Denudation and geomorphic change in the Anthropocene; a global overview

The effects of human activity on geomorphic processes, particularly those related to denudation/sedimentation, are investigated by reviewing case studies and global assessments covering the past few centuries. Evidence we have assembled from different parts of the world, as well as from the literature, show that certain geomorphic processes are experiencing an acceleration, especially since the mid-twentieth century. This suggests that a global geomorphic change is taking place, largely caused by anthropogenic landscape changes. Direct human-driven denudation (through activities involving excavation, transport, and accumulation of geological materials) has increased by a factor of 30 between 1950 and 2015, representing a ten-fold increase of per capita effect. Direct plus indirectly human-induced denudation (triggered by land surface alteration) is presently at least one order of magnitude greater than denudation due to purely natural processes. The activity of slope movements, which represent an important contribution to denudation, sediment generation and landscape evolution, also shows a clear intensification. Frequency of hazardous events and disasters related to slope movements (an indirect measure of process frequency) in specific regions, as well as at continental and global levels, has grown considerably, in particular after the mid-twentieth century. Intense rainstorm events are often related to slope movement occurrence, but the general increasing trend observed is not satisfactorily explained by climate. Sedimentation has augmented considerably in most regions and all kinds of sedimentation environments. Although the link between denudation and sedimentation is not direct and unequivocal, it is safe to assume that if sedimentation rates increase in different regions during a given period, denudation must have increased too, even though their magnitudes could be different. This augmentation, particularly marked from the second half of the last century onwards, appears to be determined mainly by land surface changes, in conjunction with climate change. The changes observed suggest: a) there is evidence at a global scale of a growing response of geomorphic systems to socio-economic drivers, being Gross Domestic Product density, a good indicator of the human potential to cause such impacts; b) Land use/cover changes enhance effects of climate change on global denudation/sedimentation and landslide/flood frequency, and appear to be a stronger controlling factor; c) Our findings point to the existence of a global geomorphic change. This manifestation of global change is especially evident since the ?great geomorphic acceleration? that began in the middle of the 20th century, and constitutes one of the characteristics of the proposed Anthropocene.This work was supported, at different stages, by projects: FEDER, AEI, CGL2017-82703-R (Ministerio de Ciencia e Investigacion, Spain) and PICT2011-1685; MTM2014-56235-C2-2215 (Ministerio de Ciencia, Tecnología e Innovacion, Argentina). We also thank Dr. Anthony R. Berger for critical review and writing assistance

Vegetation and Geomorphic Connectivity in Mountain Fluvial Systems

Rivers are complex biophysical systems, constantly adjusting to a suite of changing governing conditions, including vegetation cover within their basins. This review seeks to: (i) highlight the crucial role that vegetation’s influence on the efficiency of clastic material fluxes (geomorphic connectivity) plays in defining mountain fluvial landscape’s behavior; and (ii) identify key challenges which hinder progress in the understanding of this subject. To this end, a selective literature review is carried out to illustrate the pervasiveness of the plants’ effects on geomorphic fluxes within channel networks (longitudinal connectivity), as well as between channels and the broader landscape (lateral connectivity). Taken together, the reviewed evidence lends support to the thesis that vegetation-connectivity linkages play a central role in regulating geomorphic behavior of mountain fluvial systems. The manuscript is concluded by a brief discussion of the need for the integration of mechanistic research into the local feedbacks between plants and sediment fluxes with basin-scale research that considers emergent phenomena

Hydrogeomorphic controls on spatial pattern of fish habitat in a mountain stream

Spatial heterogeneity and arrangement of physical habitat strongly influence stream-dwelling organisms. A primary objective of this dissertation was to examine how hydrogeomorphic controls – channel morphology, bed sediment, and flow hydraulics – shape spatial patterns of habitat for small-bodied trout. Two complementary habitat types, spawning and foraging habitat, were investigated to gain more comprehensive understanding of these linkages. A secondary objective of the dissertation was to evaluate the effects of sample size on errors in estimates of hydraulic parameters critical for understanding channel dynamics and quantifying fish habitat. This research was conducted in four reaches of a small mountain stream with different channel morphologies and sediment textures. High resolution field surveys and a hydrodynamic model were used to map channel morphology, sediment, and flow properties. Habitat models, which included a bioenergetic foraging model, were then applied to evaluate fish habitat availability, quality, and disturbance at within and between-reach scales. Results indicated existence of two distinct spawning habitat domains. In coarser reaches with simple morphologies potential spawning substrate occurred only in small, hydraulically sheltered areas, which were also at high risk of disturbance due to excess fine sediment accumulation. In finer, pool-riffle reaches potential spawning substrate covered large proportion of the bed and was largely unaffected by fine sediment disturbance. Bed scour generally did not seem to be an important disturbance agent. During low flow, the most energetically profitable foraging habitat was located in deep, slow-flowing pools and zones of strong lateral gradients of velocity. Cross-channel patterns of net energy intake appeared to vary with fish body size. During high flow, however, energetically profitable habitat occurred mainly near the banks. The mean net energy intake and the proportion of channel area where fish energy budget was positive were somewhat higher in the reaches with better developed pool-riffle morphology, but the former trend partially reversed during high flow. Error analysis indicated that sample sizes commonly used in river science to represent hydraulic variables may generate large sampling errors. Errors of this magnitude in the estimated bed roughness parameter caused substantial differences in the flow field predicted by a hydrodynamic model.Arts, Faculty ofGeography, Department ofGraduat

Sediment transport and channel morphology implications for fish habitat

This chapter reviews the basic principles of sediment transport in streams, channel classification, mountain channel morphology, and associated implications for fish spawning habitats. Local sediment transport processes construct the differing channel morphologies, which are often opportunistically used by spawning fish. Sediment load in streams can be transported in various ways. Dissolved load corresponds to material transported in solution with the fluid, whose concentration depends primarily on the geochemical character of basin geologic materials, and the dissolution of these materials by groundwater flow. Sediment sources in river basins can be distinguished as two types for timescales ranging from individual floods to many flood seasons. Sediment resting on the streambed will move, or become entrained, when the overlying fluid pressure, or shear stress, exceeds some threshold value. Lumped empirical or semi-empirical expressions have been widely used to compute bedload transport rates. Sediment transport and channel morphology are important components of physical habitat for aquatic biota in rivers.Peer ReviewedPostprint (published version

Simulated instream restoration structures offer smallmouth bass (Micropterus dolomieu) swimming and energetic advantages at high flow velocities

Restoration practices aimed at fish habitat enhancement often include installation of instream structures. However, mixed outcomes have been reported regarding structure effectiveness, while mechanisms underlying success remain unclear. The interactions between fish and flow conditions generated by instream structures and their subsequent impact on fish energetics may provide some insight. This study seeks to quantify how restoration structures, simulated by cylinders in three orientations, alter the energetics and swimming stability of smallmouth bass (Micropterus dolomieu). Accelerometers measured swimming stability while a respirometer measured energy expenditure at multiple velocities. Particle image velocimetry was used to characterize flow fields behind structures. Structures generated flow conditions that benefited fish energetically. Fish had a smoother gait and expended less energy when swimming near a structure, regardless of its orientation. Benefits varied with flow conditions; reductions in energy expenditure were especially apparent at high flow velocities. Results suggest that restoration structures may be most energetically beneficial in stream systems with consistently high velocities and inform restoration by indicating flow conditions in which structures provide the greatest energetic benefits for fish.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

The Sarmatian Review, Vol. 19, No. 1

Contents: "SR INDEX"; Abraham J. Peck, "'The Two Saddest Nations on Earth:’ Poles, Jews and Memory"; Ewa M. Thompson, "Poles in Jewish Discourse: The Disabling Mode"; "BOOKS"; "Judith Olsak-Glass, "Poland’s Holocaust (review)"; "Piotr Wilczek, "Jesuits in Poland according to A.F. Pollard (review article)"; Anna M. Cienciala, "On Interpreting ‘East European’ History (review article)"; James R. Thompson, "Thaddeus Kosciuszko (review)"; "LETTERS"; "About the Authors

The Sarmatian Review, Vol. 20, No. 3

Contents: "SR INDEX"; Marcus D. Leuchter, "Reflections on the Holocaust"; Milan Jazbec, "The Small New States in Europe after the Fall of the Berlin Wall and Their Diplomacies"; "BOOKS"; Piotr Wilczek, "Speaking Volumes about Poles" (review); "LETTERS" (Anna Dadlez, Anna Cienciala, Rodi Wout, Barbara Denys, Maryann Wojciechowski); "About the Authors"; Walenty Tyszkiewicz, "Polish Diaspora in Turkmenistan: A Colonial Narrative"; "LECTURE ANNOUNCEMENT