Using fiber optics for distributed temperature sensing (DTS) in groundwater-surface water systems
BaCaTeC FlFrom 07/2008 to 12/2009
Principal Investigator: Jan Fleckenstein
The temperature dependency of backscatter from a laser signal sent through a fibre optic cable can be used to measure temperature along the cable with great precision and with high spatial and temporal resolution. This method has typically been used in industrial process control. The recent development of new rugged cables, however, has facilitated the use of this methodology in hydrologic systems. The rich data sets provided by this technique allow new insight into the dynamics of exchange between groundwater and surface waters and are therefore of great interest to environmental research. The rate as well as the temporal and spatial patterns of exchange strongly control the transport of dissolved constituents across the groundwater -surface water interface and biogeochemical transformations at the interface. Those processes in turn control the biogeochemical development of surface waters (e.g. acidification, eutrophication)and affect the mobilization and attenuation of pollutants. Therefore methods to reliably quantify and monitor exchange fluxes between groundwater and surface water are important to evaluate the long term environmental health of aquatic systems. The aim of this project is to facilitate the exchange of ideas and expertise in the use of methodologies to quantify groundwater surface-water exchange and the use of DTS in particular. The USGS currently employs a DTS-system and has long experience in the use of heat as a natural tracer in groundwater surface-water systems. In the first phase of the project an introduction to the use of DTS-systems is planned at a USGS field site. In the second phase a DTS-system will be employed in a groundwater-lake and a wetland-stream system in Germany to characterize and quantify spatial and temporal patterns of exchange and how they affect lake acidification and nutrient export from the wetland.