Natural disasters affect hundreds of millions of people worldwide every year. Emergency response efforts depend on the availability of timely information, such the movement and communication behaviours of affected populations. As such, analysis of Call Detail Records (CDRs) collected by mobile phone operators reveal new, real-time insights about human behaviour during such critical events. In this study, mobile phone activity data was combined with remote sensing data to understand how people communicated during severe flooding in the Mexican state of Tabasco in 2009, in order to explore ways that mobile data can be used to improve disaster response. By comparing the mobile data with official population census data, the representativeness of the research was validated. The results of the study showed that the patterns of mobile phone activity in affected locations during and after the floods could be used as indicators of (1) flooding impact on infrastructure and population and (2) public awareness of the disaster. These early results demonstrated the value of a public-private partnership on using mobile data to accurately indicate flooding impacts in Tabasco, thus improving early warning and crisis management.