Modelling the temporal variation in snow-covered area derived from satellite images for simulating/forecasting of snowmelt runoff in Turkey/Modélisation de la variation temporelle de la surface enneigée à partir d'images satellitaires pour la simulation/prévision de l'écoulement de fonte nivale en Turquie

Abstract

Monitoring the change of snow-covered area (SCA) in a basin is vitally important for optimum operation of water resources, where the main contribution comes from snowmelt. A methodology for obtaining the depletion pattern of SCA, which is based on satellite image observations where mean daily air temperature is used, is applied for the 1997 water year and tested for the 1998 water year. The study is performed at the Upper Euphrates River basin in Turkey (10 216 km 2 ). The major melting period in this basin starts in early April. The cumulated mean daily air temperature (CMAT) is correlated to the depletion of snow-covered area with the start of melting. The analysis revealed that SCA values obtained from NOAA-AVHRR satellite images are exponentially correlated to CMAT for the whole basin in a lumped manner, where R 2 values of 0.98 and 0.99 were obtained for the water years 1997 and 1998, respectively. The applied methodology enables the interpolation between the SCA observations and extrapolation. Such a procedure reduces the number of satellite images required for analysis and provides solution for the cloud-obscured images. Based on the image availability, the effect of the number of images on the quality of snowmelt runoff simulations is also discussed. In deriving the depletion curve for SCA, if the number of images is reduced, the timing of image analysis within the snowmelt period is found very important. Analysis of the timing of satellite images indicated that images from the early and middle parts of the melt period are more important.Key words cumulative mean daily temperature; NOAA-AVHRR images; snow-covered area; snowmelt runoff; Turkey Modélisation de la variation temporelle de la surface enneigée à partir d'images satellitaires pour la simulation/prévision de l'écoulement de fonte nivale en Turquie Résumé Suivre l'évolution de la surface enneigée dans un bassin est d'une importance vitale pour la gestion optimale des ressources en eau, lorsque la contribution principale correspond à la fonte nivale. Une méthodologie d'obtention des courbes de diminution de la surface enneigée, qui s'appuie sur des observations satellitaires et qui utilise la température moyenne journalière de l'air, est appliquée à l'année hydrologique 1997 et testée pour l'année hydrologique 1998. L'étude est réalisée pour le bassin supérieur de l'Euphrate, en Turquie (10 216 km 2 ). La période principale de fonte dans ce bassin commence début avril. La température moyenne journalière cumulée de l'air (TMJC) est corrélée avec la réduction de la surface enneigée et avec le début de la fonte. L'analyse montre que les valeurs de surface enneigée obtenues à partir d'images satellitaires NOAA-AVHRR sont corrélées de manière exponentielle avec la TMJC du bassin dans sa globalité, avec des valeurs de R² respectivement égales à 0.98 et 0.99 pour les années hydrologiques 1997 et 1998. La méthodologie appliquée permet de réaliser des interpolations entre les observations de surface enneigée, ainsi que des extrapolations. Une tell...

Use of interactive multisensor snow and ice mapping system snow cover maps (IMS) and artificial neural networks for simulating river discharges in Eastern Turkey

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A novel generative adversarial network‐based super‐resolution approach for face recognition

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