The research, led by Zakieh Rashidi Koochi of the University of Würzburg together with colleagues from Germany and Iran, tackles a long-standing gap in the environmental history of western Asia. The Central Iranian Plateau occupies a pivotal position on any map of early human dispersal, linking Europe and Central Asia along routes that prehistoric humans and later trade caravans may have followed during more humid periods. But while continuous lake sediments in western Iran and loess-paleosol sequences in the north have yielded rich paleoclimate records, the vast central deserts remain nearly blank on the scientific map. Harsh climate, difficult access, and the poor preservation of organic material in hyper-arid settings have meant that the interplay between past human migration and environmental change in this region has remained largely speculative.

To fill that gap, the team adopted an integrative approach that combined geomorphological mapping with detailed stratigraphical fieldwork. Using satellite imagery, digital elevation models, geological maps, and extensive field observations, they mapped the basin’s landforms at a scale of 1:10,000, applying the German GMK25 geomorphological mapping symbology. They then examined twelve sedimentary sections distributed across eight geomorphic units, from the mountain front to the lowest point of the playa. The sections were described using standard sedimentological and soil classification methods, capturing textures, structures, paleosols, and the distinctive gypsum-rich horizons that characterize desert soils in central Iran.

The resulting picture is one of a landscape organized around a large-scale source-to-sink sediment cascade. Sediment eroded from the Cretaceous limestones, sandstones, and shales of the Hoz-e-Mirza Mountains is transported across pediments carved into Miocene marls and mudstones, then spread across alluvial fans before reaching the endorheic playa some 14 kilometers away. Sand dunes, extensions of the vast Sargardan and Shotoran sand seas, cap the most distal parts of the pediments and block the fan deposits at the playa margins. The playa itself sits at two distinct elevations, with a dune-dammed surface standing up to 4 meters above the main playa floor, a striking testament to the power of wind-blown sand to reorganize an entire drainage system.

The stratigraphy of the alluvial fan sections revealed four recurring sedimentary units: fluvial gravels, reddish paleosols, gypsic soils, and reworked Miocene marls. The gravels show the lateral discontinuities and interbedding with finer lenses typical of braided river channels, indicating episodes of intense precipitation and high discharge in the catchment. The paleosols, with their clay-enriched reddish horizons, blocky structure, and visible clay coatings, qualify as argillic horizons that form only under wetter conditions than today and require thousands to tens of thousands of years to develop. Such horizons, the authors argue, are in situ relicts of landscape stability during periods of increased rainfall, most plausibly during Marine Isotope Stage 3 or earlier.

Because no numerical ages could be obtained directly from the Khur Basin archives, the team built a tentative chronology by systematically reviewing every available dated geoarchive from the Iranian Plateau, drawing on luminescence dating, cosmogenic exposure ages, and radiocarbon records from alluvial fans, playas, lakes, and dunes across the region. This comparative framework allowed them to identify six main stages of landscape evolution. The earliest stage, prior to and during MIS 3, saw the erosion of the ancient pediment surface, the formation of local alluvial covers, the development of paleodunes, and the first soil formation on old alluvial deposits.

The second stage coincides with the Last Glacial Maximum and MIS 2, when cold and arid conditions gripped the plateau. Intense frost weathering in the mountains increased debris production, while slightly higher precipitation than today allowed alluvial fans to prograde far into the basin interior. The same cold, dry, and windy conditions likely drove the formation of the basin’s sand dunes, consistent with dated sand ramps in central Iran that accumulated between 28,000 and 18,000 years ago and with dune origins at the margins of the Persepolis Basin attributed to the LGM. During this period, sediment supply rather than transport capacity controlled fan development across much of Iran.

The transition from the last glacial period to the Holocene brought a sharp increase in precipitation. The researchers propose that a perennial lake may have formed in the playa, or that existing lake levels rose significantly, accompanied by initial soil development and the formation of younger soils within older fan surfaces. Although no fossil lake terraces were found in the field, widespread backward-erosional features on the distal and medial fans can be interpreted as the legacy of a subsequent lake-level retreat. That retreat, the fourth stage, is linked to the severe drought of the Younger Dryas around 12,900 to 11,700 years ago, when falling lake levels across the wider region, vanishing vegetation cover, and intensified surface fragmentation triggered alluvial fan dissection and renewed dune formation.

The final two stages bring the story to the present. During the early to mid-Holocene, arid conditions, stronger and possibly shifted winds, and the collapse of vegetation and water bodies reactivated the dune fields at the basin’s edge. Migrating southeastward, the dunes dammed part of the main playa of the Great Kavir, and up to 4 meters of new playa sediments accumulated behind the sand barrier. In the late Holocene, an overall trend of increasing aridity allowed aeolian processes to dominate completely: deflation deepened the main playa, gypsum-rich soils developed on abandoned and eroded fan surfaces, and mobile wind ripples, with wavelengths of 150 to 200 millimeters aligned to the prevailing northwesterly winds, spread across the dune field, marking the active saltation that continues today.

The significance of this work extends well beyond a single desert basin. By systematically integrating stratigraphical, pedological, and geomorphological evidence that had previously been studied in isolation, the study demonstrates how discontinuous desert archives can be stitched into a coherent narrative of landscape-climate interaction. The six-stage model provides a relative chronological framework that future high-resolution dating studies can refine and quantify. It also offers a crucial environmental backdrop for archaeologists investigating when the migration routes and trade corridors of the Iranian Plateau were active, and how their use was tied to shifting climates. As the authors note, understanding how this extreme environment responded to past climate changes opens a new perspective on geomorphic responses to environmental change in the world’s drylands, a question of growing urgency as modern arid regions face an increasingly uncertain water future.

Subject of Research: Late Quaternary landscape evolution and climate-driven geomorphological processes in the Khur Basin, central Iran

Article Title: Late Quaternary geomorphological processes and landscape evolution in the Khur Basin, central Iran

Article References: Rashidi Koochi, Z., Büdel, C., Walk, J., Fuchs, M., Torabi, M., Karimi, A., Baumhauer, R., & Stauch, G. (2025). Late Quaternary geomorphological processes and landscape evolution in the Khur Basin, central Iran. E&G Quaternary Science Journal, 74(2), 193-212. https://doi.org/10.5194/egqsj-74-193-2025

Image Credits: AI Generated

DOI: 10.5194/egqsj-74-193-2025

Keywords: Khur Basin, central Iran, geomorphology, Quaternary, alluvial fans, sand dunes, playa, paleoclimate, Last Glacial Maximum, Holocene, paleosols, Great Kavir

The index was built using the Coastal Vulnerability Model within the open-source InVEST software suite, developed by the Natural Capital Project at Stanford. Seven variables feed into the calculation: shoreline type, topographic relief, the presence of protective coastal habitats, wind exposure, wave energy, storm surge and the rate of sea-level rise. Each variable is ranked on a one-to-five scale, and the final exposure value is computed as the geometric mean of the seven ranks. The researchers chose this multiplicative approach deliberately, because an additive index could allow a high score in one variable to mask low scores elsewhere, potentially hiding genuine danger. The geometric mean ensures that a coastline must score poorly across multiple dimensions before it can be labelled highly exposed.

The underlying data are among the most detailed ever assembled for the Irish coast. Wind and wave conditions were drawn from thirty years of records spanning 1995 to 2024, using the Copernicus CERRA reanalysis at 5.5-kilometre resolution and the NWSHELF wave physics reanalysis at 1.9 kilometres — both considerably finer than the global datasets often used in such studies. Storm surge and sea-level rise rates came from CMIP6-based Copernicus climate projections, while relief was calculated from a 10-metre national digital terrain model derived from LiDAR and camera sensors. Notably, the team found that the default storm surge proxy built into the InVEST model, which estimates surge from the distance to the edge of the continental shelf, correlated negatively with properly modelled surge levels around Ireland. They replaced it with hydrodynamically modelled surge data, a methodological correction that materially changed the results.

The headline finding is that exposure is not a simple story of a wild, storm-battered west versus a sheltered east. The west coast does record the highest absolute exposure values and the largest total extent of Very High Exposure coastline — Mayo alone contains 414.5 kilometres of it, with Galway County and Donegal contributing another 36 percent of the national total between them. But when exposure is measured as a proportion of each authority’s own shoreline, the picture inverts dramatically. Leitrim, with just 5.5 kilometres of coast, sees 68 percent of it classified as Very High Exposure. Meath records 57 percent of its 11 kilometres in the High Exposure band. Eastern local authorities including Dublin City, Dún Laoghaire–Rathdown, Fingal, Louth, Wexford and Wicklow hold some of the highest proportional exposure in the country, a consequence of soft, erodible Quaternary sediments and low-lying terrain rather than Atlantic storm tracks.

One of the study’s most consequential results concerns the protective role of coastal habitats. The researchers mapped four habitat types — dunes, machair, saltmarsh and seagrass — and found that 38 percent of Ireland’s coastline, some 3,299 kilometres, sits within the potential protective distance of at least one of them. Saltmarshes exert the widest influence, with over 5,000 kilometres of coast lying within 500 metres of a saltmarsh of some kind. To quantify what these ecosystems actually do, the team ran a counterfactual no-habitat scenario in which every coastal point was assigned the worst possible habitat rank. The difference was stark: in Dublin City the share of Very High Exposure coastline jumped by 15 percentage points to 29.5 percent, in Meath it rose to 89 percent, and in Galway City to 64 percent. In Fingal, the removal of habitats pushed more than 7,000 additional residents into the highest exposure zone.

The population analysis relied on a dasymetric mapping technique rather than coarse census blocks, distributing 2022 census data according to the locations of individual residential buildings at 100-metre resolution. Voronoi polygons were then used to attribute populations to their nearest coastal exposure category at buffer distances of 125, 250 and 500 metres. The results show that roughly 308,000 people live within 500 metres of the Irish coastline, and that in Dublin City and Galway City almost 10,000 residents each live within 500 metres of a Very High Exposure shoreline. In Galway City, that figure represents about 11.4 percent of the entire urban population. The vulnerability of the city was underlined in January 2025, when Storm Éowyn drove a 2.6-metre surge into Galway Bay that narrowly missed causing widespread flooding only because it coincided with a mid-tide.

Cultural heritage emerges as a second, quieter casualty. Of the 8,871 registered national monuments within 500 metres of the coast, 1,797 — one in five — fall within Very High Exposure zones, concentrated along the west and northwest. Sligo alone accounts for 383 of these sites, including the uninhabited island of Inishmurray, which holds a medieval monastic settlement and 132 registered monuments, from inscribed cross stones to leachts, the stone sepulchral monuments of early Christian Ireland. In the no-habitat scenario, the number of exposed heritage sites rises to 2,118, with the steepest proportional increases in Wexford and Fingal. Middens — ancient refuse heaps that preserve evidence of millennia of coastal life — are the most common monument type in the danger zones, a reminder that the eroding edge of Ireland is also its longest-running archaeological archive.

The team did not simply publish the index; they stress-tested it. A leave-one-out sensitivity analysis showed that removing shoreline type produced the largest shift in results, confirming that substrate erodibility is the dominant control on exposure, particularly along the east coast. Removing habitats produced the smallest overall change, which the authors attribute to the heavily modified nature of much of the Irish shoreline. They also compared four statistical methods for ranking continuous variables — quintiles, equal intervals, Jenks natural breaks and geometric intervals — and found that the choice matters enormously. Equal-interval classification collapsed the national Very High Exposure category to just 97 points, none of them on the east coast, effectively erasing the risk profile of counties that are known to be eroding fastest. The quintile approach, the model’s default, was vindicated for skewed variables such as wind, waves and relief, though the authors caution it may be less suitable for spatially uniform quantities like sea-level rise.

The findings arrive at a moment when Irish coastal policy is in flux. The Office of Public Works has completed national flood mapping and erosion projections, but no prior assessment had combined hazard characterisation with the exposure of people, ecosystems and heritage in a single framework. The new index aligns closely with independent evidence: 81 percent of points within OPW-identified wave overtopping zones rank as High or Very High Exposure, and 83 percent of segments experiencing high erosion rates in the Geological Survey Ireland shoreline change study fall into the same categories. The study also documents the cost of habitat degradation. At Rossbeigh beach in Kerry, vegetated dune cover fell by 43.2 percent between 2001 and 2019, while the Maharees Peninsula — 92 percent of which the index classifies as High or Very High Exposure — has recorded average beach retreat of 0.63 metres per year over more than a century.

The authors are careful about what the index can and cannot do. It measures relative exposure, not vulnerability; it does not account for existing engineered defences, sediment dynamics, river discharge or socioeconomic adaptive capacity, and national habitat condition assessments rate many Irish dune and saltmarsh habitats as unfavourable, meaning the baseline model may overstate the protection currently on offer. Yet as a screening tool it offers something Ireland has never had: a consistent, evidence-based map of where nature already shields the coast, where it could be restored to do so, and where hard choices about holding the line, realigning or retreating will soon be unavoidable. With global mean sea levels projected to rise by as much as 1.1 metres above 1900 levels by 2100 under high-emission scenarios, and an estimated 1.1 billion euros of Irish coastal assets at stake from a single metre of rise, that map may prove one of the most consequential documents in the country’s climate adaptation arsenal.

Subject of Research: National-scale assessment of coastal hazard exposure and the protective role of coastal habitats in Ireland

Article Title: A coastal exposure index for Ireland: relative hazard exposure and the protective role of coastal habitats

Article References: Walsh, K., de Oliveira, L. M. C., Keenahan, J., & Lim, A. (2026). A coastal exposure index for Ireland: relative hazard exposure and the protective role of coastal habitats. Natural Hazards, 122(18), Article 627. https://doi.org/10.1007/s11069-026-08361-w

Image Credits: AI Generated

DOI: 10.1007/s11069-026-08361-w

Keywords: coastal exposure, Ireland, sea-level rise, coastal habitats, nature-based solutions, InVEST, storm surge, saltmarsh, sand dunes, cultural heritage, coastal erosion, climate adaptation