Dune Stabilization Research Articles

The largest Quaternary inland eolian system in Brazil: Eolian landforms and activation/stabilization phases of the Xique-Xique dune field

Eolian systems are sensitive to vegetation and climate changes, but also to the sediment supplied by neighbor depositional systems. This sensitivity is manifested in the alternation between periods of sand dune mobility and stability. In the Xique-Xique eolian system, the largest Quaternary interior dune field in Brazil (∼8000 km2), the neighboring depositional system responsible for the sand supply is the São Francisco River. We interpreted periods of dune activity and stabilization by mapping eolian landforms of this system, describing depositional facies under them and dating by optically stimulated luminescence (OSL-SAR). The stabilized parabolic landforms characterized and mapped (all formed by SE to E winds) were simple megadunes (25.5 ± 4.4 to 5.8 ± 2.0 ka), compound dunes (15.8 ± 1.2 to 5.2 ± 1.4 ka) and perched dunes (14.0 ± 1.0 and 1.2 ± 0.1 ka). We also recognized eolian plains (14.0 ± 2.1 to 6.5 ± 0.7 ka) and active parabolic dunes. Eolian deposits of undifferentiated landforms have also been described and dated (253.8 ± 19.0 to 8.2 ± 1.3 ka). The ages obtained allowed identification of two main phases of dune activity (∼60 to 18 ka and ∼16 to 5 ka) separated by a short period of stabilization marked by a paleosol (∼18 ka). The main periods of eolian activity are associated with phases of fluvial aggradation and high sediment supply, whereas dune stabilization since 5 ka is correlated with low sediment supply during the Late Holocene fluvial incision phase. The periods of eolian activity and stabilization respond not only to climate changes in the area occupied by the eolian system but mainly to local fluvial sediment supply by the river, which in turn can respond to more regional climatic controls. The Xique-Xique eolian system results from the coupling of abundant sediment supply from the fluvial system, high eastern wind speeds, and a significant wind deceleration caused by mountains on the western border of the dune field.

Wrack placement to augment constructed dunes: A field investigation

Natural and nature-based features have become increasingly popular in recent years for several reasons including reduced costs and maintenance, sustainability, and ecological benefits. One such nature-based feature which contributes to coastal resiliency is dune systems. Extensive research shows that dune systems provide great value for coastal protection, with vegetation and belowground biomass emerging as crucial factors for dune stability. Alternative dune construction and dune maintenance methods are needed to improve the resilience and stability of these dune systems. Wrack, vegetation and macroalgae that naturally washes up along the coast, is often removed during routine beach maintenance, but could serve to increase dune biomass, sand trapping, and overall dune resiliency. This manuscript documents preliminary results following the placement of wrack along constructed dunes on the Mississippi mainland coast. Terrestrial lidar surveys were used to evaluate morphological responses of a 550 m stretch of the beach, with varying raking and wrack management practices implemented in designated sections. Elevation and volumetric change calculated from these data were compared across storm erosion and fair-weather recovery periods to quantify the potential benefits of utilizing natural wrack material in the dunes and reducing beach raking.

Diplodia scrobiculata and Neofusicoccum luteum causing dieback of Pinus halepensis in Tunisia

AbstractForest trees withering is an increasingly ubiquitous phenomenon throughout the Mediterranean basin. Aleppo pine (Pinus halepensis Mill.) is one of the dominant conifer species in this region. In the northeastern pine coastal woodland of Tunisia, Pinus halepensis stands originally afforested to stabilize sand dunes are often damaged. Fungal pathogens are among the main causes of forest tree diseases. Species of the Botryosphaeriaceae family, having a worldwide distribution, are well known as plant pathogens including Pinus spp. Pinus halepensis trees are suffering from shoot dieback, branch cankers and trunk cankers in two Tunisian forests. The objective of the present work was to characterize Botryosphaeriaceae species associated with P. halepensis branch canker in Bizerte (Rimel forest). A total of 43 isolates were obtained from infected branches of P. halepensis trees. Using morphological characteristics and phylogenetic analysis, two Botryosphaeriaceae species were identified, that is Diplodia scrobiculata and Neofusicoccum luteum. Pathogenicity tests were performed on 3‐year‐old P. halepensis plants and both isolates were found to be pathogenic. Diplodia scrobiculata was the more virulent species had a greater virulence than Neofusicoccum luteum based on the length of vascular necrosis in the wood of the P. halepensis inoculated stem. To our knowledge, this is the first record of Neofusicoccum luteum and Diplodia scrobiculata associated with P. halepensis branch canker and dieback in Tunisia and worldwide.

Extending the DPSIR framework to analyse Driver-Pressure-State-Impact-Response of sand dune management in Manawatu-Whanganui (New Zealand) since the 19th century

Coastal sand dunes are multifunctional landscapes with rich biodiversity. In New Zealand, with the establishment of European settlement around 1840, dunes in the Manawatu-Whanganui region were affected due to the removal of their vegetation cover by human activities and animal grazing. As a result, sand drifted further inland affecting villages, infrastructure and agricultural areas. The main response was to introduce marram grass (Ammophila arenaria) used in Europe to stabilize dunes. This solution caused significant environmental impacts as marram grass turned invasive and native habitats of fauna and flora significantly decreased.This paper focused on the long-term analysis of aspects related to sand dune management in the region during two-time frames: 1) from the 19th to the late 20th century and 2) from then on to the early 21st century, using the innovative spiral DPSIR (Driver-Pressure-State-Impact-Response) framework. Data for this study comes from historical records, scientific literature and present management reports.The integrated spiral framework allows for establishing the connections between historical and future management initiatives for mitigating and adapting to environmental impacts due to socio-economic drivers and their pressures. The study reinforces the paradigm shift from dune stabilization before the late 20th century to the restoration of stabilized dunes to make them active for enhancing native biodiversity should be again assessed in the context of sea-level rise during this century. Coastal managers should adopt an optimized solution between these two extreme solutions adopted from the 19th century to the present, by considering long-term and interdisciplinary analysis to better understand the systems’ evolution and the full consequences of human actions.

Middle Holocene low deposition rate caused by dune stabilization at Duolun nur in Otindag Dune Field

Dune fields in the semi-arid area are highly sensitive to the environment and climate change. When the climate is humid, enhanced vegetation cover limits aeolian activity. When the climate is dry and vegetation cover is reduced, the dunes migrate and produce dust. This will significantly affect the dust deposition flux in nearby lakes, which in turn can provide evidence of dune activity. We present the record of Duolun nur (nur means lake) in the northern Otindag dune field since 14 cal ka BP. A striking feature of the record is the very low deposition rate between 1.1 and 7.8 cal ka BP. We attribute it to the decreased dune activity and reduced dust flux. Similar periods of low deposition rates in the mid-Holocene have been also found in other lakes in the Otindag dune field. Although spatial heterogeneity exists in the low deposition rates periods of lake records and the paleosol development periods of dune records, the lake records match well with the dune records in the same location. Our finding provides new evidence of dune activity from the perspective of lacustrine deposition, and this is generally applicable to any dune field with a lake.

Environmental evolution of coastal afforestations: management strategies for dune fixation in the sandy barriers of Buenos Aires, Argentina

Tourism in the southern sandy temperate barriers has historically been one of the drivers of coastal development in Buenos Aires, Argentina. This process, which has been accompanied by dune fixation and a subsequent urbanization, began in the 1930s and occurred in the absence of coastal management policies causing several environmental problems. This work aims to analyze the historical development of two dune afforestation projects with the objective of characterizing their main environmental issues. These projects, which started almost simultaneously, are currently at completely different levels of development. For this purpose, a literature and relevant legislation review was carried out, allowing us to characterize them and generate comparisons. At the same time, it is intended to propose new strategies for dune fixation. One of the peculiarities of these afforestation projects is that two brothers carried them out: Carlos and Ernesto Gesell. Carlos initiated an afforestation that led to the sprawl of Villa Gesell. This city reached historical records of urban growth and it is actually one of the most popular bathing resorts of Argentina. Ernesto founded Dunamar on a more restricted dune field and it is currently at a significantly lower stage of development than Villa Gesell. Coastal erosion, surface runoff increase, decrease of foredune areas and replacement of native dune vegetation are some of the reported problems. Currently, there are projects for the expansion of the urban area of these villages under different strategies for dune stabilization. Although their effects have been extensively documented, they propose fixations with fast-growing exotic species. This work proposes the revegetation by means of native species corresponding to the original landscape of the dunes of about a century ago. To this end, certain aspects must be taken into account within the framework of integrated coastal management.

The Hydrologic Response to a Meteotsunami in an Isolated Wetland: Beaver Island in Lake Michigan, USA

AbstractMeteotsunamis are both a well‐known and poorly understood phenomenon. In particular, the influence of and disturbance by meteotsunamis on isolated coastal wetlands is largely unknown. This paper documents a case illustrating how water levels in an incipient foredune/swale complex in northern Lake Michigan responded to a meteotsunami event. We identified potential meteotsunami influence on wetland water levels through slope‐break and wavelet analysis, verified the presence of meteotsunami waves at surrounding lake water level gauge stations with wavelet analysis, analyzed both regional and small‐scale meteorological data to establish what source of atmospheric forcing resulted in meteotsunami formation, and used a hydrodynamic model to simulate lake surface response and meteotsunami generation. On 20 July 2019, an atmospheric bore wave propagating away from a convective storm formed a meteotsunami event in Lake Michigan that struck Sand Bay, Beaver Island and generated a 36 cm increase in subsurface wetland water levels over the course of a 1‐hr period. The potential for multiple sources of meteorological forcing and secondary wave refraction highlights several challenges with predicting generation of and effects from meteotsunami events. Additionally, while irregular, the effects of these events on isolated wetland systems have the potential to alter hydrologic and sediment budgets, vegetation growth, and dune stability; yet meteotsunami influence on isolated wetlands is an understudied phenomenon. The event presented in this study make a strong case for focused research on coastal wetland response to meteotsunamis (and meteotsunami‐like events) to address this understudied impact given its implications for coastal processes and resiliency.

Current State of Ammophila arenaria (Marram Grass) Distribution in the Eastern Cape, South Africa, and the Possible Effect of the Grass on the Dune System Dynamics.

The principal aim of this paper is to show that marram grass is not an invasive alien in South Africa although it affects the dune dynamics as a useful pioneer species in the dune successional process. The historical perspective of marram introduction as a dune stabiliser and the studies and conclusions reached from our European Union funded project, INVASS, in the 1990s and early 2000s is presented. Although these studies showed that marram was non-invasive, this was not clearly carried through to the authorities, and the use of the grass as a dune stabiliser was limited without a special permit. This prompted a survey of the current situation of marram on dune sites in the Eastern Cape. Along with earlier (1980s) data on the dunes, 69 relevés with 66 species abundance from sites along the Eastern Cape shoreline were assembled. These data were analysed with Detrended Correspondence Analysis to show the relationships of the samples (relevés) and species in a 2-dimensional scatter diagram. The survey showed that there are four dune sites where marram grass is no longer present, due to either marram being out of its climatic range, erosion of sand under storm conditions which made the habitat unsuitable, or in one case where marram simply disappeared. Marram often remains in other sites where three to five dune pioneer species were recorded. On some dunes, although marram is the most abundant dune pioneer, it is never dominant in the dune environment but has a presence of as much as 75% at any site. The eight pioneer species are widely dispersed on the DCA scatter diagram, while the shrub species characterising the Coastal Scrub are tightly clustered, showing that all the pioneer dune communities behave similarly in the dune successional series. The conclusion from these studies is that marram grass does not always persist in the dune systems. If marram does persist, it does not compete and behaves identically to the indigenous species as a dune pioneer. These studies show that marram grass is a non-invasive species that can be successfully used in dune stabilisation on Cape dunes.

Micropropagation, encapsulation, physiological, and genetic homogeneity assessment in Casuarina equisetifolia.

Casuarina equisetifolia is an important tree of the forest, cultivated in tropical and subtropical regions, providing fuelwood, land reclamation, dune stabilization, paper production, and nitrogen fixation. We have developed a systematic in vitro propagation protocol in C. equisetifolia using nodal segments (NS). Murashige and Skoog (MS) medium augmented with BA (5.0 μM) and NAA (0.5 μM) gave rise to a maximum of 32.00 ± 0.31 shoots per explant (S/E) with shoot length (SL) of 3.94 ± 0.02 cm, and a maximum of 70% regeneration potential (RP) was recorded after 8 weeks of post inoculation. For root induction, in vitro derived shoots were transferred to the nutrient medium consisting of a half-strength (½) MS medium augmented with 2.5 μM NAA, which produced a maximum of 12.68 ± 0.33 roots/shoot (R/S) with 3.04 ± 0.50 cm root length (RL) in 60% of culture after 6 weeks. Micropropagated plants with healthy shoots and roots were successfully acclimatized in vermicompost + garden soil + sand (1:2:1) and a maximum survival percentage of 95.1% was recorded. NS was taken from a 6-weeks-old in vitro derived plant of C. equisetifolia for synthetic seed production, and it was reported that CaCl2 · 2H2O (100 mM) + Na2-alginate (4%) resulted in clear and uniform beads. Furthermore, the maximum conversion of synthetic seeds into plantlets occurred over a period of 4 weeks of storage at 4°C. Scanning Electron Microscopy (SEM) revealed the formation of direct shoot buds without any intermediate callus formation. In addition, the chlorophyll and carotenoid contents of the direct regenerated and mother plant were compared. Similarly, RAPD and ISSR primers were used for genetic homogeneity assessment of the direct regenerated plants, where a total of 18 and 19, respectively, clear and reproducible bands with 100% monomorphism were recorded. The developed micropropagation protocol can certainly be used for large-scale multiplication and germplasm preservation of C. equisetifolia. It will also help in meeting the growing demands of C. equisetifolia in the forest industry.

Formation mechanism of plant diversity in mechanical sand‐control technique‐implemented dunes in China

AbstractAlthough the influence of mechanical sand control techniques on vegetation on degraded sand dunes has received much attention for a long time, our understanding of the underlying processes of plant community formation is not yet strong. Analyses of trends in the turnover and nestedness components of beta diversity can be informative of the process of response to sand dune stabilization. In this study, we applied a field investigation of sand dunes at different stabilization stages in northern China. We then used Baselga's method to calculate total beta diversity and partition it into spatial turnover and nestedness to clarify the underlying community change processes. Our study indicated that the implementation of straw checkerboard techniques significantly increased the beta diversity of the community, leading to species heterogeneity. Species turnover was the main contributor to species beta diversity, and it was caused by high environmental heterogeneity with sand dune stabilization. The contribution of the nestedness component to beta diversity decreased with dune stabilization, indicating that with stabilization, dissimilarity was largely driven by variation in community composition rather than differences in taxonomic richness. This study provides insights into the underlying variation in species composition among sites where mechanical sand fixation engineering has been implemented and important guidelines for combating desertification.

Aeolian landform processes since the last deglaciation revealed by OSL chronology and stratigraphy in the Hulunbuir dune field in NE China

The Hulunbuir dune field (HLB) is situated near the northern limit of the East Asian summer monsoon (EASM), and vulnerable to climate change. The aeolian sand–paleosol sequences of this region are crucial for understanding the past landform processes in response to climate change, but not yet understood well due to chronological controversies. Here, we presented 20 optically stimulated luminescence (OSL) ages from five aeolian sand–paleosol profiles in the HLB, and reconstructed the aeolian landform processes since 18 ka. The findings of this study suggested that the HLB was probably dominated by mobile dunes before 18 ka, as 10 out of 11 aeolian samples were dated to 18–12 ka. Two strong sandy paleosol layers were found and dated to ∼9 ka and 5–0.5 ka, indicating that strong in situ pedogenic process on the accumulative sand could occur during the Holocene. The OSL ages of samples near the top of three profiles were >9.5 ka, indicating two possible surface processes. First, the land surface was stable since 9.5 ka after stabilization, with no accumulation or erosion. Alternatively, the surface could have been erosive with the eroded sediments feeding downwind active dunes. The latter explanation is consistent with the current local landforms, which has widespread blowout pits, indicators of strong wind erosion. We emphasized that the OSL age of a sand layer sample in fossil dunes implied the onset of mobile dune stabilization, not the age of dune activity, as previously stated.

Classification of the Sardinian pine woodlands

Mediterranean pine woodlands are one of the most common wooded vegetation types across the Mediterranean Basin and are included in two habitats of European interest as they have great conservation importance. We studied the woodlands of the class Pinetea halepensis dominated by Pinus halepensis, P. pinaster, and P. pinea in Sardinia (Italy) with the aim to clarify their syntaxonomic position. We compiled a dataset of 66 original vegetation relevés, complemented with the holotypes of similar vegetation types formerly described for Italy and Corsica (France). We classified P. halepensis woodlands, native to the Island of San Pietro, to the association Erico arboreae-Pinetum halepensis. We classified P. halepensis woodlands growing on limestones of the south-western coast of Sardinia to the new association Smilaco asperae-Pinetum halepensis and woodlands typical of coastal dunes to the new association Asparago horridi-Pinetum halepensis. We also described the north-eastern Sardinia P. pinaster woodlands as the new association Arbuto unedonis-Pinetum pinastri, of which we recognised two new subassociations, typicum and cephalantheretosum longifoliae, ecologically distinguished by the xerophilous and mesophilous conditions, respectively. Furthermore, we classified P. pinea woodlands, putatively native only to stabilised sand dunes of south-western Sardinia, in the new association Querco calliprini-Pinetum pineae. This study represents the first complete survey and classification of Sardinian pine woodlands, allowing a better understanding of their ecology, floristic composition and differences with other Mediterranean pine woodlands.

Sand dune vegetation-biocrust interaction as a source of spatial heterogeneity

Abstract Vegetation and biocrust play crucial roles in dune stability and mobility, and their interaction can lead to bistability, temporal oscillations, and hysteresis. We studied a two-dimensional (2D) mathematical model of vegetation and biogenic crust cover dynamics on sand dunes. Under a certain parameter range, the space-independent version of the model exhibited the bi-stability of an oscillatory state and a steady state, and we studied the 2D dynamics of the model under these parameters. The patterns developed by the 2D model showed a high degree of spatial heterogeneity and complexity depending on the initial conditions and on the state type across the front. The results suggest that spatial heterogeneity and complexity can evolve from the intrinsic dynamics between vegetation and biocrust, even without natural geodiversity and spatiotemporal climate fluctuations. In the real world, these two types of intrinsic and extrinsic heterogeneity processes interact such that it is difficult to distinguish between them.

An ignored habitat in Türkiye: Sandy steppes

The steppes habitat in Türkiye took bedrock formed of soil as the basis, and was classified by separating into groups, such as calcareous, with gypsum, volcanic, and serpentine. However, a classification was not made that took the soil texture as the basis. In this study, the stable sand dunes’ soil texture observed in Karapınar, Konya, Turkiye erosion region, was evaluated for flora and syntaxonomy. Within the scope of the study, observations were conducted in the sandy habitats found to the south-southwest of the Karapınar county center, the plant species that preferred the habitat were determined, and the data obtained was compared with the steppes’ habitat in the close environs and with the studies made previously. Furthermore, it emphasized the necessity of analyzing syntaxonomically the sandy steppes in Türkiye, which are evaluated within the “E1.A5 - Irano-Anatolian inland dunes” habitat type according to the European Nature Information System (EUNIS).

The Short and Long-term Effects on Soil Stability of Active Sand Dunes from Filter Cake Powder Administered by Dispersal and Spraying Methods

Active sand dunes (ASD) may cause significant damage to field crops and livelihood, and therefore, it is necessary to find a treatment that would enhance ADS soil stability. Biological soil crusts (biocrusts) contain microorganisms on the soil surface. Metabolic polysaccharides secreted by biocrust cyanobacteria glue the soil particles into aggregates, thereby stabilizing the soil surface.<br/> Filter cake powder (FCP) is a waste by-product in the final stages of the production of sugar from sugarcane, and its disposal causes significant environmental pollution. FCP contains high concentrations of polysaccharides, and has recently been shown to be a soil stability enhancing agent in ASD. It has been reported that adding FCP to the ASD soil surface by dispersal significantly increases the level of penetration resistance of soil biocrust (PRSB) nine weeks after a single treatment.<br/> However, it was not known whether a similar effect could be obtained by administering the FCP in liquid form by means of spraying. It has now been found that spraying a water solution of FCP onto the ASD soil surface significantly increased the level of penetration resistance of soil biocrust (PRSB) three weeks after a single treatment.<br/> These results suggest that FCP spraying can be used as a short-term soil stability-enhancing agent for ASD, while administration by dispersal might be more efficient over the long term.<br/> Finally, an additional benefit of using FCP as a soil stabilizer, either by dispersal, or by spraying, is the reduction in environmental pollution that would otherwise result from the disposal of FCP solid waste.

Assessing the influencing factors of soil susceptibility to wind erosion: A wind tunnel experiment with a machine learning and model-agnostic interpretation approach

Soil wind erosion is a worldwide environmental concern. This study explored the feasibility of using a machine learning (ML) algorithm with a model-agnostic interpretation approach to infer the mechanism by which multiple features influence the soil susceptibility to wind erosion. Arenosols were collected from the Ulanbuhe Desert, China, and soil samples with different treatments, including wet-dry and freeze-thaw processes, were used in a wind tunnel experiment and provided a basic dataset for modelling. The Shapley additive explanations (SHAP) method was used to provide global and local interpretations for the ML model. The results showed the following. (1) The mean particle size tended to decrease and the soil organic carbon (SOC) and soil calcium carbonate (CaCO3) contents tended to increase in the transition from mobile to fixed sand dunes. (2) The ML models presented a better performance than the interpretable models, and the random forest model (R2 value of 0.898 on the test dataset) was adopted. (3) All the features except the SOC content showed monotonic or nearly monotonic relationships with the wind erosion rate. Relatively low SOC contents and high particle sizes tended to show positive interaction effects with wet-dry and freeze-thaw processes. An SOC content of 2.46 g kg−1 was deemed a threshold, above which SOC worked to resist wind erosion. ML algorithms and model-agnostic interpretation methods have the potential to improve the reliability and flexibility of inferring the mechanism by which soil is susceptible to wind erosion and thus deserve popularization in future studies.

Stabilization of Sand Dunes with Recron Fiber and Cement Kiln Dust.

This research study aims to stabilization of sand dunes by mixing locally available waste material i.e. cement kiln dust and recron fiber. The stabilization of soil program have been taken into two phases. First mixing sand dune with recron fiber with varying percentage from 0 to 2% by weight. In the second phase the optimum mixture obtained from first phase is mixed with cement kiln dust by varying percentage from 0 to 10%.From the experimental study it is observed that optimum quantity of 1.5% recron fiber with 7.5% cement kiln dust is found to be the most efficient for the stabilization of sand dune. The results shows the significant increase in the strength properties of the sand dune. The angle of internal friction of the soil is increased by 35% andthe CBR of the soil is improved by 77% in comparison to virgin soil.

Wind erodibility of Arenosols and its driving factors during sand dune fixation: A wind tunnel experiment

Determining the wind erodibility (WE) of Arenosols (sandy soils) and its driving factors is imperative for evaluating wind erosion in desert ecosystems. Here, we performed a wind tunnel experiment to determine the WE of mobile sand dunes (MSDs), semifixed sand dunes (SSDs), and fixed sand dunes (FSDs) in the Ulan Buh Desert, and revealed its relationships with soil properties, such as soil organic matter (SOM), calcium carbonate (CaCO3), and particle size distribution (PSD). Moreover, we investigated the variation in WE subject to wetting-drying processes with diverse soil moisture gradients. We suggested taking the derivative of the wind erosion content of wind speed (K) to indicate WE, which offered a fresh approach to infer WE from observations in wind tunnel experiments. The results indicated that: compared with the MSDs and SSDs, the FSDs performed better in terms of vegetation cover and soil properties, but the variation in WE was not statistically significant among different sand dunes. WE correlated positively with SOM and CaCO3 and correlated negatively with coarse soil particles. In addition, WE was substantially affected by the wetting process. The critical relative moisture content needed to hamper wind erosion ranged from 3.4 to 3.7% (gravimetric) in the Ulan Buh Desert. However, the variation in WE was not statistically significant between before and after the wetting-drying process. The results of our study are expected to provide new insights into the wind erosion of Arenosols.

Agroecological sub-zone based sustainable land use in arid Rajasthan (India)

The arid region of Rajasthan has been classified into unique agro-ecological sub-regions, zones, and sub-zones (indicated by their code number in this abstract) for which sustainable land use has been suggested based on the potentials and constraints. 2.1, 2.2 and 3.1 sub-zones need dune stabilization, silvopastural farming, and kharif cultivation in interdunes; khadin water harvesting system, as well as solar farming. 4.1 and 4.2 sub-zones need rainfed cropping under conserved moisture, agroforestry and limited irrigation, cultivation of low water requiring crops, such as mustard, cumin in rabi. In 4.3 sub-zone under conserved moisture and winter rainfall pulses and mustard are suggested. In 5.1 and 5.2 sub-zones kharif season crops and wheat, mustard, cumin, and condiments irrigated with brackish groundwater by adopting gypsum treatment are suggested. In the canal command area, the micro-irrigation system is doing well in the sandy plain and dune complex area, but in the Ned area irrigation needs to be restricted/avoided. In 5.3 and 5.4 sub-zones, rainfed irrigated crops and fruit cultivation is suggested. In 6.1 sub-zone dune stabilization is suggested; 6.2 and 6.3 sub-zones require erosion control and irrigation water management for the cultivation of cotton, paddy, groundnut, sugarcane, and kinnow.

From the micromorphology of paleoweathering fronts to paleoenvironmental analysis: A case study of the Cretaceous dune fields of Sanfranciscana Basin, Brazil

The work investigated the paleoenvironmental significance of kaolinite-rich weathering fronts developed during the Cretaceous in stabilized dune fields of Sanfranciscana Basin in Brazil. To this, was conducted a multi-scale analysis from the outcrops of paleosols to mineral grains and soil pores. The macro and micromorphology of paleoweathering fronts allow recognizing weathering features and estimating the porosity and hydraulic parameters (permeability, capillary pressure, and saturated hydraulic conductivity). Scanning electron microscope analyses were conducted to investigate surface microtextures of quartz grains for weathering process characterization based on dissolution microfeatures. Energy-dispersive X-ray spectrometry was utilized to identify chemical elements of clay minerals. The major and trace elements were analyzed using a Philips X-ray fluorescence (XRF) spectrometer (PW 2440). Our results showed that weathering fronts expand through preferential water paths (pipe and finger flow) in bedding planes in response to textural and porosity contrasts related to the bimodality (i.e., the difference of grain size distribution between overlapped sedimentary structures) of aeolian deposits. The dissolution features present in quartz grains, such as etching, pitting, total dissolution of grains, iron coatings, and booklets of well-developed kaolinite, reveal an increase in humidity and the pedogenetic kaolinization process typical of a humid tropical environment. These weathering patterns coincide with cooling events between the Albian and the Cenomanian report in the literature. Our study indicates that during the Cretaceous, the Sanfransicana Basin underwent climatic amelioration and a rise in water table level, which likely enhanced dune stabilization and the formation of an extensive geomorphic surface.