The transboundary basin of the Selenga river (the main tributary of Lake Baikal) is characterized by widespread and frequent hazardous events of climatic, hydrological and geomorphological nature. To integrate, display and analyze various data on these events, as well as provide them to the scientific community, a web GIS “Hydrological and environmental safety of the Selenga river basin” has been developed. The structure of the web GIS includes layers and databases that characterize the average long-term and extreme climatic and hydrological conditions in the basin, hazardous processes of hydrological and geomorphological nature, as well as their negative impact on landscapes, settlements and infrastructure. Both external databases and services (long-term weather and hydrological data series, WorldClim 2.0 database, ERA5-Land reanalysis and other) and previously unpublished result of the authors’ studies were used for web GIS content. The web-GIS development is based on open source software and libraries. A feature of the web GIS in comparison with previously published analogues for other river’s basins is an information rich climate section, which allows to assess various manifestations of the observed climate change in the Selenga river basin. Also, the data on several potentially hazardous natural processes like mudflows or aufeis formation are published on the service for the first time. Prospects for the development and improvement of the web GIS are associated with the publication of new GIS layers and databases compiled by the authors, with the development of hazard and risk assessment maps for various types of hazardous hydrological events. In addition, climatic characteristics based on modern ERA5 reanalysis and future climate projections for the 21st century are planned to be published.
