In mountain regions the exposure of alluvial fans to sediment-laden flows can be remarkable, the generated damages to infrastructure and property enormous and the potential death-toll significant. The knowledge and understanding of distributive processes can be relevant for improving the effectiveness of risk mitigation strategies. With the aim of deepening the knowledge of distributive processes (i.e., autogenic or allogenic or both), a set of 144 experiments of unsteady two-phase flows were analyzed. The allogenic forcings were total flow volume (3 levels), solid fraction (3 levels), water release mode (2 levels). For each forcing factor combination 8 repetitions were accomplished on an unchanneled alluvial fan according to the 'similarity by process' method. Localized avulsions (Av), symmetric bifurcations (bS) and asymmetric bifurcations (bA) were retraced. Additionally, backstepping aggradation and channel plug were distinguished qualitatively. We assessed the occurrences of the observed distributive processes and their spatial variability by determining their directed distributions (i.e., spatial deviation ellipses). Moreover, we performed a set of one-way Kruskal-Wallis ANOVAs and inferred significant rank differences between the compared data groups (i.e., distributive process occurrences associated to specific allogenic forcing conditions). Irrespectively of the imposed conditions, avulsions predominantly occur in the upper part of the alluvial fan. Symmetric bifurcations tend to align more with the fan's longitudinal axis, while asymmetric bifurcations, albeit rare, are more common on the lateral portions of the fan. Avulsions are more common with the half-opened water release mode, releasing a high total flow volume and sediment concentrations. Symmetric and asymmetric bifurcation are more common under a fully opened water release mode. Setting the half-opened water release mode, distributive processes occur more frequently with a predominance of avulsions. The extraordinary variability of the occurred distributive process and their spatial patterns considering the peculiar effect of the water release mode should be carefully considered in hazard and risk assessment.
This study investigates the uplifted marine terraces along the western and eastern coasts of the Laconic Peninsula in an attempt to reconstruct the region's Late Pleistocene tectonic and geomorphological history. Using high-resolution topography, GIS analysis and extensive field surveys, the research mapped and characterized sequences of marine terraces in three distinct sectors. The analysis identified a sequence of eight terraces in Sector A and six in Sector B on the western coast, with five lower-elevation terraces in Sector C on the eastern coast. The marked difference in terrace elevation and number between the adjacent Sectors A (higher) and B (lower) is attributed to differential uplift caused by the active Molai graben. By correlating the lowest terrace in Sector B (at 9-10 m a.s.l.) with the MIS 5a terrace in the adjacent Punta area based on a previous study, a long-term average uplift rate of 0.36 +/- 0.11 mm a-1 over the past 215 +/- 5.5 ka is established for Sector B. Assuming this constant rate, the research tentatively correlated the higher terraces in Sector B with successive Quaternary highstands: MIS 5c (Terrace B, 15-21 m a.s.l.), MIS 7a (Terrace D, 55-65 m a.s.l.), and MIS 7c (Terrace E, 80-90 m a.s.l.). These correlations are consistent with predicted elevations derived from global sea-level curves. The results confirm that the regional coastal uplift is driven by the overall proximity to the Hellenic Subduction Zone, while local variations are controlled by active normal faulting.
Flooding is a recurrent and severe natural hazard in urban areas, impacting infrastructure and public safety. This study examines flood events and their impacts across eight separate drainage basins within the city of Patras, in southern Greece, from 1909 to 2024. The studied drainage basins are Glafkos, Diakoniaris, Tritaki, Meilichos, Tholopotamos, Haradros and Selemnos rivers and unnamed stream. The elongation ratio (Re), was calculated to evaluate flood hazard and tectonic activity across the drainage basins. The flooded area during each event within each drainage basin was estimated and correlated. Moreover, the flooded area and the current urban pattern within each drainage basin were associated. The flood-affected areas of the studied drainage basins were grouped by year, and the number of buildings submerged during each event was analyzed. The data were combined and analyzed by using Geographical Information System (GIS). The drainage basins of Selemnos and Haradros rivers present the lowest Re values, and are considered highly elongated and tectonically active. While the Tritaki drainage basin with the highest Re has an oval shape. The remaining drainage basins have elongated shape, as indicated by their Re values, and exhibit tectonic influence. Among the study area Glafkos and Diakoniaris drainage basins are the most flood-prone. Indicated by repeated flood events in the region near the mouth of both rivers that has been affected, with considerable overlap in the flooded areas. High percentage of impacted urban pattern and numerous of flooded buildings in each drainage basin were calculated. Both of the drainage basins, exhibit low elevation, dense urban pattern and a high value of Re associating the susceptibility to flooding. The Meilichos River experienced two flood events with noteworthy affected area, urban pattern and buildings. The Tritaki, Selemnos, Haradros rivers and the unnamed stream each experienced one flood event of low-impact area. The Tholopotamos River is unaffected by flooding. During the years 1909 to 2024, there were 18 flood incidents in the study area. The one that was marked as the most catastrophic was in 1962, when four rivers overflowed leading to the flooding of 4,000 buildings. This study can guide local authorities, engineers and communities on flood risk and spatial planning.
The natural area between the rivers Rhine, Main and Neckar and the mountains of the Odenwald is the southern part of the federal state of Hesse in Germany. The landscape of the area is characterised by the oxbow lakes of the above-mentioned rivers, which can still be experienced today as waterlogged areas, wetlands and cultural landscape elements. The areas in between are old settlement landscapes whose use and settlement can be traced back to the Palaeolithic period. The archaeological and geoarchaeological research of the old streams in recent years shows the archaeological potential of these old waters in many aspects. They served as places for sacrifices, were transport routes and living spaces, were artificially manipulated for landscape development and form an invaluable archive for reconstructing landscapes for the different periods of cultural landscape history. The changed archaeological perception of the oxbow lakes as cultural landscape elements and monuments worthy of protection leads to overlaps with the protection claims of nature conservation for these areas. In part, this results in protection goals for the same areas due to different legal requirements. However, there are also different, in part contradictory conservation claims, which, without a higher level of consideration and decision-making, allow both interests to work side by side as an unresolved conflict. Finally, nature conservation regulations limit the possibili ties of monument research and thus of better protection and monitoring. During the contribution these experiences will be compiled and reflected upon against the background of how cooperation and the different conservation goals as a common interest can be improved in the future.
Late Cenozoic evolution of two fault parallel scarps along the segmented and seismically active Kachchh Mainland Fault (KMF) in Kachchh Rift Basin (KRB) is reconstructed. The KMF shows two fault parallel scarps developed in the footwall block characterised by structurally controlled erosional hilly topography of the Northern Hill Range (NHR). Geological setting, geomorphic data, critical analysis of drainages dissecting through the scarps and those arising from the scarps and cosmogenic dating show that erosion driven by episodic uplift of the footwall block during pre-Miocene and post-Miocene reactivation phases of the KMF produced twin fault parallel scarps [Kachchh Mainland Fault Scarp (KMFS) of relatively lower elevation and the Kas Hill Scarp (KHS) of higher elevation]. Our data also demonstrates that progressive eastward reduction in elevation of the two scarps and decrease in relief of the NHR is a reflection of the eastward propagation of the KMF. Cosmogenic exposure ages of 318 +/- 43 and 249 +/- 52 ka B.P. of the fault scarp at its eastern margin along with available OSL ages dating back to similar to 100 ka B.P. on the thin cover of colluvio-fluvial and fluvial sediments overlapping the fault zone indicate uplift of NHR and eastward propagation of KMF during the Late Quaternary.
The spatial variability of tectonic activity in a semi-arid to sub-humid climatic region of central India is accomplished effectively through the morpho-structural assessment of fluvial landform by utilizing geospatial techniques (GT). In the present study, we applied GT and MATLAB algorithms to analyze the effect of tectonoclimatic perturbation on landform development within the Ken river basin. Qualitative and quantitative assessment of morpho-structural features have been carried-out to explain the role of tectonics in geomorphic evolution of the area. The detailed assessment of drainage network suggest that the basin is strongly affected by recent tectonic activities. The observed value of asymmetric factor (Af), stream length (Lu), circulatory ratio (Rc), stream length ratio (RL), elongation ratio (Re), form factor (Ff), transverse topographic asymmetry factor (T) etc. suggests tectonic regulation in the drainage system which is reflected in the form of deviation and offset of the higher order of drainage. Drainage offset and deviations are the major/remarkable geomorphic anomaly observed within the drainage network. A quick surge in the stream length gradient index (SL) value in the middle reaches as well as a rapid increase in the steepness index (Ksn) value in lower basin strongly indicative of tectonic control over drainage network. The time dependent analysis of spectral indices shows a rise in urban expansion within the study region. In the Ken river basin, NDBI has shown a direct relation with Land surface temperature (LST) whereas, NDVI has shown an inverse relation with LST. Our findings will be invaluable for researchers delving into the implications of morphotectonic indices on tectonic activity. Moreover, this study will serve as a crucial resource for researchers in watershed management, contributing to a more sustainable and resilient environment.
Recently we showed that construction, maintenance and abandonment of cisterns and reservoirs in the Negev desert environment (southern Israel) can be dated by means of optically stimulated luminescence (OSL) (e.g. Junge et al. 2023). This article addresses two issues that stemmed from our previous research: a) looking into the challenge of OSL dating in light of incomplete bleaching due to short transport distances or limited daylight exposure of sediments moved by people and/or flash floods, and b) the potential of infill deposits within cisterns to serve as paleo-environmental archives. In the first part of the study, we simulated the construction of an open reservoir by manually digging a small experimental pit into the desert surface. We then dated the sediment by OSL before and after manual digging, to test how much luminescence signal is lost during the anthropogenic movement of sediment. We compared this to infill from a neighbouring ancient reservoir, naturally accumulated by flash floods since its abandonment. Again, we dated the material before and after manual digging, to reconstruct how sediments are bleached during the use and maintenance of a cistern. In the second part of the study, we explored the potential of pollen to serve as an environmental proxy, from infill sediments found within water reservoirs and cisterns. Our experiments show that sediments moved by anthropogenic activity have OSL signals that are reduced significantly but not always to the zero-level required for accurate dating, resulting in an age overestimation of a few tens of years. The naturally moved sediments, transported during flash floods into the cistern, also showed incomplete bleaching of a few tens of years. Pollen was found preserved in the infill sediments of the cistern, however, the pollen spectrum included grains from Casuarina and Eucalyptus, non-native plants introduced to Israel only ca. 130 years ago. These pollen grains occur throughout much of the stratigraphic sequence that according to OSL dating accumulated in the last 200-600 years or so. We propose that these pollen grains moved down-profile by bioturbation and along cracks that formed during drying cycles of the cistern. Overall, the OSL signal of infill sediments in abandoned cisterns is affected by incomplete bleaching in the order of tens of years while young pollen may be found in deposits that are a few hundred years older, due to vertical movement. Therefore, caution should be taken when studying young infill deposits in cisterns, both for age determination using OSL and for pollen as an environmental proxy.
Flash floods have emerged as one of the major hazards in the Himalayas, particularly due to the anthro-pogenic encroachment on the flood plains and increasing extreme weather events caused by global temperature rise (climate change). In comparison, mitigation measures are disproportionate, partly because the documented history of flood magnitude and frequencies are limited both in space and time, and the mitigation strategies rely more on compensatory approaches rather than having any long-term proactive planning. Because topographical and climatic elements influence flash floods, it is possible to identify hazardous land areas and model the potential impact of flash floods in a given region based on observations of extreme flood events. In the Himalayas, the hazard zone can be roughly marked between 2500 and 3500 m elevations. In this study, we model three different flash flood scenarios for a tourist destination, Gangotri town, in the northwest Himalayas, based on the flood discharge of three events in similar topography and climatic conditions. To model the flood hydrograph along the Bhagirathi River near Gangotri town, we utilised the open-source software HEC-RAS (1D). Our calculations demonstrated that the floods having discharges equal to the 2013 Gangotri, 2013 Kedarnath, and 2021 Rishi Ganga flash floods would cause water surface elevations of 1.34, 4.16, and 28.66 meters, respectively. The results suggest that a more signifi-cant part of Gangotri town is exposed to a discharge scenario similar to the Kedarnath flood of 2013. According to our preliminary assessment, the minimal loss to buildings in such a scenario would be more than Rs. 2,000 lakh. The study contributes to the most feasible and cost-effective flash flood disaster risk reduction strategy in the Himalayas.
On February 6, 2023, southeastern T & uuml;rkiye was struck by a Mw 7.8 earthquake. A few hours later, a second Mw 7.6 earthquake occurred in the province of Kahramanmara & scedil;. The combined impact of these two seismic events resulted in a significant loss of life, numerous injuries, and extensive property damage in both southeastern T & uuml;rkiye and northern Syria. These earthquakes are directly linked to the activation of the East Anatolian Fault zone (EAFZ). The primary objective of this study is to examine the correlation between earthquake-induced ground deformation and critical infrastructure in the cities of Antakya and Osmaniye. Ground deformation estimation was conducted through Sentinel-2 satellite data processing and the application of the Normalised Cross Correlation (NCC) algorithm. The results indicate that both Antakya and Osmaniye experienced movement in a North-Northwest direction, consistent with the movements of the Anatolian microplate on which they are situated. The average ground deformation was estimated at 1.7 m in Antakya and 2 m for Osmaniye, while maximum displacements reaching 5 m and 4.5 m, respectively. The study's findings were overlaid with critical infrastructure data, including educational facilities, hospitals, monuments, industrial facilities, airports, roads and railways, to facilitate rapid and precise identification of critical exposure. Damage assessments revealed that the infrastructure in Antakya was most severely affected, with 279 confirmed cases of total buildings damage, while Osmaniye reported 164 confirmed cases.
The landscape of southern Hesse is characterised by many old watercourses. These are areas worthy of protection for both nature conservation and monument protection. On the one hand, they provide special conditions for flora and fauna related to water bodies; on the other hand, from an archaeological point of view, the old watercourses are traffic routes, habitats, sacrificial sites and archives for the history of the landscape. The protection requirements of both interests leads to synergies, but also to disagreements and problems in dealing with the protected areas. Experiences resulting from cooperation are discussed in this article, as well as approaches to solutions for improving joint action.
Alluvial fan development is sensitive to environmental change, and thus, alluvial fans provide essential archives for reconstructing Quaternary paleoenvironmental conditions, notably climate, hydrology, and tectonics. Although alluvial fans have been studied across the globe for over a century, there is yet to be a unifying scheme/ framework or model to view their complete variety and modes of formation and distribution. Reviewing the global spatial and temporal range of alluvial fan types and data from selected key regions allows us to examine their varied geomorphology, formation, and distribution and hence aids in their application for Quaternary climate and environmental change studies. This approach indicates that three main regimes for alluvial fan geomorphology and formation are evident: Type I) simple small-scale alluvial fans that are limited in size and extent (radius a few km) alluvial and megafans (radius >20 km) with an increasing influence of tectonics and ages going back into the Neogene. While small-scale alluvial fans are created by shortterm events (10(-1) to 10(+1) years), mesoscale and macroscale alluvial fans develop over 10 4-5 year timescales. Type I alluvial fans are prevalent in high-latitude and high-altitude environments but may occur in numerous periglacial, semi-arid, and arid environments. In mid-latitude drylands, Type II mesoscale alluvial fans and bajadas are one of the most common fluvial systems and landform features, where they are frequently associated with steep mountain fronts, closely related, and often modified by active tectonic uplift and faulting. Their formation occurs in different settings characterized by distinct relationships between sediment production and transport capacity. Although governed primarily by the climatic setting, bedrock geology can dominate, especially for sediment production. Autocyclicity also plays a role in alluvial fan development by adjusting to changing sediment sources and deposition and changing channel slopes. Periglacial sediment production (frost weathering) appears to be a major factor in their development and provides an abundant sediment source during periods of climatic instability; hence climatic and weathering cycles are important, particularly in high-mountain and high-latitude environments. Examples of the Quaternary climate influence on alluvial fans in drylands include those of the American Southwest, Mongolia, Iran, Morocco, Northern Sahara, Argentina, Chile, Namibia, and Australia. In these regions, alluvial fan development can be linked to climate variability on glacial-interglacial cycle timescales or expressed in late Quaternary pulses of increased humidity, weathering, and sediment flux. For instance, they are common in glaciofluvial settings and periglacial areas, where streams have high bedload and transport capacity depending on the sediment supply and discharge by snow and ice dynamics. Type III alluvial fans are mainly associated with large-scale (mountain belts) Cenozoic tectonics and active uplift and are usually the oldest alluvial fans and for the most part inactive. Other Type III alluvial fans are associated with Pleistocene glaciofluvial extensive outwash plains. In semi-arid/arid cratonic and pericratonic regions where pediments or bajadas dominate, alluvial fans are less evident, and because these transition from Type III, we called them Type III'.
Flash floods with sudden and rapid flooding in built-up areas are usually difficult to predict because of the local characteristics of causative rainfall. Aside from the quantity of precipitation, the physiographic parameters of catchments determine the consequential discharge. In this study, the flash flood occurrences were identified in the Western Outer Carpathians in Czechia (2000-2020), and their small catchments with a mean area of 2.4 km2 2 located in a flysch geological context above the built-up areas were evaluated. Unfortunately, there are no measurements of flow rate. Therefore, the analyses focused on nine parameters affecting surface runoff related to geomorphic factors, land use, and pedological conditions. Using statistical analyses, namely factor analysis, principal component analysis, and cluster analysis, the characteristics of the four groups of catchments with different delay times and runoff depths were revealed. Knowledge of the physiographic parameters of catchments affected by flash floods can be used in flash flood susceptibility assessment to help anticipate where flash floods may occur with increased probability. This study gives new scientific insights for the region: the contribution lies in i) the identification of flash floods based on local observation and cross-validation with quantitative precipitation estimates from weather radar data; ii) a new and internationally applicable approach in flash flood susceptibility assessment based on a statistical analysis of geomorphic factors, land use, and pedological conditions.
The Romans carried out early river regulation and water management in the Hessische Ried already in the 1 st century AD. Roman waterways enabled the transportation of troops and material and were of strategic importance to secure the territory of the Roman Empire. Small fortlets, so called burgi (singular burgus), were constructed along the tributaries of the River Rhine in late Roman times. The burgus at Trebur-Astheim represents such a Roman military site along the so-called Rhein -Limes. Its construction is dated to AD 364/375 by a Roman coin and the shape of its construction (Heising 2012) and was obviously part of the building program realized during the reign of the Emperor Valentinian I (AD 364-375). The archaeological site is located at the Schwarzbach/ Landgraben watercourse only a few kilometers southwest from its actual mouth into the River Rhine. This watercourse connects the western fringe of the Odenwald with the city of Mogontiacum/Mainz. To study this structure, a multi -method geophysical prospection was carried out at the burgus at Trebur-Astheim. We were able to trace the ground plan of the late Roman burgus first published by Heising (2012) showing a rectangle building at the center with a wing wall to both the northern and the southern side running towards the present riverbank. On this base, detailed geomorphological and geoarchaeological studies were carried out to clarify how the burgus was connected to the watercourse of the Schwarzbach/Landgraben, to collect information on the structure and function of the building and to establish a local geochronology. Our results show that the burgus was constructed at the very edge of the Lower Terrace directly facing the watercourse. The Lower Terrace edge has its westernmost position right in between the northern and southern wing wall of the burgus forming kind of a protruding nose. In front of the burgus, a semi -enclosed artificial basin was detected. Sediments prove that the burgus must have been open towards the fluvial system and that the burgus was not enclosed by a wall from the western side. Based on stratigraphic data, the protruding nose -type Lower Terrace section in between the wing walls was modelled as ramp into the burgus basin to pull vessels on the artificial river bank. The minimum water depth was reconstructed to be 0.7 m in front of the burgus. This and the overall geographic situation let us assume that the building was located at the Schwarzbach/Landgraben channel by the time of its use and not at the River Rhine itself. This assumption is in accordance with evidence of Roman -built canal sections of the Landgraben further upstream (Hanel 1995; Becker 2019). In our study area, we found two different burgus-related sedimentary facies, namely a lower moderate to high-energy fluvial facies right on top of Lower Terrace sands and a subsequent fluvial facies reflecting a clearly reduced flow velocity. The final phase of use of the burgus was dated to the time period 425-599 cal AD. It was thus in use for maximum 235 or so years.
The term "relief generations" was created and formulated in German geology between 1920 and 1930 in order to categorise the surface forms geomorphogenetically in a meaningful way. That was a genuine paradigm shift. German geography still occupies this term today without citing the source, thus establishing its own concept of geomorphogenesis. This unique plagiarism has been clarified and revised.
Ergodic reasoning is a concept that has been widely applied, but not thoroughly tested, in some fields of geomorphology. This study aims to test whether ergodic reasoning is valid in reconstructing the evolution of a special type of gully called spoon-shaped gully (SG) in China's Loess Plateau. We use unmanned aerial vehiclebased digital elevation model data to analyze the morphometry of a sequence of SGs ordered in terms of increasing gully length. The morphological model of the SG evolution that we can propose from this analysis is similar to the established models in the literature. Therefore, time can be substituted by space when reconstructing the evolution of SGs in the Loess Plateau. By extracting morphometric information from the application of the ergodic reasoning model to our data, we identify a series of morphological patterns as SG evolves in the Loess Plateau. We also observed through detailed field studies that SG formation is strongly associated with loess piping and tunnel erosion. SG can be considered a special initial form of a hillside gully that is widely distributed in the collapsible sandy loess area. This type of hillside gully is dominated by piping and tunnel, surface fluvial, and gravity erosion.
Many aspects regarding the reduction of soil erosion and the effectiveness of nature-based solutions, such as catch crops and their spatial distribution, still remain unknown. To address these questions, in this study, we utilized a combination of the Improved Stock Unearthing Method (ISUM), surveys of biomass and vine vigor, and soil profile characterization in a Mediterranean vineyard located in the unexplored viticultural region of Valle de Lec & nacute;n (Granada, Spain). Our findings revealed that the use of catch crops after cutting the vines did not lead to significant changes in soil properties along the profile, including organic matter, aggregate stability, and nutrient content, but there were positive results in reducing soil surface lowering in specific areas. These positive outcomes also correlated with the highest levels of vine vigor, measured by assessing the vine's perimeter at three different heights. ISUM, utilizing the graft union as a passive bioindicator to assess surface lowering predominantly caused by soil erosion rates and surface changes, showed a sedimentation rate of 17.88 t ha-1yr-1. -1 yr -1 . Under the vine these rates reached a total of 13.73 t ha-1yr-1 -1 yr -1 and along the rest of the inter-row area much lower values (4.16 t ha-1yr-1). -1 yr -1 ). We identified areas that are at risk along the inter-rows, assessed the effectiveness of erosion control measures (how much and where should be used), and gave some suggestions to take steps forwards to protect soil health and productivity.
Historical documents and maps as well as diverse archaeological findings in the Wadden Sea off Nordstrand Peninsula in North Frisia (Germany) suggest a formerly settled landscape in medieval times and severe changes of the coastline since then. Based on historical maps, the area of the original Trendermarsch polder (Nordstrand) is considered, to have been much larger in the High Middle Ages than it is today. Overall, the pre-medieval land has been settled and cultivated since medieval times when extensive cultivation shaped the landscape. As typical of the region, storm surges had a powerful impact on the embanked land and led to severe changes of the medieval coastline by dyke breaches and land losses. Consequently, for the medieval Trendermarsch, it is assumed that there are archaeological remains from this time period preserved in the Wadden Sea beneath the recent tidal flat sediments. Geophysical and geoarchaeological investigations such as sedimentary, geochemical and microfaunal analyses of a sediment core were carried out in the tidal flats of the Trendermarsch to search for medieval settlement patterns and to reconstruct its development. Radiocarbon dating and historical reports were used to provide a basic chronological timeframe. Our results revealed traces of a medieval Trendermarsch settlement directly in front of today's sea dyke off Nordstrand Peninsula as part of a larger settlement area. To sum up, we found, for the first time, geoarchaeological evidence that the area of the present Wadden Sea off Nordstrand Peninsula hides various traces of the sunken medieval Trendermarsch. Yet, the study area is subject to ongoing transformation due to erosion and sediment accumulation, in relation to tides and storm events.
