Environmental monitoring with remote sensing: thermal imagery

Transcription

1 JOINT SEMINAR Min-North RESEM Environmental monitoring with remote sensing: thermal imagery Pekka M. Rossi University of Oulu, Water Resources and Environmental Engineering Research unit, P.O. Box 4300, FI University of Oulu, Finland Acknowledgements to: Kirsti Korkka-Niemi, Anne Rautio University of Helsinki, Department of Geosciences and Geography

2 Introduction Thermal infrared cameras (TIR) are rapidly becoming more available for surface temperature mapping A feasible method to map groundwater seepage when groundwater and surface water temperatures have variance: in Northern Finland the groundwater temperature in summer can be 4 C and surface waters 20 C Areal TIR imaging has been used to map headwater groundwater dependent ecosystems (GDEs) of boreal aquifers and examples are given how this data can be combined with other study methods In RESEM a treatment wetland was monitored with TIR, first results presented

3 Aquifer case sites Two day areal campaign to map GDEs on two esker areas on August (air temp 22 C) in collaboration with University of Helsinki Rokua esker aquifer 92 km 2 Viinivaara esker aquifer 15 km 2 67 different sized lakes from shorelines, a 4 km 2 pristine bog mire, three discharge streams and a 4 km 2 of esker discharge zone with forestry ditches Flir ThermaCam P-60 with resolution and 24 opening, Flight height 150 m and pixel size ~15 cm

4 Case sites

5 Lakes The lakes were divided to 1. Lakes without thermal signal of seepage 2. Point-type seepage in the thermal image 3. Several point seepages or continuous shore seepage

6 Lakes: Thermal Imaging and GW-SW model Where groundwater reaches lakes, HydroGeoSphere-model and thermal imaging Ala-aho P. et al J Hydrol 522:

7 Streams and ditches The forestry ditches of the peat covered discharge zone had a complex temperature pattern due to groundwater seepage

8 Streams and ditches The forestry ditches of the peat covered discharge zone had a complex temperature pattern due to groundwater seepage Preferential flow points discharging through peatland in the area were identifiable with low temperatures

9 Springs and peatlands In Viinivaara esker study site, the mire bog had unmapped springs km beyond the current groundwater protection area of the esker

10 Springs and peatlands Thermal imaging guiding a stable water isotope sampling campaign classify peatlands to groundwater dependent and rainwater-dominated areas Isokangas et al Water Resour. Res., 53 University of Oulu

11 Mining areas: Treatment wetland Northern trench Water sprinklers Pumping station Natural ditches Southern trench Sprinklers Fig: Sandelin (2015) 11 University of Oulu

12 Treatment wetland: Near infrared imagery 12 University of Oulu

13 Treatment wetland: Near infrared imagery 13 University of Oulu

14 Treatment wetland: Thermal imagery 14 University of Oulu

15 Treatment wetland: Near infrared imaging 15 University of Oulu

16 Treatment wetland: Thermal imagery 16 University of Oulu

17 Conclusions With carefully planned imaging route the TIR resulted to be highly informative method to map different groundwater seepages in varying surroundings TIR interpretation for temperature anomalies can guide more detailed research to cold spots that otherwise could be missed TIR only defines the surface temperature, good understanding of the method and the measured area is needed to prevent false interpretations Dense canopy can be problematic for surface temperature monitoring Combination of TIR and other methods, as stable water isotopes or modelling, can help us to define the role of groundwater in surface water hydrology

18 Thank you!