Nebkha development and sediment supply

Hesp, Patrick A.; Hernández‐Calvento, Luis; Hernández‐Cordero, Antonio I.; Gallego‐Fernández, Juan B.; García‐Romero, Leví; Silva, Graziela Miot da; Ruz, Marie‐Hélène

doi:10.1016/j.scitotenv.2020.144815

Cited by 16 publications

(14 citation statements)

References 24 publications

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“…There are problems with this classification because, for example, Davies separates ‘free dunes’ and those secondary dunes which comprise ‘transgressive dunes’. Transgressive dunes are quite commonly formed from the beach and may comprise protodunes, barchans, barchanoids, transverse dunes, and so forth, in both arid, semi‐arid and temperate environments where vegetation ranges from minimal to substantially present in the region (Dillenburg & Hesp, 2009; Hesp, 2011; Hesp et al, 2021; Hesp & Smyth, 2019; Hesp & Walker, 2013, 2021). Thus, Davies two types of free dunes and transgressive dunes would nowadays be regarded as the same type.…”

Section: Initiation Of Transgressive Aeolian Sand Sheets and Dunefieldsmentioning

confidence: 99%

“…Recent surveys of the South Australian and South African southern coasts reveal that many transgressive dunefields are derived directly from the beach (as noted earlier; Figure 1; Miot da Silva & Hesp, 2019), and not via erosion of impeded dunes (such as foredunes). In addition, in many cases on the South African south coast and Brazil coast (Santa Catarina, Maranhão, Piauí and Ceará States), the predominant winds blow alongshore, transgressive dunefield movement is alongshore adjacent to the beach, and foredune formation is impossible (Hesp et al, 2021; Hesp & Walker, 2013; Hesp, Giannini, et al, 2009; Hesp, Maia, et al, 2009; Tinley, 1985).…”

Section: Initiation Of Transgressive Aeolian Sand Sheets and Dunefieldsmentioning

confidence: 99%

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Review and direct evidence of transgressive aeolian sand sheet and dunefield initiation

Hesp

DaSilva

Silva

et al. 2022

Earth Surf Processes Landf

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The multiple hypotheses which exist to explain the initiation of transgressive aeolian sand sheets and dunefields, are reviewed and discussed. Direct evidence supporting many of these hypotheses is largely lacking. In South Australia, the Younghusband Peninsula coastal barrier extends ~180 km and predominantly comprises transgressive and parabolic dunefields. The 42 Mile Crossing area on the barrier is undergoing significant erosion at variable rates of 0.5 to 5.0 m/yr, and a new transgressive aeolian sand sheet has rapidly developed in ~1 year and is extending landwards at an average rate of 13 m/yr. This research provides unequivocal evidence that large‐scale shoreline and dunefield erosion does lead to the development of a new transgressive aeolian sand sheet (and eventual dunefield) phase thereby demonstrating an initiation mechanism that is likely linked to future sea level rise and climate change. We also show that the initiation process, and, in particular, the subsequent rate of sand sheet transgression occurs at an incredibly rapid rate (+100 m in 8 years). Plain Language Summary Coastal sand dunes border many of the world's coastlines and are highly adapted to local climate and conditions. How coastal dunes transition from predominantly vegetated and stable systems to wind‐blown sand sheets and dunefields transgressing prior terrain is a research area of pressing relevance due to forecasts of sea level rise and climate change. The factors or triggers that are considered to initiate transgressive aeolian sand sheets and dunefields are reviewed. The formation and evolution of a new transgressive aeolian sand sheet phase triggered by large‐scale shoreline erosion in South Australia is presented. According to the results from historical and satellite images, local shoreline erosion began in the late 1970s and has continued at highly variable rates. We show that once the foredune was removed, the high scarp created by wave erosion of the relict, vegetated transgressive dunefield destabilized and was then eroded by wind processes leading to the rapid development of a transgressive aeolian sand sheet. The initiation and evolution of the sand sheet provides an excellent example of how dunefields might respond to future sea level rise and climate change.

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Section: Initiation Of Transgressive Aeolian Sand Sheets and Dunefieldsmentioning

confidence: 99%

Section: Initiation Of Transgressive Aeolian Sand Sheets and Dunefieldsmentioning

confidence: 99%

Review and direct evidence of transgressive aeolian sand sheet and dunefield initiation

Hesp

DaSilva

Silva

et al. 2022

Earth Surf Processes Landf

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“…Nebkhas are unique biogeomorphological features formed by the accumulation of aeolian sand around clumps of psammophilous plants that are tolerant to sand burial and wind erosion (Lancaster, 2011; Nickling & Wolfe, 1994; Pye & Tsoar, 2009; Tengberg, 1995; Tengberg & Chen, 1998). These plants, characterised by their extensive branches, can reduce near‐surface wind speed and intercept aeolian sand, resulting in the formation of mound‐like shapes and spotted irregular spatial patterns of nebkhas (Hesp, Hernández‐Calvento, Hernández‐Cordero, et al, 2021; Hesp & McLachlan, 2000; Wang et al, 2006). Nebkhas exhibit a widespread distribution in global drylands and coastal environments (Goudie, 2022) and have significant ecological effects.…”

Section: Introductionmentioning

confidence: 99%

Biogeomorphological niche of a landform: Machine learning approaches reveal controls on the geographical distribution of Nitraria tangutorum nebkhas

Zhang,

Li,

Mason

et al. 2024

Earth Surf Processes Landf

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Nebkhas are distinctive biogeomorphological landforms prevalent in global drylands and coastal environments. They play a crucial role in supporting local biodiversity and preventing land desertification and often serve as an indicator of local environmental change. Despite their significance, the environmental factors that affect their geographical distribution and how they respond to climate change have not been fully explored. This study represents a novel application of machine learning models to quantifying the biogeomorphological niche of Nitraria nebkhas in northern China and simulating their geographical distribution under future climate change conditions. Findings underscore that climatic variables influence the growth of formative shrub species on nebkhas, whereas climate, soil and geomorphological conditions, along with their spatial configuration, determine the probability of nebkha occurrence. Predictions under medium and high greenhouse gas emission scenarios indicate a northward shift in the potential distribution of nebkhas in northern China by the end of the century, accompanied by a decrease in the south due to rising temperatures. Given the potential impact of nebkha field degradation on biodiversity and soil hydrological conditions, adaptive land use strategies should be designed to protect nebkhas and mitigate the impact of climate change. Our study not only provides valuable insights for informing policy‐making and conservation initiatives but also serves as an example for quantifying the niche of biogeomorphological landforms and simulating their dynamics by integrating machine learning approaches into empirical geomorphological studies.

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“…Among them, plant type and sand conditions strongly influence the morphological characteristics of the developing nebkhas [22]. The morphological parameters of nebkhas are not uniform under different habitat conditions, but exhibit characteristics that are adapted to the local aeolian sand environment [26].…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, nebkhas are localized and complex. On a small scale, the size and shape of nebkhas will depend on factors such as plant growth habit, plant density, and structural form [21,[26][27]. It is by plants changing the structure of near-surface wind and sand flow in three ways that nebkhas are formed: plants providing the ground coverage, slowing down the wind and blocking the flow of sand [27].…”

Section: Introductionmentioning

confidence: 99%

Changes in Morphology of <i>Nitraria tangutorum</i> Nebkhas at different Successional Stages in the Oasis-Desert Ecotone, Northwest China

Liu¹,

Wei²,

Li³

et al. 2023

Pol. J. Environ. Stud.

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Nebkhas play a tremendous role in maintaining the ecological functions of deserts and in slowing land desertification processes. Numerous nebkhas are distributed in the northwestern edge of the Ulan Buh desert, Nitraria tangutorum nebkhas are the most typical dunes in this area. However, our knowledge of the effect of those factors on the succession of nebkhas, including their succession in different sandy land types, is limited. The goal of this study was to reveal their factors influencing the morphological characteristics of N. tangutorum nebkhas in different sandy land types (shifting sandy land, semi-fixed sandy land, and fixed sandy land) in the Ulan Buh desert. Our results showed the densities of N. tangutorum nebkhas were 34, 51, and 77 dunes per ha in the shifting, semi-fixed, and fixed sandy lands, respectively. The density of N. tangutorum nebkhas gradually increased and N. tangutorum nebkhas started to degenerate with the increasing fixation of sandy land. The successional stage had significant effects on all the morphological characteristics, and sandy land types had significant effects on the length (L), height (H), volume (V), horizontal scale (D) and ratio of width to height (H/W). Almost all of the morphological parameters of N. tangutorum nebkhas were correlated at different successional stages, indicating a strong interrelationship among the morphological parameters of nebkhas. The successional stages of N. tangutorum nebkhas had significant effects on the density of branch (M), height (h), coverage (C), deadwood rate (DR), and length of new branches (LB) of the N. tangutorum shrub. The M, h, C, and LB first increased and then decreased, and DR increased with the succession of N. tangutorum nebkhas. These results indicated that we should focus on nebkhas succession to ensure the ecological stability of oases in a dessert.

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Nebkha development and sediment supply

Cited by 16 publications

References 24 publications

Review and direct evidence of transgressive aeolian sand sheet and dunefield initiation

Review and direct evidence of transgressive aeolian sand sheet and dunefield initiation

Biogeomorphological niche of a landform: Machine learning approaches reveal controls on the geographical distribution of Nitraria tangutorum nebkhas

Changes in Morphology of <i>Nitraria tangutorum</i> Nebkhas at different Successional Stages in the Oasis-Desert Ecotone, Northwest China

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