15.5 Concluding Remarks
The method developed here has been shown to be viable for detecting SWC for
specific landcover types (i.e., dense forests, sparse forests, bare field, and potato
fields). Generally, good agreement was obtained between WI and fieldmeasurement and modeled SWC, with r
2 -values ranging in between 65 % and
99 %. Our analysis has also shown the potential of using the method as an indirect
measure of SWC in forest-dominated landscapes, where C-band radar signals have
been shown to be most directly influenced by vegetation-cover water content. This
is because radar-signal penetration into the forest is limited to a small fraction of the
upper canopy. This indirect measurement of SWC is possible because of the
equilibrium established between foliage water content and SWC under normal,
non-stressed conditions. Further research is needed to evaluate the usefulness of the
method in other areas of the world.
Acknowledgements The RADARSAT-1 ScanSAR images of this study were made available at
subsidized rates from the Canadian Space Agency under the administration of the “Data Research
Use Program”. We would like to thank Mr. Don Coleman, Meteorological Service of Canada, for
providing the field measurements of SWC, and Dr. Yang Qi (University of Winnipeg) for
conducting the SWAT-model runs and for making the results of her work available for incorporation in our paper.
References
ALTRIX Systems (2000) Extraction of beta nought and sigma nought from RADARSAT.
ALTRIX Systems, Rep. AS97-5001 Rev. 4
Arnold JG, Srinivasan R, Muttiah RS, Williams JR (1998) Large area hydrologic modeling and
assessment – part 1: model development. J Am Water Resour Assoc 34:73–89
Baghdadi N, Camus P, Beaugendre N, Issa OM, Zribi M, Desprats JF, Rajot JL, Abdallah C,
Sannier C (2011) Estimating surface soil moisture from TerraSAR-X data over two small
catchments in the Sahelian Part of Western Niger. Remote Sens 3:1266–1283
Bamler R (2000) Principles of synthetic aperture radar. Surv Geophys 21:147–157
Boisvert JB, Pultz TJ, Brown RJ, Brisco B (1996) Potential of synthetic aperture radar for largescale soil moisture monitoring: a review. Can J Remote Sens 22:2–13
Bourque CP-A, Meng F-R, Gullison JJ, Bridgland J (2000) Biophysical and potential vegetation
growth surfaces for a small watershed in northern Cape Breton Island, Nova Scotia, Canada.
Can J For Res 30:1179–1195
Bourque CP-A, Cox RM, Allen DJ, Arp PA, Meng F-R (2005) Spatial extent of winter thaw events
in eastern North America: historical weather records in relation to yellow birch decline. Glob
Chang Biol 11:1477–1492
Fotelli MN, Geßler A, Peuke AD, Rennenberg H (2001) Drought affects the competitive interactions between Fagus sylvatica seedlings and an early successional species, Rubus fruticosus:
responses of growth, water status and δ
13
C composition. New Phytol 151:427–435
Grier CC, Running SW (1977) Leaf area of mature northwestern coniferous forests: relation to site
water balance. Ecology 58:893–899
15 Development of a New Wetness Index Based on RADARSAT-1 ScanSAR Data
313
The method developed here has been shown to be viable for detecting SWC for
specific landcover types (i.e., dense forests, sparse forests, bare field, and potato
fields). Generally, good agreement was obtained between WI and fieldmeasurement and modeled SWC, with r
2 -values ranging in between 65 % and
99 %. Our analysis has also shown the potential of using the method as an indirect
measure of SWC in forest-dominated landscapes, where C-band radar signals have
been shown to be most directly influenced by vegetation-cover water content. This
is because radar-signal penetration into the forest is limited to a small fraction of the
upper canopy. This indirect measurement of SWC is possible because of the
equilibrium established between foliage water content and SWC under normal,
non-stressed conditions. Further research is needed to evaluate the usefulness of the
method in other areas of the world.
Acknowledgements The RADARSAT-1 ScanSAR images of this study were made available at
subsidized rates from the Canadian Space Agency under the administration of the “Data Research
Use Program”. We would like to thank Mr. Don Coleman, Meteorological Service of Canada, for
providing the field measurements of SWC, and Dr. Yang Qi (University of Winnipeg) for
conducting the SWAT-model runs and for making the results of her work available for incorporation in our paper.
References
ALTRIX Systems (2000) Extraction of beta nought and sigma nought from RADARSAT.
ALTRIX Systems, Rep. AS97-5001 Rev. 4
Arnold JG, Srinivasan R, Muttiah RS, Williams JR (1998) Large area hydrologic modeling and
assessment – part 1: model development. J Am Water Resour Assoc 34:73–89
Baghdadi N, Camus P, Beaugendre N, Issa OM, Zribi M, Desprats JF, Rajot JL, Abdallah C,
Sannier C (2011) Estimating surface soil moisture from TerraSAR-X data over two small
catchments in the Sahelian Part of Western Niger. Remote Sens 3:1266–1283
Bamler R (2000) Principles of synthetic aperture radar. Surv Geophys 21:147–157
Boisvert JB, Pultz TJ, Brown RJ, Brisco B (1996) Potential of synthetic aperture radar for largescale soil moisture monitoring: a review. Can J Remote Sens 22:2–13
Bourque CP-A, Meng F-R, Gullison JJ, Bridgland J (2000) Biophysical and potential vegetation
growth surfaces for a small watershed in northern Cape Breton Island, Nova Scotia, Canada.
Can J For Res 30:1179–1195
Bourque CP-A, Cox RM, Allen DJ, Arp PA, Meng F-R (2005) Spatial extent of winter thaw events
in eastern North America: historical weather records in relation to yellow birch decline. Glob
Chang Biol 11:1477–1492
Fotelli MN, Geßler A, Peuke AD, Rennenberg H (2001) Drought affects the competitive interactions between Fagus sylvatica seedlings and an early successional species, Rubus fruticosus:
responses of growth, water status and δ
13
C composition. New Phytol 151:427–435
Grier CC, Running SW (1977) Leaf area of mature northwestern coniferous forests: relation to site
water balance. Ecology 58:893–899
15 Development of a New Wetness Index Based on RADARSAT-1 ScanSAR Data
313