Geomorphological Changes Research Articles

REVEALING THE GEOMORPHOLOGIC IMPACTS OF HURRICANE IAN IN SOUTHWEST FLORIDA USING GEOSPATIAL TECHNOLOGY

Abstract. Geospatial data were used to analyze changes to geomorphology of barrier islands and beaches in Southwest Florida resulting from Hurricane Ian in late September 2022. The hurricane generated high intensity winds and storm surge causing more than $112 billion in damages, along with massive sediment mobilization due to erosion and deposition. This study quantified net sediment loss and gain on specific barrier islands by storm surge (Sanibel, Naples, Fort Myers Beach, others, though this paper focuses exclusively on Sanibel) by comparing pre- and post-Ian topography generated by a drone-flown LiDAR sensor; changes in elevation were used to quantify spatial variation in sediment volume. Data were collected immediately after Hurricane Ian and compared against topographic data collected by NOAA in 2018. Digital elevation models (DEMs) were used to compare topography, shoreline positions (relative to Mean High Water), foredune position, and volumetric changes using GIS technology. In general, the shoreline position after Ian changed little, indicating that the incoming surge had little influence on the beach. The foredunes, however, were deflated and set back by surge overwash. The outgoing surge created a much more dramatic geomorphologic change. Erosional surge channels cut through the foredunes and upper beach berm along many regions of the coastline. The ebb erosion also caused extensive damage to physical structures when located immediately behind the foredune. Lastly, this work demonstrates the value of employing GIS and remote sensing technology to problems of beach and dune management, the restoration of coastal ecosystems, the enhancement of resilience capacity of both natural and developed infrastructure, and the development of new policy needed to contend with the effects of climate change.

Back to the Past. The paleogeography as key to understand the Middle Palaeolithic peopling at Grotta dei Santi (Mt Argentario – Tuscany)

The mobility of hunter-gatherer groups is crucial in understanding Palaeolithic settlement dynamics. The concept of mobility cannot be separated from the space in which it occurs, including landscape components, localization of critical resources and of other sites, and routes between them. Nevertheless, the landscape is not constant in time due to the geomorphological changes that occurred in the long timescale of Prehistory. Here we present a paleogeographic reconstruction of the coastal area around Grotta dei Santi during the Neandertal occupation. A GIS-based approach, combining geological, bathymetric, and sea-level fluctuations data, allows us to reconstruct the landscape around the cave at about 45 ky BP. The cave today opens onto a cliff facing the sea. The Neandertal occupation occurred with a sea-level 74 m lower than present-day. Consequently, the cave faced a vast coastal plain, playing a strategic role due to its position, allowing both proximity and control of essential resources.

The potential and challenges of the ‘RUSLE-IC-SDR’ approach to identify sediment dynamics in a Mediterranean catchment

Soil erosion is a natural process that can be accelerated by natural and anthropogenic disturbances and lead to land degradation and geomorphological changes. Analyzing soil erosion and catchment sediment dynamics is a complex process. In such cases, simplified methods can be applied to analyze soil erosion and sediment connectivity variations and to understand sediment flux in a river basin to inform watershed management. In this study, we tested the combined method of the Revised Universal Soil Loss Equation (RUSLE), the Index of Connectivity (IC), and the Sediment Delivery Ratio (SDR) to estimate sediment yield (SY) and investigate the spatiotemporal variation of soil erosion rates and sediment connectivity in the Mediterranean Rogativa catchment (∼53 km2), Southeast Spain. In this ‘RUSLE-IC-SDR’ approach, the sediment delivery ratio was estimated from the spatially distributed index of connectivity, calculated using SedInConnect and accounting for the trapping efficiency of 58 check dams in the channels, while assuming 100 % sediment delivery in other parts of the channels. The sediment delivery ratio was calibrated, and sediment yield was verified for the year 2001 using observed sediment yield (in 2003) behind the non-silted check dams. Predicted soil erosion, connectivity (IC, SDR, and SY), and soil erosion-connectivity maps were quantified and compared over time and space, revealing the impacts of rainfall, land use, and check dams. These maps show higher values for areas closer to the channels than on the hillslopes, and higher values on croplands than other land use types, as well as a decrease over time due to land use change and the construction of check dams. The relatively simple ‘RUSLE-IC-SDR’ approach was found to be effective in identifying the sources and hotspots on the hillslopes of a complex Mediterranean catchment. Future studies should consider the channel erosion processes as the RUSLE-IC-SDR does not take these into account.

Influence of Precipitation Conditions and Discharge Rates of River Estuary Barrages on Geomorphological Changes in an Estuarine Area

Changes in coastal topography can affect the ecological environment and marine industries. In this study, we analyzed the patterns and causes of changes in shoreline and undersea topography in the Nakdong River estuary in the southeast of Republic of Korea using depth and shoreline surveys of the estuary, as well as data on discharge, suspended sediments, and precipitation in the Nakdong River basin. The results showed that erosion and sedimentation occurred repeatedly owing to complex factors such as the discharge of the estuary and invasion by open sea waves. However, no clear unilateral trend was observed. Unlike previous survey data, a large amount of erosion occurred in the second half of 2020. Previously, sedimentation was the main process, but erosion occurred rapidly, which was observed in the summer of 2020 when the erosion was three times higher than that in other periods owing to the severe rainy season and torrential rains for over a month. In addition, regarding the flow rate and force of the river water outflow, the amount of discharge increased rapidly, causing erosion. Moreover, a strong typhoon in the summer of 2020 affected the topography of the estuary.

Coastal boulder movement on a rocky shoreline in northwest Ireland from repeat UAV surveys using Structure from Motion photogrammetry

The degree of boulder mobility in response to coastal storms likely varies spatially and temporally along rocky shorelines, but this is difficult to evaluate from field monitoring of individual boulders alone. Structure from Motion (SfM) photogrammetry can be used to analyse changes in shoreline geomorphology or boulder distributions over time and space from rocky shorelines. This study employs data from repeated Unpiloted Aerial Vehicle (UAV) surveys in 2017, 2018, 2019 and 2022 along a 1-km stretch of a rocky shoreline in northwest Ireland. SfM techniques were used to generate orthomosaics of the bedrock platform surface from which distributions and transport patterns of boulders were examined. Based on the identification of specific boulders that appear in images from successive time slices, 16–32 % of boulders had remained stationary (had either rotated or flipped on the spot, but experienced no change in boulder position), 18–39 % had moved but less than the calculated Root Mean Square Error (RMSE) value of 23 cm, and 29–66 % of boulders had moved greater than the RMSE value, and <29 m distance in one case. In addition, a significant minority of boulders also appeared or disappeared (3–23 %) between successive time slices, which may reflect their episodic transport to/from the sea or beyond the region of interest. Overall, the results indicate that boulder movement is highly variable over time and space and does not appear to correspond with episodic wave forcing. This is different to previous studies that have described a simple deterministic relationship between boulder movement and singular wave forcing events such as storms. Repeated UAV surveys provide a consistent methodology for understanding rocky shoreline and boulder dynamics, and can offer insight into shoreline sensitivity to regional wave climate operating under more normal or ‘average’ conditions.

Robert Hooke’s Science of ‘Petrifaction’, the Trattato del Legno Fossile, and the Republic of Letters

Abstract This paper is part of a larger project of investigating the reception of the Accademia dei Lincei at the Royal Society. Perhaps due to the Lincei’s hesitancy to make more use of print, they constituted somewhat of a mystery for the subsequent generations of scientific communities. This is to say that the members of Royal Society were open to or perhaps even actively searching for knowledge related to the Lynxes. In this work, I trace this through a particular case-study in the transmission of knowledge: the arrival at the Royal Society of Federico Cesi and Francesto Stelluti’s Trattato del Legno Fossile Minerale Nuovamente Scoperto [Treatise on the Newly Discovered Mineral Fossil Wood] (1637) and its accompanying lignum fossile specimen. I aim to show how Robert Hooke, early keeper of the Society’s repository, diverged significantly from the initial sense of Cesi and Stelluti: if for the latter the specimen attested for a Renaissance-type continuous chain of being, the former appropriated it in his own theory of geomorphological change and ‘petrifaction’. Throughout this article, I also reflect more broadly on other two related issues: 1. The status of the discipline of petrification during the early modern times; 2. The availability of Lincean sources in England and Europe – while pointing out that much more work needs to be done in order to properly chart the dissemination of the Lynxes’s works. I conclude by indicating that the Lynxes played a key role in Hooke’s genealogical argument on the right use of microscopy.

Morphological of the Euphrates River between Al-Qaim and Hit City Using Modern Technology

The study aims to illustrate the River characteristics, river morphology and river processes in the study area Landscape. The river and morphological variables used in the study were derived from the satellite imageries available, digital elevation models, and relevant maps. River morphology is used to describe the shapes of river channels and how they change in shape and direction over time. River channel morphology is an indicator of a number of environmental processes and conditions. The river channel is the product of many geographical and geomorphological components that are determined by many factors, which are independent variables of the landscape (Geology, Climate, And Man) and reflect their influence in shaping the variables dependent on the landscape and the channel (sediment supply, stream discharge, and vegetation). Based on the aforementioned variables, the landscapes of the Euphrates River profile between the cities of Al-Qaim and Hit were chosen, which affect the formation and development of the channel. Where it leads to creating the shape of the planform and the active river area. The topography of the study area is characterized as a plateau crossed by the Euphrates River. It was affected by tectonic activity and this was reflected in the shape planform and geomorphic characteristics.The length of the river distance for the studied profile is 348 km, and it was divided into four reaches.It appeared that the index of this distance is characterized by sinuosity, as it reached 1.4, now the meanders are present in the second and fourth reach, while braiding prevailed in the first reach. The emergence of human settlements and increased until the present time, represented by the construction of a group of dams on its basin. It led to the occurrence of a series of hydrological and geomorphological changes, which necessitates the restoration of this basin and finding ways to ensure the stability and well-being of the inhabitants of its basin.

Comments on Souza et al. (2022) “Recent geomorphological changes in the Paraiba do Sul delta, South America East Coast”

Souza et al. (2022) based on grain size analyses, Optical Stimulated Luminescence (OSL) ages in fluvial sediments, and regional topography affirmed that most of the Paraiba do Sul River Delta (PSRD) has been deposited during the Little Ice Age (LIA). Souza et al. (2022) also inferred that after the LIA, PSRD presents shoreline erosion, using OSL undetermined results, regional topography, and field photographs, suggesting the direct connection of erosion and human intervention along river basin. As the results obtained by Souza et al. (2022) present several inconsistences about coastal evolution, and question previous works about PDRD developed in the last 30 years, we discuss these in three different sections, covering geological, historical, and recent geomorphological changes in PDRD.

Reply to the comments on Souza et al. (2022) “Recent geomorphological changes in the Paraiba do Sul delta, South America East Coast”

Scientific knowledge advances by the discussions on hypotheses, methods, and results, wherein the contradictory plays a positive role developing new theoretical-methodological approaches. In a positive debate to the progress of the science, the agreements and disagreements must only permeate the scientific scope and based on ethics to be away from the conflicts of interest. From this perspective, after knowing the submission titled Comments on Souza et al. (2022) “Recent geomorphological changes in the Paraiba do Sul delta, South America East Coast” to the journal Progress in Physical Geography: Earth and Environment (PPG), which addressed several issues concerning the results published in that article, we wrote this response to clarify the doubts related to the original paper. The comment’s authors focus mainly on da Rocha et al . (2019), a locally published article that did not fully encompass the complexity of processes and geomorphological dynamics related to the delta evolution. Furthermore, it did not present the parameters used in the geochronological analyses in accordance with the international literature. Finally, the discussions presented in the original article contribute to advances in knowledge about the responses of the Paraíba do Sul delta to the Little Ice Age.

The paraglacial adjustment of an Alpine lateral moraine, Bas Glacier d’Arolla, Switzerland

ABSTRACT Within Alpine catchments, glacial landforms are subject to post-depositional reworking during and following deglaciation. Ice-marginal moraines are thought to rapidly stabilise within ~200 years in this topographic context, although ice-proximal slopes are particularly prone to alteration by debris flows and solifluction. This study investigates landform transformation, documenting geomorphological change at the Bas Glacier d’Arolla, Switzerland. Gully development on a moraine slope was assessed using archive image sets obtained in 1977, 1988 and 2009 to derive historical elevation models. Raster differencing suggests that the mean rate of surface lowering on the upper moraine slope was 7.15 ± 1.83 m (± minimum level of detection) over the observation period (1977–2009), a rate of 0.22 m yr−1. The erosion of the landform resulted in an incontiguous moraine crestline. Whilst some landforms may undergo limited transformation upon deglaciation, selected sites are subject to rapid geomorphologic change, involving crestline retreat via the initial dissection by gullies, followed by the removal of inter-gully slopes.

Evaluating geomorphological changes and coastal flood vulnerability of the Nijhum Dwip Island using remote sensing techniques

This research critically assesses the spatiotemporal changes in morphology of the Nijhum Dwip Island caused by the dynamic wave action of the Bay of Bengal. Using image analysis techniques on Landsat Satellite Data (ETM+, OLI), the nature of shoreline alterations, erosion-accretion, and lob shifting from 2003 to 2021 has been identified. The findings reveal that since 2013, the island's morphology and geographical extent have undergone considerable changes, and it has gradually reached its current stable state in the Bay of Bengal. The fluvial sediments brought by the Ganges-Brahmaputra-Meghna (GBM) river system influenced by tide is mainly responsible for the sedimentary accretion in and around the island. Due to the complex wave action, the island has experienced alternating erosion and accretion domination scenarios. Compared with its extent in 2003, up until 2021, it has lost approximately 2.57 km2 area, erosion and accretion mostly occurring in the southern part, geometrically transforming the island from a rectangular to a subrounded shape. The depocenter shifting of the island was predominantly in the south-eastern direction during the whole period but has shifted to reverse direction in 2021. The minimum and maximum lob shifting occurred in 2006 and 2015, respectively, at approximately 600 m and 1800 m. ALOS PALSAR DEM (12.5m) in combination with secondary data from the Bangladesh Meteorological Department has been used to develop and simulate flood inundation scenarios under different surge heights. The projections illustrate that in the case of 2 m, 3 m, and 4 m surge heights, approximately 46.45%, 56.51%, and 61.42% of the total land will go underwater, respectively. In all scenarios, cropland and bare ground are the most affected classes.

A Geographic Information System (GIS) based approach for drainage and morphometric characterization of Beki river basin, India

Geographic Information Systems and remote sensing, have proved to be efficient tools in delineation of drainage pattern and different geometric methodology of geomorphologic, watershed management even GIS has been widely used in several flood management, and environmental applications. The river Beki with an area of 19,354.35 sq.km2 originates at Himalayan glacier (Kula Kangri glacier in Bhutan) 26.18° N latitudes and 90.53° E longitudes and flows though the plains of Assam and finally to the mighty Brahmaputra at 26.48° N latitudes and 91.02° E longitudes has been selected for detailed morphometric analysis. Morphometric parameters via; Stream order, Stream length, Bifurcation ratio, Drainage density, Drainage frequency, Drainage texture, Form factor, Circularity ratio, Elongation ratio and Compactness ratio etc. were measured for prioritization and compound parameter values were calculated. This study will help the local people to utilize the resources in right manner for Sustainable Water Resource Development of the Basin area. Moreover, the study can also be referred as a benchmark for studies on temporal change in geomorphology due to climate change. Different Morphometric analysis provides the explanation of physical characteristics of the watershed which are useful for the areas of land use planning, soil conservation, terrain elevation and soil erosion.

Historical disconnection from floodplain alters riparian forest composition, tree growth and deadwood amount

Riparian forests are among the most dynamic but threatened terrestrial ecosystems. Their dynamism and conservation depend on historical changes in river geomorphology, which can be evaluated through changes in channel sinuosity. However, we lack long-term assessments on sinuosity and how they impact riparian forest composition, tree growth and deadwood amount. To fill this research gap, we reconstructed river sinuosity in 14 sites across the middle Ebro basin, north-eastern Spain, using historical aerial photographs taken in 1927, 1956, 1998–2003 and 2014–2015. Relationships between sinuosity, stand composition and deadwood amount and decay degree were calculated. We also reconstructed radial growth of the major tree species (Populus alba, Populus nigra, Fraxinus angustifolia, Salix alba and Ulmus minor) in two sites to evaluate how coupled it was with changes in river flow after dam building. From 1927 to 2015, sinuosity decreased passing from 1.39 to 1.20. The river dynamics were altered in the 1950s and 1960s after dam and dyke building. Sites with high sinuosity values in 1956 corresponded to mature stands with large P. nigra individuals. Sinuosity was negatively related to F. angustifolia (rs = −0.83, p < 0.001) and P. alba (rs = −0.64, p = 0.02) abundance, whereas sites dominated by P. alba and U. minor presented abundant decayed deadwood. A loss of sinuosity and a contraction of the riverbank gradient increased disconnection of active channel from floodplain, with a mixing of more (e.g., P. nigra) and less phreatophytic species (e.g., U. minor). River flow diversion reduced growth and increased the tree-to-tree P. alba growth coherence. Hydrological droughts contributed to growth decline and dieback of U. minor, which is sensitive to spring river flow. Conservation and restoration of riparian forests must consider historical changes in river geomorphology related to human activities.

Sedimentary Facies and Morpho-dynamics of Sand Spit and Island Inference as Coastal River Process

Abstract This study aimed to characterize the sedimentary facies and understand the morphodynamics of the study area, and their results were correlated with various analytical methods. Different analyses such as depositional environmental, statistical, shoreline change, and grain size illustrated the temporal and spatial distribution of sediments. It has previously been claimed that current research locations are locii to fluvial landforms and are affected by fluvial processes. However, there are currently no rivers in the study region. This study was done to better understand the presence of fluvial landforms and to evaluate the previous findings. The dynamic behavior of the coast was revealed through shoreline analysis, which was done using satellite images from various years. Oceanographic parameters and longshore sediment transport play a vital role in geomorphological changes in coastal zones. According to the grain size analysis results, mean values showed that the deposits predominantlyare medium grained. The outcome discussed the spatiotemporal variations in geomorphology, sedimentation, and the function of coastal and fluvial processes on the beach of an island and a sand spit. Also highlighted was the role that wave action, fluvial currents, and tidal currents had in the long-term evolution of coastal geomorphological features such as spits, beaches, open coasts, and islands. The standard deviation signifies that the sediments are very well sorted to poorly sorted. Skewness ranges from fine skewed to strongly fine skewed and the kurtosis values show that the sediments are predominately very platykurtic which implies a low-energy environment of deposition. Four sedimentary facies (Facies A, B, C, D) have been found and facies A, B, and C may be wave-influenced deposits, but facies D may be formed by fluvial processes and contain medium to sand-sized particles. The direction of the tip area is also pointing to the south and this result concluded that the tip area is continuously growing. Thus, the results of this study revealed that sediment transport and coastal geomorphology evolution may be governed by two main processes such as the present ocean hydrodynamics and paleo fluvial processes of the study regions.

Structural characteristics of tropical headwater streams draining native vegetation and sugarcane cultivation

There is a great relationship between riparian native vegetation and freshwater ecosystems, influencing the functioning and structure of streams and ensuring the maintenance of ecological integrity and functions, such as bank stability, structural stability, organic matter supply, sediment reduction, and thermal regulation, among others. However, several small streams are inserted in large-scale agricultural areas, suffering pressure due to the expansion of agriculture. One of the monocultures that causes stream degradation in São Paulo, Brazil, is sugarcane, causing changes in riparian vegetation characteristics, bank stability, channel geomorphology and hydraulics, and substrate cover, among others. The objective of this study was to evaluate which structural features are most affected in streams draining sugarcane crops and compare them with streams draining native vegetation, also verifying the seasonal influence on each land use. For this, we applied two protocols that characterize aquatic ecosystems, observing the distinction between land use and seasonality in the studied streams. Our results showed that the relevant and most affected parameters were vegetation cover, presence of riparian forest, bank stability, extent and frequency of rapids, velocity/depth regime, epifauna/substrate cover, alteration in the river/stream channel, and streamflow. PERMANOVA analysis comparing structural importance parameters, among different land uses showed significant difference (p < 0.01; F = 73.74) among land uses and showed no significant difference between seasonal periods for streams draining native vegetation (p > 0.05; F = 0.68) and draining sugarcane cultivation (p > 1; F = 0.82). Thus, our study demonstrated the importance of native vegetation in promoting better structural characteristics of headwater streams.

Stability of Solid Residue After Integral Treatment of Acid Mine Drainage

Acid mine drainage poses a significant environmental challenge resulting from mining activities. It can occur during and after the exposure of sulfide minerals to water, oxygen, or oxidizing bacteria. Extensive copper ore exploitation, processing, and the deposition of substantial amounts of mining waste have caused severe geological, hydrogeological, and geomorphological changes, including soil contamination, as well as local or even regional-scale pollution of rivers and groundwater. This study focuses on the utilization of waste mine waters and unbalanced portions of the mine deposit, such as flotation tailings, to transform their negative characteristics into environmentally friendly ones. In previous research by the authors, acid mine water from Robule, a part of the Bor copper mining and smelting complex in Serbia, was effectively treated using flotation tailings, resulting in a solution suitable for safe discharge. This paper investigates the characteristics of the solid residue remaining after the treatment of modified flotation tailings to assess the feasibility of its safe disposal back into the environment. Standard procedures such as TCLP and EN 12457-4 tests were employed to evaluate the leaching characteristics of the solid residue. Additionally, the residue underwent long-term leaching with melted snow to simulate environmental conditions over one year, and the drainage water was analyzed and compared with the results of the standard leaching procedures. The investigated treatments demonstrate improved economic and environmental outcomes, with a process tailored to environmental preservation.

Wind–Wave Conditions and Change in Coastal Landforms at the Beach–Dune Barrier of Cesine Lagoon (South Italy)

Several coastal barriers experienced significant erosion and change in shape throughout the Mediterranean coasts over the past decades, and the issue has become of increasing concern for scientists and policymakers. With reference to a case study and by meteorological and geomorphological investigations, this note aims to define the wind–wave conditions, infer the net longshore transport, and detect the geomorphological processes that shape the landforms of the Cesine Lagoon barrier (South Italy). Despite the importance of the site in coastal defense and environmental conservation, there are still no specific studies. A challenge for this research was to obtain significant results from publicly available sources and simple and inexpensive methods. Geomorphological changes, such as the retreat of dune toes, accretion of washover fans, and formation of gravel beaches, are related to the analyzed wind–wave conditions. The net longshore transport is found in accordance with the direction of the more intense winds. The role of extreme events in the shaping of coastal landforms is yet to be established, even if they greatly increase the vulnerability to flooding of the study area. The results achieved so far are starting points for further data collection and analysis in the perspective of assessing the impact of climate changes and the threatening hazards on the lagoon barrier.

A new perspective on the molecular dating of the brown trout complex with an extended phylogeographic information on the species in Serbia

Abstract To elucidate the historical biogeography of a species, the patterns of population divergence must be understood, and the evolutionary history of the species must be accurately known. For brown trout (Salmo trutta complex), estimating divergence times remains a challenge due to the lack of well-defined time calibration points and insufficient phylogeographic coverage in previous studies. The present work aims to improve molecular dating of mitochondrial control region sequences by using a multicalibration framework based on the latest paleogeological evidence for dating the origin of Lake Ohrid and two available Salmo fossils, including the overlooked Salmo immigratus. Our results clearly show that, contrary to common belief, the major divisions within the brown trout occurred in the Late Pliocene, not the Pleistocene. The Pliocene origin suggests that the brown trout lineages did not form because of geo(hydro)morphological changes during glaciation cycles but may be the result of orogeny and drainage evolution. In addition, increased sampling, particularly in Serbia, led to the identification of a new haplogroup (da-int) occupying an intermediate position with respect to da-es and da-bs haplogroups. While the control region can delineate brown trout lineages, its phylogenetic resolution is limited, so even extensive sampling could not further resolve the lineage level polytomies.

Geomorphological Changes by the Action of Coastal Processes and Anthropogenic Activties along the Coastal Zone between Ras Al-Jalaiah And Ras Az-Zour, Southern Kuwait

The coastline is one of the most important linear features on the earth’s surface, which displays a dynamic nature. The natural processes that interact with the coastal environment of Kuwait are tides, currents, and waves. The main shoreline of the coast of Kuwait is about 325 km long. In the north, the coast is characterized by wide intertidal mudflats, bounded by a large-scale coastal sabkha, partly covered with sand drifts. The southern shore is characterized by relatively steep sand beaches with narrow to moderately wide rocky intertidal platforms, which are partly covered by sand and algal mats. The area of interest is the coastal area between Ras al-Julaiha and Ras Az-Zour in the southern area of Kuwait. Sandy berm and wave-cut cliff bound this southern intertidal environment. The study area is a superficial, open, vulnerable bay of a maximum depth of 28 m extending along the southern shore of Kuwait. Ras Al-Jalaiah promontory bounds the area northwards and Ras Az-Zour promontory bounds it southward, with a distance measured vertically of 18.085 km.

Geospatial Assessment of Long-Term Changes (1937–2019) in Mangrove Vegetation and Shoreline Dynamics of Godavari Estuary, East Coast of India

Godavari mangroves are the second largest mangrove ecoregion of India located on its eastern coast. Mangroves perform major ecological functions including shoreline stabilization and coastal protection. They have undergone serious alterations, largely induced by human activities resulting in increased vulnerability to coastal flooding. A reliable database on mangroves distribution and temporal changes is essential for their effective management and conservation. Present study analyzes the long-term changes in mangroves, as well as the geomorphological changes along the coast of Godavari Estuary over a span of 82 years (1937–2019), using topographical maps, remotely sensed multi-temporal satellite imageries for five time periods. Results indicated that the rate of land uses conversions of agricultural fields, degraded areas, mudflats and mangrove vegetation into aquaculture significantly increased during the late 1990s. About 40 percent of it was constructed on mangrove areas between 1980 and 2019. The area under aquaculture was estimated to be 6,388.62 ha in 2000, almost doubling-up to 11,924.67 ha in 2019. Mangrove cover in this region increased by 15.95 percent between 2000 and 2019 (including 11.9 percent in Coringa Wildlife Sanctuary) due to increased protection, consequent regeneration and accretion. Shift in Hope Island spit was observed in north and northwest directions, gradually growing nearly 3.84 km. High-resolution declassified satellite data were found very helpful for long-term mangrove mapping and analyzing geomorphological changes; enabling a better understanding of these regions to help decision makers/planners to find better solutions to existing coastal issues. The paper concludes with some recommendations to restore and conserve the existing mangrove cover in the study area.