From the webpage:
A project by the United Nations Office for the Coordination of Humanitarian Affairs to make humanitarian data easy to find and use for analysis.
HDX will include a dataset repository, based on open-source software, where partners can share their data spreadsheets and make it easy for others to find and use that data.
HDX brings together a Common Humanitarian Dataset that can be compared across countries and crises, with tools for analysis and visualization.
HDX promotes community data standards (e.g. the Humanitarian Exchange Language) for sharing operational data across a network of actors.
Data from diverse sources always creates opportunities to use topic maps.
The pilot countries include Columbia, Kenya and Yemen so semantic diversity is a reasonable expectation.
BTW, they are looking for volunteers. Opportunities range from data science, development, visualization to the creation of data standards.