The Varsom Regobs System: Enhancing Natural Hazard Forecasting, Community Preparedness and Recreational Outdoor Activities through In-situ Crowd-Sourcing Observations 

The Varsom platform has been a success in Norway for more than a decade, with users from organizations and the public. It fosters a participatory approach encompassing recreational activities, hazard assessments, emergency preparedness, search and rescue, and forecasting. Here, we will present Varsom Regobs (Registering of Observations), an innovative crowd-sourced system within Varsom enabling registration, sharing, querying, and real-time storage and publication of field observations. Varsom Regobs aids decision-making for the warning services on snow avalanches, landslides, lake ice, and floods at the Norwegian Water Resources and Energy Directorate (NVE). Users utilize the Varsom app, website (www.regobs.no), and API to submit and retrieve diverse in-situ observations on the categories snow, ice, water, and soil, tailoring the level of detail. The app has gained widespread recognition within the community, boasting over 120,000 unique visitors between October 2023 and January 2024. In 2023 alone, a total of 22,000 observations across all categories were submitted. The app and website, available in multiple languages, have gained traction in numerous European countries, recording 500 observations outside Norway in 2023 thanks to the open-access policy. One successful aspect of enhancing natural hazard and hydrology monitoring has been the reciprocal engagement with users, and specific examples showcasing this will be provided. To address trust issues regarding non-academic observers, a star-based quality system has been implemented, aligning with an observer's training courses. Moreover, all users must possess an NVE-account login to submit their observations. Other challenges, such as managing spam-like entries and delicately targeting and engaging specific user groups for each category, will also be highlighted. Examples demonstrating the combined usage of the in-situ Varsom Regobs component, NVE's forecasting models, and NVE’s operational products derived from Copernicus satellite data will be showcased. The Regobs API v.5 ensures the utilization of observations in scientific projects by research institutes and universities. Varsom Regobs stands as a sustained citizen science initiative due to its integration into Norway's operational warning services, serving as an exemplary model for long-term engagement and collaboration.