Intensity Of Aeolian Processes Research Articles

Applicability of Unmanned Aerial Vehicles in Research on Aeolian Processes

Surface dynamics and instabilities are characteristic of aeolian formation. The method of surface comparison is regarded as the most appropriate one for evaluation of the intensity of aeolian processes and the amount of transported sand. The data for surface comparison can be collected by topographic survey measurements and using unmanned aerial vehicles. Time cost for relief microform fixation and measurement executing topographic survey are very high. The method of unmanned aircraft aerial photographs fixation also encounters difficulties because there are no stable clear objects and contours that enable to link aerial photographs, to determine the boundaries of captured territory and to ensure the accuracy of surface measurements. Creation of stationary anchor points is irrational due to intense sand accumulation and deflation in different climate seasons. In September 2015 and in April 2016 the combined methodology was applied for evaluation of intensity of aeolian processes in the Curonian Spit. Temporary signs (marks) were installed on the surface, coordinates of the marks were fixed using GPS and then flight of unmanned aircraft was conducted. The fixed coordinates of marks ensure the accuracy of measuring aerial imagery and the ability to calculate the possible corrections. This method was used to track and measure very small (micro-rank) relief forms (5–10 cm height and 10–20 cm length). Using this method morphometric indicators of micro-terraces caused by sand dunes pressure to gytia layer were measured in a non-contact way. An additional advantage of the method is the ability to accurately link the repeated measurements. The comparison of 3D terrain models showed sand deflation and accumulation areas and quantitative changes in the terrain very clearly.

Aeolian processes and their effect on sandy desertification of the Qinghai–Tibet Plateau: A wind tunnel experiment

To determine the contribution of aeolian processes to sandy desertification, we applied different wind velocities to soils from the Qinghai–Tibet Plateau that were subjected to the human activities such as wholesale destruction of vegetation. We then employed field investigations, soil sampling in the field, wind tunnel experiments, particle size analyses, and nutrient analyses. After the ground surfaces were crushed to simulate land degradation, the aeolian transport in this region varied from 0.00 to 43.49gm−2s−1 and was dependent on the particle size composition, and variation in the intensity of aeolian processes. During the aeolian processes our wind tunnel results show differences between the nutrient contents of the transported materials and those of the surface soils, and the loss of total nitrogen (TN), total carbon (TC) and total phosphorus (TP) varied between 0.00 and 8.81, 0.10 and 122.27, 0.00 and 1.14gm−2, respectively. In addition, variations in wind velocities did not result in significant differences in the particle size fractions of the transported materials. On the Qinghai–Tibet Plateau, although an increase in human activity may trigger sandy desertification, the occurrence of sandy desertification was not significant in the early 21st century, and hence it is likely to be controlled by climate even though human impacts have undeniably exacerbated its effects.

LATE GLACIATION AND HOLOCENE DEVELOPMENT OF THE EROSION- ACCUMULATION PROCESSES IN THE SMALL BASINS OF THE WESTERN TRANSBAIKALIA

Detailed investigations of soil-sediment sequences of three sections (Nizhnyaya Bulanka, Nadeino and Kuytun) in the Kuytunka river basin (Western Transbaikalia) was carried out. Three stages of activation of erosion- accumulation processes in small drainage basins of Western Transbaikalia are determined: Pre Holocene (13.0– 10.7), Early- (10.3–8.0) and Late Holocene (last 2.5 14C kyr). During these stages several phases of sedimentation and soil-forming process are distinguished. High intensity of aeolian processes together with washout and sedimentation during time spans of 10.7–10.0 and 9.5–9.0 kyr were determined on erosion landforms and alluvial fans. The main causes of deposition processes intensification have been revealed and quantitative data about their intensity were obtained. Intensification of soil-forming process in conditions of mountain-forest-steppe landscapes of Western Transbaikalia begins when sedimentation rates reach 0.06–0.37 mm/yr. Within the sedimentation rate interval 0.3–0.6 mm/yr humus interlayers alternate with layers of colluvial and aeolian deposits. At the rate above 0.6 mm/yr sedimentation of sandy loam and sands with inclusions of rubble are observed. Duration of soil development is 300–3500 years. Sediment accumulation phases have duration from 70 to 2000 years. Development of erosion-accumulation processes are characterized by polychronicity related to different response of small drainages basins to global, regional and local environmental changes. Rhythmical development of the washout, erosion, accumulation and soil-forming processes provides long-term activity of erosional landforms.

Determinants of sediment properties and organic matter in beach and dune environments based on boosted regression trees

AbstractGrain size properties and the variation of organic matter in coastal beach and dune environments are assumed to be controlled by the intensity of aeolian processes, time and the sediment source. However, assumptions are based on relatively limited empirical studies. In this study, we examined which environmental variables are the main predictors of multiple topsoil properties. To achieve this, we analysed an extensive dataset systematically collected across all beach zones and a large geographical area at the Finnish Baltic Sea coast characterized by post‐glacial land uplift. We included a comprehensive set of predictors in the analysis and applied boosted regression trees, a modern modelling technique particularly suited for analysis without prior assumptions of the data model. The results suggest that mean grain size and sorting are mainly determined by northing and fetch. Northing, disturbance and fetch predicted the variation of soil organic matter while litter cover was strongly related to disturbance. Based on the analyses, we were able to identify the main drivers of multiple topsoil properties on land uplift beaches. Parent material is suggested to determine sediment textural properties, which largely masks the effects of transient processes. Mean grain size and sorting are highly interdependent: grains become finer and sorting improves with increasing shore exposure. The intensity of momentary geomorphic processes controls the accumulation of litter whereas the slower accumulation of organic matter in the soil is influenced also by the static exposure setting. Skewness and kurtosis of the grain size distribution are mainly influenced by unmeasured processes, potentially relating to the geomorphological origin of the sediment. Copyright © 2014 John Wiley & Sons, Ltd.

Phytogenic hillocks as an effect of indirect human activity

Phytogenic hillocks are landforms typical for areas built of blown sands. They occur in desert areas with hot and dry (desert) climate as well as in sandy areas in moderate humid climate. They are an effect of cooperation of wind with bushy vegetation of specific features. Under natural desert conditions they are created at e. g. participation of tamarisks and they can reach the height of 6–7 m. In moderate climate, e. g. in area of seaside dunes they are formed at participation of other species and reach decidedly smaller heights. They can also originate in areas of blown inland sands, which were uncovered owing to human activity. One of such areas is located in Silesian Upland in southern Poland (so-called Bledow “Desert”), which beginning goes back to the Middle Ages. It is connected with deforestation, mainly for the needs of contemporary lead, silver and zinc metallurgy. Presently this area is covered in result of intentional vegetation introduction as well as by natural vegetation expansion and succession. One of species intensively entering into this area is Salix arenaria. And just at participation of this bushy willow in deflation areas very characteristic phytogenic hillocks of heights reaching up to 1,5 m are here created using more humid clayey insertions of substratum. They are an effect of these bushes covering up, thanks to which this plant spreads and creates larger and larger landforms. In area discussed it is possible to observe different development stages of phytogenic hillocks – from initial through mature to disappearing ones. The oldest from them were started to create in the period 1973–1976, wherefore the youngest – in the years 2000–2002. The age of hills was determined on the base of dendrochronological analysis. These hills have different shapes and heights, which are conditioned by the intensity of aeolian processes. It is possible to state that phytogenic hillocks of so-called Bledow “Desert” are created by natural physicogeographical processes but conditions for their development were prepared by human being. Thus they are the effect of indirect anthropogenic activity.

The Allerød/Younger Dryas transition in Wolin Island, northwest Poland, as reflected by pollen, macrofossils, and chemical content of an organic layer separating two aeolian series

A palaeoecological study including pollen, macrofossils, and chemical analyses of an organic sediment separating two series of aeolian cover sands has enabled us to reconstruct environmental changes during the Allerod/Younger Dryas transition in Wolin Island, northwest Poland. The Allerod woodland dominated by Pinus sylvestris became more open at the beginning of the Younger Dryas, when aeolian (wind) activity resulted in instability of the soil. During the early phase of the Younger Dryas the water level in the local basin distinctly raised, indicating a change to a wetter climate. This short-lasting phase was followed by an increased frequency and intensity of aeolian processes. However, the main aeolian event took place before the major expansion of Juniperus, not later than 10,780±120 b.p. Frequent woodland fires, probably due to the activities of Palaeolithic people, have been documented both for the Allerod and the Younger Dryas periods. Macrofossils of Alnus sp. found in the Allerod layer are of special interest in showing the presence of alder trees in northwest Poland as early as the Late-glacial.

The degree of aeolization of Quaternary deposits in Poland as a tool for stratigraphic interpretation

The aim of the study was to test if it is possible to distinguish Quaternary sediments bearing evidence of the impact of aeolian processes during their accumulation. It was also important to verify if distinguishing of these series would be useful in the accurate determination of stratigraphic position, determined previously using lithological, petrographic and palynological methods. The sediments were sampled from five boreholes, reaching the Tertiary, and from six exposures, all from Central, East and North Poland. The following features were taken to indicate a significant role of aeolian processes during sediment accumulation: high percentage of quartz grains (0.8–1.0 mm) in the sand fraction characterized by distinct rounding and frosting; high quartz content and low feldspar content (0.8–1.0 mm), and the composition of the heavy minerals fraction (0.1–0.2 mm). Garnets are particularly resistant to mechanical abrasion, whereas micaeous minerals are susceptible to winnowing. This spectrum of textural features, that indicates the effects of intensive aeolian processes, was termed “deposit aeolization”. Sediment aeolization may be observed in sediments of various origin: aeolian, fluvial or lacustrine. The study proved that the highest degree of aeolization occurred in alluvial (fluvioperiglacial) sediments accumulated before the first Riss (Odra) glaciation and in aeolian and fluvial sediments during the decline of Weichselian glaciation. Sediment aeolization is a valuable supplement to previous methods to indicate the stratigraphic position. The degree of aeolization allows the delimitation of the boundary between the Quaternary and Tertiary; it identifies glacitectonic and tectonic deformations; and it distinguishes fluvial and fluvioperiglacial sheets from fluvioglacial sheets. It is useful in estimating the length and intensity of aeolian processes; it adds to the interpretation of climatic conditions at the time of deposition and defines the limits of interglacial sheets within sandy sediments (30 to about 100 m thick) separating boulder clay units.

Controls on aeolian activity: some new perspectives from the Kelso Dunes, Mojave Desert, California

The extent and intensity of aeolian processes in the Kelso aeolian geomorphic system of the Mojave Desert have varied in a complex way in time and space. Geomorphic, stratigraphic, and sedimentologic studies allow the identification of areas of relict, dormant, and active dunes. In this area, dune activity has been affected by sediment supply, climatic changes (including changes in the seasonal distribution as well as the amount of precipitation), and topographic position. Understanding of the factures that influence dune activity has been facilitated by knowledge of the history of aeolian activity and its relationship to regional environmental change.