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Monitoring Volumetric Surface Soil Moisture Content at the La Grande Basin Boreal Wetland by Radar Multi Polarization Data
- Source :
- Remote Sensing, Vol 5, Iss 10, Pp 4919-4941 (2013), Remote Sensing; Volume 5; Issue 10; Pages: 4919-4941
- Publication Year :
- 2013
- Publisher :
- MDPI AG, 2013.
-
Abstract
- Understanding the hydrological dynamics of boreal wetland ecosystems (peatlands) is essential in order to better manage hydropower inter-annual productivity at the La Grande basin (Northern Quebec, QC, Canada). Given the remoteness and the huge dimension of the La Grande basin, it is imperative to develop remote sensing monitoring techniques to retrieve hydrological parameters. The main objective of this study is to find out if multi-date and multi-polarization Radar Satellite 2 (RADARSAT-2) (C-band) image analysis could detect seasonal variations of surface soil moisture conditions of the acrotelm. A change detection approach through the use of multi temporal indexes was chosen based on the assumption that the temporal variability of surface roughness and natural vegetation biomass is generally at a much longer time scale than that of surface soil moisture (Δ-Index is based on a reference image that represents dry soil, in order to maximize the sensitivity of σ° to changes in soil moisture with respect to the same location when soil is wet). The Δ-Index approach was tested with each polarization: σ° for fully polarimetric mode (HH, HV, VV) and the cross-polarization coefficient (HV/HH). Results show that the best regression adjustment with regard to surface soil moisture content in boreal wetlands was obtained with the cross-polarization coefficient. The cross-polarization multi-temporal index enables precise volumetric surface soil moisture estimation and monitoring on boreal wetlands, regardless of the influence of vegetation cover and surface roughness conditions (bias was under 1%, standard deviation and RMSE were under 10% for almost all estimation errors). Surface soil moisture estimation was more precise over permanently flooded areas than seasonally flooded ones (standard deviation is systematically greater for the seasonally flooded areas, at all analyzed scales), although the overall quality of the estimation is still precise. Cross-polarization ratio image analysis appears to be a useful mean to exploit radar data spatially, as we were able to relate changes in wetland eco-hydrological dynamics to variations in the intensity of the ratio.
- Subjects :
- Peat
010504 meteorology & atmospheric sciences
0211 other engineering and technologies
Soil science
Wetland
02 engineering and technology
RADARSAT-2
01 natural sciences
boreal wetland
law.invention
remote sensing
law
Surface roughness
cross polarization
Satellite imagery
SAR
soil moisture
Radar
lcsh:Science
Water content
Acrotelm
021101 geological & geomatics engineering
0105 earth and related environmental sciences
Hydrology
geography
geography.geographical_feature_category
15. Life on land
Boreal
General Earth and Planetary Sciences
Environmental science
lcsh:Q
Subjects
Details
- Language :
- English
- ISSN :
- 20724292
- Volume :
- 5
- Issue :
- 10
- Database :
- OpenAIRE
- Journal :
- Remote Sensing
- Accession number :
- edsair.doi.dedup.....cdd625fb841483ccd21c0b42a7e76058