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The study area of Cala Gonone in NE Sardinia (Italy) consists of a wide terraced re-entrance/valley crowned inland by carbonate hills and, near the coast bounded laterally and partly floored by thin basaltic lava lying over carbonate bedrock. In this re-entrance, several inland alluvial fans (500 m length by 700 m wide) have developed, and a local ~ 30 m high, about 10 m wide (thick), 400 m long scarp body-remnant of semi-consolidated alluvial fan deposits is exposed along the coast. The fans experience depositional events mostly developed during the late Pleistocene. They although nowadays dormant may be reactivated by major rainstorms during strong climate changes. In these last few decades, the touristic village of Cala Gonone has been rapidly expanding over the mid to lower parts of two coalescing alluvial fans (Stadium and Gustui) and along the coastal marine scarp edge (Palmasera alluvial fan system). The village thus may become exposed to natural hazards if extreme climatic conditions may re-occur. Moreover, rock falls and the instability of the costal scarp due to wave erosion may add addition hazards for habitations built near the scarp crest and visitors to the frontal replenished beach. As commonly occurring elsewhere since antiquity, the risk perception of such events is low because of the centennial, millennial of longer recurrence. Such perception does not negate the hazards but a long event recurrence may be accepted as a reasonable risk for the human's activity. Nevertheless, serious consideration should be given to potential problems and plan and build for amelioration and defense. The evidence of what environmentally did and could still happen in the Cala Gonone and similar other area is in part clearly imprinted on the landscape: geology, geomorphology, and relative details in the stratigraphy and sedimentology of the deposits. [ABSTRACT FROM AUTHOR]

A variety of aqueous deposits and soils from gullies, fluvial channels, mountain slopes, alluvial fans, playas, polygons, and yardangs have been found on Mars. However, the occurrence of sedimentary organic matter (SOM) in these landscapes under hyperarid and strongly radiative conditions has yet to be fully assessed. With various desiccated landforms analogous to those on Mars, the Qaidam Basin in northwestern China is considered a promising hyperarid Martian analog. Here, aqueous deposits and soils from nine landforms across the extremely dry northwestern Qaidam and from four landforms across the dry southeastern Qaidam were sampled and investigated. Our results reveal that landform and moisture are important controls on organic carbon distribution across the Qaidam Basin, while sedimentary origin has a dominant effect in the extremely dry northwestern Qaidam. Combined with previous studies, low organic carbon contents of soils in the extremely dry northwestern Qaidam suggest possibly low rates of microbial carbon input and of organic carbon degradation in Mars‐like environments. High organic carbon contents of aqueous deposits together with increasing trends along rivers indicate preservation of relic SOM and possibly slow degradation rates of organic matter as compared to their exposure timescale. Moreover, soils from the distal alluvial fan are found to favor the concentration of pedogenic organic carbon as compared to those from other landforms in the dry southeastern Qaidam and from all landforms in the extremely dry northwest. This suggests that subsoils in the distal fans are promising candidate targets for biosignature detection on Mars. Plain Language Summary: The search for life signals has been one of the most important objectives in Mars exploration. Since the launch of Viking 1 and 2, many landers and rovers have been sent to hunt for biosignatures on Mars. In addition to in situ detection, investigations of terrestrial Mars analog provide significant implications for life detection on Mars. Diverse dry water‐forming landforms including gullies, fluvial channels, mountain slopes, alluvial fans, playas, polygons, and yardangs in the Qaidam Basin, northwestern China, are analogous to those found on the Martian surface. To determine whether the aqueous deposits and soils can hold sedimentary organic matter (SOM) under Mars‐like conditions, we systematically investigated the surface and subsurface distribution patterns of organic carbon contents, moisture contents, pH, and mineral compositions in different landforms across the Qaidam Basin. Our results show that under extremely dry and strongly radiative conditions, different aqueous deposits are able to preserve residual SOM while soils contain very low contents of organic carbon on the surface. Moreover, we find that in the arid conditions, distal alluvial fans are promising candidates for soil organic carbon enrichment. These findings offer useful insights into the biosignature detection on Mars for future exploration missions. Key Points: The distribution of organic carbon contents in various aqueous deposits and soils across the Mars‐like Qaidam Basin has been investigatedResidual sedimentary organic matter of aqueous deposits can be preserved in the extremely dry northwestern Qaidam BasinSubsoils in the distal alluvial fan are ideal candidates for life detection on Mars [ABSTRACT FROM AUTHOR]

Damage to rural buildings in mountainous regions caused by flash floods accounts for a significant proportion of economic losses from disasters. The unreinforced masonry (URM) wall is the most vulnerable structural element of rural buildings exposed to flash floods. The failure of a URM wall indicates damage to rural buildings in flash floods. Based on the yield line theory of out-of-plane damage of URM walls and the virtual work method, brittle failure criteria for URM walls under the impact of flash floods were established. According to the field investigation data of the 26 June 2020 flash flood event in Damawu Gully and the corresponding simulation results of FLO-2D, the disaster-causing process was analysed, and the failure criteria were validated. Three building parameters were identified to influence the flood-resistance of URM walls, including the mortar grade, the span-to-height ratio of the wall, and the number of floors of the rural building. The results showed that the cause of the 26 June disaster was the diversion of a 50-year flash flood into the residential community on the alluvial fan. The affected buildings were constructed with hollow blocks and lacked flood-resistance reinforcement. The critical failure depth of a URM wall restrained at the top by ring beams (RBs) under hydrostatic load conditions is 1.17 to 1.20 times greater than that of a URM wall without RBs, and the difference is even more pronounced when lower-strength mortar is used. The flood-resistance of a URM wall constructed with Mb 7.5 mortar and restrained by RBs is almost as strong as that of a URM wall constructed with Mb 20 mortar and without RBs. The span-to-height ratio of a URM wall should not be greater than 1.875 in this case. However, the flood-resistance of a URM wall with RB restraint is almost independent of the span-to-height ratio. The brittle fracture energy of masonry mortar is more crucial to the flood-resistance of 4-edge restrained URM walls if L/Z > 1.875. The flood-resistance of the URM wall of the first storey increases linearly with the number of floors. Single-storey rural buildings should be given priority to the use of high-grade masonry mortar and high-density blocks to improve flood-resistance. The failure criteria and the influence laws of building parameters on the flood-resistance of URM walls can provide references for flash flood mitigation and flood-resistance reinforcement of rural buildings in mountainous regions of Southwest China. [ABSTRACT FROM AUTHOR]

The lateral migration of river channels is an important control on the evolution of alluvial fans, deltas, and floodplains. Lateral migration consists of both gradual riverbank migration and abrupt shifts in location due to avulsions or cutoffs. Methods exist to measure bank migration, but abrupt shifts in position are rarely considered or are not emphasized. Here we describe a new method using Landsat‐derived water occurrence images that primarily focuses on detecting when a channel has abruptly shifted position, either from avulsion or cutoff. The method does not assume any a priori model of channel geometry or evolution. Within a given area of interest, binary channel images created from the fluvial water occurrence record are stacked through time. Then a channel shift intensity, Ai, is created by estimating the number of possible ending times for fluvial water voxels (a point in three‐dimensional space) in the stacked occurrence record. The number of possible end‐times for fluvial water voxels within a given region of the occurrence record reveals the likelihood that a reach of a river underwent an abrupt channel shift during the observation period. We present the results of this analysis for a 194 481 km2 region of the Amazonian basin. Follow‐up validation found three avulsions and 270 cutoffs within regions identified by this method. We show that areas above a threshold Ai contain an avulsion or cutoff with high probability. This highlights the method's potential to detect and quantify abrupt channel shifts at the basin scale. The method also successfully distinguishes between abrupt channel movement and complex braiding behaviour. As this method is applicable to any binary water‐masked time series images, future applications of this method have the potential to provide insight into the controls and spatial variance of avulsions and cutoffs across a variety of scales. [ABSTRACT FROM AUTHOR]

Excavations in the Bruges' Medieval outer ports of Hoeke and Monnikerede, located along the Zwin tidal inlet, revealed numerous rounded cobbles of exotic geological provenance among which were two specimens of remarkable mineralogical composition. An interdisciplinary study combining archeological, geological, petrographic-geochemical, and historical research has demonstrated their Mediterranean, i.e., Italian, provenance. A first stone is identified as Carrara marble originating from the alluvial fans of the Apuan Alps, deposited along the Versilian coast near the Renaissance towns of Lucca, Pisa, and Genoa. The second cobble is determined as a bioclastic calcarenite limestone from the Apulian shores. Both finds are interpreted as part of the non-saleable ballast once put in the holds of Italian carracks and galleys that touched the Flemish ports during the late thirteenth to fifteenth centuries. As such, both seemingly ordinary objects constitute a rare material and lithological testimony of an important late Medieval commercial network between the Mediterranean and North Sea coasts. Furthermore, the very rare occurrence of these Mediterranean cobbles compared to thousands of Scando-Baltic and Anglo-Scottish ballast stones in the whole of the Bruges outer harbor area can be related to differences in maritime traffic frequency and sheer commercial volumes. Also, the nature of the ballast itself and the ballasting procedures are important, the whole making Mediterranean ballast stones considerably less detectable in the Bruges' harbors than their North-European equivalents. [ABSTRACT FROM AUTHOR]

Urmia Lake, the largest saline lake in Iran and the Middle East, in the northwest of Iran, has shrunk over the past decades. The reduced water level has increased the area of dry land around the lake allowing new environmental hazard such as sand dunes encroachment, particularly on the western side of the lake. New land has emerged as a consequence of lake shrinkage, and this new land is a major sediment source for the creation of sand dunes around the lake. This shrinking of the lake has created emerging lands. These lands play a major role in creating sand dunes around the lake. There are five terrain types that could contribute sediment to the dunes, and it is the main aim of this research to identify the contributions to the dunes of each terrain type. Fifteen surface samples were collected from the five most erodible terrain types, and eight samples were collected from the dunes both downwind and upwind from the lake, and major element components were measured using X-ray fluorescence. According to the Besler classification, all samples are in the saline class. Also, the chemical index of alteration values in all samples were less than 50, indicating weak weathering. Based on multivariate statistical analysis, suitable tracers were selected and were imported to the sourcing equations. Quantification of uncertainty and the creation of two new fingerprinting models for aeolian sediments based on both Bayesian and GLUE procedures were used. The highest proportion comes from the salty and puffy lands (44.2%) followed by salty polygon land (23.5%), clay-salty areas, puffy-flaky lands (7.01%), the terminus of the fine sandy alluvial fan (13.2%) and clay-salty abandoned lands (12.1%). It is concluded that if land managers use these results, they can more efficiently decrease the hazards posed by dune formation, reactivation and migration through implementation of soil conservation on the affected lands around the dried lake. [ABSTRACT FROM AUTHOR]

Global warming significantly impacts sediment dynamics in glaciated catchments, affecting water resource operations, water quality, recreational activities, and ecological systems. The propagation of climate-change-induced geomorphic changes and the catchment's sediment yield are moderated by sediment connectivity, defined as the degree to which a geomorphic system facilitates sediment transfer. Quantifying functional sediment connectivity at the catchment scale remains a challenge. To address this, we propose a novel approach combining graph theory with the morphological method. This approach is exemplified through a detailed case study of a 2022 thunderstorm event in the Grastal valley, Tyrol, Austria. First, a graph of potential sediment cascades is constructed using a geomorphological map, a digital elevation model and a flow routing algorithm. A short-term Digital Elevation Model of Difference (DoD) from consecutive ALS surveys is then used to infer sediment fluxes and calculate the Sediment Delivery Ratio (SDR) for each landform. The primary sediment mobilising processes were debris flows and fluvial erosion, with a significant proportion of debris flow material being deposited on slopes, not reaching the fluvial corridor. Strong fluvial erosion was observed in the proglacial area, but the propagation of these geomorphic changes is halted by an alluvial fan and a lake. Most landforms can be clearly categorised as connecting or disconnecting features based on their SDR. In total, a maximum of 12 % of mobilised sediments exited the catchment. Our findings demonstrate that (i) short-term, catchment-wide DoDs are valuable for assessing functional connectivity at an event temporal scale, (ii) using landforms as fundamental spatial units allows for the identification and in-depth analysis of critical sediment sinks and sources, and (iii) graph analysis facilitates the catchment-wide calculation of sediment delivery ratios between meaningful fundamental units and the delineation of significant sediment cascades. • The morphological method was used to infer sediment fluxes of a 2022 debris flow event • Functional connectivity was assessed at catchment scale using graph theory with landforms as fundamental units • Most landforms could be clearly classified as connecting or disconnecting features • The fluvial system had high sediment delivery ratios, indicating supply limitation • Important disconnecting features were talus slopes, an alluvial fan and a lake at the margin of the proglacial area [ABSTRACT FROM AUTHOR]

The hyperarid Atacama Desert is one of the driest and oldest deserts on Earth, rendering it a valuable climate archive. However, unraveling its past climate is particularly challenging and the few studied paleoclimate records of the region reveal strong temporal and spatial variabilities. To enhance our understanding of these dynamics we investigated a sedimentary record in the Yungay valley located in the southern hyperarid Atacama Desert. We employed paleomagnetic and radiocarbon dating, and for the first time for Atacama Desert sediments, a meteoric 10Be/9Be based method for determining the depositional age. The respective 4.20 m deep profile comprises a lower alluvial fan deposit with a maximum age of 3.8 ± 0.8 Ma, and an upper 1.84 m thick clay pan deposit that has accumulated over the last 19 ka. Different proxies including grain size, salt concentration, and elemental composition indicate an aridity increase around 2.3 Ma ago and repeated dry and wet phases during the late Pleistocene and the Holocene. The latter climatic shifts can be assigned to variabilities of the South American Summer Monsoon and El Niño Southern Oscillation with moisture sources from the Atlantic and the Pacific Ocean, respectively. This study provides deeper insights into the heterogeneous climate of the hyperarid Atacama Desert and underlines the importance of interdisciplinary investigations to decipher climate systems and their effect on potential habitable regions in such an extreme environment. • Paleo record in the hyperarid Atacama Desert: clay pan deposits (~100 m Ma−1) cover alluvial fan deposits (~1 m Ma−1). • First application of 10Be/9Be age dating on terrestrial deposits in the Atacama Desert. • Alluvial fan deposits record an increase of aridity at 2.3 Ma. • Clay pan deposits record multiple wet phases during late Pleistocene and Holocene. • Climate shifts can be linked to variabilities in the South American Summer Monsoon and El Niño Southern Oscillation. [ABSTRACT FROM AUTHOR]

• We study a ∼1000 km-long sinistral fault in central Tibet: the Qixiang Co fault. • We determine a post ∼120 ka horizontal slip rate of 3.5 ± 0.2 mm/yr along the fault. • This fault connects central Tibet to the Ganzi-Xianshuihe fault in eastern Tibet. • It acts as a major tectonic boundary that governs eastward escape of central Tibet. • Including this fault is now essential in models of Tibetan Plateau deformation. A quantitative kinematic model of present-day deformation across the Tibetan Plateau is essential to understand its growth mechanism. Dominant dextral movement along the ≥2500 km-long Karakorum-Jiali fault zone, long considered the southern boundary of plateau-wide eastward extrusion, was later challenged by a locally restrained, symmetrical shortening model co-involving short (200-300 km) conjugate strike-slip faults. Here, based on meter-resolution satellite data and field measurements, we document a previously undocumented, ∼1000 km-long, ∼ENE to E-trending sinistral fault, the Qixiang Co fault (QXCF), that wholly crosses central Tibet to connect the Ganzi-Xianshuihe fault in eastern Tibet with the Gyaring Co fault and Tangra Yum Co rift in central/southern Tibet. High-resolution unmanned aerial vehicle (UAV) topographic surveys, 10Be cosmogenic and U-series dating of a lake shoreline and several alluvial fans at 3 sites ∼240 km apart, show that up to ∼450 m of sinistral offset accrued in the last ∼120 ka, implying a horizontal slip rate of 3.5 ± 0.2 mm/yr along the fault. Four recent large paleoearthquakes (M w 7.9–8.0) may have ruptured a > 300 km stretch of the QXCF with characteristic slips of ∼9–10 m and return times of ∼2500–2900 a. Such results demonstrate that the hitherto previously undocumented QXCF is the single most important tectonic boundary across the Qiangtang terrane, contributing predominantly to large-scale eastward escape of central Tibet and challenging the 'V-shaped conjugate faults' model. Including this major fault is thus now essential in models of Tibetan Plateau deformation. [ABSTRACT FROM AUTHOR]

The Tarim Block, northwest China, was positioned on the periphery of Rodinia during the Neoproterozoic Era, and preserves a geological archive chronicling the assembly and breakup of the supercontinent. Due to its antiquity and limited exposure, sedimentary records along the margin of the Rodinia supercontinent remain sparsely documented. This study focuses on the Xifangshan and Dongqiaoenbrak formations, the oldest sedimentary units in the northwestern Tarim Block, which comprise a Neoproterozoic sedimentary record at the supercontinent margin during the transition from subduction to breakup. A comprehensive analysis employing sedimentology, petrology, elemental geochemistry, and U Pb detrital zircon chronology was undertaken, to elucidate paleoenvironment, parent rocks, and tectonic-sedimentary evolution. Findings show that the Neoproterozoic witnessed the subduction of an oceanic plate beneath the Tarim Block, resulting in the formation of a continental margin magmatic arc. The Xifangshan Formation, deposited during the late phase of this arc (with the earliest sedimentary age recorded at 770 Ma), represents a submarine fan dominated by turbidity currents. Around 760 Ma, rapid crustal uplift occurred, and the tectonic setting gradually shifted from subduction to rift, giving rise to the coastal alluvial fan sedimentary system observed in the Dongqiaoenbrak Formation. Both the Xifangshan and Dongqiaoenbrak Formations record deposition in an oxic to suboxic marine environment with moderate salinity, influenced by a semiarid to semihumid palaeoclimate. The continental margin arc served as the primary source for sedimentation in both formations, and a few magmatic products linked to extension (syenite, monzonite) were also cannibalized into the sedimentary system of Dongqiaoenbrak Formation. This transition from a turbidite system to a coastal alluvial fan represents a sedimentary response to the subduction-to-breakup dynamics along the margin of the Rodinia supercontinent. • The Xifangshan Formation was formed by a subducting and turbidite system. • The Dongqiaoenbrak Formation was formed by a rift transition and coastal fan system. • The continental margin magmatic arc was the main provenance of the two formations. • (4) 770–760 Ma, Northwestern Tarim experienced a transition from subduction to breakup. [ABSTRACT FROM AUTHOR]

The geochemical data from sediments in avulsion channels provide historical evidence of climate change and human-induced alterations in river basin environments. The present study focused on the particle size of sediments in cores and the level of geochemical variation in avulsion channels of the Lower Yellow River Delta (YRD), China. The sediment samples were collected in a depth range of 20–400 cm in avulsion channels. The collected samples were analyzed for sediment particle size and geochemical composition using standard methods. The results demonstrated rapid increases in agriculture practices, rainfall pattern changes, and terrestrial sediment runoff reduction in river basins after the 1960s. The reduced sediment loads in the Sanmenxia Reservoir significantly changed the sediment grain size and geochemical levels in the avulsion channel from August 1960.8 to January −1961.1. In particular, TC, TN, and C/N levels decreased with increasing sediment depth. The C/N values of <12 denoted completely reduced terrestrial sources of organic matter in the channel during the August 1960–January 1961 period compared to the July 1953–August 1960 period. The two-way ANOVA p- values were (p < 0.016- p< 0.001) strong between the avulsion periods but had no significant variation within the avulsion periods. We emphasize that this study provides a close interplay of different historical periods of geochemical variation in avulsion channel sediments in the alluvial fan YRD, and we argue that the evolution of the middle upstream river basin was subjective by climate change and human developmental actions, which impacted the YRD. In particular, reservoir-interrupted water flow and sediment reduction impacts associated with geochemical fluctuations are documented in the YRD. • There was very little human interference in the Yellow River middle upstream basins during the July 1953–August 1960 periods. • The sediment grain size and geochemicals highly changed in the avulsion channel at the LYR alluvial fan delta during the August 1960–August 1961 period. • >12 C/N ratios at avulsion channel (July 1953–August 1960 periods) and <12 C/N (August 1960–January 1961 periods). • Terrestrial-based organic matter sources had a significant reduction in the Yellow River after the 1960s. [ABSTRACT FROM AUTHOR]

The sedimentary record of fluvial systems is known to preserve important archives of the effects of climate change on the landscape over time and space. While temperate and arid (semi-arid) regions are relatively well studied, our understanding of fluvial dynamics in tropical mountainous areas throughout the Quaternary is poorly known. Here, we propose a model of the landscape evolution of the Upper Caquetá River in the Northern Tropical Andes (NTA) over the past 130 ka, based on mapping and optically stimulated luminescence (OSL) dating of the sediments building alluvial fans and fluvial terraces. The OSL ages indicate that the distributary system was active from 130 to 65 ka; from 65 to 31 ka channels carved the deposits, reorganizing the drainage network to a tributary pattern with rivers flowing into incised valleys. Four fluvial terrace levels were mapped in these valleys and OSL ages indicate sediment deposition around 30, 15, 5, and 1 ka. Based on available palaeoenvironmental data, we have interpreted that the shift in the fluvial landscape from distributary to tributary incised system is related to precipitation change in the NTA, driven by the variation in the latitudinal position of the Intertropical Convergence Zone (ITCZ) due to insolation cycles. Our data suggest that the decreased rainfall, caused by the northernmost position of the ITCZ, combined with the expansion of arboreal elements in the Andean Piedmont, favoured alluvial deposition by both the distributary system (Marine Isotopic Stage - MIS 5 and 4) and the tributary (MIS 2 to the present). Our data supports that following an incision phase during MIS 3, the decrease in the amplitude of precession and obliquity signals led to greater stability of the landscape and to the transition of the distributary fluvial pattern in the upper Caquetá River to its present tributary pattern. • Equivalent doses in quartz grains from Caquetá River are up to 250 Gy. • We demonstrate a drainage rearrangement in the Eastern Cordillera's Piedmont • The alluvial fans complex (130–60 ka) changed to a tributary system (30 ka) • Variations in climate and vegetation drove the evolution of the Caquetá River • Tectonic activity is slower in Putumayo Basin than in Llanos during late Quaternary [ABSTRACT FROM AUTHOR]

Exhumed early rift alluvial fan and braided fluvial fan systems are rare and consequently understanding facies distribution, stratal architecture, reservoir connectivity, and controls on stratigraphic development of these systems is quite difficult. The outcrops of early Oligocene to early Miocene Al Wajh Formation in the Red Sea region of Saudi Arabia provide an opportunity to investigate the depositional architecture and reservoir potential of an early rift alluvial to fluvial system. Eleven lithofacies (F1-F11) and four facies associations (alluvial fan facies association (FA1), braided fluvial fan facies association (FA2), floodplain facies association (FA3) and delta front facies association (FA4)) are identified in four subbasins (Maqna 1–2, Sukk and Ifal), suggesting deposition in an alluvial-braided fluvial fan system. FA1 (36–100%) and FA4 (9–13%) have higher relative proportion and widely distributed in the northern subbasins (Sukk and Ifal subbasins) while the relative proportion of FA2 (50–82%) and FA3 (18%) increases towards southern subbasins (Maqna-1 and Maqna-2 subbasins). Distribution of facies associations, relative reduction in the clast diameter, and general southward paleoflow direction suggest that the northern subbasins (Sukk and Ifal) represent the proximal settings and southern subbasins represent medial (Maqna-1 subbasin) and distal settings (Maqna-2 subbasin) of a large alluvial-braided fluvial fan environment. Stratal architecture of proximal conglomeratic channel deposits highlight that despite reasonable thickness and spatial connectivity (several meters), these deposits may have marginal reservoir quality because of poor sorting and high matrix content. Sandstone beds occurring in medial settings have a higher potential to act as hydrocarbon reservoirs by displaying excellent reservoir properties on the account of their significant thickness (up to few meters), coarse grain sizes, better sorting, considerable spatial connectivity (10s of meters) and lower proportion of interbedded mudstone. • The facies and facies associations show deposition in alluvial-fluvial to delta front areas • Tectonics played a key role in the stratigraphic architecture of the Al Wajh Fm. • Medial braided fan has better connectivity versus alluvial proximal and fluvial distal • Distal floodplain deposits may act as flow barriers, forming stratigraphic trap [ABSTRACT FROM AUTHOR]

Determining slip rates is essential for assessing earthquake hazards and understanding their recurrence intervals. However, in regions characterized by slow deformation, the long intervals between seismic events present challenges in understanding the long-term seismic behavior. This study focused on the Yangsan Fault (YF) on the Korean Peninsula, which is a major active fault in a slowly deforming area. We identified paleo-surface ruptures and validated stratigraphic evidence of paleo-earthquakes by geomorphological analyses and trench surveys along the YF. Landform restoration analyses indicate a lateral offset of ~320 m, which is supported by downstream changes in gravel composition in channels that cross the YF. Our investigation into the notable changes in gravel composition within channels forming in the alluvial fan revealed sediments with compositions unlikely to originate from the current topography. Observations of the sediment composition in channels within the alluvial fan, flowing from east to west, suggest a dextral slip sense focused around the YF. The minimum slip rate for the lateral offset was calculated to be 0.38–0.57 mm/yr using a burial age of ca. 698 ka for a gravel deposit exposed in a trench wall. The results show the importance of using diverse approaches to mitigate methodological uncertainties in measuring fault displacements and ages, particularly when determining the long-term slip rate in intraplate settings. • Deriving long-term slip rates of strike-slip faults in intraplate environments • Estimating offset using geomorphic offset markers and verifying with provenance analysis of sediments • Age dating using cosmogenic nuclides • Discussing differences with various methods for estimating offset • Discussing various factors that may cause differences in slip rates [ABSTRACT FROM AUTHOR]

This study investigates the sediment dynamics resulting from the extreme Storm Alex in October 2020 in the Roya Valley and its tributaries in the Alpes-Maritimes region, France. The storm, triggered by a low-pressure system, led to unprecedented rainfall, causing extensive flooding and erosion in the region. Despite limited pre-flood data, the study employs aerial and satellite imagery, digital elevation models, and field surveys to quantify sediment mobilization and its effects on the Viévola alluvial fan in the Roya Valley. The Roya Valley’s complex geomorphology, characterized by steep gradients, gullies, and torrential streams, played a significant role in sediment transport. The study reveals that the Dente and Rabay torrents were major sediment contributors, with gullies in these areas producing substantial erosion. Bank erosion in the Dente valley was particularly prominent, attributed to geological factors and glacial deposits. The analysis, relying on topographical comparisons and digital data, assesses sediment volumes eroded and deposited during the event. Despite challenges in data quality, the study offers valuable insights into sediment dynamics during extreme hydro-sedimentary events. The Viévola catchment area is a focal point, emphasizing the importance of scree and fluvio-glacial deposits as primary sources of sediment. The findings emphasize the need for improved pre-event data and monitoring in mountainous regions susceptible to extreme events. The study’s methodology, despite limitations, contributes to a better understanding of geomorphic responses to extreme events. Expanding similar studies to cover a wider range of catchment areas and incorporating field data offers potential for enhanced hazard assessment and management strategies. The research underscores the critical role of sediment transport in shaping landscapes and impacting human infrastructure during extreme flood events. [ABSTRACT FROM AUTHOR]

• New research framework to characterize time lag pattern of GWLs to Precipitation. • Based on variation point to describe the evolution of GWL before and after the SWDP. • The GWL in the toe of alluvial fans exhibit stronger declines due to over-extraction. • The toe of alluvial fans in the eastern plain exhibits longer lag times than western. • Groundwater extraction being the dominant factor affecting GWL fluctuations. The fluctuations in groundwater levels (GWLs) in the Beijing Plain area are profoundly affected by precipitation (Pre) and groundwater (GW) overexploitation, altering regional water cycle processes and constraining regional economic and ecological development. The South-to-North Water Diversion Project (SWDP) has altered water supply structure in Beijing, leading to a new pattern in GWL fluctuations. This study quantitatively analyzes the evolution patterns of shallow GWLs and quantifies the response relationship between Pre-driven GWL-response on spatial and temporal scales before and after the SWDP. Using GWL and Pre data from 2000 to 2021, employs the coefficient of variation to analyze interannual variability, identifies variation points using the Pettitt and sliding T-test combined with correlation coefficient-based method for the classification of jump degree (R_Jump degree), subsequently divides the sub-sequences. The hydrological trend variation classification method based on correlation coefficient (R_Trend) is used to quantify the spatiotemporal evolution patterns of GWLs in each sub-sequence, and cross-correlation analysis is utilized to examine the time-lag characteristics of GWL responses to Pre in each sub-sequence. The results indicate: (1) GWLs exhibited jump variations in 2015 and 2017, with variation degrees mainly of moderate and strong, and correlation coefficients ranging from 0.18 to 0.67; (2) The overall trend of GWLs shifted from a significant decline to a substantial rebound before and after the SWDP. However, GWLs in the toe of the alluvial fan continued to show a decreasing trend until 2017; (3) The time lag between Pre and GWLs shortened by 6–10 months before and after the SWDP, with the toe of the alluvial fan showing a longer lag time due to over-exploitation. The Pre-GWL lag pattern mainly depends on GW extraction. Compared to existing methods, this paper proposes a research framework for systematically and comprehensively quantifying the evolution of GWLs and their response patterns to Pre, clearly revealing the natural-artificial water cycle processes in the Beijing Plain, providing scientific basis for ecological conservation and water resource management. [ABSTRACT FROM AUTHOR]

• We studied the spatial vegetation distribution pattern in the Gobi region. • Dominant species Ephedra przewalskii populations in different parts of the alluvial fan were assessed. • Dominant species E. przewalskii populations distribution information was extracted from unmanned aerial vehicle images. • Complex null models were used to analyse the formation mechanism of vegetation spatial distribution pattern. • Using UAVs for sparse vegetation pattern analysis exhibited good applicability. Understanding the spatial pattern of vegetation in the Gobi area is of paramount importance for preserving its vegetation and the overall stability of the ecosystem. Here, we investigated the populations of the predominant species, Ephedra przewalskii , at various locations within the alluvial fan situated in the southern foothills of the Tianshan Mountains in the Gobi area. The location of the E. przewalskii distribution in the sample plot was extracted from unmanned aerial vehicle (UAV) images. This article analyzes the distribution patterns of the predominant species based on different null models, tests whether the distribution patterns are affected by habitat heterogeneity, and examines whether other ecological processes affect these patterns. Additionally, using the variance decomposition method, we analyze the explanatory power of habitat factors on the distribution patterns of the predominant species. The results show that: (1) Using UAVs to locate the distribution of vegetation information for sparse vegetation pattern analysis in the Gobi region has good applicability and prospects; (2) the frequency, density, and coverage of E. przewalskii decrease sharply with decreasing altitude. At a small scale (0∼10 m), the E. przewalskii population is mainly aggregated, whereas on a large scale (>10 m), it primarily exhibits uniform or random distributions; (3) the E. przewalskii population distribution pattern is significantly affected by habitat heterogeneity, mainly on a large scale. The species distribution in the study area strongly correlates with the altitude, soil moisture, and topographic wetness index. Habitat factors can explain 64.2 % of the reasons for species distribution; and (4) The clustering of E. przewalskii population at the apex of the alluvial fan is primarily driven by facilitation, whereas at the middle and bottom sections, it is predominantly influenced by habitat heterogeneity and restricted diffusion. The results enhance our comprehension of the spatial patterns and environmental adaptation mechanisms exhibited by the predominant species in the study area. Furthermore, they provide a scientific foundation for ecological conservation and biodiversity protection in the environmentally vulnerable Gobi region. [ABSTRACT FROM AUTHOR]

A substantial reservoir of nitrogen (N) in soil poses a threat to the quality and safety of shallow groundwater, especially under extreme precipitation that hastens nitrogen leaching into groundwater. However, the specific impact of varying precipitation intensities on the concentration and sources of nitrate (NO 3 −) in groundwater across diverse hydrogeological zones and land uses remains unclear. This study aims to elucidate the fluctuations in NO 3 − concentration, sources, and controlling factors in shallow groundwater under different intensities of precipitation (extreme heavy precipitation and continuous heavy precipitation) in a typical alluvial-pluvial fan of the North China Plain by using stable isotopes (δ2H–H 2 O, δ18O–H 2 O, δ15N–NO 3 -, δ18O–NO 3 -), hydrochemical analyses and the SIAR model. Affected by extreme heavy precipitation the depleted isotopes of δ2H–H 2 O and δ18O–H 2 O in groundwater of the entire area suggested the rapid recharge of fast flow by precipitation. The enriched isotopes of δ2H–H 2 O and δ18O–H 2 O of north part in alluvial fan after continuous heavy precipitation showed the recharge of translatory flow of soil water. NO 3 −concentrations increased to 78.9 mg/L after extreme heavy precipitation and increased to 105.3 mg/L after continuous heavy precipitation when compared to those in normal year (56.8 mg/L) of north part of the alluvial fan. However, NO 3 − concentrations had slight variation after continuous heavy precipitation of south part of the fan due to the deep vadose zone. The contribution ratio of sources of NO 3 − in groundwater by using SIAR analysis revealed manure & sewage (MS) as the primary NO 3 − source (accounting for 59.7–78.1%) before extreme heavy precipitation, chemical fertilizer (CF) making a minor contribution (6.9–17.3%). Different precipitation events and land use types lead to changes in NO 3 − sources. Affected by extreme heavy precipitation, the contribution of MS decreased while CF increased, particularly in vegetables (26.2–28.1%) and farmland (29.2–34.7%). After continuous heavy precipitation, MS increased again, particularly in vegetables (50.0%) and farmlands (20.4–66.4%), with CF either increasing or remaining steady. This indicated that continuous heavy precipitation accelerated the leaching of nitrogen (organic manure application) stored in deep soil to groundwater and it has a larger influence on the increasing of NO 3 − concentrations of groundwater than extreme heavy precipitation which carried nitrogen (chemical fertilizer application) in shallow soil to groundwater by fast flow. These findings underscore the importance of considering soil chemical N stores and their implications for groundwater contamination mitigation under future extreme climate scenarios, particularly in agricultural management practices. [Display omitted] • Continuous heavy precipitation has a greater leaching effect on nitrate in groundwater compared to extreme heavy precipitation. • Extreme heavy precipitation accelerated the contribution of chemical fertilizer nitrogen to groundwater. • Continuous heavy precipitation tends to promote the leaching of organic manure nitrogen in deep soil to groundwater. • Vegetable area is significantly more susceptible to nitrate contamination from groundwater than farmland area. • N sources stored in soil pose a substantial threat to groundwater under varying conditions. [ABSTRACT FROM AUTHOR]

Korea's Paleolithic sites are primarily located in riverine environments and the margins of alluvial fans. More than 100 Paleolithic excavations have been conducted in the Korean Peninsula, but the relationship between the locations of these sites and past climate change has received little attention. In this study, we investigated this relationship at a Paleolithic site in Wonju city, Korea, that contained two cultural layers and yielded a total of 336 stone artifacts. The lithological units present at the site indicate that the sedimentary environment changed from a riverine sandy channel to an alluvial plain owing to channel migration at the Marine Isotope Stage (MIS) 4. The alluvial plain sediments deposited during MIS 4–2 are characterized by low sand content (<5%) and two soil wedges. Most Paleolithic artifacts were excavated from the upper soil wedge, deposited during MIS 3 under relatively warm and wet conditions associated with global climatic changes (as indicated by sea level or continental ice volume) and the East Asian summer monsoon. The number of Paleolithic cultural layers increases in late MIS 3 in other regions, suggesting that climate conditions are an essential factor in the development of Paleolithic cultural layers. [ABSTRACT FROM AUTHOR]

Sediment supply is widely believed to be a key control on alluvial fan morphology and channel dynamics. Although the sediment supply to natural fans is rather episodic, experimental studies of alluvial fans often use constant sediment supply rates, making it difficult to relate fan dynamics to the magnitude and frequency of sediment supply in the field. This paper presents a series of experiments designed to test the impact of episodic sediment supply on fan evolution and dynamics. We compare four experiments, each with the same mean sediment supply but different durations of high- and low-supply periods. The experiments show that fan morphology and channel dynamics respond systematically to the temporal elongation of sediment supply oscillations: longer supply cycles generate flatter fans with more trenched channels. These results highlight how different basin conditions might generate different fan morphologies: supply-limited basins with intermittent sediment supply might generate fans that are flatter than expected. Our results raise the question of whether a constant sediment supply in experimental models can adequately characterise the dynamics of natural fans in the field. We therefore suggest that experimental modellers should include variability when investigating fan responses to sediment supply. [ABSTRACT FROM AUTHOR]

Rifting initiation and development in Western Sundaland is spectacularly synchronous and diffuse spatially, with only one exception, the Malay Peninsula that appears as a large crustal horst, weakly deformed and thus isolated from the presently offshore stretched crust. Cenozoic stratigraphic records are limited onshore, with only isolated conglomeratic series that are keys to integrating the Malay Peninsula in the regional chronology of events. This study focuses on the Lawin and Chenderoh conglomeratic series, located in the Perak Valley, Peninsular Malaysia, that were previously interpreted as Late Tertiary to Quaternary in age, albeit without proper basin analysis and/or geochronological data. Through a GIS‐based kinematic analysis, we investigate the deformation affecting the basement rocks, while a field‐based study and palynomorph analysis were used to constrain the tectonic framework at the time of deposition of each conglomeratic series. Our findings reveal that the Lawin alluvial fan was deposited during an episode of E–W extension controlled by a N–S normal fault. The fan evolved from debris flow to sheet flooding depositional stages. The palynomorph study suggests a burial from the Pliocene onwards (<5 Ma) but older series are suspected at depth. From the Oligocene Chenderoh shale unit, a Miocene age of the conglomeratic series is inferred. Chenderoh conglomerate is believed to have developed within pre‐existing isolated depressions formed during regional transtensional events. Our study reveals that the Malay Peninsula was indeed affected by extension in the Late Palaeogene‐Early Neogene, but with low rates of subsidence as compared to rapidly subsiding offshore basins. [ABSTRACT FROM AUTHOR]

Understanding the extent and quantity of groundwater drawdown is critical for developing a mitigation strategy for water management. This study illustrates that the data‐driven model can be used for the spatial estimation of groundwater drawdown using interferometric synthetic aperture radar (InSAR)‐based deformation data. Here, InSAR derived from Sentinel‐1 imagery is used to estimate surface deformations in the Choshui river alluvial fan, Taiwan, between 2016 and 2018. Spatial regression (SR) is applied to estimate the annual groundwater drawdown with a calculated R‐square of 0.96, which is shown to be superior to a nonspatial model. This study demonstrates the potential of the satellite‐based groundwater drawdown map prediction using InSAR‐derived land deformation. In predication, the SR model can reliably catch the patterns of annual predicted drawdown without requiring detailed groundwater observations. [ABSTRACT FROM AUTHOR]

The sand bodies formed by braided fluvial fan deposits have a certain distinctiveness. They not only have the characteristics of fluvial facies sandbodies but also follow the distribution law of alluvial fan sand bodies. The variation law of sandbodies that are present along and perpendicular to a channel is relatively complex. Therefore, constraints in the modeling process of sand–mudstone facies of this type of reservoir are essential. This study selects the second member of the Shanxi Formation reservoir formed by a braided fluvial fan in the middle of Ordos Basin to perform sand–mudstone facies modeling. First, by studying the lithology and sedimentary structure of the area, the sedimentary characteristics and sand body distribution law of braided river fan are analyzed. Then, the original data points are analyzed, the variation function with high convergence is obtained, and the sand–mud facies model under the constraint of sedimentary facies is established using the random modeling method. Finally, the accuracy of the established random model is tested via single-well thinning, multi-well thinning, and random seed model similarity. The test results confirm that the distribution law of the sand and mudstone in the model is highly similar to that of the actual stratum. And it also conforms to the sedimentary model of braided fluvial fan. The accuracy of the model established by this method is reliable, and the method can be used to predict sand body distribution in areas with low well pattern density. [ABSTRACT FROM AUTHOR]

Bedrock gorges occurring on the Indian Peninsula are sites of intense erosive activity where thick sequences of fluvial sediments are conspicuously absent. We identified unusually thick and coarse fluvial sequences within the Dhadgaon (DG) gorge in the lower reaches of the Narmada River in central India. Stratigraphic interpretations, sediment character and optically stimulated luminescence (OSL) ages revealed episodic aggradation at ~70 ka and ~28 ka in response to tectonically induced steepening of the upstream channel gradient. Incision of the DG gorge and sedimentation of the alluvial fan downstream was facilitated by a climatically induced decrease in the sediment supply/discharge ratio in addition to the tectonic slope. The final evacuation of sediments from the DG gorge and incision of the Banganga channel occurred during the early Holocene. Collectively, the results show a major influence of tectonics, hillslope processes and lithology on aggradation–incision patterns supported by climatic conditions during the late Quaternary. [ABSTRACT FROM AUTHOR]

Vesicular horizons are common on the surface of landforms in arid regions and play an important role in the hydrological properties and pedogenic processes in these areas. Vesicular pores are a characteristic feature of vesicular horizons and include separate pores with spherical to elliptical shapes and dimensions of micrometers to millimeters in diameter (Dietze et al., 2012). The eastern region of Isfahan located in the eastern part of the Zayandehroud River basin is affected by environmental disasters due to severe environmental drought, destructive human activities, and desertification processes. Although vesicular horizons are frequent in the soils and landforms of the eastern region of Isfahan (Bayat et al., 2018), there is no information about the geochemical and mineralogical properties of these horizons. The aim of the present study was to investigate the physical, chemical, geochemical, and mineralogical properties of vesicular horizons at different elevation levels of three landforms in the eastern region of Isfahan. Materials and Methods The study area is located in the center of Iran, east of Isfahan and around Segzi Playa. According to the meteorological stations of the region, the mean annual precipitation and temperature are about 107 mm and roughly 15 ˚C, respectively. Groundwater in piedmonts and plateaus of the region is deep and there are no signs of groundwater activity in the studied soils and landforms. The studied landforms include a remnant paleosurface across the Zayandehroud River (RP), a pediment in Jey industrial city (JP), and an alluvial fan near the Zefreh (ZA). Seven samples of vesicular horizons were taken from vesicular horizons in RP (at altitudes of 1542 and 1552 m), ZA (altitudes of 1623, 1764, and 1901 m), and JP (at altitudes of 1542 and 1557 m) landforms. The samples were described according to Schoenberger (2012) and analyzed regarding standard methods (Soukup et al., 2008; Soil Survey Staff, 2014). Results and Discussion The thickness of the studied vesicular horizons varied in the range of 3-6 cm, and on the alluvial fan, the thickness of the horizon increases with increasing the elevation. The chemical properties of the studied samples indicated very low electrical conductivity and organic carbon content and were similar to vesicular horizons in the Mojave Desert of California (McFadden et al., 1998). The particle size distribution indicated the predominance of sand particles in all samples and all samples were characterized by a bimodal distribution of particle sizes suggesting the contribution of at least two mechanisms in the transfer of particles to the studied vesicular horizons (Karimi et al., 2017; Sweeney et al., 2013). Mineralogical analysis of the samples showed the predominance of quartz and calcite in all samples and varied concerning the presence of mica and fibrous minerals. It seems that quartz is inherited from the parent material while calcite and mica minerals originated from the parent material and were also added by the wind. Fibrous minerals were probably of autogenic origin. The geochemical properties of the samples were consistent with the mineralogical results and showed the abundance of SiO2 and CaO in all samples. Among the trace elements, the highest abundance is observed in the strontium, which is due to the association of this element with carbonates (Ding et al., 2019). A comparison of geochemical properties of vesicular horizons with associated rocks showed the enrichment of SO3 and CaO relative to corresponding parent material indicating the addition of soluble ions, carbonates, and especially gypsum to the surface of the studied landforms. The Zr/Al ratio showed an increasing trend with increasing the silt content which proved the aeolian source of the silt particles as previous studies have shown a very strong correlation between aeolian sediments and the element zirconium (e.g., Waroszewski et al., 2018). Conclusions Increasing the amount of silt and the ratio of fine-grained particles to sand with increasing the elevation indicated the role of aeolian processes in adding fine-grained particles to the surfaces of different landforms of eastern Isfahan. Mineralogical and geochemical evidence also confirms the effect of dust on the formation of these horizons, so that the addition of mica minerals along with silt particles has occurred at higher altitudes. The geochemical study of vesicular horizons and application of Zr/Al ratios show that the composition of past and current dust in eastern Isfahan was the origin of dust for different landforms of the region is the same. Finally, the existence of developed vesicular horizons in the surfaces of the landforms of the region demonstrates long-term processes of wind erosion and dust influx into the soils. These natural processes are probably intensified by anthropogenic activities in recent years. [ABSTRACT FROM AUTHOR]

Located on the northern Vietnam onshore/offshore transition, the Hoanh Bo Trough is an excellently exposed terrestrial Palaeogene sedimentary sequence that may be treated as an analogue for regional interpretations of the sedimentary and structural evolution of the northern Song Hong Basin. The Hoanh Bo Trough lies to the north of the northern Song Hong Basin and to the west of the Beibuwan Basin, the origin and evolution of which are linked with Palaeogene South China Sea rifting. Field and archival well sedimentological observations were made throughout the Palaeogene succession of the Hoanh Bo Trough, and samples were collected for palynological, petrographical, and geochemical analysis. Based on the coexistence of particular lithofacies, proximal alluvial fan, distal alluvial fan, fluvial alluvial plain with channels, alluvial plain and/or lake margin, and lacustrine facies associations were distinguished. Palynological analyses suggest the sedimentary infill of the Hoanh Bo Trough is of the Late Eocene–Early Oligocene age and was deposited in a very warm tropical/subtropical climate. In turn, geochemical results demonstrate that the deposits have intermediate chemical maturity and were probably reworked from older sedimentary rock sources. Moreover, it is suggested to combine the Dong Ho and Tieu Giao formations and synonymize them as the Dong Ho Formation. The sedimentary pattern, age, climatic conditions, and structural evolution of the Hoanh Bo Trough align well with the rift initiation, rift development, and rift termination tectonic system tracts. Moreover, the Hoanh Bo Trough could be treated as a landward keyhole for the offshore basins: for instance, the Kien An Basin in the northern Song Hong Basin. [ABSTRACT FROM AUTHOR]

• Trend of channel braiding of a tropical river is assessed using braiding index, channel count and length indices. • The planform indices portray allometric growth patterns during the observation period (1990–2020). • The simulation of bar growth using ARIMA model indicates an oscillatory behaviour controlled by local morphotectonics. • The future forecast of bar growth for 2030 and 2050 has been tested with the RMSE and BIC. • The characterization of complex braiding patterns implies significant regional policy implications. Channel braiding is one of the fundamental fluvial processes in the context of sediment-energy nexus. The present study intends to simulate the channel braiding pattern of a tropical river (Jaldhaka River) on the Himalayan foreland plains. The grain size of the bed material in the Jaldhaka River decreases with distance from the mountain front, as does the surface gradient from the piedmont plains to the northern alluvial plains accompanied by the development of alluvial fans. Such assemblage results in multiple facets of hydro-geomorphic controls on channel planform dynamicity. This study is one of the pioneering attempts to characterize the spatial and temporal trend of channel braiding in any river running through the foreland region of the Sikkim-Bhutan Himalayas. The type of channel braiding is determined by the three indices – (1) Braiding Index (BI*), (2) Channel Count Index (BI), and (3) Channel Length Index (P t), in cases where no gradual and uniform trend of development has been seen. The spatial allometric growth of the channel braiding and time series association using the ARIMA model was examined on the twenty stretches of the river. The results depict nonuniformity in planform development with distance downstream during a 30-year time span (1990–2020). The nature of the planform value distribution concerning all three applied indices has projected a polynomial trend where certain intermediate channel segments break the general trend of the braiding intensity with downstream distance. Since the downstream braiding intensity of the Jaldhaka River hasn't decreased either linearly or exponentially, we were unable to find any significant relationship of it with surface gradient. The nature and association of the channel braiding of the Jaldhaka River point towards the influence of local controls (e.g. river terracing on the upper part and faultline controls in the middle part) on channel planform dynamicity. The prediction of channel braiding for 2030 and 2050 coupled with the model fitted with RMSE, and BIC bears great significance in revealing the future bar growth which may be useful for the different planners and stakeholders concerned with the river basin development. [ABSTRACT FROM AUTHOR]

Copyright of Geology & Resources is the property of Geology & Resources Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In October 2015, heavy rains brought by Typhoon Koppu generated landslides and debris flows in the municipalities of Bongabon, Laur, and Gabaldon in Nueva Ecija province. Satellite images and clusters of landslides show that most of the rain fell in the Sierra Madre mountains in Nueva Ecija and Aurora provinces. Landslides of rock, soil, and debris then converged in the mountain stream networks where they were remobilized into debris flows that destroyed numerous houses and structures. Approximately 42 million cubic meters of materials were mobilized into debris flows. Accurate forecasts enabled the municipal governments to warn residents to prepare for flooding and landslides. The debris flows occurred during the day, which may have helped to prevent deaths, unlike the 2004 Aurora debris flows which occurred at night, or the 2012 New Bataan disaster that happened very early in the morning. Here, we explain why the Typhoon Koppu debris flows caused no casualties due to mitigation mechanisms that were in place. We feature the people-centered early-warning system embedded in the Pre-Disaster Risk Assessment protocol of the Office of Civil Defense after the 2004 and 2012 debris flow disasters killed 1440 people. [ABSTRACT FROM AUTHOR]

Understanding how fault systems interact and transfer strain over seismogenic timescales (seconds to ka) requires temporal records of past ruptures along adjacent and intersecting fault networks. Here we document the record of Late Holocene ruptures as recorded in the geomorphology of alluvial deposits along the Ash Hill fault, in the Eastern California Shear Zone (ECSZ). We leverage a multi‐faceted approach to evaluate the relative timing of Ash Hill fault ruptures to those of nearby faults in the ECSZ. We determine the number and timing of Late Holocene earthquakes on the Ash Hill fault using high‐resolution tectono‐geomorphic mapping, a locally calibrated alluvial fan stratigraphy, feldspar luminescence dating, and fault offset analysis from field observations, LiDAR, and drone‐based digital surface elevation models. We find evidence for three surface‐rupturing earthquakes that have occurred since ~4 ka, each with ~1.0 ± 0.2 m of oblique slip per event (Mw ~ 6.9–7.0), and we constrain the timing of these earthquakes by dating deposits that bracket each event. The timing of these three ruptures is similar to the paleoseismic record along the adjacent range‐bounding fault in southern Panamint Valley. Specifically, the two adjacent faults exhibit similar numbers of earthquakes during the Late Holocene, with similar recurrence intervals and rupture timing. These data suggest that it is possible that these two faults have ruptured in the same or closely temporally related events throughout the Late Holocene. Similar spatio‐temporal clustered earthquakes have been recognized in both historic and paleoseismic records in the region, and such behaviour may be common in complexly interlinked fault networks, like those that exist in the ECSZ. [ABSTRACT FROM AUTHOR]

An alluvial fan is a good area to install open-loop geothermal heat pump (GHP) systems due to shallower aquifers, faster groundwater flow, and fewer land subsidence risks. The natural temperature change in groundwater occurs in alluvial fans due to the recharge of river water and faster groundwater flow, and the thermal impact of the open-loop system has not been studied well in such areas. The purpose of this research is to understand the thermal impact of open-loop GHP systems on an alluvial fan. A regional 3D model of groundwater flow with heat transport was created to determine the distribution of flow velocity and temperature of groundwater. After that, two local models with different groundwater velocities were constructed to demonstrate the thermal impact of an open-loop GHP system using one extraction and one injection well. The results indicated that the local model with faster groundwater flow had a smaller thermal impact. The natural temperature change in groundwater causes groundwater temperature to be lower in the summer and higher in winter during the operation in the local model, with faster groundwater flow. [ABSTRACT FROM AUTHOR]

Tectonics imparts a first-order control on the overall morphology of alluvial fan systems in extensional settings by influencing sediment flux and accommodation space, while other factors such as climate, catchment lithology, and fault footwall characteristics are secondary. Previous alluvial fan modeling studies have focused on the link between the three-dimensional development of alluvial fans and rock uplift, however, despite the potential influence of tectonics on the overall three-dimensional morphology of alluvial fans, the controlling mechanisms, as well as their relative importance, remain largely unquantified in a natural setting with a targeted source-to-sink approach. Here, we examine 45 alluvial fans and their catchments along the southern mountain front of the Aydın Range, delimited by segmented normal faults in the western Anatolia Extensional Province, to quantify the role of rock uplift. We quantify river incision rates and catchment-wide erosion rates together with a series of topographic analyses across the southern flank of the Aydın Range as a proxy for rock uplift. Our results indicate that the spatial distribution of thicker and steeper alluvial fans fit well with higher rock uplift rates along the strike of the mountain front. In contrast, a lower uplift rate is responsible for prograding alluvial fans with decreasing thickness and gradients. Also, our data shows that alluvial fan thickness compared to other alluvial fan metrics strongly associated with the pattern of the rock uplift. This study demonstrates a field-based, quantitative linkage between three-dimensional alluvial fan morphology and rock uplift which has significant implications for improving alluvial fan models and understanding how alluvial fans respond to tectonics in extensional regions. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology & Engineering Geology / Shuiwendizhi Gongchengdizhi is the property of Hydrogeology & Engineering Geology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Flash floods occur almost exclusively in small basins, and they are common in small Mediterranean catchments. They pose one of the most common natural disasters, as well as one of the most devastating. Such was the case of the recent flood in Euboea island, in Greece, in August 2020. A field survey was accomplished after the 2020 flash floods in order to record the main impacts of the event and identify the geomorphological and man-made causes. The flash flood susceptibility in the urbanized alluvial fans was further assessed using a Geographic Information System (GIS)-based approach. Our findings suggest that a large portion of the alluvial fans of Politika, Poros and Mantania streams are mainly characterized by high and very high hazard. In fact, ~27% of the alluvial fans of Politika and Poros streams are characterized with very high susceptibility, and ~54% of Psachna area. GIS results have been confirmed by field observations after the 2020 flash flood, with significant damages noted, such as debris flows and infrastructure damages, in buildings, bridges and the road networks. In addition, even though the adopted approach may be more time-consuming in comparison to purely computational methods, it has the potential of being more accurate as it combines field observations and the effect of past flooding events.

Piggyback basins are common and well-studied features of thrust belts, but they are also known to form in front of advancing ice sheets. However, these glacitectonically developed basins and their syn-glacitectonic fillings have so far received little attention. Here, we present a detailed study of a cliff section on Jasmund peninsula, SW Baltic Sea, where syn-kinematic deposits of Late Weichselian age (MIS2) accumulated in a piggyback basin. Sedimentological analyses, including micromorphology and field studies, resulted in a distinction of at least five tectono-depositional sequences of syn-glacitectonic basin fills. The sediment record indicates a stepwise evolution of the basin, controlled by propagating thrust faults and the resulting thrust-bound ridge morphology. A fast-changing depositional environment with glacifluvial, glacilacustrine, alluvial fan and fan delta depositional systems, show a rapid transformation of the overall morphology of the study area. The main controlling factors are the propagating thrust faults (determining anticline and syncline orientations) and the advancing ice margin, which caused sudden changes or even temporal obstruction of the meltwater drainage system. The proposed stages of basin evolution illustrate the dynamic formation and stepwise syn-tectonic fill of piggyback basins in glacitectonic complexes. Our evolutionary model will increase our understanding of basin fills on glacitectonic thrust- and fold-belts that were formed by approaching ice sheets in ice-marginal settings. [ABSTRACT FROM AUTHOR]

We report the isotopic composition of the surface water and groundwater of the Kosi River fan on the Himalayan Foreland, India. We have collected 65 water samples from surface water (Kosi River (n = 2), streams (n = 9), waterlogging (n = 29), and canal (n = 4)), and groundwater (n = 21) for δ18O and δ2H analysis during December 2019. We obtained groundwater level data measured at the observation wells from the Central Groundwater Board, India, for 1996 and 2017. The groundwater level varies from 1.0 to 8.1 m below ground level (bgl) and from 0.5 to 9.0 m bgl during 1996 and 2017, respectively. We have used water table fluctuation approach to estimate the recharge rate. The recharge rate in the Kosi Fan varies from 0.7 to 21.4 mm/year from 1996 to 2017. Further, we have used δ18O and δ2H values of water samples to identify the source and the interaction between surface water and groundwater. The δ18O value of groundwater shows a wide variation (from −9.3‰ to −5.6‰) compared to the surface water, i.e., streams (−7.8‰ to −6.4‰) and canals (−6.9‰ to −6.0‰), suggesting mixing in groundwater during recharge processes. Furthermore, we have used a two-component mixing model to assess the fraction contribution from streams and precipitation to groundwater. The estimated fraction contribution from stream water to groundwater ranges from 45 to 83%. We also suggest higher recharge is limited up to the depth of 6 m bgl. We suggest precipitation and surface water actively recharge groundwater. We conclude that marked spatial variation in the isotopic composition of groundwater is mainly due to the local recharge sources and interaction between surface water and groundwater. [ABSTRACT FROM AUTHOR]

In the Cordillera Blanca, the glaciers delineated by some of the highest peaks in the tropical Peruvian Andes have experienced a fast retreat over the last few decades. At the foot of Artesonraju Peak, the glacier‐fed river conveys fine sediments to Parón Lake, which is enclosed in the proglacial area created by the retreating glaciers of the unique confluence of the Huandoy, Chacraraju, Nevado Caraz and Artesonraju peaks (above 6000 m.a.s.l.). This research addresses the sediment contributions of main glacial landforms to sediment mixtures delivered to the river and lake system (1.6 km2) by applying novel conservativeness and consistency methods for tracer selection and a frequentist unmixing model. A total of 27 surface soil and sediment sources (0–3 cm) were sampled from moraines, alluvial fans and recent colluvium, and 10 composite sediment mixtures, including suspended sediments, were collected to identify the sediment provenance. The unmixing results reveal large variability of the contributing sources related to their predominance and the locations of the mixtures. The largest contributions were from moraines, in percentages varying from 28% to as much as 77%. Alluvial fans contributed between 23% and 47% of the sediments, and colluvium material contributed the least, between 6% and 28%. At the time of sampling, ice melt discharge incising moraines and alluvial fans and eroding riverbanks were the main mechanisms of fine sediment delivery. Runoff over the bare surfaces of recently exposed moraines and the lack of vegetation cover in very active landforms also control sediment mobilization. Overall, highly dynamic changes in this paraglacial environment involve active sediment fluxes accompanying snow and ice melt. Our results indicate that in high tropical mountains, shrinking glaciers expose new surfaces of glacial materials, which deliver fine sediments. Identifying the contributing sources is of interest for water and sediment evaluation and management programs. [ABSTRACT FROM AUTHOR]

Across the Himalayan foreland area, alluvial fans respond to fluvial depositional landforms created by active tectonics and are incorporated within hydro-sediment processes. Each tributary of the master stream has its water and sediment to discharge, which assists in initiating several mesolevel fans in response to the active tectonics in Jaldhaka basin. Along the mountain front, active MBT (Main Boundary Thrust), MFT (Main Frontal Thrust) and lineaments (parallel and transverse to Himalaya) have governed the tectonically active Quaternary foreland area where numerous meso-level fans have developed. The study aims to estimate the tectonic activeness of each meso-fan using the morphotectonic indicators. The tributaries of the Jaldhaka River are permuted to the recent tectonism or neotectonics to form each meso fan with its basin displaying the varying degree of their activeness and aggradation system. Statistical methods like technique for order performance by similarity to ideal solution (TOPSIS) and VIKOR (Vlse Kriterijumska Optimizacija Kompromisno Resenje) that specify multicriteria optimization and compromise solution, in Serbian have ranked the Fan 2 as mostly active and Fan 4 is comparatively tectonically stable. The hydro-sediment characteristics reveal the topographic spatial dynamics of Fan 4 where lobe 3 has elevated from 1984–2014. The XRD analysis specifies the scientific key in response to the dominance of dolomite in the aggraded elevated bed sediments carried by the Rohtikhola River. The conceptual fan models of Fan 2 and 4 display the fan development phases through four stages. It has clearly defined the extension of the fan lobes of Fan 2 and 4. It is summarized that within a common climatic zone and similar neo-tectonic setting, meso-level fans have differential morphotectonic signatures with dynamic aggradation processes. [ABSTRACT FROM AUTHOR]

To study the soil-landscape change in the Chaldoran region, 9 representative soil profiles were studied in 5 dominant geomorphic units of the study area including piedmont plain, mantled pediment, alluvial fan, plain, and flood plain. The results showed that the accumulation of pedogenic carbonate in some soils was concretion and light in color. In control soils in the piedmont plain (profile 5 and 7), mantled pediment (profile 6), and flood plain (profile 8) clay transferred from the surface horizons and accumulated in the lower horizon, due to relatively good rainfall in the region and distinct dry and wet seasons has led to the formation of argillic horizons along with the formation of crust on the surfaces of aggregates and building units and has formed the Alfisoils order. Mineralogical results showed the presence of chlorite, illite, kaolinite, and smectite minerals. According to the evidence, illite, chlorite, and kaolinite minerals were inherited and smectite minerals were formed due to weathering and evolution of illite, chlorite, or palygorskite minerals. Also, the results of the CIA index in the region indicated that the soils of the region are in the stage of weak to moderate weathering. In general, the results indicated the critical role of drainage, land use, and parent materials in the soils of the study area. [ABSTRACT FROM AUTHOR]

Problem definition: Geomorphic phenomena have a primary impact on the locations, dispersions, spheres of influence, physical developments, and morphologies of settlements. In other words, geomorphic units and topographic elements are very important in physical development of settlemenets and play a significant role in the spatial distribution patterns of cities, as well as influencing the morphologies, constructions, and textures of them. Accordingly, location, orientation of mountains, and the type of landform have an undeniable role in issues such as urban construction and urban population movement. Nowadays, the increase in human population has created an increasing need to land occupation around residential areas; this is closely related to the geomorphic indicators of each area. Then, if the process of creating new settlements is formed with no proportion to natural capacities and facilities, it will create adverse effects and results in the physical-biological problems of cities, such as natural hazards, which cause disturbing the balance of the environment and disrupting services. Evidence of hazards in recent years show that most developing countries, especially in their rural areas, have high-risk physical structures that are often vulnerable to hazards. Therefore, based on various studies, there is a close relationship between geomorphological components and human settlements. These components have sometimes caused the growths and developments or emergence and expansions of settlement centers, which have sometimes appeared to be dangerous and repulsive. Therefore, recognizing the natural environment characteristics and the features and capabilities of landforms is important and necessary for identifying suitable and sustainable points for the creation and development of human settlements. Purpose: The purpose of this study was to investigate and analyze the roles of geomorphic features and components in the formations, developments, evolution, and patterns of settlements around Shirkuh Mountain in the arid and warm region of Central Iran. Methodology: To do this research, topographic and geological maps, Google Earth images, and, most importantly, field studies and observations were used. This study was based on descriptive phenomenological method. Accordingly, geomorphological factors, including altitude, direction, and lithology, geomorphic features, including fluvial landforms, such as alluvial plains, alluvial fans, plains, lake and river terraces, and glacial landforms like cirques, valleys, and glacial terraces were surveyed and analyzed. Then the role of each factor in the creation, development, and transformation of the settlements was studied and evaluated. Results: The results showed a different settlement pattern on the northern and southern slopes, as well as the western and eastern slopes of Shirkouh. Most of the settlements of the southern slopes were located at high altitudes between 2450-2550 m along the ice-water equilibrium line. However, the settlement range elevation on the northern slopes varied between 1700 and 1650 m, while fluvial landforms, such as river terraces, alluvial fans, and pediments, had not played a role in the formations of these settlements even with relatively good water resources unlike most other parts of Iran and the world. The settlement on glacial landforms at altitudes above 2000 m probably dated back to very dry and hot periods and the settlement on the edge of the current playa depression referred to the Late Quaternary cold periods. The formations and developments of settlements in the two completely different environments and climatic conditions, namely the high altitudes and the margins of the downstream depressions, indicated a climate change and consequently vertical displacements of the settlements along the Holocene. The results also revealed that other factors, such as geographical direction, altitude, slope, and lithology, had played an effective role in the densities and developments of these settlements. Innovation: This study showed that the alluvial fans had never been used to build a settlement anywhere in the study area until the last 3 decades due to heavy rainfall and heavy flooding. Although according to previous studied, most of the settlements in Iran, whether urban or rural settlements, especially in the central and eastern parts, have been located on alluvial fans, even the prehistoric settlements. Also, this study showed that glacial landforms located at the high altitudes had been the most desirable place for the creation and transformation of settlements due to specific climatic reasons. [ABSTRACT FROM AUTHOR]

Fossil records of canids are rare and incomplete in South America. In Chile, all well-identified taxa are part of the "South American Canid Clade" and come from sites located in southern Patagonia. Here, we report the first record for Chile of a taxon of the "Canis clade," assigned to cf. Aenocyon dirus. The fossil remains consist of a partially complete left hind limb, exposed by aeolian deflation, which facilitated its discovery at an isolated setting in Quebrada Maní, named QM38 site, in the southern sector of the Pampa del Tamarugal basin, part of the hyperarid core of the Atacama Desert, northern Chile. Measurements of the fossil are larger than the Protocyon troglodytes, falling in the smaller size range of A. dirus and within the larger range of Theriodictis platensis. Its morphological features compared with bone references of large extinct canids show that the fossil belongs to a small-sized Aenocyon. The remains occur in surface silty clays deposited by an alluvial fan that was active in the Pampa del Tamarugal basin in the Late Pleistocene. A radiocarbon date from bone apatite yielded an age of 14,660 cal years BP, placing it within the first half of the Central Andean Pluvial Event when this basin was wetter, well vegetated, and inhabited by large, medium, and small herbivores. No other large predator records are known from this basin, and our find affords a more complete view of this ecosystem which thrived in the hyperarid core of the Atacama during the Late Pleistocene. [ABSTRACT FROM AUTHOR]

The characteristics of nitrogen contamination of shallow groundwater were evaluated through current status analysis and trend detection of ammonium–N and nitrate–N concentrations under various cropping patterns to assess the effectiveness of rational fertilization in the Choushui River alluvial fan, central Western Taiwan. The influence of cropping patterns on both ammonium–N and nitrate–N contamination associated with redox conditions/dissolved oxygen (DO) in shallow groundwater was also discussed in this study. The analysis revealed that shallow groundwater beneath double rice cropping and rotational cropping regions is still characterized by high ammonium–N concentration despite rational fertilization promotion. However, very few monitoring wells showed an upward trend of ammonium–N/nitrate–N concentrations, indicating that shallow groundwater is not further deteriorated by nitrogen pollution in most parts of the study area. Therefore, the remediation of nitrogen contaminated groundwater will be a long-term process and more effort must be invested. Moreover, the strict redox conditions defined by a single DO threshold value may not account for groundwater nitrogen pollution in the study area. It is difficult to determine the redox conditions and predominant nitrogen pollution patterns of shallow groundwater purely from cropping patterns. Instead, contamination may have resulted from an integrated process governed by several other factors. Tracing the potential sources of nitrogen pollution and establishing a more integral monitoring network should be implemented to formulate a more comprehensive nitrogen pollution control strategy in this area. [ABSTRACT FROM AUTHOR]

The haor landscape is a wetland ecosystem in northeast Bangladesh, comprising shallow depressions that undergo large changes in water inundation between the monsoon and dry seasons. Sediment is supplied to the haor from rivers originating in the adjacent Shillong Plateau, and can adversely affect these largely arable agricultural lands. The critical adverse effects of changing hydrology and enhanced sedimentation due to anthropogenic change include the reduction of natural water storage capacity, changes in the timing and magnitude of floods, and increasing loss and damage to crops, which consequently affect the livelihoods of wetland dwellers. This study employs a mixed‐methods approach to investigate how sedimentation has affected the livelihoods of the residents and the pressures they experience. Cross‐sectional surveys and interviews were conducted with 180 respondents in Lubar and Pochashul Haors (LPH), Sunamganj District, and allied with an analysis of satellite images that reveals the nature of landscape change over the past 56 years. Our findings confirm that sedimentation has been promoted through both natural processes of alluvial fan progradation and anthropogenic forcings. Enhanced sedimentation threatens the agriculture of the region and affects the livelihood of local inhabitants, leading to other societal issues related to income, education, employment, health, displacement, and sexual harassment. The mixed methods employed herein are essential tools to reveal these effects. In order to reduce the vulnerability of the local population, a transboundary dialog between India and Bangladesh is needed to realize measures to protect wetland resources and achieve progress towards environmental sustainability. Key Points: Sedimentation has fostered a new pattern of local disasters in wetland areasBoth natural and anthropogenic factors cause accelerated sedimentationEnhanced sedimentation can lead to societal issues related to income, education, employment, health, displacement, and sexual harassment [ABSTRACT FROM AUTHOR]