Radar remote sensing of the source areas from the Coët-Dan catchment
✍ Scribed by Philippe Gineste; Christian Puech; Philippe Mérot
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 940 KB
- Volume
- 12
- Category
- Article
- ISSN
- 0885-6087
No coin nor oath required. For personal study only.
✦ Synopsis
As interest shifts to the development of models for predicting runo quality, identi®cation of the source areas for runo becomes increasingly important. Active microwave remote sensing has a unique potential for surveying source areas at the catchment scale. Thresholding of the back-scattering coecient was initially proposed but proved unsatisfactory when applied to the ERS-1 SAR multitemporal images acquired during winter 1992 over the CoeÈ t-Dan catchment, concomitantly with ground observations. Dierence images may, instead, allow the wettest part of the catchment to be identi®ed provided that the two images encompass a marked hydrological event. A saturation plot could not however be obtained for each date; the use of a pair of images may be further limited by the residual speckle (although carefully ®ltered using the multitemporal information) and a slight inaccuracy in the SAR image calibration. It is therefore argued that considering the whole temporal back-scatter pro®le would be, at present, a safer approach to the remote sensing of saturated areas. The back-scatter temporal standard deviation appears, in this light, as a possible good indicator of the local saturation likelihood during the period of study: it is based on the fact that saturation develops on parts of the catchment that are wetter than the others through lateral recharge. Possible applications within the TOPMODEL framework are discussed.