Seismic Advances in Process Geomorphology

One of the pillars of geomorphology is the study of geomorphic processes and their drivers, dynamics, and impacts. Like all activity that transfers energy to Earth's surface, a wide range of geomorphic process types create seismic waves that can be measured with standard seismic instruments. Seismic signals provide continuous high-resolution coverage with a spatial footprint that can vary from local to global, and in recent years, efforts to exploit these signals for information about surface processes have increased dramatically, coalescing into the emerging field of environmental seismology. The application of seismic methods has the potential to drive advances in our understanding of the occurrence, timing, and triggering of geomorphic events, the dynamics of geomorphic processes, fluvial bedload transport, and integrative geomorphic system monitoring. As new seismic applications move from development to proof of concept to routine application, integration between geomorphologists and seismologists is key for continued progress. ▪ Geomorphic activity on Earth's surface produces seismic signals that can be measured with standard seismic instruments. ▪ Seismic methods are driving advances in our understanding of the occurrence, triggering, and internal dynamics of a range of geomorphic processes. ▪ Dedicated seismic-based observatories offer the potential to comprehensively characterize geomorphic activity and its impacts across a landscape. ▪ Collaboration between seismologists and geomorphologists is fostering the development of new applications, models, and analysis techniques for geomorphic seismology. Expected final online publication date for the Annual Review of Earth and Planetary Sciences, Volume 50 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Late quaternary palaeoclimates of western India : A geoarchaeological approach

Western India comprises parts of the states of Rajasthan, Gujarat and Maharashtra. This region has varied climate and landscape. Northwestern Rajasthan is an area of internal drainage, with dunes, playas and rocky pediments. The Luni, Sabarmati and Mahi basins to the south of this zone show the influence of both aeolian and fluvial processes. Aeolian landforms are absent in the Nrmada, Tapi, Godavari and Bhima basins and fluvial aggradation has alternated with erosion in response to climatic change. Dominance of semi-arid to arid climate throughtout the Quaternary in the entire region has ment that Quaternary geological processes have been weak, preserving many features of the Tertiary in the present landscape. The variation in the geomorphic processes shaping the landscape and the complex links between geomorphic proceses and climate mean that our understanding of palaeoclimates in western India in far from complete. This paper gives an overview of the Late Quaternary palaeoclimate of western India, based primarily on recent work by the authors in Rajasthan and Maharashtra. Some issues in the palaeoclimatic interpretation of the geological record are discussed. Signatures of Late Pleistocene aridity, fluctuating climate during the Pleistocene Holocene transitional period, early Holocene humid climate and increased aridity from the middle Holocene onwards are reflected in different ways in the different landscape settings.

Scratching the Surface(s): Examining the complexity of geological contexts for the Palaeolithic of the Sonar Basin, Madhya Pradesh

The Sonar River Valley is centrally located in Madhya Pradesh, flanked by rich Palaeolithic and fossiliferous localities in the Son and Narmada Valleys and has historically been overlooked in favour of the latter rivers, that tend to preserve well stratified Quaternary formations along varying portions of their length. Here an attempt is made to look at the Sonar basin through a broader lens, examining the various landforms found in the district of Damoh through which the Sonar flows before joining the Ken. The objective of this paper is threefold: to bring together the geomorphology of the area both in association with and as a result of fluvial action but also as a product of other geomorphic processes; to understand the consequence these processes have on the visibility of the prehistoric archaeological record within the region; and to look at this geoarchaeological relationship in the wider context of some of the major river basins in Madhya Pradesh, notably the Son and Narmada. Secondary sources on geology and geoarchaeology have been integrated with preliminary fieldwork in Districts Damoh and Narsinghpur, and to a smaller extent in Sagar, Chhatarpur and Panna. This work demonstrates the complexity of the South Asian Palaeolithic record that stretches beyond fluvial contexts, in turn helping to spatially expand our understanding of hominin behaviour beyond narrow riverine corridors.

Erosion due to a century of road construction and maintenance at Mount Diablo State Park, California

ABSTRACT Mount Diablo State Park exemplifies many other conservation areas where managers balance the dual missions of protecting natural resources while providing public access. Roads and trails that crisscross the park are etched into the geomorphic surface, capturing and redirecting storm runoff, and presenting both a challenge for soil conservation and a consequence of construction and maintenance. We used field mapping, remote sensing, and modeling to assess erosion along the roads and trails in Mount Diablo State Park, which encompasses the headwaters of several urbanized watersheds. The field mapping in 2011 determined that 56% of the assessed roads and trails required either repair or reconstruction to control erosion and that ~67% of the culverts in the park required either repair or replacement. Aerial photography and modeling showed that other erosion (unrelated to roads or trails) preferentially occurred during wet periods, in specific lithologies, and on convergent slopes. Although lithology and climate drive slope-forming geomorphic processes, we found that the road and trail system (1) expanded the stream network with a capillary-like system of rills, (2) catalyzed prolonged erosion, and (3) altered the timing and pattern of sediment yield. In addition to water-driven erosion during wet periods, road and trail surfaces were subject to mechanical and wind erosion during dry periods. Spatially, dry erosion and runoff both conformed with and crossed topographic gradients by following the road and trail network. Road- and trail-induced erosion occurred across a wider range of rock properties and slope geometries than is typical for other erosion. Hence, the roads and trails have expanded the spatial and temporal boundary conditions over which geomorphic processes operate and, due to continual soil disturbance, have accelerated erosion rates. Although road density is a commonly used metric to rank road-related impacts at watershed scales, it misses both spatial variability and the opportunity to identify specific road and trail segments for remediation. We developed a spatially explicit scoring scheme based on actual erosion and the potential for sedimentation of discrete waterbodies. The data were incorporated into the park’s road and trail management plan in 2016.

Ecosystem Services of Large Wood: Mapping the Research Gap

It is well known that large wood affects geomorphic processes and functions in rivers. It enhances the quality of the habitat but it can also cause a threat to the population. These processes and functions of the environment can be transformed into ecosystem (dis)services, which represent direct or indirect (dis)benefits that the society obtains from nature. The goal of this paper was to describe the current relations between large wood and ecosystem services and map the related knowledge gaps. Firstly, we conducted a systematic literature review that was elaborated according to the six-stage and PRISMA protocols and workflow diagram. We found 499 papers; however, only 137 were eligible for the following analyses. Secondly, we made a transformation of research information from the articles (n = 135) into ecosystem services. The highest number of ecosystem services detected in the articles belonged to the regulation and maintenance section (n = 126), followed by the provisioning (n = 15) and cultural (n = 11) sections. The detected classes with the highest frequency of studies were specific habitat creation and increased channel heterogeneity. The findings show that the number of research papers on this topic is still insufficient; however, anaylzing ecosystem services could be useful to advocate the presence of large wood in the rivers.

Glacier-Induced Alluvial Fan Development on the Northeast Tibetan Plateau Since the Late Pleistocene

The origin of alluvial fans at the drainage basin or the margins of the arid sedimentary basin on the northeastern Tibetan Plateau (NETP) has been a focus of debate among scientific communities. Extensive alluvial fans had developed in the mountain-basin systems of this region during the late Pleistocene. Based on geomorphic/stratigraphic studies and the optically stimulated luminescence (OSL) chronology, we investigated numerous alluvial sequences in the drainage basin of the coupled mountain-basin system on the NETP. Sedimentologic analyses showed that these alluvial sediments mainly comprise crudely meter and decimeter beds of fanglomerate and sandy lenticles, which occasionally contain boulders in the thinner layers. OSL dating results showed that the alluvial sediments were mainly developed during the late MIS 5, MIS 3, and Last Glaciation and Deglaciation (maximum aggradations), while little had occurred during the early Holocene. Comparing our ages and their probability density curves with those of glacial advances from the northeastern/eastern TP, the consistency of both records during different stages since the late Pleistocene suggested that the development of alluvial fans was driven by glacier activities, which yielded abundant outwash, feeding alluvial aggradations. Based on this finding, together with results of previous studies, we argued that the dynamics of alluvial geomorphic processes had a paleoclimatic origin rather than surface uplifts. Further studies indicated that the precipitation of glaciations originated from the ISM northward intrusion during the late MIS 5, MIS 3, and Holocene; however, it was mainly influenced by the westerlies during the Last Glaciation and Deglaciation. Therefore, the development of alluvial fans on the NETP represents coupling signals of the ISM and the westerlies on the interglacial–glacial cycle timescales. The coupling evolution of glacier activities and alluvial aggradations in the drainage basins of mountain-basin systems on the NETP provides a model for assessing the linkages between regional geomorphic processes and atmospheric circulations on hemispheric scales.