Geomorphological Properties Research Articles

Differential terrace configurations in the Upper Yangtze River: Evaluating distinct intensifies of external perturbation and their impact on river behaviors

The interplay of tectonics, climate and topography shapes the river dynamics that give rise to terrace formation in mountainous regions. Unraveling the distinct influences of these factors on fluvial processes is a complex challenge due to their intricate interactions. By combining field observations with optically stimulated luminescence (OSL) dating, we have discerned and examined the sedimentary and geomorphological attributes of terraces, as well as the distinctive event sediments linked to recurrent mass movement across four varied reaches of the Upper Yangtze River. Each reach exhibits distinct tectonic settings, such as subsidence depressions, uplift gorges, or relict planation topography, which have imparted varied responses of river processes since the penultimate glacial period. Evidence from all study reaches indicates the presence of two cycles of fluvial aggradation-incision, yet the differentiated tectonic activities, precipitation patterns, and topographic reliefs have elicited divergent river behaviors across different reaches. In the subsidence depression, a single set of terraces has been formed, whereas in the most upstream region, characterized by relict planation topography, two superimposed sets of terraces have developed. In contrast, two separate sets of terraces have emerged in the uplifted gorge since the post-penultimate glacial period. The striking differences in terrace configurations across the valley reaches suggest that the magnitude of environment perturbations has exceeded critical thresholds of the different equilibrium conditions. One transition in equilibrium conditions relates to the minimum riverbed sediment thickness required to supply abrasive agents necessary for riverbed armoring. Another transition triggers a shift from fluvial-dominated processes to those dominated by extreme events, with critical sediment inputs modulating this transition, particularly within the gorge setting.

Prioritization of sub-watersheds based on quantitative morphometric analysis of the Narmada River, India, using SRTM-DEM and GIS techniques

Investigating the contribution of basin to the cycle of hydrological and the area's size, shape, and creation through quantitative analysis of these characteristics of the local scenery. Additionally, estimates of the denudation rate and hypsometric analysis were made in order to comprehend the sub-basin's quantitative geomorphological properties. The link between the morphometric parameters shows that the local geological and geomorphological features significantly influence the drainage system. On a less elevated surface with a moderate slope, stream geometry displays a pattern as semi-dendritic in greater stream order flow. On mountainous terrain surfaces, main-order streams display a dendritic drainage pattern combined with a coarse texture of drainage. The center zone of the Narmada River basin's sub-watersheds area (9461 km2) underwent morphometric investigation utilizing geographical information systems (GIS) with remote sensing methods. It highlights the usefulness of using Shuttle Radar Topographic Mission – Digital Elevation Model (SRTM-DEM) and satellite images to enhance basin management to evaluate and comprehend many geo-hydrological aspects, like topographic & drainage analyses. ArcGIS hydrological modeling has been used to identify and study basins utilizing SRTM-DEM having 10 m resolution. For the micro-level research of its physiographic characteristics and flow structural control along with runoff, using morphometric parameters like relief, aerial, and linear is also beneficial. This may assist in predicting floods, their extent, and their severity.

Landslide susceptibility mapping of a hilly region through a semi-quantitative technique

ABSTRACT Characterization of landslide susceptibility carries great importance in hilly regions as it is one of the frequently occurring natural hazards which comes with huge destruction of life as well as property. Identification of such landslide susceptible zones is usually decided based on the necessity and available resources. It is considered a valuable input for planning developmental activities by policymakers. The current study focuses on Pabbar Catchment, located in the state of Himachal Pradesh in India and prepares a Landslide Susceptibility Map (LSM) at a catchment scale using Analytical Hierarchy Approach (AHP). Eleven geo-morphological attributes of the catchment called causative factors were used in thematic form while creating the LSM. Being a semi-quantitative method, AHP performed satisfactorily to produce a realistic distribution of landslide susceptibility with a prediction accuracy of 0.768 under the Area Under Curve (AUC) technique. Approximately 72% of the geographical area from the catchment falls under the ‘high’ landslide susceptible zone. Unavailability of LSM at this scale is addressed through this study that may be useful to regional planners for future land use planning.

Urban storm water prediction by applying machine learning techniques and geomorphological characteristics

ABSTRACT The Storm Water Management Model (SWMM) is a reliable software program for simulating stormwater runoff in combined drainage facilities. However, it faces challenges in efficiency, especially when executing real-time forecasting. This research explores an alternative machine learning (ML) approach to predict water levels in sewer and street drainage systems utilizing SWMM data for model training. The goal is to construct a hybrid ML model for urban flooding prediction, considering hydrological conditions, geomorphologic properties, and drainage facility features. A robust training method is introduced to deliberate complex flow conditions. The suggested approach achieves favourable performance in predictive accuracy and computational efficiency. Findings include: (1) similarity between ML and SWMM flooding depth on street nodes increases from 62.3% to 96.2% with the proposed training; (2) the proposed model is about 50 times faster than SWMM in urban flood simulations; (3) reliable predictions from the ML model are demonstrated through four accuracy metrics.

Rock glacier distribution and kinematics in Shigar and Shayok basins based on radar and optical remote sensing

AbstractRecent studies have demonstrated the rock glacier destabilisation and permafrost thawing induced by warming climate represent a continuous threat to life, infrastructure and socio‐economic development in the mountainous regions of the Hindu Kush Himalaya. This study presents the first systematic rock glacier inventory for the Shigar and Shayok basins, quantifying rock glacier geomorphology and kinematics based on morphological evidence using Google Earth images and interferometric synthetic aperture radar (InSAR). The certainty index of each inventoried rock glacier is recorded, along with its geomorphological properties and kinematic attributes. The rock glacier velocity is estimated through the InSAR time series analysis of Sentinel‐1 images from 2020 to 2021, with temporal baselines at 12‐day intervals. We developed a rock glacier inventory consisting of 84 rock glaciers covering an area of 29 km2 for the Shigar Basin and 2206 rock glaciers encompassing 369 km2 for the Shayok Basin. Among these rock glaciers, 69% and 52% are categorised as active rock glaciers, respectively. Rock glaciers in both catchments are confined to elevations between 3600 and 5875 m a.s.l., with a mean area of 0.22 km2. The maximum recorded velocity for active rock glaciers in the Shigar Basin is 101 ± 9 cm year−1, with a median of 27 ± 10 cm year−1, and in the Shayok Basin 114 ± 10 cm year−1 (median of 29 ± 9 cm year−1). Temporal variations in the surface velocities of the rock glaciers reveal that they increase with rising temperatures in both catchments, highlighting the seasonality in the rock glacier surface velocity. In total, we recorded the kinematic attributes of 98% of the inventoried rock glaciers in the study area.

FOCA: a new quality-controlled database of floods and catchment descriptors in Italy

Abstract. Here we present FOCA (Italian FlOod and Catchment Atlas), the first systematic collection of data on Italian river catchments for which historical discharge time series are available. Hydrometric information, including the annual maximum peak discharge and average daily annual maximum discharge, is complemented by several geomorphological, climatological, extreme rainfall, land-cover and soil-related catchment attributes. All hydrological information derives from the most recently released datasets of discharge and rainfall measurements. To enhance the reproducibility and transferability of the analysis, this paper provides a description of all the raw data and the algorithms used to build the basin attribute dataset. We also describe the approaches adopted to solve problems encountered during the digital elevation model elaboration in areas characterized by a complex morphology. Details about the data quality-control procedure developed to detect and correct errors are also reported. One of the main novelties of FOCA with respect to other national-scale datasets is the inclusion of a rich set of geomorphological attributes and extreme rainfall features for a large set of basins covering a wide range of elevations and areas. Using this first nationwide data collection (available at https://doi.org/10.5281/zenodo.10446258, Claps et al., 2023), a wide range of environmental applications, with a particular focus on flood studies, can be undertaken within the Italian territory.

Geovisor implementation for visualization of geodynamic and geomorphological properties of the subsoil: Case study Cuenca, Azuay, Ecuador

Globally, the development of cities and the increase in their population accelerate construction processes, significantly contrasting with soil studies of the soils on which buildings are built, whose. research results advance at a slower pace than required, often resulting in the occupation of spaces without these previous studies. Mainly due to the null or limited available information is scattered across different sources, files, and formats, and searching for it is a long and difficult process that generates unproductive spaces. This leads to high vulnerability of structures to different events that modify soil behaviour. To address these limitations, the present study aims to generate a standardized database that compiles existing information and processes it so that it can be easily and quickly accessed. A geovisor (based on geographic information systems GIS) is proposed as an ideal way to geographically display on the web the collected data from the studied region (for this work: Cuenca – Azuay – Republic of Ecuador). The information for this study has a seismic focus, being the variables of interest: primary wave speed Vp, secondary Vs, soil type according to the classification of local regulations (NEC-SE-DS) and international SUCS, and soil period. It also incorporates geological and geotechnical information, and stratigraphic subsurface profiles. This constitutes the first national-level database that combines all this information in a single format, forming a great tool for professionals and the community in general in making decisions when infrastructures are emplaced. This information is presented in a geovisor designed for quick access and easy understanding, avoiding the omission of important processes in civil works.

An alternative for predicting real-time water levels of urban drainage systems

Storm Water Management Model (SWMM) developed by the United States Environmental Protection Agency (EPA) has been widely applied throughout the world for analysis associated with stormwater runoff, combined sewers, and other drainage facilities. To appropriately manage the runoff in urban areas, an integrated system including the simulations of sewer flow, street flow, and regional channel flow, called the 1D/1D SWMM model, was advocated to be performed. Nevertheless, the execution efficiency of this integrated system still needs to be promoted to meet the demand for real-time forecasting of urban floods. The objective of this study is to seek an alternative for predicting water levels both in the sewer system and on the streets within an urban district during rainstorms by utilizing a dynamic neuron network model. To strengthen the physical structure of the artificial intelligence (AI) model and simultaneously make up for the lack of measured data, simulation results of the 1D/1D SWMM model are provided as labels for the training of the proposed model. The novelty of this research is to propose a new methodology to effectively train the AI model for predicting the spatial distributions of depths based on the hydrologic conditions, geomorphologic properties, as well as the network relation of the drainage system. A two-stage training procedure is proposed in this study to consider more possible inundation conditions in both sewer and street (open channel) drainage networks. The research findings show that the proposed methodology is capable of reaching satisfactory accuracy and assisting the numerical-based SWMM model for real-time warning of drainage systems in the urban district.

Refining patterns of melt with forward stratigraphic models of stable Pleistocene coastlines

Abstract. The warmest peak of the Last Interglacial (ca. 128–116 ka) is considered a process analogue and is often studied to better understand the effects of a future warmer climate on the Earth's system. In particular, significant efforts have been made to better constrain ice sheet contributions to the peak Last Interglacial sea level through field observation of paleo relative sea level indicators. Along tropical coastal margins, these observations are predominantly based on fossil shallow coral reef sequences, which also provide the possibility of gathering reliable U-series chronological constraints. However, the preservation of many Pleistocene reef sequences is often limited to a series of discrete relative sea level positions within the interglacial, where corals suitable for dating were preserved. This, in turn, limits our ability to understand the continuous evolution of paleo relative sea level through an entire interglacial, also affecting the possibility of unraveling the existence and pattern of sub-stadial sea level oscillations. While the interpretation of lithostratigraphic and geomorphologic properties is often used to overcome this hurdle, geological interpretation may present issues related to subjectivity when dealing with missing facies or incomplete sequences. In this study, we try to step back from a conventional approach, generating a spectrum of synthetic Quaternary subtropical fringing reefs for a site in southwestern Madagascar (Indian Ocean). We use the Dionisos forward stratigraphic model (from Beicip-Franlab) to build a fossil reef at this location. In each model run, we use distinct Greenland and Antarctica ice sheet melt scenarios produced by a coupled ANICE–SELEN glacial isostatic adjustment model. The resulting synthetic reef sequences are then used test these melt scenarios against the stratigraphic record. We propose that this sort of stratigraphic modeling may provide further quantitative control when interpreting Last Interglacial reef sequences.

OWERVIEW OF GEOHERITAGE ASSESSMENT METHODS

The assessment of geoheritage and geodiversity is a necessary prerequisite for the development of measures to preserve unique geological and geomorphological objects. Various foreign and domestic researchers have developed a low-level methodology for evaluating and determining the recreational value of geological and geomorphological objects. Leading developers of methodological approaches in the field of geoheritage assessment are foreign scientists Reynard (Reynard, 2012), Brilha (2016), Rocha (2014), Pereira (2013), Ferrero (Ferrero, 2012), Gray (2013 ), Fassoulas (Fassoulas, 2012), Zouros (Zouros, 2007), Asrat (Asrat et al., 2012) and others. In Ukraine, V. Hrytsenko (2006), Yu. Zinko (2003, 2009, 2019), V. Brusak (2011, 2013, 2014, 2019), S. Bortnyk, V. Stetsyuk, etc. (2020), V. Stetsyuk, (2021), G. Bayrak, L. Teodorovych (2020), G. Bayrak, A. Manko (2021) and others are engaged in the study of geological and geomorphological objects promising for geoconservation. The meaning of the concepts "geoheritage", "geodiversity" and "geoconservation" and their relationship should be distinguished. Geoheritage is geological and geomorphological objects that have special value in scientific, educational, aesthetic, recreational and other aspects, and geoconservation is the process of protecting and preserving these objects. Geoheritage is a part of geodiversity, which, in addition to geological and geomorphological properties, includes pedological, hydrological and other elements of inanimate nature in certain territories. Geodiversity, along with biodiversity, is a component of the World Natural Heritage. Geoheritage is studied at five levels – global (world), continental, national, regional and local. Two types of geoheritage assessment methods have been developed – direct and indirect. According to the evaluation procedure, the methods are divided into qualitative, quantitative, and qualitative-quantitative. Qualitative assessment consists in determining the total value of objects based on the results of descriptive studies and without any quantitative expression. Quantitative evaluation consists in defining clear evaluation criteria, their gradation and assigning certain points for each degree of evaluation gradation. Each of the criteria is divided into sub-indices that allow covering the entire spectrum of qualitative assessment of geoheritage objects. Scientific, educational, recreational, economic, prospective and other values are distinguished as evaluation criteria. The total final value of the geoheritage site is determined by the sum of points. The choice of methods for evaluating geoheritage objects was chosen depending on the characteristics of the object of study and the natural features of the studied territory. Key words: geoheritage; geoconservation; geodiversity; geoheritage assessment methods.

Impact of Climate Change on the Stability of the Miacher Slope, Upper Hunza, Gilgit Baltistan, Pakistan

Especially in recent years, the study of landslide phenomena is considered as very important because of the effects of climate change. The aim of this paper is to examine the stability of the slope located in Miacher Nagar village along the Hunza River (HR), using the Limit Equilibrium Method (LEM). The Miacher slope rises to a height of 900 m from the foot of the Hunza River and has a base angle of 50 degrees. Meta-sediments and quaternary recent glaciated deposits make up the majority of the slope’s composition. The slope movement of Miacher was first triggered in 1995, and was further triggered in 2010 and 2013. The slope was geologically, geomorphologically, geotechnically and geochemically investigated as well as modeled by Slope/w to determine the safety factor. Soil samples were analyzed for their geotechnical, geological and geomorphological properties. The Limit Equilibrium Method (LEM) was employed in this study to analyze the Factor of Safety (FOS) of the slope, based on assumptions of the Morgenstern and Price, Ordinary, Janbu and Bishop Methods, using the Slope/w software. Various factors, including pore water pressure, unit weight, cohesion, angle of internal friction and overburden, were examined by analyzing different scenarios. The findings showed that an increase in cohesion and angle of internal friction resulted in an increase in FOS, whereas an increase in unit weight and overburden caused a decrease in FOS. The influence of pore water pressure was positive to a certain extent, but a further increase led to a significant reduction in FOS. The results showed that the Miacher slope is currently stable, as all FOS values were greater than one, based on the existing strength parameters and simulated results obtained using Slope/w.

Tam Hai – an important complex geosite of the coastal zone in Quang Nam province, Vietnam

Tam Hai commune, Nui Thanh district, Quang Nam province, is located in the Tam Ky-Phuoc Son suture zone, which is part of the Kon Tum high metamorphic massif’s northeastern edge. Its geology is diverse, ranging from late Proterozoic metamorphic rocks to Quaternary sediments. This location also has a distinct landform in which a spit connects the mainland coast to an island known as a tombolo. Furthermore, the Truong Giang River is unique in that it flows parallel to the sea and is separated from it by a vast expanse of sand dunes. As a result, Tam Hai has unique geological and geomorphological properties. Furthermore, due to the long tradition of a fishing village, this geosite has significant additional value. The Tam Hai geosite is evaluated qualitatively and quantitatively for conservation and sustainable tourism development planning using the methods of literature reviews, geosite assessment, GIS, and field survey. The Tam Hai complex (geological, geomorphological, and hydrological) geosite and surrounding area map were created to highlight the scientific and additional values of the geosites: 1) carved rocky coastline in Ban Than mountain, 2) two islets, Mang and Dua, 3) two accumulation-abrasion coasts, and 4) the Truong Giang river. Our study also identifies and assesses the geosite’s risks in order to support the geosite’s conservation and protection, as well as tourism development here.

Reviews and Syntheses: Promoting the Advancement of Hillslope Hydrology and Stability in Taiwan from the Perspective of Critical Zone Science

Owing to active orogenic movement and the monsoon climate, rainfall-induced landslide disasters often occur in Taiwan. Hence, hillslope hydrology and stability have received considerable research attention. However, it remains difficult to accurately estimate the duration and consequences of hillslope instability induced by hillslope hydrology. Research on hillslope hydrology and stability is complicated by spatial heterogeneity, hydrological processes operating at various scales, spatiotemporal evolution, and geomorphological properties. Recent advances in critical zone science have provided an approach to extend geoscience studies. The “deep coupling” concept is essential for integrating physical, chemical, and biological processes on various spatiotemporal scales and for providing a macro and unified framework for evaluating internal properties and processes. Critical zone science and hillslope hydrology and stability both depend on interdisciplinary perspectives and approaches, monitoring strategies, and model analysis of integrating and coupling processes. They both share the characteristics of spatial heterogeneity, continuous evolution, and relevance to ecosystem services. To address the challenges related to hillslope hydrology and stability in Taiwan, we reviewed the progress in, relevance between, and common challenges to hillslope hydrology, stability, and critical zone science. We then presented a process-based integrated monitoring strategy, an interdisciplinary perspective, and a coupling analysis framework and model. The aim of this study was to promote the advancement of research on hillslope stability and hydrology in Taiwan.

Delineation of drainage potential area using geospatial techniques: A case study in the Indravati River Basin of India

For end users who use river networks and channel branches, the geo-hydrological examination of a basin is always of utmost relevance. With the aid of a remote sensing technique and GIS tool, this study attempted to evaluate the geomorphological properties of the strategic basin situated at Indravati River, Chhattisgarh, India. The findings might provide details about the basin's structural configuration, topographic features, and current geological variation. With dendritic, parallel, and trellis drainage patterns, the Indravati watershed was dispersed over a region of 29,408 km2 in the state of Chhattisgarh. The study area was classified as a fifth-order basin based on the findings. Lower and middle order streams pre-dominate the basin, which has gentle to steep slope terrain, medium-dense vegetation, and less permeable soil. When determining the ideal locations for recharge structures, the findings from the morphometric assessment of the basin can help to more effectively assess and manage water resources.

Multi-component avalanches for rock- and ice-falls to potential debris flow transition modelling

Rock/ice avalanches are complex gravitational flows involving three important physicalprocesses: entrainment, phase-changes, and flow transitions. The basic complexity of modelling rock/ice avalanches lies in the fact that the flow is a mixture of rock, ice, water, snow, soil sediments. The interaction of these components can lead to flow transitions which is difficult to model with simplified flow rheologies. For example, a flow initially composed of rocks and ice can transition into a long-runout debris flow, dependent on the entrainment of water, water-saturated sediments and/or snow. The dynamic behaviour of rock/ice avalanches is therefore highly difficult to predict because the flow mixture is dependent on the hydrological and geomorphological properties along the avalanche track. These properties can vary from year to year but even from season to season. The problem is intensified by the fact that frictional shearing can produce enough heat energy to melt ice and snow, leading to additional water in the flow. In this contribution, we present a new RAMMS module specifically designed to simulate single- and multicomponent avalanches of rock, ice, water, snow, and ice. The rheology of the flow is treated by using the concept of component activation energy. The model includes both snow and sediment/water/ice entrainment modules. A unique feature of the model is that it tracks the temperature of the rock, ice and water phases and therefore can treat phase changes. We apply the model on the Chamoli case-study to highlight the potential and present limitations of the model..

Landscape forming factors of the Karkaraly low mountains

The territory of geosystems of the Karkaraly low mountains is mainly forest landscapes and dark-chestnut soil cover. The paper reflects the state of the soil and vegetation cover of the forest landscapes of the Karkaraly low mountains in the Karaganda region. The paper provides the results of chemical soil tests, describes the vegetation cover samples using geoinformation technologies based on the standard quantitative index NDVI (Normalized Difference Vegetation Index), confirmed in field studies in the summer of 2020. The work performed aims at a comprehensive assessment of the physical, chemical, and biological characteristics of the components of geosystems. In course of the field study, a brief description of phytodiversity was compiled, indicating the geomorphological attributes of key areas. To study the vegetation, sample plots of the underlying soil and vegetation cover were set. Overview and thematic maps of the object under study were created. At the final stage of the study, the interpretation of the results is presented with the identification of cause-and-effect relationships of the state and fluctuations of geoecosystems. Data sources include satellite images of Landsat-8 (US Geological Survey) and field studies along the routes and four key areas. The results of the work allow defining the object under study, determining the distinctive properties in key areas, as well as possible reasons for the difference in the studied territory of geosystems.

Ландшафтообразующие факторы Каркаралинских низкогорий

The territory of geosystems of the Karkaraly low mountains is mainly forest landscapes and dark-chestnut soil cover. The paper reflects the state of the soil and vegetation cover of the forest landscapes of the Karkaraly low mountains in the Karaganda region. The paper provides the results of chemical soil tests, describes the vegetation cover samples using geoinformation technologies based on the standard quantitative index NDVI (Normalized Difference Vegetation Index), confirmed in field studies in the summer of 2020. The work performed aims at a comprehensive assessment of the physical, chemical, and biological characteristics of the components of geosystems.
 In course of the field study, a brief description of phytodiversity was compiled, indicating the geomorphological attributes of key areas. To study the vegetation, sample plots of the underlying soil and vegetation cover were set. Overview and thematic maps of the object under study were created. At the final stage of the study, the interpretation of the results is presented with the identification of cause-and-effect relationships of the state and fluctuations of geoecosystems. Data sources include satellite images of Landsat-8 (US Geological Survey) and field studies along the routes and four key areas. The results of the work allow defining the object under study, determining the distinctive properties in key areas, as well as possible reasons for the difference in the studied territory of geosystems.

Topographic thresholds for gully head formation in badlands

AbstractGully erosion is a particularly damaging process which is not yet sufficiently understood and parameterized. Gully head topographic threshold relative to Hortonian runoff have been studied in cropland, rangeland and forest. This study extends such modelling approach to badlands. Different badlands (eight sites) have been studied in the Mediterranean environment in Italy and Spain, characterized by diversified climatic, lithological, and geological settings under different anthropogenic conditioning. Many badlands have been characterized by their specific human history in addition to their geomorphological properties. Land use, as part of the human history, strongly affected many badland formation and development, through extremely impacting land exploitation (usually overgrazing). The effect of geological and geomorphological processes are usually particularly well visible. While the weakening effect of joints is confirmed, the different geological layer bedding orientation with respect to the slope aspect generates a different development of badland morphologies and different values of gully head thresholds values (as shown in two badlands sites on the same geological material and climate.The selection of Curve Number values, at the base of the introduction of land use into the gully head thresholds, has been more objectively defined in order to reduce arbitrariness in threshold application. The study additionally revises some of the physical basics behind the gully head threshold concept, requiring a description of the soil resistance in terms of frictional and cohesive components. This implies the explicit inclusion of rock fragment into the grain size distribution, which cannot be limited to fine grains. It results into an enriched threshold formulation that allows to describe the condition for gully head initiation and retreat as the result of the tradeoff between the frictional and cohesive components of the soil resistance forces. Eventually, the gully head threshold concept is confirmed and extended to include badlands.

Beach reprofiling to improve reproductive output at the world’s largest remaining green turtle rookery: Raine Island, northern Great Barrier Reef

Raine Island is a low-lying reef island located on the outer edge of the northern Great Barrier Reef (nGBR). It is part of the Raine Island National Park (Scientific) and is managed to protect and conserve its exceptional natural, cultural, ecological and scientific values. High amongst these values is Raine Island's importance as the world's largest green turtle (Chelonia mydas) rookery. However, since at least the late 1990s the number of turtle hatchlings produced from nests on the island has significantly declined. The ramifications of reduced hatchling production at Raine Island for the nGBR green turtle population resulted in the establishment of the Raine Island Recovery Project (RIRP), a 5-year $AUS 7.95 million collaborative project involving government, industry and Traditional Owners. A primary aim of the RIRP is to restore viable turtle nesting habitat on Raine Island. Although reduced hatchling production and the potential demise of the nGBR green turtle population are very much an ecological concern, the key to understanding and addressing this management issue is largely geomorphological. Here we detail how the geomorphological attributes of Raine Island contributed to the drop in hatchling output, and outline how understanding and working with the geomorphology and coastal processes at Raine Island have contributed to the mitigation of that decline. In particular, geomorphological investigations established that the sand losses that have reduced the elevation of turtle nesting beaches were unlikely to be replenished by natural processes, and they informed strategic movements of beach sand to increase nesting habitat above tidal inundation which has boosted hatchling production by as much as 640,000 over the past five years. Although this outcome is undoubtedly a success, the future remains challenging as anthropogenic climate change impacts progress.

Combined influence of human disturbance and beach geomorphology on Ghost Crab, Ocypode cursor, burrow density and size in the eastern Mediterranean

Ghost Crabs, Ocypode cursor (Linnaeus, 1758), are used as a bioindicator species to evaluate the ecological condition of sandy beaches. Studies using Ghost Crabs as bio-indicator have often focused on the influence of human disturbance and beach geomorphology, separately. However, the relative importance of these variables should be assessed to maintain community structure. Here, I used an indirect burrow examination technique to understand whether Ghost Crabs respond to human disturbance stronger than to geomorphological properties of the sites. I analysed sand compaction rate, sand grain size, beach width, and beach slope as geomorphological features and urbanization index as a measure of human disturbance on each site. I further examined Ghost Crab burrows by counting and measuring the openings. Ghost Crabs showed lower population density and individual body sizes as a response to human disturbance, and the level of this response was partly related to the geomorphological features of the sites. However, human disturbance explained approximately 72% of the variation in the Ghost Crab burrow density and about 70% of the variation in the burrow size, alone. The findings of this study corroborate the use of Ghost Crabs as an efficient bioindicator species of human disturbance on sandy shores to achieve efficient beach management, yet suggest that managers and scientists should combine the influences of geomorphological features of the beaches and the degree of human disturbances in their ecological assessments.