نتایج جستجو برای: fluvial current
تعداد نتایج: 781632 فیلتر نتایج به سال:
Insights into Titan’s geology and hydrology based on enhanced image processing of Cassini RADAR data
The Cassini Synthetic Aperture Radar has been acquiring images of Titan’s surface since October 2004. To date, 59% of Titan’s surface has been imaged by radar, with significant regions imaged more than once. Radar data suffer from speckle noise hindering interpretation of small-scale features and comparison of reimaged regions for change detection. We present here a new image analysis technique...
The Sahara experienced several humid episodes during the late Quaternary, associated with the development of vast fluvial networks and enhanced freshwater delivery to the surrounding ocean margins. In particular, marine sediment records off Western Sahara indicate deposition of river-borne material at those times, implying sustained fluvial discharges along the West African margin. Today, howev...
Geochemical analysis of suspended sediment is a key requirement in nutrient and contaminant transfer studies, but the collection of fluvial suspended sediment samples is problematic due to the highly episodic nature of its transport. Traditional approaches involve the collection of instantaneous samples, but uncertainties regarding intraand inter-storm variations in sedi ment-associated nutrie...
Biodiversity declined markedly over the past 150 years, with the biodiversity loss in fluvial ecosystems exceeding the global average. River restoration now aims at flood safety while enhancing biodiversity and has had success locally. However, at the scale of large river distributaries, the recovery remained elusive. We quantify changes in biodiversity of protected and endangered species over ...
Reservoirs are manmade habitats, intermediate between rivers and lakes, presenting distinct hydrological and morphometric characteristics, with differential mean water residence time. They also present proper vertical and horizontal organisations, and their evolution depends on several variables acting on different special and temporal scales. The water quality evolution of the Itaipu Reservoir...
Here we report multiple lamniform shark teeth recovered from fluvial sediments in the (Campanian-Maastrichtian) Cerro Fortaleza Formation, Santa Cruz Province, Argentina. This small tooth assemblage is compared to various lamniform sharks possessing similar dental morphologies, including Archaeolamna, Cretalamna, Dwardius, Dallasiella, and Cretodus. Although the teeth share numerous morphologic...
This paper reviews the current GeoAI and machine learning applications in hydrological hydraulic modeling, optimization problems, water quality fluvial geomorphic morphodynamic mapping. effectively harnesses vast amount of spatial non-spatial data collected with new automatic technologies. The fast development provides multiple methods techniques, although it also makes comparisons between diff...
The chemicalmineralogical composition of the sand fractions of mortars found in Roman villas dating from the 1 st century A.C. located in Northern Italy has been investigated by optical microscopy, scanning electron microscopy plus energy dispersive spectroscopy microanalysis and x-ray diffractometry. The petrographic results on the mortar samples have been compared with mineralogical data avai...
A drainage basin simulation model introduced here incorporates creep and threshold slumping and both detachmentand transport-limited fluvial processes. Fluvial erosion of natural slopes and headwater channels is argued to be dominantly detachment-limited. Such slopes undergo nearly parallel retreat and replacement with alluvial surfaces under fixed base level, in contrast with gradual slope dec...
[1] Ground-penetrating radar (GPR) helps to constrain the origin of relict and largely buried fluvial channels in the Bir Kiseiba region of southern Egypt. Our results indicate that the trunk channel to a tributary system identified in Shuttle Imaging Radar data is incised 10–12 m into bedrock, was southwest draining in its final configuration and laterally migrating toward the northwest, and a...
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