Mineral dust aerosol particles are tiny soil particles mobilized and entrained into the atmosphere by wind. Suspended in the atmosphere and transported away from source regions by prevailing wind systems, dust aerosol alters the Earth’s radiation budget, stimulates cloud and precipitation formation processes, and modulates the carbon cycle as it may enhance bio-productivity due to its mineralogical composition. In the light of the manifold dust feedbacks with relevance to the climate, knowledge on the atmospheric pathway of dust from source to sink is essential for accurate climate simulations. Thereby, the spatio-temporal variability of dust source activity, and consequent dust production and entrainment into the atmosphere is of particular interest as dust emission marks the beginning of the atmospheric dust cycle. Although crucial for the understanding of the climate system, detailed knowledge on the interannual variability of dust source characteristics (i.e., emissivity and their susceptibility to wind erosion) and activity (i.e., occurrence frequency of dust emission events and emission fluxes) is still somewhat limited. In particular the impact of changing environmental conditions on dust sources and their emission variability is not fully understood yet and requires further research. This is also of importance in order to assess the spatially and temporally changing contribution of dust sources to the local and regional atmospheric dust burden and related dust feedbacks.

This presentation will provide an overview of different dust source types, their key characteristics, and their response to environmental changes due to climate change with regard to emission flux and dust source activity. It will include examples from remote sensing approaches and dust modelling in order to examine the interannual variability in a changing climate.

How to cite: Schepanski, K.: Mineral dust in the climate system: Dust source types and their response to environmental changes in a changing climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11443, https://doi.org/10.5194/egusphere-egu24-11443, 2024.

Dryland soil salinization strongly affects soil properties, with severe consequences for regional ecology, agriculture and the aeolian dust dynamics. Given its climate-sensitivity it forms a serious environmental hazard, and to cope with this challenge during current global warming it needs to be better understood.

The Bajestan Playa, located in the heavily salinization-affected drylands of Iran, is home to several protected areas and serves as a crucial source of regional dust emissions. Consequently, soil salinization in this region affects both local ecosystems and societies but was not systematically studied yet.

Using an unprecedented comprehensive approach, we systematically monitored regional soil salinity from 1992 to 2021 through a combination of remote sensing, on-site field measurements, and laboratory analyses. We linked these data with regional and global climatic information to achieve three main objectives: (i) understanding the spatio-temporal dynamics of soil salinity, (ii) assessing the impact of regional and global climate changes on salinization processes, and (iii) exploring the potential applications of our approach for future soil salinity studies.

Our high-resolution annual data over three decades have provided significantly deeper insights into soil salinization dynamics. Furthermore, this pioneering, multidisciplinary research showcases substantial potential for future applications in other salinity-affected drylands forming a foundational knowledge base to address the consequences of ongoing global climate change.

How to cite: Khosravichenar, A., Aalijahan, M., Moazeni-Noghondar, S., R. Lupo, A., Karimi, A., Ulrich, M., Parvian, N., Sadeghi, A., and von Suchodoletz, H.: Monitoring and simulating dryland soil salinization and assessing the impact of climate change and global warming on soil salinity processes over the past three decades in the Bajestan playa (NE Iran), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2355, https://doi.org/10.5194/egusphere-egu24-2355, 2024.

Climate change continues to impact diverse ecosystems. Drylands stand out as particularly vulnerable environments, as they are highly responsive to key indicators of change. The sensitivity and response time of these regions remain largely unknown, underscoring the need for a deeper understanding of their systems.

Arid regions are considered optimal for Earth Observation based research, primarily due to factors such as minimal anthropogenic disturbance, sparse vegetation cover, and low cloud coverage. These attributes make drylands advantageous for studying and monitoring the impact of climate change, providing valuable insights into these vulnerable ecosystems.

Southern Mongolia stands out as an especially well-suited study area to test novel approaches and to detect land surface changes over both space and time. The basin of Orog Nuur was selected in this study to observe long-term environmental changes, building on significant prior studies conducted around the drainage basin.

Our approach emphasizes the utilization of state-of-the-art earth observation technology to unveil the dynamics of desert ecosystems. This involves cloud-based processing, such as Google Earth Engine and the German High Performance Data Analytics (HPDA) platform “terrabyte”. Throughout the project, we will apply various multispectral and active SAR techniques spanning 50 years to monitor geomorphological processes, ecosystem changes and ongoing surface dynamics linked to climate change indicators. Some of important pillars of the long-term time series analysis can be listed as greening and precipitation events, lake level dynamics, dune movement rates, mapping of sedimentological, geomorphological provinces and aeolian coverage, in order to understand frequency-magnitude relationships.

The findings will be supported by a series of fieldworks covered by UAS campaigns and auxiliary ground-truth sensors, ensuring the accuracy of our estimations by in-situ measurements. Based on the derived surface characteristics, various ecosystems will be defined, and a high-level ecosystem integrity model will be developed. Ultimately, our model aims to represent the intactness, functioning and structure of the different ecosystems within arid regions. Additionally, due to our high temporal study concept, the model will serve as the base for quantifiable measurements of the responsiveness and adaptiveness of the ecosystems.

Having a model for ecosystem intactness not only help to preserve fragile ecosystems but also strengthens the resilience and adaptive capacity of communities. Furthermore, the transferability of our framework to other drylands may also lead to a comprehensive understanding of the arid characteristics.

Keywords: Earth Observation, arid regions, dryland, remote sensing, climate change, impact, geomorphological process, ecological modelling, land surface dynamics

How to cite: Arisoy, B., Ullmann, T., and Stauch, G.: Desert Sensing – Characterizing recent surface dynamics in arid regions through high-performance data analytics of multi-sensor Earth Observation archives and in situ records, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10337, https://doi.org/10.5194/egusphere-egu24-10337, 2024.

Sand control is one of the most important components of environmental protection. In the middle reaches of the Yarlung Zangbo River, the phenomenon of desertification is becoming serious, which has a great impact on the local ecological environment protection and economic development. The accurate estimation of the volume of aeolian sediment is of great significance to the formulation of the treatment plan. However, most of the existing studies are based on remote sensing interpretation to estimate the area of aeolian sediment, and the research on the volume of aeolian sediment is relatively weak. To make up for this research gap and provide reliable basic information for sand control in the middle reaches of the Yarlung Zangbo River, we carried out research on estimation of aeolian sediment volume based on GPR and LiDAR. The experimental area of this study is located in Zhanang County in the middle reaches of the Yarlung Zangbo River, with an area of approximately 1.8 km². We set up six GPR survey lines in the experimental area and obtained the bottom interface and corresponding average elevation of aeolian sediment. Subsequently, high-precision surface elevation of the study area was obtained by LiDAR, and the average surface elevation was calculated. Then we obtained the average thickness of the aeolian sediment is 3.25 m by subtraction of the average surface elevation and the elevation of the aeolian sediment bottom interface. Finally, we determined that the volume of aeolian sediment in the experimental area was about 5,850,000 m³. Our study has realized the volume estimation of typical aeolian sediment area in the middle reaches of Yarlung Zangbo River, which has important guiding significance for sand control.

How to cite: Ling, J., Qian, R., Liu, X., Huang, Z., Wang, D., Hu, K., and Zhang, J.: Estimation of aeolian sediment volume in the middle reaches of the Yarlung Zangbo River based on GPR and LiDAR, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5537, https://doi.org/10.5194/egusphere-egu24-5537, 2024.

Dunes react quickly to climatic changes, with the main drivers being the dominating wind regime (e.g. magnitude and direction), precipitation, and temperature. Further, human impact can alter dune movement by fixation of active dunes through greening projects, or reactivation of stationary ones through overgrazing by animals. The north-eastern Tibetan Plateau shows a high variability of climatic parameters like wind, temperature, and precipitation within a high elevation environment, situated between the mid-latitude westerlies and the East Asian Summer monsoon. The presented studies asses active barchan dunes in different climatic settings, from the arid southern margins of the Badain Jaran Desert, to the humid Zoige Basin.

Since climate stations on the Tibetan Plateau are rare and their measurements often cover only a short time span, climatic changes were studied from ERA-5 reanalysis data, dating back to the 1950s. These metrics were processed via cloud computing, using Google Earth Engine, and were then compared to dune migration rates, which were deduced from optical satellite imagery. Here, the CORONA KH-4B images from the late 1960s, the Landsat archives, and up-to-date high resolution data (GeoEye and WorldView) were used. The Normalized Difference Vegetation Index (NDVI) was implemented to observe changes in vegetation. As a newly tested metric, dune field density changes were calculated, in order to investigate dynamics of dense dune field setting.

Over 500 dunes were mapped and analyzed in total within four focus-areas for comparative purposes. The results highlight a wide range of different behavioral patterns of dunes within the environment of the north-eastern Tibetan Plateau. This showcases how dunes can be influenced by and linked to climatic changes.

How to cite: Dörwald, L., Lehmkuhl, F., Walk, J., Yang, X., Zhang, D., Baas, A., Delobel, L., Boemke, B., and Stauch, G.: Dunes on the north-eastern Tibetan Plateau as influenced by climate change: a remote sensing study of the past 5 decades , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1649, https://doi.org/10.5194/egusphere-egu24-1649, 2024.

The densely populated Thar Desert in the northwestern part of the Indian subcontinent contains a complex spatial pattern of now vegetated dune morphologies. There is a growing dataset of luminescence ages that demonstrates a dominance of Holocene dune dynamics in the preserved record (e.g., Srivastava et al, 2020; Parida et al., 2023; Nitundil et al., 2023). This region is undergoing rapid change in recent decades with widespread flattening of dunes for agricultural land, which is fed by the Indira Gandhi Canal that provides water for irrigation.

Our work has developed a training set of >40 samples with published luminescence ages to create a calibration approach for the signals measured using portable luminescence readers (POSL) (Nitundil et al., 2023). Other POSL signal characteristics, such as IRSL:BSL ratios are a good indicator that the Thar sands have a broadly common sedimentary provenance, as well as transport processes and post-depositional histories of mineral weathering. During this work, a rigorous exploration of sediment properties, including moisture content and presence of carbonate was undertaken, and from this, guiding principles for building a calibration curve were developed.

Vegetated linear dunes have been sampled in five regions along a ~75 km north-south transect in the western Thar. The POSL calibration has been applied to determine estimated ages for three dunes at the second most northerly site, to shallow depths (2 m) (Nitundil et al., 2023), and from multiple profiles within two dunes at each of three other sites along the transect (a further 19 shallow, 2 m profiles). Fieldwork in September 2023 focussed on obtaining close to full dune vertical profiles via auguring (~10 m depth) from three sites, as well as exploring dynamics across and along a dune using ~0.8 m hand dug pits. This presentation will highlight key findings from the calibration exercise, and present POSL-based ages estimates across the western Thar to explore what they reveal about Holocene dune accumulation in this region. 

References

Nitundil, S., et al. (2023) Applicability of using portable luminescence reader for rapid age-assessments of dune accumulation in the Thar desert, India. Quat. Geochron. 78, 101468.

Parida, S. et al. (2023) Luminescence Dating of Dunes in the Western Thar Desert:  New Data and Regional Synthesis. XXI INQUA Congress, 14-20th July 2023, Rome, Italy.

Srivastava, A., et al. (2020) Holocene palaeoenvironmental changes in the Thar Desert: An integrated assessment incorporating new insights from aeolian systems. Quat. Sci. Rev. 233, 106214.

How to cite: Nitundil, S., Stone, A., Srivastava, A., and Songara, K.: Holocene linear dune accumulation in the western Thar desert, India. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21074, https://doi.org/10.5194/egusphere-egu24-21074, 2024.

Aeolian-Fluvial interactions range from aeolian- to fluvial-dominated processes, often resulting in unique morphologies and complex stratigraphies along dunefield margins. In the Northwestern Negev dunefield (Israel) desert, a key factor influencing transitions from aeolian- to fluvial-domination, is the basin size. While medium-sized (40-200 km²) and large (>200 km²) basins were breached before or during the early Holocene, small basins are still dammed by dunes. Often their surficial and buried palaeochannel is comprised of a sequence of remain of dune-dammed water bodies in the form of fossilized playas. Unlike medium and large basins, where incision exposes Aeolian-Fluvial deposits after the dune-dam breaching, small dune-dammed fluvial systems necessitate sampling techniques such as drilling into continuously aggrading Aeolian-Fluvial deposits to reconstruct the stratigraphy and interpret paleoclimate and palaeoenvironmental records. We demonstrate the potential of a SUERC Portable-OSL (port-OSL) for interpreting palaeo-records in small dune-dammed basins.

The Shivta-East basin (3.3 km²) was hand-augered along an ephemeral stream's propagation path into the dunefield, at three disconnected playa-like sediments of seasonal dune-dammed waterbodies. At each dune-dammed waterbody sediments, samples were taken at 15-25 cm intervals and analyzed using the port-OSL reader. Their estimated ages were interpolated according to a calculated regional linear regression based on the northwestern Negev dunefield luminescence age database. This regression, generated by training a data set of thirty-two aeolian sand samples, analyzed for both OSL dating and port-OSL Net counts, accounts for 72% of the age variability, with a standard error of 3.4 ka between the model and the data. Due to the absence of modern-day OSL dated samples, the regression line was reconstructed for the LGM until the early Holocene. The regression model enables dating of the Last Glacial Maximum, Heinrich-1, and Younger Dryas sand incursions, previously described as the main active periods of the aeolian system.

K-means cluster analysis based on the port-OSL signals, reveals three distinct clusters, which points to alternations of the sedimentary units, between sand and fluvial sourced fine-grained sediments. The three clusters are understood to reflect both the mineralogical composition and burial age of the deposits. The overlying cluster mainly consists of fine-grained sediments deposited in the dune-dammed waterbody, while the other two units are sandy deposits.

Interpolation of the sandy samples from all three playas along the palaeochannel in the linear regression demonstrates that during the Heinrich-1 and Younger Dryas events, an aeolian-dominated environment dune-dammed the fluvial system, enabling aeolian sand deposition. Later, coevally with the fluvial system's propagation into the second (middle) dune-dammed waterbody, aeolian domination persisted until the Early Holocene generating the third and upstream dune-dammed waterbody.

This study demonstrates the potential and limitations of the port-OSL reader combined with statistical methods for chrono-stratigraphic analysis of hand-augered samples collected from an altering depositional environment. The ability to rapidly estimated depositional ages and associated palaeoclimatic periods highlights the potential for further exploration of the port-OSL reader in different environmental settings.

How to cite: Greenbaum, N., Robins, L., and Joel, R.: Regional Depositional Age Assessment using Portable-OSL of Hand-Augered Aeolian-Fluvial Deposits along a chain of Small Dune-Dammed Basins in the Northwestern Negev Dunefield Margins, Israel , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12423, https://doi.org/10.5194/egusphere-egu24-12423, 2024.

The Great Central Desert of Iran, located at the center of the Iranian plateau, bears valuable but scattered geological and geomorphological archives. However, the scarcity of data on the paleoenvironment and paleolandscape of this area is attributed to challenging accessibility and harsh climatic conditions. The Khur area in the eastern edge of the Iranian Central desert was selected for this investigation due to its distinctive geomorphological features and improved accessibility.
This study aims to delineate Late Pleistocene-Holocene landscape evolution in central Iran by utilizing sedimentary and morphostratigraphical evidence of aeolian-fluvial sequences. In a first step, geomorphological features were mapped based on satellite imagery, digital elevation models, geological maps and field observations. Subsequently, localities for excavator sections were deduced from these findings, guaranteeing accessibility and further ensuring their incorporation of anticipated stratigraphic key features, including contact zones of distinct geomorphological environments. Stratigraphic description of the excavated profiles was recorded, and sedimentary logs were drawn.
The preliminary results reveal complex interactions of Aeolian, fluvial, and lacustrine morphodynamics during the Late Pleistocene and Holocene. Seven landform groups including aeolian dunes and interdune areas, sandy mud flat, alluvial fans and fluvial plains, dissected fan toe with backward erosional valleys were recognized. Within these, five interfingering sedimentary units were identified based on distinctive geometry and layering and their internal facies distribution: Fluvial flood deposits, well to poorly-sorted alluvial deposits, aeolian sand deposits, fluvially reworked marl (fine-grained mud), paleosol horizons.
In summary, repeatedly changed depositional environments and cyclical climatic changes, where dune development took place during phases of increasing aridity, whereas non-aeolian deposition and paleosol formation might have occurred during more humid conditions and more stable paleosurfaces.
Luminescence dating, sedimentological and geochemical analyses, will determine climatic cycles, sedimentary environments and landscape evolution history.

How to cite: Rashidi Koochi, Z., Büdel, C., Torabi, M., Baumhauer, R., and Fuchs, M.: Towards Late Pleistocen-Holocene stratigraphy and landscape evolution of Khur area, Central IranTowards Late Pleistocen-Holocene stratigraphy and landscape evolution of Khur area, Central Iran, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12653, https://doi.org/10.5194/egusphere-egu24-12653, 2024.

The Tibetan Plateau (TP) is extremely sensitive to climate change. Widely loess deposits distributed in the Tibetan Plateau are important archives for studying the past environmental changes of the Tibetan Plateau. However, little information is understood due to the poorly age constrained of the TP loess. In this study, we use the single-aliquot regenerative dose optically stimulated luminescence (OSL) method, and the post-infrared infrared stimulated luminescence protocol (pIRIR) to date the well-preserved loess–paleosol sequences in the eastern TP and discuss the applicability and reliability of OSL dating of the TP loess for establishing a reliable numerical age framework. We found that quartz OSL signal of TP loess is dominated by fast component, and the equivalent dose can be measured by SAR method. The growth curve shapes and saturation dose shows that the quartz OSL signal in this region saturated at ~200～230 Gy. The prior-IR stimulation plateau test, dose recovery, recycling ratio and recuperation indicated that pIR₂₀₀IR₂₉₀ could be used for the equivalent dose estimation of potassium feldspar. Our results contribute to an improved understanding of the TP dust history and paleoenvironmental changes in the Last Glacial cycles.

How to cite: Yang, S., Liu, L., Li, Q., Li, P., and Luo, Y.: Optically stimulated luminescence dating of loess sequences in the Tibetan Plateau and their palaeoenvironmental implications, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15208, https://doi.org/10.5194/egusphere-egu24-15208, 2024.

Sedimentary sequences with major aeolian dust contribution blanket the flat to hilly landscapes of eastern New South Wales. Originally identified by Butler in 1956 within the Riverine Plain and adjoining hills, these widespread clay-rich sediments were termed "Parna”. Parna – which has often been compared to loess – is thought to be fine-grained sediment generated through exogenic processes in arid environments and transported as stable aggregates by prevailing westerly winds during the Quaternary. The primary hypothesized source regions for Parna are arid and semi-arid river and lake systems situated in the western Murray-Darling Basin. Despite the prolonged critical discourse surrounding the concept and terminology of Parna, investigations addressing unresolved questions have been limited, with absolute dating of the aeolian sequences being restricted to only a few sites.

Given the complexity of the Parna sequences resulting from the interaction of aeolian, hillslope and pedological processes, we choose a multimethodological approach combining field observations, grain size analysis, geochronological and geochemical methods to investigate the processes and time frames of sedimentation and sediment provenance. Results of optically stimulated luminescence (OSL) dating for several Parna sites in the Wagga Wagga (Beattie 1972) and Yass region, show age estimates reaching back 150,000 years. Sedimentological parameters are used to distinguish between material derived from local hillslope and aeolian input. Geochemical characteristics will help to trace sources and pathways of the aeolian material. Advancing our understanding of the Parna concept, implying large-scale deposition but also deflation of aeolian material, is one component of reconstructing Quaternary landscape development and environmental conditions in south-eastern Australia.

Butler, B.E., 1956. Parna-an aeolian clay. Australian Journal of Science, 18(5), 145-151.

Beattie, J.A., 1972. Groundsurfaces of the Wagga Wagga Region, New South Wales. C.S.I.R.O Soil. Pub Australia. No. 28.

How to cite: Lauer, F., Marx, S., Dare-Edwards, A., and May, J.-H.: Reconstructing timeframes, processes and environmental implications of Late Quaternary aeolian Parna deposition in south-eastern Australia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13466, https://doi.org/10.5194/egusphere-egu24-13466, 2024.

The development of alluvial fans is sensitive to environmental change and, thus, alluvial fans provide essential archives for reconstructing Quaternary paleoenvironmental conditions, particular climate, hydrology, and tectonics. Although alluvial fans have been studied across the globe for over a century, there is no unifying scheme/framework or model to consider their complete variety and mode of formation. By reviewing the global spatial and temporal range of alluvial fan types and data from selected key dryland regions, we are able to develop a conceptual scheme/framework for their geomorphology and formation, and thus aid in their application for Quaternary climate and environmental change studies. This approach suggests that there are three main regimes for alluvial fan geomorphology and formation: Type I) microscale mountain alluvial fans, small in size and extent (radius < a few 100 m); Type II) mesoscale (radius

How to cite: Lehmkuhl, F. and Owen, L. A.: A conceptual model for alluvial fan formation and development , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1752, https://doi.org/10.5194/egusphere-egu24-1752, 2024.

 In view of the problem that the Cretaceous favorable sedimentary facies belt in Kedong structural belt in the southwest depression of the Tarim Basin is not clear, in order to reduce the uncertainty of the research on the spatial and temporal distribution of source sink sedimentary systems in low drilling density areas, the applicability of sedimentary forward modeling in the Tarim Basin is explored. Based on existing geochemical data, statistical analysis of trace elements and rare earth elements is conducted to explore the ancient sedimentary environment during the sedimentation process of the Cretaceous Kizilsu Group, which is a prerequisite for conducting sedimentary forward modeling. By comprehensively utilizing drilling, seismic and other data, combined with previous research results, DionisosFlow sedimentary forward simulation software is applied to clarify the development characteristics of sedimentary systems. The results show that based on different element abundances, ratios, and sedimentary markers, the study of ancient sedimentary environments shows that the ancient climate is mainly characterized by semi humid, semi dry, and dry hot climate conditions; During the sedimentation period of the Kizilsu Group, the overall water depth was relatively shallow, and the ancient redox environment was a shallow underwater oxidation environment. The favorable paleoenvironmental conditions and abundant material sources provide favorable conditions for the development of shallow water delta sedimentary systems. The Kizilsu Group mainly develops braided river delta sediments in the northern gentle slope zone, with front edge sediments as the main type. The southern steep slope zone develops alluvial fans and fan delta sedimentary systems, and the central part develops shoreline shallow lake facies sediments. The western Kunlun Mountains in the south are the main source of material supply, while the Maigaiti ancient uplift in the north is the secondary source of material supply. The ancient uplift during the sedimentation period of the Kizilsu Group has a blocking effect on the delta that flows into the lake, dividing the southern fan delta and lake sedimentary system from the northern braided river delta and lake sedimentary system.

How to cite: Zhang, Y. and Zhang, L.: Application of Sedimentary Forward Simulation in the Kezilesu Group of the Kedong Structural Belt, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2738, https://doi.org/10.5194/egusphere-egu24-2738, 2024.