Baca, World Bank; Banner image, Miki Fernandez

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