In the past few years speleological research in Supramonte di Baunei has allowed to discover a subterranean drainage pattern that mostly confirms the hydrogeological hypothesis formulated until now. The fact that the major submarine karst springs of the Gulf have been located (Cala Luna resurgence, Bel Torrente cave, Mudaloro resurgence) and the difficulty in quantifying their flow rate have pushed the Authors to analyse satellite images aiming to verify the possibility to locate the fresh water exits in the sea with a certain precision and also to formulate a methodology for estimating their flow rate. The digital image processing was first of all performed on a series of 7 Landsat TM5 and ETM+ images to enhance thermal anomalies in the spectral band 6. This conventional analysis is strongly affected by spatial resolution and the temperature of the uppermost water layer is very much influenced by the climatic conditions. In this analysis the fresh water outlets cannot be clearly defined using only the thermal band.The transparency analysis instead, seams to give better results at least for the location of the fresh water outlets. In fact, around these outlets the transparency of the water diminishes because of suspended particles and the mixing of salt and fresh water. To be able to analyse all these anomalies an interpretation model that takes into account the climatic and physical conditions of the water should be made
Nuovi dati sull'idrogeologia del Supramonte di Baunei ottenuti mediante la ricerca speleologica e l'analisi di immagini telerilevate
MELIS, MARIA TERESA
2003-01-01
Abstract
In the past few years speleological research in Supramonte di Baunei has allowed to discover a subterranean drainage pattern that mostly confirms the hydrogeological hypothesis formulated until now. The fact that the major submarine karst springs of the Gulf have been located (Cala Luna resurgence, Bel Torrente cave, Mudaloro resurgence) and the difficulty in quantifying their flow rate have pushed the Authors to analyse satellite images aiming to verify the possibility to locate the fresh water exits in the sea with a certain precision and also to formulate a methodology for estimating their flow rate. The digital image processing was first of all performed on a series of 7 Landsat TM5 and ETM+ images to enhance thermal anomalies in the spectral band 6. This conventional analysis is strongly affected by spatial resolution and the temperature of the uppermost water layer is very much influenced by the climatic conditions. In this analysis the fresh water outlets cannot be clearly defined using only the thermal band.The transparency analysis instead, seams to give better results at least for the location of the fresh water outlets. In fact, around these outlets the transparency of the water diminishes because of suspended particles and the mixing of salt and fresh water. To be able to analyse all these anomalies an interpretation model that takes into account the climatic and physical conditions of the water should be made
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