Field testing a wireless sensor network for reactive environmental monitoring

Wireless sensor network technology promises to reveal fine-grained, dynamic changes in monitored variables of an outdoor landscape. But there are significant problems to be overcome in translating this vision to working systems. This paper describes the design and implementation of a reactive, event driven network for environmental monitoring of soil moisture and evaluates the effectiveness of this solution. A novel feature of our solution is its reactivity to the environment: when rain falls and soil moisture is changing rapidly, measurements are collected frequently, whereas during dry periods between rainfall events measurements are collected much less often. Reactivity allows us to focus on dynamic responses and limit the amount of useless data gathered, as well as improving robustness and network lifetime. The main contribution of the paper is to demonstrate that a reactive sensor network can deliver useful data on soil moisture responses to rainfall. Field trial results on the reactivity, robustness and longevity of the network are evaluated, and future improvements proposed.