5 Conclusion: The Future Looks Optically Bright!

In closing, the earth sciences have been part of an instrument and computing revolution during the last two decades, often benefiting from advances in other disciplines. Fiber-based hydrogeophysical sensing has moved far beyond single point sensors and now provides truly distributed or high spatial-resolution measurements of temperature, strain, and strain rate. As our remote-sensing colleagues have been able to do for years with high spatial-resolution imagery, now hydrogeologists can resolve thermal and stress-related features at very small spatial scales in the subsurface and relatively high temporal frequency. As in all science, the closer and faster you look, the more you understand the basic physics of processes!

Fiber-based distributed hydrogeophysical sensing has only taken the “low-hanging” fruit to date. Buried optical fiber is ubiquitous across the built environment. Exploiting this unused telecommunication fiber could lead to a low-cost yet high-resolution continuous-monitoring network for infiltration, heat flow and strain. Just as cell-phone signals can be used to infer precipitation rates (Overeem et al., 2011; Overeem et al., 2013), existing infrastructure and tools from other industries should be explored for hydrogeophysical monitoring. The explosion in fiber-based acoustic sensing is just beginning as of this writing, with the seismology community fully embracing this new tool. Hydrogeologists and hydrogeophysicists will be needed to help these other communities understand the role of hydrology in their signals, and we too can learn from the approaches employed by others.