review of The influence of Holocene vegetation changes on topography and erosion rates: A case study at Walnut Gulch Experimental Watershed, Arizona

2016 ◽  
Author(s):  
Anonymous
Keyword(s):  
Vegetation Changes ◽  
Erosion Rates ◽  
Walnut Gulch

scholarly journals The influence of Holocene vegetation changes on topography and erosion rates: A case study at Walnut Gulch Experimental Watershed, Arizona

2016 ◽  
Author(s):  
Jon D. Pelletier ◽  
Mary H. Nichols ◽  
Mark A. Nearing
Keyword(s):  
Vegetation Change ◽  
Late Quaternary ◽  
Drainage Density ◽  
Vegetation Changes ◽  
Arid Environments ◽  
Decadal Time Scale ◽  
Erosion Rates ◽  
Order Of Magnitude ◽  
Walnut Gulch ◽  
The Impact

Abstract. Quantifying how landscapes have responded and will respond to vegetation changes is an essential goal of geomorphology. The Walnut Gulch Experimental Watershed offers a unique opportunity to quantify the impact of vegetation changes on landscape evolution over geologic time scales. The Walnut Gulch Experimental Watershed (WGEW) is dominated by grasslands at high elevations and shrublands at low elevations. Paleovegetation data suggest that portions of WGEW higher than approximately 1430 m a.s.l. have been grasslands and/or woodlands throughout the late Quaternary, while elevations lower than 1430 m a.s.l. changed from a grassland/woodland to a shrubland c. 2–4 ka. Elevations below 1430 m a.s.l. have decadal time-scale erosion rates approximately ten times higher, drainage densities approximately three times higher, and hillslope-scale relief approximately three times lower than elevations above 1430 m. We leverage the abundant geomorphic data collected at WGEW over the past several decades to calibrate a mathematical model that predicts the equilibrium drainage density in shrublands and grasslands/woodlands at WGEW. We use this model to test the hypothesis that the difference in drainage density between the shrublands and grassland/woodlands at WGEW is partly the result of a late Holocene vegetation change in the lower elevations of WGEW, using the upper elevations as a control. Model predictions for the increase in drainage density associated with the shift from grasslands/woodlands to shrublands are consistent with measured values. Using modern erosion rates and the magnitude of relief reduction associated with the transition from grasslands/woodlands to shrublands, we estimate the timing of the grassland-to-shrubland transition in the lower elevations of WGEW to be approximately 3 ka, i.e., broadly consistent with paleovegetation studies. Our results provide support for the hypothesis that common vegetation changes in semi-arid environments (e.g. from grassland to shrubland) can change erosion rates by more than an order of magnitude, with important consequences for landscape morphology.

scholarly journals The influence of Holocene vegetation changes on topography and erosion rates: a case study at Walnut Gulch Experimental Watershed, Arizona

2016 ◽  
Vol 4 (2) ◽  
pp. 471-488 ◽  
Author(s):  
Jon D. Pelletier ◽  
Mary H. Nichols ◽  
Mark A. Nearing
Keyword(s):  
Vegetation Change ◽  
Late Quaternary ◽  
Drainage Density ◽  
Vegetation Changes ◽  
Arid Environments ◽  
Erosion Rates ◽  
Order Of Magnitude ◽  
The Difference ◽  
Walnut Gulch ◽  
The Impact

Abstract. Quantifying how landscapes have responded and will respond to vegetation changes is an essential goal of geomorphology. The Walnut Gulch Experimental Watershed (WGEW) offers a unique opportunity to quantify the impact of vegetation changes on landscape evolution over geologic timescales. The WGEW is dominated by grasslands at high elevations and shrublands at low elevations. Paleovegetation data suggest that portions of WGEW higher than approximately 1430 m a.s.l. have been grasslands and/or woodlands throughout the late Quaternary, while elevations lower than 1430 m a.s.l. changed from a grassland/woodland to a shrubland ca. 2–4 ka. Elevations below 1430 m a.s.l. have decadal timescale erosion rates approximately 10 times higher, drainage densities approximately 3 times higher, and hillslope-scale relief approximately 3 times lower than elevations above 1430 m. We leverage the abundant geomorphic data collected at WGEW over the past several decades to calibrate a mathematical model that predicts the equilibrium drainage density in shrublands and grasslands/woodlands at WGEW. We use this model to test the hypothesis that the difference in drainage density between the shrublands and grassland/woodlands at WGEW is partly the result of a late Holocene vegetation change in the lower elevations of WGEW, using the upper elevations as a control. Model predictions for the increase in drainage density associated with the shift from grasslands/woodlands to shrublands are consistent with measured values. Using modern erosion rates and the magnitude of relief reduction associated with the transition from grasslands/woodlands to shrublands, we estimate the timing of the grassland-to-shrubland transition in the lower elevations of WGEW to be approximately 3 ka, i.e., broadly consistent with paleovegetation studies. Our results provide support for the hypothesis that common vegetation changes in semi-arid environments (e.g., from grassland to shrubland) can change erosion rates by more than an order of magnitude, with important consequences for landscape morphology.

scholarly journals MATLAB Virtual Toolbox for Retrospective Rockfall Source Detection and Volume Estimation Using 3D Point Clouds: A Case Study of a Subalpine Molasse Cliff

Geosciences ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 75
Author(s):  
Dario Carrea ◽  
Antonio Abellan ◽  
Marc-Henri Derron ◽  
Neal Gauvin ◽  
Michel Jaboyedoff
Keyword(s):  
Point Cloud ◽  
Natural Hazard ◽  
Point Clouds ◽  
Volume Estimation ◽  
Natural Phenomena ◽  
Frequency Distributions ◽  
Erosion Rates ◽  
3D Point Clouds

The use of 3D point clouds to improve the understanding of natural phenomena is currently applied in natural hazard investigations, including the quantification of rockfall activity. However, 3D point cloud treatment is typically accomplished using nondedicated (and not optimal) software. To fill this gap, we present an open-source, specific rockfall package in an object-oriented toolbox developed in the MATLAB® environment. The proposed package offers a complete and semiautomatic 3D solution that spans from extraction to identification and volume estimations of rockfall sources using state-of-the-art methods and newly implemented algorithms. To illustrate the capabilities of this package, we acquired a series of high-quality point clouds in a pilot study area referred to as the La Cornalle cliff (West Switzerland), obtained robust volume estimations at different volumetric scales, and derived rockfall magnitude–frequency distributions, which assisted in the assessment of rockfall activity and long-term erosion rates. An outcome of the case study shows the influence of the volume computation on the magnitude–frequency distribution and ensuing erosion process interpretation.

Geomorphological controls on vegetation changes: a case study of alluvial fans in southwest of Miami City, Northeastern Iran

2021 ◽  
Vol 14 (5) ◽  
Author(s):  
Sepideh Imeni ◽  
Hasan Sadough ◽  
Shahram Bahrami ◽  
Ahmadreza Mehrabian ◽  
Kazem Nosrati
Keyword(s):  
Vegetation Changes ◽  
Alluvial Fans

Effects of simulated water level management on shore erosion rates. Case study: Baskatong Reservoir, Québec, Canada

2001 ◽  
Vol 28 (3) ◽  
pp. 482-495 ◽  
Author(s):  
Diane Saint-Laurent ◽  
Bachir N Touileb ◽  
Jean-Phillippe Saucet ◽  
André Whalen ◽  
Benoit Gagnon ◽  
...  
Keyword(s):  
Bank Erosion ◽  
Water Levels ◽  
Reservoir Water ◽  
Field Surveys ◽  
Erosion Rates ◽  
Sandy Material ◽  
Water Level Management ◽  
Wave Erosion ◽  
Main Factor

This study was carried out as part of a feasibility study on the construction of a hydroelectric generating station at Mercier dam at the outlet of the Baskatong reservoir in Québec. The study dealt mainly with a comparison of the current and future bank erosion rates of the reservoir. Given the year of impounding of the Baskatong reservoir, i.e., 1927, it was possible to track bank erosion rates using field surveys and photogrammetric and numerical analyses. It was noted that in certain areas, such as Du Diable Bay and Windigo Bay, the Baskatong reservoir banks were substantially affected by erosion. Estimates indicate that the banks have receded by about 10 to 15 m over a 20-year period. The banks most affected by erosion are those containing sandy material of fluvioglacial or glaciolacustrine origin with bluffs greater than 2 m in height and characterized by the longest fetches. In one section of Windigo Bay, banks had receded by about 30 m in 20 years. Wave action is the main factor responsible for bank erosion, especially in areas highly exposed to long fetches. In fact, there is a correlation between bank erosion rates, fetch distribution, and the erosive energy of waves. It has been noted that receding banks with the highest erosion rates are linked to the greatest wave erosion energy. Based on the values obtained using simulated reservoir water levels, while taking into account the future construction of a new generating station, bank erosion rates appear to be comparable to those measured under actual conditions, though erosion rates could increase by about 28–30% in the areas most affected by erosion at the present time.Key words: bank erosion, waves and fetch, erosion rates estimated, Baskatong Reservoir, Québec, Canada.

scholarly journals Thermophilous fringe communities as an indicator of vegetation changes: a case study of the “Murawy Dobromierskie” steppe reserve (Poland)

2015 ◽  
Vol 40 (1) ◽  
pp. 77-104
Author(s):  
Tomasz Szygendowski ◽  
Andrzej Brzeg
Keyword(s):  
Field Studies ◽  
Species Group ◽  
Vegetation Changes ◽  
Collective Group ◽  
Moss Layer ◽  
Fringe Communities ◽  
Notable Increase ◽  
Systematic Group ◽  
Geranion Sanguinei

Abstract In this paper, changes of the non-forest xerothermic vegetation of the “Murawy Dobromierskie” steppe reserve which occurred in the period 1993-2012 are examined. The material comprises 50 relevés, of which 43 date from 2012 and the other 7 - from 1993. Reléves were arranged in 5 analytic tables. A synoptic table was also compiled, and for each syntaxonomical species group distinguished, values of the cover coefficient (C), the collective group share index (G), and the systematic group value (D) were estimated and compared. On the basis of the obtained results, a significant decline in abundancy and/or constancy was observed within the following groups: Ch. Artemisietea vulgaris, Ch. Cirsio-Brachypodion pinnati, Ch. Festuco-Brometea, Ch. Geranion sanguinei, Ch. Koelerio-Corynephoretea, and Ch. Origanetalia and Trifolio-Geranietea sanguinei, whereas for the taxa of the Rhamno-Prunetea, a notable increase in the share of the reserve vegetation was recorded. A sizeable expansion of the moss layer was also observed in this period. The results are discussed with special regard to differences in the methodical background of both field studies.

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