Search

The extent of mountainous and desert areas in Iran has caused the emergence of well -known geomorphological phenomena .Alluvial fans are landforms found in various locations. Identifying and evaluating their impacts can be valuable for natural hazard management and land use planning. In this study an attempt hs been made to evaluate the status of tectonic activities in the south of the slopes of the Khar qan mountain range in the northeast of Hamedan province. Different maps were utilized to examine the development process of alluvial fans and present evidence of tectonic activity, including the Gozal Valley, Karafs, and several smaller alluvial fans. The findings of this study revealed that tectonic activity in the Gozal Valley cone remains active, while the alluvial fans located between the Gozal Valley are inactive. Further evidence in the bed of the Gozal Valley cones suggests tectonic changes caused by fault activity, resulting in the alteration of the riverbed's drainage pattern and subsequent destruction and erosion of the surrounding areas. Additionally, changes in drainage patterns and sediment depth on the surface of alluvial fans can be attributed to tectonic activities within these fans. Geological logs illustrate both prolonged, slow periods and active periods during various geological eras in the study area. Ultimately, tectonic activity initiated with a lengthy, sluggish phase, followed by continued tectonic activities and fluctuations. [ABSTRACT FROM AUTHOR]

Floods stand out as one of the most significant disasters impacting human life, causing widespread economic and social damage across the globe. Numerous research studies have concentrated on comprehending the contributing factors of flooding. Despite the prevalence of morphometry-based basin flood susceptibility analyses in existing literature, a comprehensive examination that encompasses anthropogenic features in alluvial fans is notably lacking. This study aims to evaluate the flood susceptibility of alluvial fans and their catchments in urbanised areas, integrating individual and collective basin/fan (B/F) morphometry and land use characteristics with flood inventory data. The study area selected for this investigation is the basin and fan systems situated on the northern slope of the Uludağ Massif (2543 m), the highest point in the Marmara Region, northwestern Türkiye. Twelve basin morphometric parameters were applied to 5 m resolution Digital Elevation Model data, while six fan morphometric and anthropogenic parameters were applied to alluvial fans. In addition, the results were assessed using the Normalised Morphometric Flood Index method to mitigate subjectivity in result ranking. According to the integrated basin/fan flood susceptibility results obtained through bivariate analysis, B/F6 exhibits a very high susceptibility, while B/F1, B/F3, B/F2, B/F5, B/F4, and B11/F8 demonstrate high susceptibility. B7, 8, 9, 10/F7 display a moderate potential for generating floods. These findings align significantly with historical flood events in the basin/fan area. [ABSTRACT FROM AUTHOR]

Abstract “Leaky weirs” are rock structures installed in dryland streams, which are anchored into exposed bedrock, loosely cemented, and designed to allow water to slowly pass through. They are being tested at a ranch in southeastern Arizona, USA, to restore and conserve the historic range and desert wetlands. Data are collected to assess how leaky weirs impact surface water, subsurface water, and groundwater recharge—including stream discharge, timing, and depth of infiltration, and groundwater elevations. Three adjacent watersheds, two with outlets just below leaky weirs and one with leaky weirs farther upstream, were instrumented with water-level loggers, wildlife cameras, and crest stage instruments with temperature sensors in the soil. As most groundwater recharge is assumed to be focused along the mountain fronts in this region, mountain-block recharge is also evaluated to differentiate between the two using isotope analyses. Finally, a single, late-season flood event is scrutinized to consider the leaky weir effect on all monitored components in the water budget. Results indicated groundwater flow is primarily from the mountains to the east via older, regional mountain-block recharge. However, the development of shallow alluvial aquifers is supported by the leaky weirs, that slow flows, capture permeable sediments, and allow infiltration, thus enhancing mountain-front recharge. In turn, these new pockets of water help support the restoration of historic wetlands. Sediment accumulates where leaky weirs are installed, reducing flashy peak flows, and resulting in a series of infiltration ponds along the channel that support vegetation during growing seasons and recharge the shallow aquifer during non-growing seasons.

The morphology of alluvial fans provides valuable information about changes in tectonic, climate, base level, and drainage basin characteristics. This study aims to evaluate the relationship between active tectonics and morphometric characteristics of alluvial fans in the less studied southern region of the Joghatay mountain, northeast Iran. The study area includes 13 alluvial fans and their corresponding catchment basins in a region with semi-arid climate. Morphometric characteristics of alluvial fans and their corresponding drainage basin including fan area, fan slope, sweep angle, fan toe length, fan radius, basin area, basin slope, fan's width-to-length ratio, asymmetry factor, and basin shape were measured. Our results revealed a negative relationship between the slope of alluvial fans and their corresponding basin area. The weak correlation between the drainage basin area and the fans area may be attributed to the lithology and active tectonics in the study area. The small sweep angle values of the studied alluvial fans can be attributed to the activity of thrust faults and presence of an uplifting anticline that resulted in formation of elongated alluvial fans in our study area. Analysis of the relationship between the morphometric characteristics of the fans and their corresponding basins indicated a negative correlation, which can be attributed to the sediment transport efficiency of the basins. [ABSTRACT FROM AUTHOR]

In recent years, extensive exploration has contributed to significant advancements in the geological formations of the Kuqa Depression. In particular, the Paleogene Kumugeliemu Formation exhibits the development of expansive bedded evaporites. The combination of red sandstone, red mudstone, and gypsum-salt layers holds immense potential as a reservoir and cap association, thereby offering promising prospects for oil and gas exploration. However, our understanding of the sedimentary system and model governing this formation remains limited, impeding progress in the field of oil and gas exploration. To address this gap, this study delved into a detailed examination of the stratigraphy, depositional system, and model of the Kumugeliemu Formation through the application of core samples, logging data, and seismic analyses. The primary objective of this study was to establish a comprehensive theoretical foundation for future oil and gas exploration efforts targeting the Kumugeliemu Formation. The findings revealed a distinct division of the Kumugeliemu Formation into two 3rd order sequences, each characterized by a lowstand systems tract, transgressive systems tract, and highstand systems tract. Moreover, all systems tracts were further subdivided into 14 parasequence sets. During the depositional period of the Kumugeliemu Formation, alluvial fan, delta, and salt lake deposition systems developed from the periphery to the central region of the Kuqa Depression. The alluvial fan mainly exhibited braided channel sedimentary microfacies, whereas the delta region indicated plain distributary channels, submerged distributary channels, and interdistributary sedimentary microfacies. The salt lake area is characterized by shore-shallow lacustrine mud, beach-bar, salt mud flat, and salt flat sedimentary microfacies. Throughout the deposition of the Kumugeliemu Formation, the climate of the Kuqa Depression oscillated between arid and humid. During arid periods, the depression experienced diminished water body extent, heightened salinity levels, and extensive distribution of salt and salt mud flats within the basin, with alluvial fans and delta deposits primarily confined to the basin margins. Conversely, during the humid period, the depression experienced an expansion in the extent of the water bodies, leading to a decrease in salinity levels. The distribution of salt flat and salt mud flat deposits within the basin diminished, whereas alluvial fan and delta deposits advanced extensively across the basin. The establishment and spatial arrangement of the sedimentary system within the Kumugeliemu Formation were governed by a complex interplay of certain factors, such as the semi-closed paleotectonic pattern, paleoclimatic conditions of both dry and wet alternation, and the salt source supply brought by the transgression of the Paleo-Tethys Ocean. The findings of this study offer not only a valuable reference framework for the prospective exploration of hydrocarbon resources within the Kumugeliemu Formation of the Kuqa Depression but also potential insights into the evolution of similar depressions in other basins. [ABSTRACT FROM AUTHOR]

Sediment gravity flows (SGFs) cause serious damage in the Alpine regions. In the literature, several methodologies have been elaborated to define the main features of these phenomena, mainly considering the rheological features of the flow processes by laboratory experiments or by flow simulation using 2D or 3D propagation models or considering a single aspect, such as the morphometric parameters of catchments in which SGFs occur. These very targeted approaches are primarily linked to the definition of SGFs' propagation behavior or to identify the predisposing role played by just one feature of catchments neglecting other complementary aspects regarding phenomena and the environment in which SGFs can occur. Although the research aimed at the quantification of some parameters that drive the behavior of SGFs provides good results in understanding the flow mechanisms, it does not provide an exhaustive understanding of the overall nature of these phenomena, including their trigger conditions and a complete view of predisposing factors that contribute to their generation. This paper presents a research work based on the collection and cross-analysis of lithological, geomechanical, geomorphological and morphometrical characteristics of Alpine catchments compared with sedimentological and morphological features of SGF deposits, also taking in to account the rainfall data correlation with historical SGF events. A multidisciplinary approach was implemented, aiming at quantifying SGF causes and characteristics starting from the catchments' features where the phenomena originate in a more exhaustive way. The study used 78 well-documented catchments of Susa Valley (Western Italian Alps), having 614 historical flow events reported, that present a great variability in geomorphological and geological features. As the main result, three catchment groups were recognized based on the dominant catchment bedrock's lithology characteristics that influence the SGFs' rheology, sedimentological and depositional features, triggering rainfall values, seasonality, occurrence frequency and alluvial fan architecture. The classification method was also compared with the catchments' morphometry classification, demonstrating that the fundamental role in determining the type of flow process that can most likely occur in a given catchment is played by the bedrock outcropping percentage, regardless of the results provided by the morphometric approach. The analysis of SGF events through the proposed method led to a relative estimate of the hazard degree of these phenomena distinguished by catchment type. [ABSTRACT FROM AUTHOR]

Alluvial fans have been proven to have great utilisation potential in QTP, but to what extent they are suitable for agricultural development is unknown. Therefore, using the alluvial fan in the Lhasa River Basin (LRB) as a case study, this paper established an evaluation system of land suitability for agriculture (LSA). Principal component analysis (PCA) and the exhaustive method (EM) were used to define the minimum dataset (MDS) and then the LSA of the alluvial fan in the LRB was evaluated using a comprehensive index of LSA. Two scientific approaches were implemented to improve the LSA using a scenario simulation. The results showed that the MDS assessed by the EA was more representative compared to the PCA. Alluvial fans with suitable grades are mainly distributed in the Lhasa River's middle and lower reaches. Developing facility agriculture and repairing roads accessing the alluvial fans are effective approaches to improve the LSA, which can increase the suitable-grade area from 58.62% to 97.82% and 63.85%, respectively. Therefore, most alluvial fans in the LRB are suitable for developing agriculture, and under the influence of human activities, there will be more alluvial fans suitable for developing agriculture. Our research provides scientific methods for the sustainable development of land in alpine regions. [ABSTRACT FROM AUTHOR]

Sediment gravity flows (SGFs) cause serious damage in the Alpine regions. In the literature, several methodologies have been elaborated to define the main features of these phenomena, mainly considering the rheological features of the flow processes by laboratory experiments or by flow simulation using 2D or 3D propagation models or considering a single aspect, such as the morphometric parameters of catchments in which SGFs occur. These very targeted approaches are primarily linked to the definition of SGFs’ propagation behavior or to identify the predisposing role played by just one feature of catchments neglecting other complementary aspects regarding phenomena and the environment in which SGFs can occur. Although the research aimed at the quantification of some parameters that drive the behavior of SGFs provides good results in understanding the flow mechanisms, it does not provide an exhaustive understanding of the overall nature of these phenomena, including their trigger conditions and a complete view of predisposing factors that contribute to their generation. This paper presents a research work based on the collection and cross-analysis of lithological, geomechanical, geomorphological and morphometrical characteristics of Alpine catchments compared with sedimentological and morphological features of SGF deposits, also taking in to account the rainfall data correlation with historical SGF events. A multidisciplinary approach was implemented, aiming at quantifying SGF causes and characteristics starting from the catchments’ features where the phenomena originate in a more exhaustive way. The study used 78 well-documented catchments of Susa Valley (Western Italian Alps), having 614 historical flow events reported, that present a great variability in geomorphological and geological features. As the main result, three catchment groups were recognized based on the dominant catchment bedrock’s lithology characteristics that influence the SGFs’ rheology, sedimentological and depositional features, triggering rainfall values, seasonality, occurrence frequency and alluvial fan architecture. The classification method was also compared with the catchments’ morphometry classification, demonstrating that the fundamental role in determining the type of flow process that can most likely occur in a given catchment is played by the bedrock outcropping percentage, regardless of the results provided by the morphometric approach. The analysis of SGF events through the proposed method led to a relative estimate of the hazard degree of these phenomena distinguished by catchment type.

Early human habitation of the arid to semiarid Central Iranian Plateau was strongly connected to the availability of water and associated natural hazards, such as flooding and drought events. In this geoarchaeological study, we focus on the occupation at the prehistoric site of Ajor Pazi within the formerly active fluvial environment of the Varamin Plain. Through radiocarbon and luminescence‐dated sediment cross‐sections, we apply multivariate statistics to sedimentological characteristics of bulk samples collected during a rescue excavation in 2018. Based on facies interpretations, we differentiate depositional processes and present their implications for the environs of Ajor Pazi. Our results show evidence of settlement activities between 6.4 and 5.6 ka cal B.P. (4.4–3.6 ka cal. B.C.E.). Phases of reduced geomorphodynamics can be distinguished when soil‐forming processes take place. Our findings provide insights into the hitherto scarcely explored Transitional Chalcolithic II period during which the site of Ajor Pazi emerged and began to shape its environs. [ABSTRACT FROM AUTHOR]

Autogenic feedbacks can produce large‐scale, organized stratigraphic patterns in alluvial fans, but autogenic depositional signatures of specific upstream boundary conditions remain challenging to interpret. Here, a combination of theory, experiment and field application is used to explore how autogenic lithofacies changes can be interpreted as stratigraphic indicators of upstream boundary conditions. Six experiments were conducted to test the effects of sediment supply and water discharge rates on autogenic advance and retreat of the lithofacies boundary (grain‐size transition) in an alluvial fan with two dominant grain sizes. Migration of the grain‐size transition caused a short‐term zigzag pattern in the grain‐size transition position in the dip‐directional deposit section. For each experiment, time‐lapse images and laser topographic scans of the fan surface and stratigraphic cross‐sections of the final deposits were used to quantify characteristic timescales of autogenic processes. Timescales for fan‐margin migration, surface wet‐fraction change and grain‐size transition migration generally shorten as sediment supply rate increases and water discharge rate decreases. Increasing the sediment supply rate shortens the duration of the fluvial sediment storage and release cycle, producing higher frequency zigzags in the grain‐size transition trajectory. Increasing the water discharge tends to widen channels and lengthens the duration of the fluvial sediment storage and release cycle, constructing lower frequency zigzags in the grain‐size transition trajectory. Increasing the water discharge also enables more sediment to transport further downstream during release events, leading to higher magnitude zigzags in the grain‐size transition trajectory. These relationships between upstream boundary conditions and the grain‐size transition trajectory demonstrate how autogenic stratigraphic signals could be used as a tool to infer relative changes in boundary conditions. [ABSTRACT FROM AUTHOR]

Copyright of Revista de la Asociación Geológica Argentina is the property of Asociacion Geologica Argentina 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.)

The occurrence of high-concentration turbid water due to a large landslide in the upper reaches of the Tedori River Basin in Japan in May 2015 led to a rapid decline in the groundwater levels within the alluvial fan. However, factors other than turbid water, such as changes in precipitation patterns, can have a significant impact on groundwater levels but have not been thoroughly investigated. By analyzing the relationship between river water and groundwater levels, we found that by 2018, conditions had returned to those observed prior to the turbidity events. Regarding seepage, we found that approximately 24% of the Tedori River's discharge contributed to seepage before the turbidity event. In contrast, during the post-turbidity years, seepage decreased between 2015 and 2017 and returned to the pre-turbidity levels by 2018. Furthermore, by constructing a hydrological model and examining the contributions of turbidity and precipitation, we found that in 2015, turbidity contributed to 76% of the groundwater level changes, whereas precipitation accounted for 24%. In contrast, in 2016, turbidity contributed to 67%, while precipitation contributed to 33%. In essence, the first year was characterized by a significant contribution from turbidity, while precipitation also played a significant role in groundwater level fluctuations in the second year. [ABSTRACT FROM AUTHOR]

The spatial cover of biocrusts represents a suitable habitat for the activity of soil microorganisms in semi‐arid and arid regions. Microorganisms are one of the essential components of soil quality. Therefore, it is necessary to understand the processes of biocrust habitat formation in landforms and their mutual relationship with soil properties. We studied the spatial distribution of biocrusts and their effect on soil microbial biomass and carbon activity in a semi‐arid alluvial fan in NE Iran. A total of 72 soil samples (using plots 0.25 m2) from the topsoil layers (0–5 cm) were collected along the alluvial fan in September 2020. Soil surface properties and microbial biomass in two categories of biocrust and non‐biocrust were investigated in three classes of biocrusts coverage obtained by geostatistics. Our results revealed that biocrusts had a negative correlation with gravel coverage and elevation; in contrast, the suitable spaces for biocrusts growth were created by cobble clasts. The biocrusts have provided favourable conditions for soil microorganisms by altering the properties of the soil (such as increasing organic carbon, nitrogen and available phosphorus and decreasing pH), and thus they increased basal soil respiration and microbial biomass. Different microbial activities were led by the predominant type of biocrusts, as the chlorolichen crusts had the most significant effect on increasing the microbial biomass phosphorus while cyanolichen crusts increased the microbial biomass carbon. Moss and cyanolichen crusts increased microbial activity and respiration more than cyanobacteria crusts. Therefore, the soil quality has improved by biocrusts in semi‐arid ecosystems. [ABSTRACT FROM AUTHOR]

Alluvial glutenite reservoirs have obviously stronger heterogeneous and more complex control factors than sandstone reservoirs. Taking the Binxian Uplift area in the Boahi Bay Basin as an example, the aim of this study is to clarify the characteristics and control factors of the alluvial glutenite reservoir quality and the influence of reservoir properties on hydrocarbon accumulation. Pore types in the study area mainly include residual intergranular pores, intergranular dissolved pores, intragranular dissolved pores, and mold pores. The residual intergranular pores and intergranular dissolved pores are the main pore types. Most samples have porosity greater than 15% and permeability is mainly concentrated between 50 mD and 500 mD. It is shown that lithology type, microfacies, and diagenesis have significant impact on the reservoir quality. The reservoir qualities of very fine sandstone and fine sandstone are better than those of conglomerate and gravel-bearing sandstone. Instead of grain size, sorting affects the alluvial glutenite reservoir quality significantly. Oil-bearing samples commonly have sorting coefficient less than 2 while non-oil-bearing samples have sorting coefficient larger than 2. There are significant differences in reservoir physical properties of different sedimentary microfacies. The stream flow in mid-alluvial fan (SFMA) and braided channels outside alluvial fans (BCOA) have relatively weaker compaction and better reservoir quality than the overflow sand body (OFSB) and debris-flow in proximal alluvial fan (DFPA). Calcite cementation, the main cement in the study area, commonly developed at the base of SFMA and BCOA and near the sandstone-mudrock contacts. The source of calcium carbonate for calcite cement mainly came from around mudstone. High calcite cement content commonly results in low porosity and permeability. Individual glutenite thickness is also an important influencing factor on reservoir quality. Reservoirs with large thickness (>4 m) have high porosity and permeability. Dissolution occurred in the reservoir, forming secondary dissolution pores and improving reservoir quality. The dissolution fluid for formation of secondary pores is mainly meteoric waters instead of organic acid. The reservoir property has an important influence on hydrocarbon accumulation. The lower limit of physical properties of an effective reservoir is a porosity of 27% and permeability of 225 mD. The findings of this study can be utilized to predict the reservoir quality of alluvial glutenite reservoirs effectively in the Bohai Bay Basin and other similar basins. [ABSTRACT FROM AUTHOR]

Alluvial fans play a significant role in fluvial systems and are a subject of great interest in geomorphology. This research aims to provide a comprehensive understanding of the key factors that influence alluvial fan morphology, which include climatic conditions, tectonism, and base level changes. The paper discusses the morphological development of alluvial fans along the Maymundağı fault, which borders the northwest of the Acıgöl graben. The fault exhibits a NE-SW strike that veers into an E-W direction in the south. Two different alluvial fan systems were observed, intersecting in front of the E-W trending mountain. This development was previously associated with the high level of the Pleistocene lake, but later studies have shown that there was no rise in the lake level that affected the development. In this study, it was revealed that the morphological development occurred as a result of active faulting in the lower part of the fan.

Copyright of Acta Sedimentologica Sinica is the property of Acta Sedimentologica Sinica 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.)

Debris flows in alpine environments are prone to occur in the context of global climate change (i.e., elevated air temperature and higher frequency of strong precipitation events). (Alluvial) Fans often develop at the outlet of tributaries after high‐intensity debris flows. Most debris‐flow fans in alpine canyon areas extend directly to the main river channel and become the forefront of the interaction between the tributary gully and the main river channel. Clarifying the development processes/dynamics, evolutionary mechanisms and driving factors of alluvial fans would shed light on understanding the geomorphological effects and genesis of river valleys in alpine canyon areas. Here, we report the development of debris‐flow fan at the outlet of the Tianmo Gully, a formerly hazard‐free but currently hazard‐active tributary of the Parlung Tsangpo Basin, Southeast Tibet, where debris flows have occurred frequently in the last two decades. Combining remote‐sensing images, DEM data, UAV aerial photography, RTK topographic survey and other fieldwork, the development processes and morphological characteristics of the Tianmo fan under the influence of four large debris flows were analysed. Both primary events (described as episodic debris‐flow events characterized by high‐magnitude mass movement) and secondary events (corresponding to perennial stream flow processes with much lower sediment concentrations) affected the development of the Tianmo fan. Episodic debris‐flow events drastically shape the macroscopic morphology of the fan, with rapid deposition and expansion of the fan body, whereas perennial stream flow processes slowly modulate the fan during the intermittent period between debris flows, mainly with gradual retrogressive incision and lateral migration of flow channel on the fan body. Influenced by the strong sediment‐transport process of debris flows and the alluvial fan development, the planform of the Parlung Tsangpo River evolved from a relatively narrow and single‐thread pattern to an alternating‐wide‐and‐narrow pattern, with a corresponding staircase‐like longitudinal profile. [ABSTRACT FROM AUTHOR]

Summary: Sedimentary units in alluvial fans may record gradual transport and deposition during multiple floods or sediment‐laden flows or, conversely, during few catastrophic events. While outcrops are a valuable source of direct information to constrain past geomorphic and hydrologic processes, such exposures are scarce, especially along aggrading rivers or those that have been subject to recent catastrophic sedimentation. In this context, near‐surface geophysical techniques can constrain the dimensions, internal architecture, composition, and petrophysical properties of different sedimentary units. We consider the Grimmbach alluvial fan in the cuesta landscape of southwestern Germany, which was heavily impacted by sediment and wood loads during a flash flood in 2016; published radiocarbon dates indicate that at least three floods similar to the one in 2016 may have occurred since the 17th century. To test whether and to which detail near‐surface geophysics might reveal the sedimentary legacy of these floods, we survey the Grimmbach alluvial fan using detailed topographic data and geophysical imaging based on electromagnetic induction, electrical resistivity tomography (ERT), and ground‐penetrating radar. Our geophysical results indicate former channel courses and two coarse bar deposits up to 3 m below the surface, which are comparable with the more extensive bar deposits of the 2016 flood. From the ERT models, we interpret coarse, up to 5 m thick, gravel lag overlying bedrock at a maximum depth of 10 m. Our geophysical results also highlight patches of finer materials derived from gradual sedimentation and soil development. Overall, our results show that the Grimmbach alluvial fan may have formed and reshaped during catastrophic flows, which likely caused channel avulsions. Our findings point to the need to reconsider flash flood and debris‐flow hazards in similar headwaters and fans of this seemingly quiescent cuesta landscape in southern Germany. [ABSTRACT FROM AUTHOR]

The Pergamon micro-region (western Türkiye) has experienced several phases of increased geomorphodynamics during the Holocene. However, the role of local–regional human activities during a transformation between Hellenism and the Roman Imperial period and supra-regional climate fluctuations is still under discussion. Five sediment profiles from the alluvial fan of the rural Deliktaş catchment are analyzed and radiocarbon-dated to provide a sedimentological record covering the Holocene. Our results indicate seven phases of changing sediment dynamics. Five Holocene cycles of coarse- and fine-textured fan sediment deposition covered the paleochannel deposits of the Çaylak creek, and the floodplain sediments of the receiving Geyikli river which aggraded toward the piedmont during the Mid-Holocene. The landscape became stable on the Deliktaş fan and Geyikli floodplain at least ca. 4–3.4 cal ka BP as indicated by paleosols. These paleosols were again buried by fan sediments marking the first phase of accelerated geomorphodynamics during the Late Holocene. Both the local onset of human activities and the regional Mid-Holocene aridization with rapid climate changes play a role. The increased number of archeological sites and high human pressure on the environment during the Hellenistic–Roman transformation in the Deliktaş area and Pergamon micro-region were hypothesized to contribute to a phase of increased geomorphodynamic activity during the last 2.5 ka. This, however, is less apparent in our record. Our study emphasizes the importance of both, the climatic system and rural-urban cultural history, on landscape development, suggesting potential responses of locally diverse geomorphodynamics on regional-scale transformation in the eastern Mediterranean. [ABSTRACT FROM AUTHOR]

The Niger River (NR) is threatened with silting up due to the evolution of alluvial fans (AFs) in the Niamey region. The most significant is the Kourtéré AF. This study aims to map the spatial extent of this AF and analyze its progression and impact on the NR using a machine learning algorithm such as support vector machine on Landsat and Sentinel-2 images from between 1985 and 2021. Sentinel-1 data were then used to generate a digital terrain model at 10 m resolution through the Interferometric Synthetic Aperture RADAR (InSAR) technique to understand the Kourtéré watershed hydrology. Results show that the AF area increased from 55.19 ha in 1985 to 303.86 ha in 2003 and 237.18 ha in 2021. The AF has invaded a section of the NR since 2000 and began to invade its main bed in 2016. More than 73.71 ha of NR were converted into AF between 1985 and 2016. The flow direction of the NR has been disturbed by changes in AF, making it easier to overflow at flows much lower than previously. The Kourtéré watershed is dominated by a dense network of gullies with a Sediment-Transport Index of 424.4, which facilitates significant sediment transport into the AF and NR and leads to its silting up. [ABSTRACT FROM AUTHOR]

We develop a robust and simple rule‐based algorithm to autonomously simulate alluvial fan deposition and evolution under continuously developing landscape conditions without prescribing deposition locations or imposing topographic constraints. Augmented with this algorithm, landscape evolution models are capable of dynamically detecting locations of potential fan deposition by statistical measures of surface topography and fluvial dynamics, then depositing fan sediments where and when the developed conditions require. To assess the method's efficacy in depositing sediment at a mountain‐valley transition zone characterized by a transport surface that permits unobstructed exit of sediment and water, a hypothetical scenario is created that involves a frontal, normal fault. It is followed by a series of sensitivity analyses to ascertain the influence of parameters affecting fan deposition and secondary processes. Uplift (u) and precipitation significantly impact fan morphological characteristics, which are within the range of real‐world fans. Higher rates of each cause the notable expansion of the fan area except in cases of exceptionally high precipitation rates. Fan area has a power‐law relationship with most of the tested parameters, Af∝u0.94μ0.31lf−0.14Kmax−0.65Acβ, where μ is erodibility (lithology), lf and Kmax are fluvial parameters, and Ac is catchment area (β~0.9). This study is the first showcasing fan power‐law relationships using numerical modelling. While fan area increases with precipitation, there exists a threshold beyond which fan area diminishes, and the formation of fans ceases altogether. The algorithm provides a basis for improving mechanistic understanding of fans by offering a robust platform for testing process dominance and scaling. The results demonstrate its applicability for landscape evolution simulation over a long time and broad spatial scales. We also investigate the hydrological significance of including autonomously generated alluvial fans in coupled landscape evolution—hydrology models that focus on groundwater as well as surface water hydrology. [ABSTRACT FROM AUTHOR]

Alluvial fans have been proven to have great utilisation potential in QTP, but to what extent they are suitable for agricultural development is unknown. Therefore, using the alluvial fan in the Lhasa River Basin (LRB) as a case study, this paper established an evaluation system of land suitability for agriculture (LSA). Principal component analysis (PCA) and the exhaustive method (EM) were used to define the minimum dataset (MDS) and then the LSA of the alluvial fan in the LRB was evaluated using a comprehensive index of LSA. Two scientific approaches were implemented to improve the LSA using a scenario simulation. The results showed that the MDS assessed by the EA was more representative compared to the PCA. Alluvial fans with suitable grades are mainly distributed in the Lhasa River’s middle and lower reaches. Developing facility agriculture and repairing roads accessing the alluvial fans are effective approaches to improve the LSA, which can increase the suitable-grade area from 58.62% to 97.82% and 63.85%, respectively. Therefore, most alluvial fans in the LRB are suitable for developing agriculture, and under the influence of human activities, there will be more alluvial fans suitable for developing agriculture. Our research provides scientific methods for the sustainable development of land in alpine regions.

This study analyzed long-term fluctuations of groundwater levels in six shallow observation wells in the Nasunogahara alluvial fan, Japan's second largest source of agricultural irrigation groundwater, and presented a simple method for predicting groundwater levels in April prior to the annual planting of paddy rice. The 22-year time-series of groundwater levels (1998–2019) clearly showed seasonal periodicity, with higher levels in summer than in winter. In particular, groundwater levels were lowest in April when groundwater demand was greatest. Groundwater levels in two wells at the beginning of the April irrigation period showed long-term declining trends that can be attributed more to changes in land use than to changes in precipitation or air temperature. A simple linear regression of mean groundwater level in April to antecedent precipitation provided reasonable predictions of April groundwater levels, which were significantly influenced by precipitation in the preceding 3–5 months. Further modeling after subtraction of long-term seasonal trends (detrending) improved these estimates. The performance of the linear regression model for prediction of April groundwater levels is comparable to that of the statistical benchmark model. Using long-term monthly or seasonal weather forecasts, the modeling presented here can be applied to inform appropriate changes of water use practices, such as decreasing groundwater extraction by implementing rotational water supply, changing rice-cropping seasons, or targeting deeper aquifers. The identification of the critical period of antecedent precipitation that affected April groundwater levels in the Nasunogahara alluvial fan is also important for understanding appropriate precipitation periods to be targeted in modeling for future drought risk assessments under climate change. [ABSTRACT FROM AUTHOR]

The analysis and design of nearshore coastal infrastructure, offshore foundations, and deep-sea mining along the Red Sea require a robust understanding of the various sediments involved. This study analyzes their formation history, conducts a comprehensive experimental program to determine their engineering properties, and evaluates their physical characteristics in the context of extensive databases gathered for worldwide sediments. Results show that sub-angular alluvial deposits and coarse-grained sand dunes in the Red Sea coastal plain exhibit high friction angles and are potential sources for construction materials. Wind-transported dust particles provide nutrients, influence climate, and affect engineered systems such as photovoltaic panels. Ubiquitous marine biogenic grains—from microfossils to nearshore shells—pack at low density and have high compressibility; the low yield stress level due to grain crushing will limit the allowable stress for engineering designs. The residual sediments that remain after the dissolution of the massive evaporites delay further salt dissolution and regulate the Red Sea salinity. Fluid expulsion induces authigenic mineralizations from centimeter-sized sulfur-enriched nodules to several-meters-tall carbonate chimneys and flat-crust hardgrounds. Deep-sea mining of metalliferous deposits in the central Red Sea can benefit from differences in specific gravity for separation, but offshore tailing disposal will experience prolonged settling times due to their very high specific surface area. [ABSTRACT FROM AUTHOR]

Copyright of Turkish Journal of Geographical Sciences / Coğrafi Bilimler Dergisi is the property of Cografi Bilimler Dergisi 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.)

Evidence points out that increasing plant productivity associated with greater erect shrub abundance alters soil organic carbon (SOC) stocks in the Arctic. However, the underlying plant economic traits remain poorly examined, which limits our understanding of plant–environment interactions driving tundra carbon cycling. We explored how erect shrub abundance leads to SOC variation in a High Arctic tundra (Bylot Island, Nunavut, Canada), where the only erect shrub, Salix richardsonii, has settled along currently active and abandoned channel zones of alluvial fans. The effects of vegetation and local environmental changes on SOC were evaluated through a paired sampling of soil materials and plant aboveground functional traits associated with plant carbon supply and nutrient demand processes. The occurrence of S. richardsonii, characterized by a tenfold increase in aboveground biomass, induced a 28% increase in SOC compared to adjacent plots dominated by prostrate shrubs and graminoids. Yet, this vegetation effect was solely observed along active channels, where higher SOC was associated with greater leaf and stem biomass. A path analysis showed that shrub leaf area index and total leaf nutrient content best represented plant carbon supply and nutrient demand dynamics, respectively, and jointly regulated SOC variation. This study underscores that vegetation structural changes associated with increasing erect shrub abundance in the Arctic can promote soil organic carbon storage, but that this pattern may be mediated by strong plant–environment interactions. Accounting for changes in functional traits driving plant carbon supply and nitrogen demand proves important for a better mechanistic understanding of how shrubification impacts tundra carbon cycling. [ABSTRACT FROM AUTHOR]

The timing and character of the initial marine flooding of extensional basins has implications for their tectonic history. Yet, the recognition of such flooding is difficult along rift basin margins due to the dominance of coarse‐grained systems and the lack of marine fauna. This study conducts detailed facies and stratigraphic analysis of a Mio‐Pliocene alluvial fan and fan‐delta succession in the Fish Creek Vallecito Basin in southern California. Our goal is to characterize the marine flooding surface, determine the paleogeographic position of the shoreline and estimate the magnitude of relative base‐level rise that occurred during the marine incursion associated with the opening of the Gulf of California. Our results show that the flooding of the Elephant Trees alluvial fans is often marked by an abrupt lithologic and facies change from meter‐scale boulder‐rich subaerial debrites (proximal alluvial fan facies association) to centimetre‐scale granule‐rich subaqueous debrites, ripple‐laminated sandstones and mudstones (prodelta facies association). By delineating the zone of transition between the subaerial and subaqueous facies, we place the initial flooding paleo‐shoreline 4 km up the alluvial fan's paleo‐depositional slope. Considering alluvial fan slope gradients between 1° and 5°, this 4 km transgression would require an estimated 70–350 m of water depth during the initial marine incursion. Interfingering of fan‐delta deposits with subaqueous marine and planktonic‐rich evaporites suggests that the basin was below sea‐level after, and perhaps even before, the marine flooding. Subaerial subsea‐level basins exist in Death Valley and the Salton Trough today within similar extensional and transtentional tectonic regimes. This subaerial subsea‐level interpretation might explain the high magnitude and abrupt relative base‐level rise recorded by the facies transitions in the Fish Creek Vallecito Basin. These results suggest that the Fish Creek Vallecito Basin underwent significant extension during its early and nonmarine depositional phase, allowing it to reach subsea‐level elevations. The tectonic history of the Fish Creek Vallecito Basin maybe similar to other extensional basins where rapid subsidence allows the accumulation of nonmarine strata below sea‐level prior to the marine flooding, then restricted and deep marine strata immediately after flooding. [ABSTRACT FROM AUTHOR]

The article presents the stages of development of the alluvial fan of the Stryi River (tributary of the Dniester River), which is the largest alluvial cone in the foreland of the Eastern Carpathians. The alluvial fan has a diverse morphology and complex structure, and its formation is the result of the accumulation and erosion activity of several rivers. In order to reconstruct the evolution of the alluvial fan, geological cross-sections of the Stryi, Svicha and Dniester river valleys were made on the basis of archival drillings and field research. The stratigraphy of the alluvial fills is based mainly on morphological (morphostratigraphic) criteria and the correlation of terrace levels with those of adjacent areas. Fluvial sediments from the Late Glacial and Holocene were dated by the radiocarbon method, which allowed the determination of the age of fan dissection. The main factor controlling the course of accumulation and erosion on the alluvial fan was climate change. The accumulation of alluvial covers was preceded by phases of erosion, which generally fell at the end of the glacial periods (late glacial) and the beginning of the interglacials. Differences in the depth of dissection of the strath and the thickness of the accumulated alluvial sediments in the northern and southern parts of the fan may be the result of different tectonic movements and/or the transport capacity and size of river discharges. In the Late Glacial (Alleröd-Younger Dryas) and the Early Holocene the alluvial fan was dissected to a depth of 10-15 m due to the erosion of the Stryi and Dniester rivers. [ABSTRACT FROM AUTHOR]

Copyright of Cuaternario y Geomorfología is the property of Cuaternario y Geomorfologia 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.)

Copyright of Acta Zoologica Lilloana is the property of Fundacion Miguel Lillo 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.)

We used transient electromagnetic (TEM) to map the hydrogeological structures in the Choushui River Alluvial Fan in Yunlin County of central Taiwan. A total of 63 TEM measurements were collected using the FASTSNAP system with 50 × 50 m in-loop configurations in the middle and distal fan. The 1D model, based on prior information, was constructed from the inverted soundings. Results showed a thin, resistive shallow layer and a 40 m low-resistive (6–42 ohm-m) zone beneath it. High-resistive zones (50–170 ohm-m) were found from 50–120 m depth, and low-resistive zones were revealed below 120 m in some areas. Results were consistent with resistivity and lithology logs from nearby wells. The inverted TEM models provide reliable subsurface information when prior informations of vertical electrical sounding and TEM were considered. We interpolated resistivity at 10 m, 50 m, 100 m, and 160 m depth from the 1D model results to produce a slice map of the area, which indicated variations, trends, and depths of the sediment deposits. The TEM method successfully identified the hydrogeological structures, showing that the upper 40 m of sediment acts as a confining layer for the aquifer structure from 50 m to 120 m depth. [ABSTRACT FROM AUTHOR]

Among the common hazards related to alluvial fans, flooding is one of the most important. Nonetheless, in populated alluvial fans, not only the natural processes are effective in floods, but the artificial structures and modifications can change the behavior of flooding and its potential risks. This study aims to indicate the flood-prone landforms in a set of populated alluvial fans in an arid region and investigate the role of anthropogenic activities in controlling/exacerbating flooding in alluvial fans. To achieve this goal, 15 Ground Range Detected in High resolution (GRDH) SAR Sentinel-1 images, covering a total of 24 alluvial fans, were acquired. Pre-processing and post-processing steps were applied to all images to identify flood-prone sections of the studied alluvial fans. The results showed that feeder channels, spreading sites, and wide interfluves are the most flood-prone landforms of alluvial fans. In terms of anthropogenic modifications to mitigate flooding, a rampart system is distributed in the study area. Ramparts are levee like structures formed from the fan material. They aim to mitigate flood hazard on residential areas, infrastructures, and agricultural lands of the study area. Results show that the rampart system can reduce the danger of floods, but it cannot be considered a long-term solution. Therefore, a comprehensive flood protection system distributed throughout the whole alluvial fan system is needed. Results also reveal that in regions where flood monitoring is challenging, SAR images can be used as a freely available data set to monitor and identify flooding hotspots. [ABSTRACT FROM AUTHOR]

Abstract This study was done to describe and interpret the facies, the provenance of sediments, pedogenesis processes, and the model of the Abyek alluvial fan in the northern margin of Qazvin Plain, using 45 sediment samples in the form of nine profiles and nine surface samples. The facies study led to the determination of six facies grouped into two facies associations including coarse-grained lithofacies (Gms, Gcs, Gci, Gcp/Gmp, Gmg, and Glns), and calcrete facies (Plc). This alluvial fan is dominated by the episodic matrix to clast-supported gravel (interbedded with a subordinate) and red, matrix-supported gravel which were deposited by non-cohesive debris flow. The results of granulometry analysis showed that the size of the sediments of the alluvial fan shows wide variations from gravel to clay, and the texture of the sediments of this alluvial fan is mainly gravel and sandy gravel with very poorly sorting and fine skewness. The study of macromorphology and micromorphology of calcrete showed that their occurrence was controlled by pedogenic processes. Micromorphological studies also revealed alpha and beta features such as coated grains, pisoid, laminar crust and strong brecciation. Keywords: Alluvial fan, facies, Calcrete, Qazvin Plain, Abyek. Introduction Alluvial fans are, more often, coarse-grained and serve as an excellent proxy for unrevealing past changes in climate, hinterland tectonics and sea/lake level. Besides tectonics, climate and hinterland lithology exert significant influence on the volume and grain size of sediments received in such systems (Chakraborty and Paul 2013). In this regard, the classification of alluvial fans by Blair and McPherson (1994) based on sedimentary processes strengthens the old hypothesis of dry and wet alluvial fans. Although the validity of this climate-response hypothesis has been questioned. The purposes of this study are 1) to investigate of sedimentary features and description and interpretation of sedimentary facies to identify sedimentary facies and the facies model of the Abyek alluvial fan and 2) to discuss the role of climate, tectonics, and lithology of the source area on the sedimentary facies. Material & Methods In order to study Abyek alluvial fan, 45 samples of different facies were collected in the form of nine sediment profiles and nine surface samples. The characteristics of representative profiles including sedimentary structures, texture, bed geometries, and lithology were used to describe fan facies. In addition, paleocurrent directions were depicted using azimuth measurements of imbricated pebbles. Facies were described following Miall’s (2006) facies classification. Also, in order to study thin sections, 11 samples from the sand-size sediments and 12 calcrete samples were prepared, respectively, in order to determine the provenance of sediments and microscopic characteristics (Carver 1971). Folk’s (1980) classification was used to name gravelly and sandy sediments in terms of composition. Modal analysis for sandstone samples was done by counting more than 250 points in each section based on the Gazzi-Dickinson method (Gazzi 1966; Dickinson 1970). In this study, in order to analyze calcrete samples, six thin section samples and two blocks with dimensions of 1 x 1 cm were prepared and imaged by FESEM electron microscope. Scanning electron microscopy (SEM) was performed on the representative samples at the Beamgostar Laboratory, Iran (Mira3-TESKAN Scanning Electron Microscope, 20KV). Also, five powder samples and three oriented clay samples were analyzed to determine the mineralogy of clay fraction. The mineralogical composition of representative bulk and oriented samples was investigated by X-ray diffraction (XRD) in Malayer University, Iran (Italstructures, 40 Kv, Cukα 30mA). Finally, by combining field, laboratory data, the sedimentary facies, the origin of sediments and the model of the Abyek alluvial fan and the features of diagenesis and pedogenesis of its sediments were identified and analyzed. Discussion of Results & Conclusions The study of facies of Abyek alluvial fan led to the identification of six facies in two groups: the first group includes coarse-grained lithofacies, which includes matrix-supported gravel (Gms), clast-supported gravel (Gcs), inversely graded clast-supported gravel (Gci), rhythmic gravelly and sandy planar couplets (Gcm and Gmm/Sm), graded clast- to matrix-supported gravel (Gmg) and Grain- to ground-supported lenticular gravel (Glns) and the second group includes calcrete (Plc). The debris-flow deposits, red-coloration, interbedded mudflow, polygonal mud cracks, and calcretes of the studied areas are indicative of a generally warm and arid climate (Gile et al. 1965; Hayward 1983; Kraus 1999; Clyde et al. 2010), which also exists in other areas of the Qazvin Plain. Subaerial debris flows require abundant clastic debris, a steep slope, and a high discharge for their initiation. Abundant clastic detritus resulting from mechanical weathering during long dry periods are transported by flash floods, with little vegetation to inhibit run-off (Miall 1977). Also, non-cohesive debris flows are caused by watersheds with a small amount of mud (especially clay). In this study, the granulometry results show that the amount of mud in the analyzed samples is very small (less than 5%). Since the silty and clay fractions are the product of hydrolysis of feldspar and secondary minerals or they were formed through severe tectonic cuts (Blair 1999); therefore, such reactions are very slow in warm and dry climates and lead to an insignificant amount of mud fraction (Blair and McPherson 2009). On the other hand, the presence of ancient soil (red horizons) indicates periodic sedimentation and warm and dry climate conditions (Yan et al. 2007). The presence of calcrete in the alluvium as well as the palygorskite clay mineral, which is a clay mineral specific to calcrete (Zucca et al. 2017), are other clear signs to confirm the warm and dry climate. On the other hand, the composition and analysis of the palaeoflow direction based on the imbrication of pebbles shows that the alluvial sediments were mostly transported from north to south; Therefore, the tectonic uplift caused by the southern Alborz fault has a significant contribution to the formation of alluvial fans on the northern edge of the Qazvin Plain. Stable tectonic conditions and warm and dry climates (Reeves 1983; Wright and Tucker 1991) are the main factors controlling the formation of calcrete in this alluvial fan. According to granulometry, the sediments of this alluvial fan are mainly composed of a wide range of semi-coarse to fine-grain sediments. The percentage of boulders is very low and coarse pebbles are rarely found in the studied samples. In other words, among the gravel clasts larger than 6 cm, the superiority is with gravels with a diameter of 6 to 12 cm (40 to 90 percent). This shows that coarse rock fragments rarely form in the catchment area. The main reason for the formation of relatively fine-grained deposits in the alluvial fan is the watershed lithology, which is mostly limestone (especially marl), fine-grained volcanic rocks, sandstone, siltstone and shale derived that easily have been decomposed and crushed. A small abundance of coarse rock fragments can also occur where strong tectonic shears have pulverized the rocks of the catchment area (Blair 2003). However, according to the watershed lithology in the catchment basin, the lithological composition of the parent rock is the main reason for the formation of such deposits. In addition, the most mature type of calcrete has been found in the Abyek alluvial fan with a calcareous lithological composition, which clearly shows the dominant contribution of calcareous parent rock to the formation of calcrete. Abyek alluvial fan due to specific features such as the frequency (80–95%) of Gms facies, the presence of red horizon, the amount of mud less than 5%, and the small radius (approximately 3.5 km) can be considered as a fan caused by the accumulation of non-cohesive debris flow (Blair and McPherson 2009). This alluvial fan is a special type of fan resulting from non-cohesive deposits (with a very low percentage of clay) that were formed during sudden discharges. The very small abundance (10–15%) of gravelly facies caused by runoff shows that the contribution of floods to the initial accumulation of alluvial fan sediments was very small and only leads to the transportation and redeposition of sediments locally.

Geomorphological forms each at different stages of the process of environmental change and evolution, stable conditions and instabilities under the influence of external and internal processes. One of these forms is igneous masses, which take on a distinct shape and change due to tectonic movements and fault movements. This change can be shown using geomorphological evidence and indicators. The igneous massif is located beyond the Sanandaj-Sirjan metamorphic belt in the western part of Qom province. By examining different patterns such as drainage patterns, color tone, slope, circular rings, and geomorphological indices, mass growth was revealed in this area. The pattern index completely indicates the instability of this mass. Most of the surfaces of the alley mass slopes are composed of triangular shapes, the formation of which is the result of the performance of active internal processes against external processes. The color tone of this cone is light and indicates that it is active. The circular rings of the mass indicate the expansion of the eastern slopes. The slope of this mass is between 5-10.5 which is justified by tectonic action and all the alluvial fans of the surface morphology are in the form of ducts and small ridges 2 cases of erosion were observed in the southeastern part of the intrusive mass, which is advancing towards the top of the alluvial fan. Captivity and diversion of waterways in the region is another piece of evidence that is influenced by active tectonics. Due to the instability of the slopes and alluvial fans, no human activity (except in special cases) has been formed in the area. In general, the indicators and evidence of instability and active tectonic movements in different parts of the intrusive rock of diorite and the lack of news of the day. Due to the active tectonics and instability of this environment is fully approved.

In view of the key geological factors restricting reservoir development, the reservoir heterogeneity of an alluvial fan sandy conglomerate reservoir in the Qie12 block of Qaidam Basin, Northwest China, and its influence on remaining oil distribution, were studied according to geology, wireline logging data, and dynamic production data. This study illustrates that the difference in pore structures, which are controlled by different sedimentary fabrics, is the main cause of reservoir microscopic heterogeneity. Besides, the temporal and spatial distribution of architectural units in the alluvial fan controls reservoir macroheterogeneity. Our results show that the thick sandy conglomerate develops two types of pores, two types of permeability rhythms, two types of interlayers, two types of interlayer distribution, two types of effective sand body architecture, and four types of sand body connecting schemes. The strongest plane heterogeneity is found in the composite channel unit formed by overlapping and separated stable channels of the middle fan, and the unit's permeability variation coefficient is >0.7. However, the variation coefficient in the range of 0.3–0.5 is found in the extensively connected body unit sandwiched with intermittent channels of the inner fan. The distributions of the remaining oil vary significantly in different architectural units because of the influence of reservoir heterogeneity, including distribution patterns of flow barriers, permeability rhythm, and reservoir pore structures. The composite channel unit formed by overlapping and separated stable channels, or the lateral alternated unit with braided channel and sheet flow sediment of the middle fan, is influenced by the inhomogeneous breakthrough of injection water flowing along the dominant channel in a high-permeability layer. The microscopic surrounding flow and island-shaped remaining oils form and concentrate mainly in the upper part of a compound rhythmic layer. Meanwhile, in the extensively connected body unit sandwiched with intermittent channels of the inner fan, poor injector–producer connectivity and low reservoir permeability lead to a flake-like enrichment of the remaining oil. [ABSTRACT FROM AUTHOR]

A four-day glacier-melt flood (13–16 August 2013) caused abrupt geomorphic changes in the proglacial gravel-bed Scott River, which drains the small (10 km2) Scott Glacier catchment (SW Svalbard). This type of flood occurs on Svalbard increasingly during periods of abnormally warm or rainy weather in summer or early autumn, and the probability of occurrence grows in direct proportion to the increase in temperature and/or precipitation intensity. In the summer of 2013, during the measurement season, the highest daily precipitation (17 mm) occurred on 13 August. During the following four days, it constituted in total 47 mm, i.e., 50% of the precipitation total for the measurement period of 2013. The largest flood in 20 years was caused by high precipitation with a synchronous rise in temperature from about 1.0 to 8.6 °C. These values exceeded multi-year averages (32 mm and 5.0 °C, respectively) at an average discharge of 0.9 m3/s (melt season mean 1986–2011). These conditions caused a rapid and abrupt response of the river with the dominant (90%) glacier-fed. The increase in discharge to 4.6 m3/s, initiated by the glacial flood, mobilized significant amounts of sediment in the river bed and channel. Geomorphic changes within the alluvial fan as an area of 58,940 m2, located at the mouth of the Scott River, were detected by multi-sites terrestrial laser scanning using a Leica Scan Station C10 and then estimated using Geomorphic Change Detection (GCD) software. The changes found involved 39% of the alluvial fan area (23,231 m2). The flood-induced total area of lowering (erosion) covered 26% of the alluvial fan (6035 m2), resulting in the removal of 1183 ± 121 m3 of sediment volume. During the final phase of the flood, two times more sediment (1919 ± 344 m3) was re-deposited within the alluvial fan surface, causing significant aggradation on 74% of its area (17,196 m2). These geomorphic changes resulted in an average lowering (erosion) of the alluvial fan surface of 0.2 m and an average rising (deposition) of 0.1 m. [ABSTRACT FROM AUTHOR]

Copyright of Acta Sedimentologica Sinica is the property of Acta Sedimentologica Sinica 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.)

The piedmont forming the southern foot-hill plain of the Himalayan mountain chain in the Jalpaiguri district of West Bengal, India, is composed of coalesced alluvial fan deposits of the Quaternary Period. Neotectonic dislocations affected the piedmont plain and controlled the river system that reincised the fan deposits. Stream length gradient index, sinuosity index, braiding index, channel migration, and change of position of the confluence of the Jaldhaka and Daina rivers are estimated for 90 years (1930–2020) to decipher the role of neotectonism and climate on the channel evolution pattern. Neotectonics have played a major role in the pattern of channel evolution. Still, variable monsoonal discharges have also controlled the channel characteristics to a large extent, particularly in the lower reaches. [ABSTRACT FROM AUTHOR]

Alluvial fans are an important land resource with agricultural potential in Qinghai–Tibet Plateau. The spatiotemporal variation in land use/cover is an important indicator to understand the value of alluvial fans and protect and make scientific use of such fans. In this study, the spatiotemporal characteristics of land use/cover are determined by analysing the land use/cover changes of alluvial fans in the Lhasa River Basin (LRB) at different times, counties/districts, altitudes, and gradients. Results show that the area of cultivated land and the artificial land provided by alluvial fans for LRB has continuously increased. In 2000, 2010, and 2020, 17.72%, 21.84%, and 24.17% of cultivated land and 7.89%, 7.51%, and 25.24% of artificial land in LRB were provided by alluvial fans, respectively. At all altitudes and slopes, cultivated land and artificial land are increasing but the increasing part is basically due to the massive loss of grassland. The spatiotemporal changes in all land use/cover types of alluvial fans were dominated by human activities, although they were also influenced by natural factors to some degree. [ABSTRACT FROM AUTHOR]

Fluvial aggradation and incision are often linked to Quaternary climate cycles, but it usually remains unclear whether variations in runoff or sediment supply or both drive channel response to climate variability. Here we quantify sediment supply with paleo‐denudation rates and provide geochronological constraints on aggradation and incision from the Sfakia and Elafonisi alluvial‐fan sequences in Crete, Greece. We report seven optically stimulated luminescence and ten radiocarbon ages, eight 10Be and eight 36Cl denudation rates from modern channel and terrace sediments. For five samples, 10Be and 36Cl were measured on the same sample by measuring 10Be on chert and 36Cl on calcite. Results indicate relatively steady denudation rates throughout the past 80 kyr, but the aggradation and incision history indicates a link with climate shifts. At the Elafonisi fan, we identify four periods of aggradation coinciding with Marine Isotope Stages (MIS) 2, 4, 5a/b, and likely 6, and three periods of incision coinciding with MIS 1, 3, and likely 5e. At the Sfakia fan, rapid aggradation occurred during MIS 2 and 4, followed by incision during MIS 1. Nearby climate and vegetation records show that MIS 2, 4, and 6 stadials were characterized by cold and dry climates with sparse vegetation, whereas forest cover and more humid conditions prevailed during MIS 1, 3, and 5. Our data thus suggest that past changes in climate had little effect on landscape‐wide denudation rates but exerted a strong control on the aggradation–incision behaviour of alluvial channels on Crete. During glacial stages, we attribute aggradation to hillslope sediment release promoted by reduced vegetation cover and decreased runoff; conversely, incision occurred during relatively warm and wet stages due to increased runoff. In this landscape, past hydroclimate variations outcompeted changes in sediment supply as the primary driver of alluvial deposition and incision. [ABSTRACT FROM AUTHOR]

Al-Shihaby alluvial fan is considered a significant and major geomorphologic phenomenon that evolved on the east side of Mesopotamia. It is located in the Wasit Governorate, near the Iraqi-Iranian borders. The fandom's dominant trend is southwest-northeast. This study aims to enhance our understanding of the indications and continuity of the fan's neotectonic activity. To reach this aim, we used software such as Arc GIS, Global Mapper, and Surfer, in addition to using data from USGS to identify the stages of the fan. A merging of spectral bands (composite bands), a contour map, and longitudinal and transverse topographic sections were done to analyze and interpret the neotectonics of the study area. This study concluded that the fan has passed through five stages in different periods and that its continuation to the present indicates that the fan is still active. These five stages recognized within the fan belong to the Pliocene- Late Pleistocene age range. Each stage is a breakpoint in sedimentation, and when tectonic activity occurs, the next stage begins. Besides that, the study concludes that the elevation range of the area from the cross sections is from 15 m in the southwest of the area to 120 m in the northeast above sea level from the elevation map derived from the DEM file. Besides that, the increase in sediment thickness on the western side of the fan compared to the eastern side, which belongs to the streams on the west side of the fan, in addition to the deposition of the alluvial fan, was related to the Mandali-Badra-Amara Faults (Zagros Front Fault (ZFF)) and its activity, as well as the relative uplifting of the Hemrin structure versus the subsidence of the Mesopotamia Plain. • Arc GIS, Global Mapper, and Surfer software programs, the USGS, were used to study the indications of the notectonic activity of the fan. • Composite bands, a contour map, and longitudinal and transverse topographic sections were done to interpret the neotectonics in the study area. • There are five stages recognized depending on the breakpoints that the fan pass through. • Many neotectonic indications were recognized in the study area. [ABSTRACT FROM AUTHOR]

Daluo Mountains lie at front of the arcuate tectonic belt at the northeastern margin of the Tibetan Plateau, and are the landform boundary zone between the active Tibetan Plateau and the stable North China Craton. Studying of the late Cenozoic uplift evolution of Daluo Mountains is important for understanding the expansion mechanism of the northeastern margin of the Tibetan Plateau and its influence on the western North China Craton. In this study, the late Cenozoic uplift of Daluo Mountains is constructed from the development of the late Cenozoic alluvial fan around Daluo Mountains. The entire sedimentary sequence and framework of the fan was revealed by the newly obtained drilling core data. The cosmogenic nuclide, optically stimulated luminescence, and detrital zircon U‐Pb dating results provide new evidences for discussion about the initial timing of the late Cenozoic uplift of Daluo Mountains and the key stages of uplift during the Pleistocene. The late Cenozoic alluvial fan at front of Daluo Mountains overlies a set of fluvial‐facies strata; therefore, development of the alluvial‐fan marks the start of late Cenozoic uplift of Daluo Mountains. The timing of this event can be constrained to ∼4.64 Ma. Two extensive gravel layers (dated to ca. 0.76–0.6 Ma and ∼0.05 Ma) developed during the Pleistocene, indicating two episodes of considerable uplift. This study provides a new time scale for the uplift and expansion of the arcuate tectonic belt at the northeastern margin of the Tibetan Plateau. [ABSTRACT FROM AUTHOR]

Lulehe Formation is discovered in the Mahaidong Area of Northern Qaidam Basin. In order to clarify the sedimentary facies types and favorable reservoir facies, the sedimentary characteristics of the Lulehe Formation were systematically studied by observation of field and core sedimentary structures, particle size analysis, logging facies analysis and so on. On the basis, the sedimentary filling law was analyzed and the sedimentary facies model is established. The results show that alluvial fan deposits are widely developed in the Lulehe formation in the northern margin of Qaidam Basin, and the fan root sub-facies turn into the fan middle sub-facies and then the fan marginal sub-facies from the basin margin to the basin. The alluvial fan from the Qilian Mountains in the north-east direction is overlaid to the Ma Bei ancient uplift in the basin, which controls the stratigraphic distribution and sedimentary evolution law in the middle section of Northern Qaidam Basin. Three sand formations are developed in Mahaidong area, which are located in fan middle-fan marginal sub-facies of alluvial fan, and develop channels and sheet-flood deposit micro-facies. The favorable reservoir facies zone in alluvial fan are channels and sheet-flood deposit in the fan middle sub-facies and channels in the fan marginal sub-facies. [ABSTRACT FROM AUTHOR]