Effects of stone-made wind shelter structures over an arid nebkha foredune.

Beach users often use a range of strategies to shelter from the wind and blown sand. This involves building structures made of stacking stones. Different from other portable wind blockers, stone-made wind shelters can remain in the landscape for a long time. The process of stone removal from their original place and stone-stacking at another location has well-known effects on rock-dwelling wildlife. Less known are the impacts of stone wind shelters on biogeomorphological processes of beach-dune systems, especially those in arid coastlines, where foredunes formed by nebkhas are naturally discontinuous. This is the case of Playa del Inglés beach (Gran Canaria, Spain), the main sediment input to the Maspalomas dunefield, where the presence of stone wind shelters (goros) made by users has increased in recent decades following an increase of visitors. This research aims to investigate the effects of stone wind shelters on the dynamics of an arid beach-dune system at various spatiotemporal scales. The methodology includes the use of aerial photography to study the appearance and evolution of stone shelters in Playa del Inglés and some of their long-term effects on the foredune. Field data was also collected to investigate the effects that stone shelters have over a representative foredune nebkha in detail, by monitoring the changes (topography, airflow, and vegetation) of an individual landform as we progressively remove pebbles from a previously built stone shelter. Results show that stone stacking has an impact on airflow and sediment transport dynamics around landforms, limiting sediment accumulation inside nebkhas and therefore arid foredune growth. Stone stacking also constrict vegetation growth and its ability to retain sediment. The impacts of these artificial structures can be reverted following their removal but that the process of dismantling stones must be carefully planned. We elaborate some recommendations here to do it avoid damaging foredune vegetation.

Environmental variables affecting an arid coastal nebkha.

Foredunes in arid coastal dune systems comprise nebkhas, which originate by interactions between vegetation and aeolian sedimentation. While continuous foredunes in temperate climates have been widely studied, knowledge of interactions between biotic and abiotic drivers in foredunes formed by nebkha is still scarce. With the aim of exploring variables affecting arid foredunes, a range of morphological, sedimentological, and vegetation characteristics were measured on a single nebkha formed by a Traganum moquinii plant located in the foredune of Caleta de Famara beach (Lanzarote, Canary Islands). Variables were sampled at 120 plots in a 0.5 × 0.5 m square grid. A two-step process using multiple linear regression (MLR) analyses was developed to characterize 1) the influence that morphological variables and distance from the sea have on plant and sediment patterns on nebkha, and 2) the influence of plants on depositional sediment characteristics. Results indicate close relationships between distance from the sea, plant coverage, and sediment patterns. Empirical results were used to develop a conceptual model that explains the spatial distribution of bio- and geo-morphological characteristics of an arid nebkha foredune.

TEMPORARY REMOVAL: Sand, Sun, Sea and Sex with Strangers, the "five S's". Characterizing "cruising" activity and its environmental impacts on a protected coastal dunefield.

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Assessing the scenic quality of transgressive dune systems on volcanic islands. The case of Corralejo (Fuerteventura island, Spain).

The formation of transgressive aeolian sedimentary systems on hot-spot volcanic islands results in globally singular conditions. The natural attractions and landscape features of these spaces can result in the concentration of urban-tourist developments in their surroundings, altering their physical integrity and their ecological and scenic functionality. This has been the case of the Corralejo dunefield in Fuerteventura (Canary Islands, Spain), where the strong pressure exerted by tourism is endangering the area's natural and landscape resources. This study aims to qualitatively assess the landscape heritage through a number of indicators, some of which are developed on the basis of user perception. Four landscape dimensions (substratum, sea, vegetation, and scenic background) were used to analyse the 24 landscape units into which the Corralejo beach-dune system was divided. The results show that this system presents a high landscape value, as do its four different dimensions. This value was found to decrease in areas bordering the urban area or where tourists were commonly present. Recommendations are proposed to improve the area based on user perceptions. This type of research is of interest for future planning, ordinance preparation and management with a view to establishing a balance between the physical medium and anthropic pressure.

Nebkha development and sediment supply.

This study examines the role of sediment supply in controlling the formation and the spatial patterns of nebkha, numbers and sizes, present in foredunes fronting coastal dunefields of the arid northwest African and the Canary Islands coasts. Sediment supply is estimated qualitatively and quantitatively by various measures, and the number and size of nebkhas are obtained on a range of beach-dune systems. In the case of the Canary Islands, LiDAR data and orthophotos with high spatial resolution (0.25 m) are used to measure sediment supply/activity, nebkha numbers and sizes, and vegetation variables, whereas data availability is less on the African coast. Results show that sediment supply exerts a major control on nebkha development such that as sediment supply increases, the number of coastal nebkha decreases, and the size of individual plants/nebkha increases. Once sediment supply is large, nebkha can only form on the immediate backshore if space is available, and a point is reached when the sediment supply is so large that nebkha do not, or cannot form. The data presented here provide two indicators which could be applicable to other dune systems. Firstly, by estimating the number of nebkha and the vegetation cover, the degree of aeolian sedimentary activity or sediment supply might be estimated. Secondly, the type of aeolian landform present provides a qualitative indication of sediment supply and aeolian activity.

Spatiotemporal analysis of the impact of artificial beach structures on biogeomorphological processes in an arid beach-dune system.

The research hypothesis considered in this study is that decisions adopted on beach use and management in arid environments can result in significant changes in the biogeomorphological processes of the beach-dune system of which it forms part. Different information sources and geographical information systems were used to make a spatiotemporal analysis of possible correlations between the presence of beach equipment, services and uses in the backshore area of an arid beach-dune system, such as the beach named Playa del Inglés (Gran Canaria island, Spain) and environmental changes detected in the same area. The period considered in the study covers from 1961 (before the development of the mass tourism on the island) to 2018. Significant variations in vegetation cover over the course of the study period were detected, as well as an overall increase in erosion (topographic and erosive aeolian landforms) and foredune fragmentation and a decrease in geomorphological resilience. The study found not only relationships between management decisions and environmental impacts, but also that environmental impacts of management decisions on beach use made in the 1970s and 1980s continue to be felt today. Moreover, the results also reinforce the idea that management decisions made based on the results of scientific research studies (management-research binomial) can lead to more environmentally sustainable actions.

Decadal monitoring of Traganum moquinii's role on foredune morphology of an human impacted arid dunefield.

Foredunes in arid zones have been little studied, being significantly different than tropical and temperate foredunes. In the case of the foredune of the arid Canary Islands' dune systems, Traganum moquinii is the predominant plant species, forms nebkhas and nebkhas fields, and acts as a structuring element in the dune field. In this work, the eco-anthropogenic evolution of the foredune surface, and the morphology and distribution of Traganum moquinii species in the Maspalomas dunefield (Gran Canaria, Canary Islands) are analysed, to understand the role that this plant species plays on the foredune's geomorphology and on the biogeomorphological processes altered by human actions. Eight variables were measured in 10 plots at five different times, from the 1960's to the present, through historical aerial photographs and orthophotos, integrated in a GIS. Significant decadal changes in the number and distribution/morphology of Traganum moquinii plants and also in the morphology of the foredune are observed, although not in a spatially homogeneous manner, as three different foredune behaviors are observed. The number of nebkhas/number of T. moquinii plants, has decreased between 1961 and 2012. The largest changes occurred in the north and south of the study area, and the lowest numbers of nebkhas occur where tourist activities and services are intense. In addition, the distance between Traganum moquinii individuals and variables measured in the foredune front (e.g. the diameter of the individuals) have significant relationships. Also, the greater the distance between plant individuals in the foredune front, the greater is the distance of T. moquinii individual plants in the rest of the plot. The alongshore variations in foredune development are due to natural processes (e.g. natural decline or growth of plants), and human impacts (e.g. carpark and kiosk construction, heavy tourist use). This research could be useful for the management of foredunes in arid regions.

A DIY Low-Cost Wireless Wind Data Acquisition System Used to Study an Arid Coastal Foredune.

Environmental studies on coastal dune systems are faced with a considerable cost barrier due to the cost of the instrumentation and sensory equipment required for data collection. These systems play an important role in coastal areas as a protection against erosion and as providers of stability to coastal sedimentary deposits. The DIY (Do-It-Yourself) approach to data acquisition can reduce the cost of these environmental studies. In this paper, a low-cost DIY wireless wind data acquisition system is presented which reduces the cost barrier inherent to these types of studies. The system is deployed for the analysis of the foredune of Maspalomas, an arid dune field situated on the south coast of Gran Canaria (Canary Islands, Spain), for the specific purpose of studying the dynamics of a dune type (tongue dunes), which is typical of this environment. The results obtained can be of interest for the study of these coastal environments at both the local level, for the management of this particular dune field, and at the general level for other similar dune fields around the world.

An historical ecological assessment of land-use evolution and observed landscape change in an arid aeolian sedimentary system.

Coastal areas worldwide are undergoing major changes and degradation due to a set of combined natural and anthropogenic stressors. In arid aeolian sedimentary systems these changes can be even more acute given their sensitivity to perturbances in landscape dynamics. While in many such areas recent (20 year) observations have been made regarding measurable differences in dune coverage and stability, few studies have assessed and quantified the long-term relationships of transitioning exploitation and land-use changes in order to fully evaluate their importance. Land management, therefore, does not always benefit from the more holistic picture that a combined deeper time historical ecology and geographical approach provides and can contribute to decision making. The Jandía isthmus, in Fuerteventura (Canary Islands, Spain) presented an ideal field laboratory in which to assess these phenomena in actual conditions and test a combined methodology using historical and current sources (historical documents, aerial photographs, orthophotos, LiDAR data, field work and oral sources). By doing so, different phases of land exploitation associated with changing land ownership were identified and the consequences of each on the dune system assessed. It is concluded that the transition from traditional land uses (livestock and fuel extraction) to more recent ones (aggregate extraction, construction of new roads and urban-touristic resorts, and some recreational uses) has altered aeolian sedimentary transport, inducing stabilization of the landforms, as well as producing significant changes in the vegetation. The wider application of this type of study can benefit the many other areas worldwide that are facing similar pressures.

Climate as a control on foredune mode in Southern Australia.

Foredunes are formed by aeolian sand deposition in vegetation on the backshore of beaches. In this paper, the foredune mode (nebkha, discontinuous foredune, and continuous foredune), and transgressive dunefield development is studied along the Great Australian Bight (GAB), 2668 km of coastline. Orthophotos are used to classify the foredune mode, coastal landforms and the vegetation, through geographic information systems (GIS), with fieldwork support. The results show that the foredune mode is strongly controlled by rainfall and temperature with respect to latitude, and to drift potential with respect to longitude across the GAB. Between 200 and 300 mm annual rainfall, nebkha predominate. When the annual rainfall is between 300 and 400, at latitude 32°, a clear pattern is not observed in foredune mode and this is identified as a transition zone. Discontinuous foredunes and continuous foredunes are strongly represented in regions experiencing above 400 mm annual rainfall. The main contribution of this study is the identification of foredune modes which are not only related to a climatic gradient and latitude, but also related to variations in longitude, vegetation cover and diversity, and dune mobility indices. Finally, there are other environmental relationships between the wind and longitude, where the geomorphology of the bay could be playing an important role.

Beach vegetation as an indicator of human impacts in arid environments: Environmental conditions and landscape perception in the Canary Islands.

Human occupancy of beaches is an important cause of environmental and landscape transformations, some of which are identifiable through vegetation analysis. Commonly, arboreal vegetation has been socially perceived in a positive way, as it contributes to the creation of environments appreciated as beautiful and natural. This type of vegetation has been recreated in urban coastal areas worldwide, including those located in arid environments where it is not always common or endemic to these areas. The typology of plant species, human impacts on beach environments, and the social perception of vegetation contrast were analyzed to understand the landscape influence and human impact on beach environments from arid regions. The study was carried out on 12 beaches with different degrees of human occupation (4 urban, 4 semi-urban and 4 natural) in Gran Canaria island (Spain). The results indicate that the number of exotic and ruderal (first to colonize human disturbed environments) species increases with human occupation of the beaches. A greater number of arboreal species were identified on urban beaches, while shrub and herbaceous species were more common on less occupied beaches (semi-urban and natural). However, when surveyed, the users of semi-urban and natural beaches, considered that arboreal vegetation compose a more attractive landscape than other with herbs or shrubs, even though tree species appear occasionally on these types of beaches. This inconsistency identifies a conflict of values between the development and conservation of beaches in arid environments. This study can be used to establish environmental sustainability strategies on beaches. Conservation and environmental information about ecosystem services related with indigenous plant species is and important issue for integrated management on beaches from arid regions, especially those that may be urbanized in the near future.

Biogeomorphological processes in an arid transgressive dunefield as indicators of human impact by urbanization.

Urban and tourist developments can have long-lasting impacts on coastal environments and fundamentally alter the evolution of coastal dune systems. This is the case of the Maspalomas dunefield (Gran Canaria, Canary Islands), hosting one of the largest tourist resorts in Spain. The resort was built on top of a sedimentary terrace at 25 m above sea level (El Inglés) in the 1960s, and has subsequently affected local winds and therefore aeolian sediment transport patterns. Buildings on the terrace deflect the winds to the south of the dunefield, where the rate of sediment transport accelerated. A shadow zone appeared to the lee side of the resort with a consequent decrease in wind speed and aeolian sediment transport and an increase in vegetation cover. In this paper, first we characterize the environmental changes around El Inglés terrace in recent decades, and describe the changes in the shadow zone through an analysis of the evolution of sedimentary volumes and vegetation characteristics (density, spatial patterns, and plants communities). A series of historical aerial photographs, recent orthophotos and digital elevation models obtained by digital photogrammetry and LiDAR, as well as fieldwork were used to characterize plant communities and spatial-temporal changes in erosive landforms. Results show changes in the pattern and migration rates of dunes located at the southern edge of the urbanization, as well as the formation of blowouts and large deflation areas, where the vegetation increases in density and number of plant communities. We discuss eco-anthropogenic factors that have produced these environmental changes.

Assessing the geomorphological vulnerability of arid beach-dune systems.

In this study, an arid dune vulnerability index (ADVI) is developed using a system of indicators to evaluate the geomorphological vulnerability of beach-dune systems of arid regions. The indicators are comprised of three analytical dimensions (susceptibility, exposure and resilience) and their corresponding sub-indices and variables and were assessed for eleven sites located in four aeolian sedimentary systems of the Canary archipelago (Spain). The selected sites have varying geomorphological characteristics, vegetation types, marine and wind conditions and human pressure degrees, and have seen different trends in their geomorphological evolution since 1960. The eleven sites were separated into three groups according to their different conservation status and different management needs, and the results of the ADVI dimensions and variables were compared and analyzed for these three groups. In general, the results obtained in the analyzed sites reveal that susceptibility and exposure dimensions are related to low-moderate values, while resilience was high. Only one site presented a state of critical vulnerability, due to the loss of its capacity to maintain its geomorphological function in recent decades. Given the lack of knowledge about geomorphological vulnerability processes in foredunes of arid regions, ADVI is the first approximation to geomorphological diagnostic in these environments and can be useful for managers.

Measuring geomorphological vulnerability on beaches using a set of indicators (GVI): A tool for management.

A system of indicators has been developed to evaluate beach geomorphological vulnerability (GVI) through: intrinsic susceptibility, the agents that model them, and their ability to remain stable over time. The method is applied to 34 beaches on the island of Gran Canaria (Spain) that experience different levels and conditions of human occupation, marine incidence, landforms and sediments, and spatial evolution that have been recorded since 1960. In contrast with other studies, the analysis of these dimensions (and their relationships) allows a diagnosis of the geomorphology of the beaches with an integrated approach. The results illustrate the numerous causes that generate geomorphological vulnerability, such as wave intensity, the presence of dikes or breakwaters, coastline variations, the absence of foredunes and embryonic dunes, the width of the intertidal zone, or the absence of beachrocks or lavic stones outcropping onto the shore. These variables combine and operate differently in five defined groups of beaches with different management needs. The most vulnerable ones were those with strong marine incidence, which require maintenance of their landforms in order to guarantee their stability. The opposite situation is found in beaches with little impact from anthropic and marine components. These beaches are less vulnerable since they have moderate susceptibility and high resilience. Their management requirements consist of soft measures since they have a strong geomorphological robustness. In this context, the proposed indicator system is a potentially relevant contribution to the management of beaches, especially for those that are under threat.