The Experts below are selected from a list of 2865 Experts worldwide ranked by ideXlab platform
Sergio Fagherazzi - One of the best experts on this subject based on the ideXlab platform.
-
numerical models of salt marsh Evolution ecological geomorphic and climatic factors
Reviews of Geophysics, 2012Co-Authors: Sergio Fagherazzi, Glenn R. Guntenspergen, Matthew L Kirwan, Stijn Temmerman, Andrea Dalpaos, Simon M Mudd, Johan Van De Koppel, John M Rybczyk, Enrique ReyesAbstract:Salt marshes are delicate Landforms at the boundary between the sea and land. These ecosystems support a diverse biota that modifies the erosive characteristics of the substrate and mediates sediment transport processes. Here we present a broad overview of recent numerical models that quantify the formation and Evolution of salt marshes under different physical and ecological drivers. In particular, we focus on the coupling between geomorphological and ecological processes and on how these feedbacks are included in predictive models of Landform Evolution. We describe in detail models that simulate fluxes of water, organic matter, and sediments in salt marshes. The interplay between biological and morphological processes often produces a distinct scarp between salt marshes and tidal flats. Numerical models can capture the dynamics of this boundary and the progradation or regression of the marsh in time. Tidal channels are also key features of the marsh landscape, flooding and draining the marsh platform and providing a source of sediments and nutrients to the marsh ecosystem. In recent years, several numerical models have been developed to describe the morphogenesis and long-term dynamics of salt marsh channels. Finally, salt marshes are highly sensitive to the effects of long-term climatic change. We therefore discuss in detail how numerical models have been used to determine salt marsh survival under different scenarios of sea level rise.
-
the legacy of initial conditions in landscape Evolution
Earth Surface Processes and Landforms, 2012Co-Authors: Taylor J Perron, Sergio FagherazziAbstract:Landscapes subject to constant forcing tend to evolve toward equilibrium states in which individual Landforms have similar characteristics. Yet, even in landscapes at or near equilibrium, there can be significant variability among individual Landforms. Furthermore, sites subject to similar processes and conditions can have different mean Landform characteristics. This variability is often ascribed to on-going transient Evolution, or to heterogeneity in processes, material properties, forcing, or boundary conditions. Three surprising outcomes of Landform Evolution models suggest, however, that such variability could arise in equilibrium landscapes without any heterogeneity in the physical processes shaping the topography. First, homogeneous systems subjected to constant forcing can generate a heterogeneous distribution of equilibrium Landforms. Second, even simple non-linear systems can have multiple stable equilibrium states. Third, evolving landscapes can exhibit path dependence and hysteresis. We show how these three mechanisms can produce variability in Landforms that arises from the characteristics of the initial topographic surface rather than from heterogeneity in geomorphic processes. Numerical experiments on the formation of low-order fluvial valleys and transportational cyclic steps in erodible streambeds illustrate why it is important to consider the influence of initial conditions when comparing models with natural topography, estimating the uncertainty of model predictions, and studying how landscapes respond to disturbances. Copyright © 2011 John Wiley & Sons, Ltd.
-
models of deltaic and inner continental shelf Landform Evolution
Annual Review of Earth and Planetary Sciences, 2007Co-Authors: Sergio Fagherazzi, Irina OvereemAbstract:AbstractThe morphology of passive continental shelves is dictated by the input of sediments from rivers and their redistribution by waves, currents, and gravity-driven flows. The pathways followed by sediments sculpt a landscape whose diversity is rarely matched on Earth's surface. Sediments are released to the shelf from triangularly shaped, elongated, and dendritic deltas. Barrier islands rise from gently sloping areas, tidal channels dissect flats and saltmarshes, fine sediments form broad convex deposits, and shallow submarine valleys convey sediments and water to the deep ocean. This morphological diversity is based on two main building elements: water and sediments. Fluxes of water and sediments are particularly suitable to be modeled with numerical methods based on the continuum hypothesis and hydrodynamics theory. In recent years, a series of models have been developed to explore and understand the formation of shelf Landforms from the dynamics of sediment transport. Herein we present an overview ...
Stefan Hergarten - One of the best experts on this subject based on the ideXlab platform.
-
modeling glacial and fluvial Landform Evolution at large scales using a stream power approach
Earth Surface Dynamics, 2021Co-Authors: Stefan HergartenAbstract:Abstract. Modeling glacial Landform Evolution is more challenging than modeling fluvial Landform Evolution. While several numerical models of large-scale fluvial erosion are available, there are only a few models of glacial erosion, and their application over long time spans requires a high numerical effort. In this paper, a simple formulation of glacial erosion which is similar to the fluvial stream-power model is presented. The model reproduces the occurrence of overdeepenings, hanging valleys, and steps at confluences at least qualitatively. Beyond this, it allows for a seamless coupling to fluvial erosion and sediment transport. The recently published direct numerical scheme for fluvial erosion and sediment transport can be applied to the entire domain, where the numerical effort is only moderately higher than for a purely fluvial system. Simulations over several million years on lattices of several million nodes can be performed on standard PCs. An open-source implementation is freely available as a part of the Landform Evolution model OpenLEM.
-
a stream power law for glacial erosion and its implementation inlarge scale Landform Evolution models
Earth Surface Dynamics Discussions, 2021Co-Authors: Stefan HergartenAbstract:Abstract. Modeling glacial Landform Evolution is more challenging than modeling fluvial Landform Evolution. While several numerical models of large-scale fluvial erosion are available, there are only a few models of glacial erosion, and their application over long time spans requires a high numerical effort. In this paper, a simple formulation of glacial erosion which is similar to the fluvial stream-power model is presented. The model reproduces the occurrence of overdeepenings, hanging valleys, and steps at confluences at least qualitatively. Beyond this, it allows for a seamless coupling to fluvial erosion and sediment transport. The recently published direct numerical scheme for fluvial erosion and sediment transport can be applied to the entire domain, where the numerical effort is only moderately higher than for a purely fluvial system. Simulations over several million years on lattices of several million nodes can be performed on standard PCs. An open-source implementation is freely available as a part of the Landform Evolution model OpenLEM.
Garry Willgoose - One of the best experts on this subject based on the ideXlab platform.
-
laboratory simulation of the salt weathering of schist 1 weathering of schist blocks in a seasonally wet tropical environment
Earth Surface Processes and Landforms, 2006Co-Authors: T Wells, Garry Willgoose, Phillip Binning, G R HancockAbstract:Data describing sediment generation focusing on the temporal Evolution of size gradation are required for the prediction of long-term Landform Evolution. This paper presents such data for the salt weathering of a quartz-chlorite schist obtained from the Ranger Uranium Mine in northern Australia. Rock fragment samples are subjected to three different climate regimes: (1) a dry season climate; (2) a wet season climate (both based on observations at the Ranger site); and (3) an oven-drying sequence designed to test the sensitivity of the weathering process by exposing the rocks to more extreme temperatures. Two MgSO4 salt solutions are applied, one being typical of wet season runoff and the other a more concentrated solution. Salt solution is applied daily in the wet season experiments and once only at the beginning of the dry season experiments. Results of the experiments reveal four stages of weathering. The kinetics of each stage are described and related to the formation of sediment of different sizes. Wet season climate conditions are shown to produce greater moisture variability and lead to faster weathering rates. However, salt concentrations in the wet season are typically lower and so when climate is combined with observed salt concentrations, the dry and wet season experiments weather at approximately equal rates. Finally, small variations in rock properties were shown to have a large impact on weathering rates, leading to the conclusion that rock weathering experiments need to be carefully designed if results are to be used to help predict weathering behaviour at the landscape scale. Copyright © 2006 John Wiley & Sons, Ltd.
-
mathematical modeling of whole landscape Evolution
Annual Review of Earth and Planetary Sciences, 2005Co-Authors: Garry WillgooseAbstract:▪ Abstract The mathematical modeling of Landform Evolution consists of two components: the processes represented (i.e., considered dominant) in the model and the (typically computer) model representation of these processes. This review discusses the current debates surrounding processes represented in Landform Evolution. The potential impact on both evolving Landforms and computer model structure is discussed. Issues specifically discussed include (a) the fundamental nature of mass conservation and the role of detachment- and transport-limited processes in mass conservation equations, (b) the interaction between detachment- and transport-limitation in channels, (c) the role of hillslope erosion and soil properties and their interaction with channel processes, (d) the interactions with tectonics when applying these models at large scale, (e) depositional structures and implications for paleo-climatic interpretation, (f) engineering applications of these models, and (g) numerical issues in the computer imp...
-
medium term erosion simulation of an abandoned mine site using the siberia landscape Evolution model
Soil Research, 2000Co-Authors: G R Hancock, Garry Willgoose, K G Evans, D R Moliere, M J Saynor, R J LochAbstract:This study forms part of a collaborative project designed to validate the long-term erosion predictions of the SIBERIA Landform Evolution model on rehabilitated mine sites. The SIBERIA catchment Evolution model can simulate the Evolution of Landforms resulting from runoff and erosion over many years. SIBERIA needs to be calibrated before evaluating whether it correctly models the observed Evolution of rehabilitated mine Landforms. A field study to collect data to calibrate SIBERIA was conducted at the abandoned Scinto 6 uranium mine located in the Kakadu Region, Northern Territory, Australia. The data were used to fit parameter values to a sediment loss model and a rainfall–runoff model. The derived runoff and erosion model parameter values were used in SIBERIA to simulate 50 years of erosion by concentrated flow on the batters of the abandoned site. The SIBERIA runs correctly simulated the geomorphic development of the gullies on the man-made batters of the waste rock dump. The observed gully position, depth, volume, and morphology on the waste rock dump were quantitatively compared with the SIBERIA simulations. The close similarities between the observed and simulated gully features indicate that SIBERIA can accurately predict the rate of gully development on a man-made post-mining landscape over periods of up to 50 years. SIBERIA is an appropriate model for assessment of erosional stability of rehabilitated mine sites over time spans of around 50 years.
Jingdong Zhao - One of the best experts on this subject based on the ideXlab platform.
-
quaternary glaciations and glacial Landform Evolution in the tailan river valley tianshan range china
Quaternary International, 2015Co-Authors: Jingdong Zhao, Jie Wang, Jonathan M Harbor, Shiyin Liu, Xiufeng YinAbstract:Abstract The Tailan River originates on the southern slope of Tumur Peak, the largest center of modern glaciation in the Tianshan Range. Five moraine complexes and associated fluvioglacial deposits in this valley record a complex history of Quaternary glacial cycles and Landform Evolution. Electron spin resonance (ESR) dating of glacial sediments was carried out using germanium (Ge) centers in quartz grains, which are sensitive to both sunlight and grinding. Based on the dating results as well as geomorphic and stratigraphic data, the Piyazilike end moraines (the second moraine complex) were deposited during Neoglaciation (the largest glacial advances during the last 3–4 ka in western China) and an early Holocene glacial advance, the third set of moraines was deposited in marine isotope stage (MIS) 2–4, and the glacial Landforms of the Tailan glaciation (the fourth moraine complex), which include hummocky moraines on the piedmont, were formed in MIS 6 (penultimate glaciation). The end moraines of the innermost moraine complex (the first moraine complex) are inferred to have been deposited during the Little Ice Age (LIA). Thus the Landforms and dates indicate compound valley glaciers from the LIA to MIS 2–4, and piedmont glaciers during MIS 6. The oldest tills studied belong to the “Kokdepsang Glacial Stage”, and occur on a high plateau. Based on similar glacial Landforms (glacial deposits on a high plateau and a high glacial terrace) and their ESR ages in adjacent valleys on the southern slope of Tumur Peak, the Kokdepsang Glacial Stage is assigned to MIS 12.
-
osl and esr dating of glacial deposits and its implications for glacial Landform Evolution in the bogeda peak area tianshan range china
Quaternary Geochronology, 2012Co-Authors: Jingdong Zhao, Shiyin Liu, Zhongping Lai, Yougui Song, Xiufeng YinAbstract:The Bogeda Peak area is the largest center of modern glaciation in the eastern Tianshan range in China. Four moraine complexes and associated fluvioglacial deposits are well preserved in the valleys, indicating multiple Quaternary glaciations in this region. Optically stimulated luminescence (OSL) and electron spin resonance (ESR) dating were used to determine the ages of the glacial tills and associated sediments in the Gubanbogeda and Heigou valleys. A total of eighteen samples were collected from moraines and fluvioglacial deposits. Fourteen samples were dated using OSL with a single-aliquot regenerative-dose (SAR) protocol, and the other four samples were analyzed by ESR dating of germanium (Ge) centers in quartz grains, which are sensitive to both sunlight and grinding. The results indicate that the fluvioglacial deposits are more suitable for OSL dating than the tills. Most ages show good agreement with the geological setting and field investigations, and the OSL and ESR ages are consistent with each other for the samples collected from the fourth set of moraines. Based on the ages as well as geomorphic and stratigraphic, the first and second moraine complexes of the Bogeda Peak area were deposited during the Little Ice Age (LIA) and Neoglaciation respectively. The low and high glacial terraces of the third set of moraines in the Gubanbogeda and Heigou valleys were deposited during marine oxygen isotope stages (MIS) 2 and 4. The fourth set of moraines has MIS 6 ages associated with the penultimate glaciation.
Xiufeng Yin - One of the best experts on this subject based on the ideXlab platform.
-
quaternary glaciations and glacial Landform Evolution in the tailan river valley tianshan range china
Quaternary International, 2015Co-Authors: Jingdong Zhao, Jie Wang, Jonathan M Harbor, Shiyin Liu, Xiufeng YinAbstract:Abstract The Tailan River originates on the southern slope of Tumur Peak, the largest center of modern glaciation in the Tianshan Range. Five moraine complexes and associated fluvioglacial deposits in this valley record a complex history of Quaternary glacial cycles and Landform Evolution. Electron spin resonance (ESR) dating of glacial sediments was carried out using germanium (Ge) centers in quartz grains, which are sensitive to both sunlight and grinding. Based on the dating results as well as geomorphic and stratigraphic data, the Piyazilike end moraines (the second moraine complex) were deposited during Neoglaciation (the largest glacial advances during the last 3–4 ka in western China) and an early Holocene glacial advance, the third set of moraines was deposited in marine isotope stage (MIS) 2–4, and the glacial Landforms of the Tailan glaciation (the fourth moraine complex), which include hummocky moraines on the piedmont, were formed in MIS 6 (penultimate glaciation). The end moraines of the innermost moraine complex (the first moraine complex) are inferred to have been deposited during the Little Ice Age (LIA). Thus the Landforms and dates indicate compound valley glaciers from the LIA to MIS 2–4, and piedmont glaciers during MIS 6. The oldest tills studied belong to the “Kokdepsang Glacial Stage”, and occur on a high plateau. Based on similar glacial Landforms (glacial deposits on a high plateau and a high glacial terrace) and their ESR ages in adjacent valleys on the southern slope of Tumur Peak, the Kokdepsang Glacial Stage is assigned to MIS 12.
-
osl and esr dating of glacial deposits and its implications for glacial Landform Evolution in the bogeda peak area tianshan range china
Quaternary Geochronology, 2012Co-Authors: Jingdong Zhao, Shiyin Liu, Zhongping Lai, Yougui Song, Xiufeng YinAbstract:The Bogeda Peak area is the largest center of modern glaciation in the eastern Tianshan range in China. Four moraine complexes and associated fluvioglacial deposits are well preserved in the valleys, indicating multiple Quaternary glaciations in this region. Optically stimulated luminescence (OSL) and electron spin resonance (ESR) dating were used to determine the ages of the glacial tills and associated sediments in the Gubanbogeda and Heigou valleys. A total of eighteen samples were collected from moraines and fluvioglacial deposits. Fourteen samples were dated using OSL with a single-aliquot regenerative-dose (SAR) protocol, and the other four samples were analyzed by ESR dating of germanium (Ge) centers in quartz grains, which are sensitive to both sunlight and grinding. The results indicate that the fluvioglacial deposits are more suitable for OSL dating than the tills. Most ages show good agreement with the geological setting and field investigations, and the OSL and ESR ages are consistent with each other for the samples collected from the fourth set of moraines. Based on the ages as well as geomorphic and stratigraphic, the first and second moraine complexes of the Bogeda Peak area were deposited during the Little Ice Age (LIA) and Neoglaciation respectively. The low and high glacial terraces of the third set of moraines in the Gubanbogeda and Heigou valleys were deposited during marine oxygen isotope stages (MIS) 2 and 4. The fourth set of moraines has MIS 6 ages associated with the penultimate glaciation.
