Estimation of water equivalent of the snow cover in Lebanese mountains by means of RADARSAT-1 images

• Published in: Hydrological sciences journal Vol. 50; no. 2; pp. 355 - 370
• Main Authors: Corbane, C, Somma, J, Bernier, M, tin, J P, Gauthier, Y, Dedieu, J P
• Format: Journal Article
• Language: English
• Published: 01.04.2005
• ISSN: 0262-6667
• DOI: 10.1623/hysj.50.2.355.60657

The assessment of the spatial and temporal distribution of water resources in Mediterranean region is crucial for the better management of available resources. In Lebanon in particular, the snow is a crucial parameter for water supply. However, few research works were performed until now to study this potential resource because of difficulties inherent to the measurement of the water volume stored by snow. Remote sensing, and more specifically radar imaging, is the favourite tool for investigating the snow water equivalent. This study aims to assess the potential of synthetic aperture radar (SAR) imaging for estimating the snow water equivalent in relation with eight experimental sites distributed over the high plateaus of the Lebanese mountains. With this purpose, an algorithm was tested, which links the backscattering coefficient to physical parameters of the snow and underlying soil, and which allows to assess the water equivalent from the backscattering ratios of a winter scene and a reference scene taken during a period with no snow. To this end, four RADARSAT images were acquired during winter 2001, concurrently to field observations. The model was developed in Quebec for regions with low relief, whereas relief has a decisive influence on the radar signal and on the geometry of images, in a context of high mountains. Consequently, radiometric and geometric corrections were compulsory in order to reduce distortions dues to topographical effects. The preliminary results corroborate the existence of a series of limitations to the application of the algorithm to the particular conditions of the Lebanese snow cover: heterogeneity, accelerated metamorphism and high content of liquid water.