ICG2022-6

The area of NE Poland, Lithuania and NW Belarus is often studied in terms of palaeoenvironmental changes that occurred at the end of the last glaciation In this area there are numerous lakes, peat bogs, river valleys, kettle holes where limnic and paludic sediments accumulated. Based on the literature, 55 sites from this region were analysed. On the basis of palynological studies, and radiocarbon dating their deposition time was determined as Late glacial period (LG). There are also sites whose age is determined only on the basis of palynology or plant macrofossils. Often in the analysed sediment profiles there is no record of the full LG succession, but there is usually a BØ-AL-YD sequence. The thickness of the described LG sediments ranges from 8 cm to 325 cm. Large thickness LG sediments were found at the sites Stare Biele (thickness 325 cm, Poland, Podlasie; Kupryjanowicz, 2000), Ginkūnai (290 cm, Middle Lithuania; Stančikaitė et al., 2015), Lopaičiai (180 cm, NW Lithuania; Kabailienė et al., 2015). The range of radiocarbon averaged ages for the analysed sediment profiles is from 9,176 to 25,250 ka cal BP. Some of them are subject to error (aged by pollen redeposition or rejuvenated by reservoir effect). Typically, macrofossils isolated from gyttjas, peats or silts were dated.

A few km north-east of Suwałki (NE Poland) there is an extensive, irregularly shaped depression, consisting of several larger reservoirs connected by constrictions. Most of its area is covered with peat bogs. Using the GEOPROPBE intact biogenic sediment profile was drilled (profile OS – 10,40 m). So far, palaeobotanical, geochemical, and stable oxygen and carbon isotopes have been performed in the collected sediments. In the near future, ¹⁴C AMS dating of selected plant remains is planned.

The conducted palynological analysis of OS profile shows that the functioning of the water reservoir near Suwałki began in the OstD, when the area was overgrown by vegetation of open communities. Slight warming of BØ resulted in high Pinus pollen values, which may indicate the development of rare interstadial pine forests. Re-cooling of OD resulted in the withdrawal of these communities and the spreading of herbaceous and shrubs vegetation. Another warming - AL, led to the development of rare pine and birch forests with numerous sea buckthorn. The cooling of the YD brought the domination of open shruby and steppe-tundra communities. The thickness of the sediments from the LG period containing the full record is 81cm. Considering the location of the Osinki site and the significant continental character of this region climate, it can be concluded that it is a stratotype site of LG for this part of Europe.

The above research results are presented thanks to the grant of the National Science Center (2018/31/B/ST10/00976) "Geomorphological evidence and palaeogeographic implications of catastrophic floods and glacial charges of the southern sector of the Scandinavian late Vistulian ice sheet (MEASSIS)" and the funds of Nicolaus Copernicus University in Toruń as part of the Emerging Filds "Global changes in the environment".

How to cite: Karasiewicz, T., Hrynowiecka, A., Pawłowski, D., Rzodkiewicz, M., and Weckwerth, P.: Environmental changes during the Late glacial period inferred from sedimentological archives  of NE Poland, Lithuania and Belarus, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-393, https://doi.org/10.5194/icg2022-393, 2022.

We studied two geo/morphological elements located southern the town of Gallipoli (Apulia region, southern Italy): the Il Carmine-Li Foggi paleo littoral ridge (CLlr) and the fossil dunes of Il Campo locality, both dating back to MIS 5.5.

A detailed study was conducted on the aeolian units present within CLlr (AU1 and AU2) and at Il Campo locality (unit AU3), in order to reconstruct the paleo-directions of the winds andthe atmospheric pressure patterns. AU1 is the first aeolian unit to settle, it is concentrated at the northern and southern extremities of CLlr and shows wavy to cross-bedding co-sets, dipping in various directions. The accumulation of AU1 at the northern and southern edges of CLlr indicates an effective aeolian transport both northward (due to winds from the southern quadrants) and southward (due to winds from the northern quadrants); the same conclusion can be drawn from the internal structure of AU1. The AU1 unit therefore allows us to recognise a “first aeolian phase”. It involved an autumn-winter pressure pattern characterised by an Atlantic footprint similar to the current one: the Atlantic lows entering the Mediterranean caused, as happens today, the onset of winds from the S and NW, respectively before and after the passage of the low-pressure minima over Apulia. Even in spring-summer, the pressure fields were likely very similar to the current one, with the Azores high on the central-western Mediterranean and the low pressure on the eastern Mediterranean: consequently, the prevailing winds showed a marked unimodality from NW but their speed was generally weak, and therefore these winds were not able, just as it happens today, to significantly impact wind transport; this summer regime leaved the prevailing imprint of the Atlantic winter regime, therefore NW-S bimodality, as recorded by AU1.

AU2 and AU3 settled later than AU1, in a “second aeolian phase” of MIS 5.5. AU2 is characterised by south-eastward-dipping foresets. AU3 consists of domal-linear dunes, the latter oriented in the NW-SE direction. We interpret AU2 and AU3 as coastal dunes originating in a prevailing NW wind regime.

Based on the principle of actualism and on literature data, we conclude that AU2 and AU3 settled under a pressure pattern similar to the current one in fall-winter, that is, characterised by Atlantic cyclones transiting over the Mediterranean, and consequent NW-S bimodality of the winds; in the spring-summer, instead, the regime was characterised by a pressure gradient from west (high) to east (low) much stronger than the current one, causing NW winds stronger than today. Such strong summer winds from NW, effective for wind transport, coupled with the NW-S bimodality in fall-winter, caused the overall prevalence of NW winds during the “second aeolian phase”. This pressure gradient on the Mediterranean greater than today was caused by a summer strengthening of the east Mediterranean low-pressure, in turn caused by the northward shift of the ITCZ, widely documented during the Sapropel S5 event and verified during the MIS 5.5 after sea level had risen to the highstand.

How to cite: De Santis, V., Scardino, G., Scicchitano, G., Ortiz, J. E., Sánchez-Palencia, Y., and Caldara, M. A.: Wind regime change from mis 5.5 aeolian dunes in the Apulia region. A key for the reconstruction of a Meditterranean pressure pattern during the last interglacial., 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-349, https://doi.org/10.5194/icg2022-349, 2022.

At 53° S, pans, shallow lakes, lacustrine terraces, perched dunes and paleosols are most of the typical landforms and features of the Fuegian steppe conditioned by climate. They are in a cold, semi-arid, oceanic climate highly affected by the Southern Westerlies winds (SWW).

During spring and early summer, rainfall, snow melting, and runoff promote the infill of the pans that become in brackish, shallow lakes. When the systems are filled with water, the permanent, high-speed SWW generates waves on the lakes' coasts; whereas the shallow lakes dry up again, bottom sediments are deflated. Wind erosion on the coastal rocky cliffs and deflation contribute to the perched dunes formation.

Since the Late Glacial, multi centennial wet/dry cycles allowing the development of specific landforms and features are also recorded by proxy studies. During the dry intervals, erosion removed fine sediments from the marine sandstones and limestones cliffs while deflation deepened the dried basins contributing with bottom lake sediments, diatoms and organic matter remnants in the dune deposits. Both processes provide sediments which accumulate on the top of the cliffs forming perched dunes.  Accumulation rates varied through different time intervals allowing the perched dunes to grow and increase their heights, while the spreading of halophytes around the lakes evidence that its area diminished. The algae and ostracod assemblages suggest mesohaline or slightly alkaline conditions, higher conductivity, and enhanced evaporation whereas there was a remarkable change in diatom assemblages from planktonic to common species in terrestrial and dry settings. All these evidences suggest a lowering in lake water levels. 

Conversely, during the wet intervals, lake water levels were relatively higher and probably deeper than today. Several lacustrine terraces extend around the lake’s margins more than 10 m above the present lake levels. During these intervals, grasses expanded, and halophytes retracted. The algae and ostracods assemblages indicated freshwater supply, high nutrient loading, oligohaline and deeper water body. At this time, diatom assemblages were more diverse including planktonic species. Also, the presence of sedges and hygrophilous taxa pointed to the development of moist environments surrounding the lake. Dune formation was interrupted and pedogenetic processes occurred on their upper layers until renewed aeolian deposition, a dry cycle, buried them again. Paleosol structures varied over time according to the availability of environmental humidity, with a less developed pedological structure towards the Middle and Late Holocene. These paleosols showed the dominance of local herbaceous and/or shrub vegetation along with the presence of arbuscular mycorrhizal fungi.

These wet-dry cycles were conditioned by the latitudinal migration of the SWW core. When it migrates northwards, the intensity of winds diminishes and the entrance of humid air masses from the Atlantic is favoured. By the contrary, dry cycles result from the position of the SWW core in latitudes close to 50°S, allowing the wind to reach the region with high speed and frequency, preventing entry of moist air from the Atlantic and promoting a rain-shadow effect in the landscape.

How to cite: Coronato, A. M., Borromei, A. M., Fernández, M., Musotto, L., Mehl, A., Ponce, J. F., Candel, S., Laprida, C., and Cusminsky, G.: Geomorphic and environmental responses to climatic changes in the Fuegian steppe, southern south America, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-149, https://doi.org/10.5194/icg2022-149, 2022.

Tropical cyclones have repeatedly provoked intense devastation over the course of the last decades, and societal drivers such as unplanned urbanization and the lack of flood risk assessments have worse the problem further. Landslides and floods are frequent hazards linked to tropical cyclones. This is not the exception in Costa Rica, where more than 90% of all disasters are hydrometeorological in nature. Different climatic change scenarios indicate that more and stronger tropical cyclones will affect the North Atlantic Basin, where Central America and the Caribbean lie. This study gathers the different methodologies used to understand the geomorphic effects of tropical cyclones in Costa Rica. This study present geomorphic, hydrological, dendrochronological, and risk assessment approaches that look to reduce the human and economic impacts of tropical cyclones in the Central American country. Finally, this study is a call to apply geomorphic assessments in order elucidate the endogenic and exogenic processes related to tropical cyclones affectation on low latitudes.

How to cite: Quesada-Román, A.: Geomorphological effects of tropical cyclones in Costa Rica, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-51, https://doi.org/10.5194/icg2022-51, 2022.

The impact of climatic conditions on eco-geomorphic processes was studied at a number of research stations along the climatic transect extends between the Judean Mountains (mean annual rainfall 700 mm, temp. 17°C) and the Dead Sea (mean annual rainfall 100 mm, temp. 23°C). The research stations are located on hillslopes having similar gradients, aspects, and lithology.

At each station, climatic and soil variables (rainfall depth and intensity, temperature, soil moisture at different depths), as well as overland flow yield from runoff plots of different lengths (7 m, 14 m, 21 m), were measured. Typical infiltration curves were obtained in field experiments, and soil samples were taken to the laboratory to determine the relevant soil properties (aggregates stability, organic matter content, etc.).

The results show that:

• On a regional scale, there is a correlation between the average climatic conditions and eco-geomorphic processes and variables: the organic matter content, the aggregates size and stability, and the infiltration rate decrease from the Mediterranean to the arid region while the runoff coefficient increases. However, the rate of change of these variables along the climatic transect is non-linear; A step-like threshold exists at the semi-arid region which sharply separates the Mediterranean eco-geomorphic system from the arid one. Such a threshold means that even a relatively small climate change will cause a spatial displacement of the aridity boundary. As many regions having Mediterranean climate are located adjacent to semi-arid regions, they are at risk of desertification even in the case of a slight climate change.
• On the hillslope scale, different spatial patterns of soil properties values and of overland flow generating areas characterize different sections of the climatic transect. In the Mediterranean and the arid regions the spatial distribution of soil properties values is uniform but the values themselves are very different. While in the Mediterranean region the values promote infiltration, in the arid region they promote overland flow generation. In addition, the vegetation cover in the Mediterranean region is almost 100% while in the Arid zone it is close to 0%. The result is that in the Mediterranean region infiltration is the dominant process all over the hillslope while in the arid region overland flow predominates. In contrast to the uniform spatial distribution of processes in these two regions, the semi-arid region is dominated by a mosaic-like spatial pattern, consisting of locally “dry” water source patches and “moist” water sink patches. These patterns express different adaptation/survival strategies of eco-geomorphic systems under different climatic conditions.

Changes in the spatial patterns of soil properties values and of vegetation together with a change in the ratio source/sink areas can be used as quick response indicators of climate change and of desertification.

Regarding rehabilitation strategies, triggering the regeneration of a mosaic soil-vegetation pattern in the semiarid region should be preferred as a more sustainable option than treating areas as homogeneous landscape units.

How to cite: Lavee, H.: Impact of climate change on eco-geomorphic systems and desertification, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-100, https://doi.org/10.5194/icg2022-100, 2022.