Relationships between drainage basin morphology, vegetation, and water availability in an arid, carbonate landscape in Oman

Abstract:

The relation between rainfall, vegetation, and morphological characteristics of watersheds landscapes was studied in an arid, carbonate landscape in southern Oman mountains. Water availability is expressed in terms of vegetation and cloud cover. The cloud cover was quantified from the Landsat QA band clouds pixels, and the vegetation cover was quantified from the Landsat the Normalized Difference Vegetation Index (NDVI). The hypsometric curve integral and the statistical moments of the hypsometric curve were used to determine whether hyper-arid fluvial watersheds are significantly different from seasonally wet watersheds.

Results show that vegetation and cloud periods are correlated , with locations with longer cloud periods also having a longer period with vegetation. The analysis showed that the hypsometric curve and the curve statistical moments could captured the morphological difference between wet areas shaped by sapping and dry areas with a fluvial morphology. The variance analysis of clouds cover, vegetation and hypsometric integral show that the hypsometric integral of the watersheds differs as a function of water availability. Despite their proximity and shared base level, we could separate the watersheds draining these mountain range in two distinct groups based on their bimodal hydrological and morphological characteristics of the watersheds.