Development in new technology, big data processing and artificial intelligence creates new possibilities for environmental assessment and analysis, where a virtual model of the ecosystem can simulate and provide evidence of ecosystem health and anthropogenic impact. Digital twins represent a robust approach where predictions and scenarios have also led to an understanding of deeper interconnections and chain processes, and how this vulnerable system responds to human intervention and climate change. Linking to real-time monitoring can increase the response to negative impacts and is applied to disaster risk reduction through improved recovery, policy-making, resilience, forecasting, resource allocation, scenario testing, lessons learned, community engagement, and decision-making. Here, three different examples are presented where a precise 3D model is connected with real-time data and the decision-making process for solving problems in smart cities and urban greenery and forestry, flood disaster management by digital twins, and application of digital twins of the river to detect ecosystem degradation and management.