88,392 research outputs found
Introduction to remote sensing of geomorphology
No full textIn this book you will find chapters reviewing and exploring state-of-the-art remote-sensing techniques relevant to geomorphology. We hope that the chapters will serve as both a reference for experienced practitioners and a guide to geomorphologists looking to use remote-sensing techniques to benefit their studies
Reservoir theory for studying the geochemical evolution of soils
Get PDFLinking mineral weathering rates measured in the laboratory to those measured at the landscape scale is problematic. In laboratory studies, collections of minerals are exposed to the same weathering environment over a fixed amount of time. In natural soils, minerals enter, are mixed within, and leave the soil via erosion and dissolution/leaching over the course of soil formation. The key to correctly comparing mineral weathering studies from laboratory experiments and field soils is to consistently define time. To do so, we have used reservoir theory. Residence time of a mineral, as defined by reservoir theory, describes the time length between the moment that a mineral enters (via soil production) and leaves (via erosion and dissolution/leaching) the soil. Age of a mineral in a soil describes how long the mineral has been present in the soil. Turnover time describes the time needed to deplete a species of minerals in the soil by sediment efflux from the soil. These measures of time are found to be sensitive to not only sediment flux, which controls the mineral fluxes in and out of a soil, but also internal soil mixing that controls the probability that a mineral survives erosion. When these measures of time are combined with published data suggesting that a mineral's dissolution reaction rate decreases during the course of weathering, we find that internal soil mixing, by partially controlling the age distribution of minerals within a soil, might significantly alter the soil's mass loss rate via chemical weathering.</p
An analytical biogeomorphic model for salt-marsh equilibrium states and transient dynamics
No full text
Salt marsh equilibrium states and transient dynamics in response to changing rates of sea level rise and sediment supply
No full textSULLA RISPOSTA DEI SISTEMI DI BARENA AVARIAZIONI DELLA DISPONIBILITÀ DI SEDIMENTO EDEL TASSO DI INCREMENTO DEL LIVELLO MEDIO DEL MARE
No full textIn questa nota si analizza la risposta degli ecosistemi di barena a variazioni della
disponibilità di sedimento, della produttività della vegetazione e del tasso di
incremento del livello medio del mare relativo. L’analisi è condotta sulla base di un
modello analitico puntuale in grado di catturare il ruolo esercitato dai principali
processi di natura fisica e biologica sull’evoluzione ecomorfodinamica dei sistemi di
barena.
Le analisi suggeriscono che i sistemi di barena caratterizzati da elevata
disponibilità di sedimento e produzione di suolo organico rispondono più
rapidamente a variazioni delle forzanti, rispetto a sistemi caratterizzati da modesta
disponibilità di sedimento e produzione organica. Nei sistemi macrotidali, la
risposta delle superfici di barena a variazioni delle forzanti è più rapida che nei
sistemi microtidali. In generale, i risultati del modello suggeriscono che i sistemi di
barena sono più resilienti a diminuzioni del tasso di incremento del livello medio del
mare che ad aumenti, di pari entità, dello stesso tasso. Inoltre, i sistemi di barena
risultano più resilienti ad un incremento, rispetto che ad un decremento, nella
disponibilità di sedimento. Infine, la capacità delle superfici di barena di resistere a
crescenti tassi di incremento del medio mare aumenta all’aumentare della
disponibilità di sedimento, della produzione di suolo organico e dell’ampiezza
dell’onda di marea
Catchment-Averaged Erosion Rates Reveal Signals of Divide Migration and Drainage Capture - Datasets
No full textThis dataset relates to work presented in the article Hoskins A., Attal M., Mudd S., Castillo M., 'Catchment-Averaged Erosion Rates Reveal Signals of Divide Migration and Drainage Capture' (in submission).
Abstract: Divide migration and drainage capture contribute to drainage reorganisation. The relative contributions of each are debated, alongside the extent to which an observable signal of drainage reorganisation may be preserved in quantifiable erosion rates. We numerically model divide migration and drainage capture, and monitor the effects on catchment-averaged erosion rates in the growing (area gaining) and shrinking (area losing) catchments. Divide migration produces a rapid increase in catchment-averaged erosion rates in the headwaters of the growing catchment. However, we find this catchment-averaged erosion rate signal is quickly obscured with increasing distance downstream in non-uniform uplift settings, limiting our ability to detect divide migration through catchment-averaged erosion rate measurements in non-uniform uplift settings. Drainage capture produces the strongest catchment-averaged erosion rate signal immediately adjacent to the point of capture. We find this signal persists in the landscape longest, and without depleting in magnitude, in the area upstream of the point of capture. The Sierra la Laguna mountain range (Mexico) displays substantial evidence of recent and ongoing drainage capture across the main drainage divide, including: beheaded catchments, windgaps, barbed drainages, chi profiles and across divide Gilbert Metrics. We use the Sierra la Laguna to test the detectability of drainage reorganisation related catchment-averaged erosion rate signals in a natural setting. 10Be-derived catchment-averaged erosion rates are found to be twice as fast in the suspected growing catchment headwaters (0.17 mm/yr) relative to the shrinking catchment headwaters (0.09 mm/yr). Catchment-averaged erosion rates, with distance downstream, share similarities with our drainage capture modeling
Modelling the influence of hydroperiod and vegetation on the cross-sectional formation of tidal channels
No full textThe evolution of the cross section of a salt-marsh channel is explored using a numerical model. Deposition on the marsh platform and erosion
and deposition in the channel affect the tidal prism flowing through the cross section, such that the model captures the evolution of the stagee
discharge relationship as the channel and marsh platform evolve. The model also captures the growth of salt-marsh vegetation on the marsh
platform, and how this vegetation affects flow resistance and the rate of sedimentation. The model is utilized to study the influence of hydroperiod
and vegetation encroachment on channel cross section. Numerical results show that a reduction in hydroperiod due to the emergence of
the marsh platform causes an infilling of the channel. Vegetation encroachment on the marsh surface produces an increase in flow resistance and
accretion due to organic and mineral sedimentation, with important consequences for the shape of the channel cross section. Finally, modeling
results indicate that in microtidal marshes with vegetation dominated by Spartina alterniflora, the width-to-depth ratio of the channels decreases
when the tidal flats evolve in salt marshes, whereas the cross-sectional area remains proportional to the tidal peak discharge throughout channel
evolution
Topographic Response to Horizontal Advection in Normal Fault-Bound Mountain Ranges
No full textThis dataset relates to work presented in the article Hoskins A., Attal M., Mudd S., Castillo M., 'Topographic Response to Horizontal Advection in Normal Fault-Bound Mountain Ranges' (in submission)
- …
