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  • Open access
  • 16 Reads
Machine-learning Simulation of the XRain rainfall data against rain gauge over complex topography

In the last decade, rainfall radar has been deployed at volcanoes like Mt. Merapi in Indonesia, and can even cover a whole country like in Japan, where the X-Rain (eXtended Radar Information network) product has been available for local research. However, the linkage between raingage data and radar spatial data (over a 250 m x 250 m grid) still presents discrepancies, and these challenges are particularly accurate in regions of high local-topographic variations like at Mount Unzen in Japan. As the volcano is over the Shimabara peninsula, it is surrounded by the sea with topography locally rising to 1,483 m.

To improve the forecast and to better understand the triggering mechanisms of lahars (volcanic debris-flows) at Mount Unzen, quantifying the spatial distribution of rainfalls is essential, and as a first step it is important to first understand how data taken locally by rain-gages relate to the radar data. Because empirical models have not been able to show any clear correlation, the present contribution has been developing a neural-network with two hidden layers that takes into account the rainfall per hour, the temperature and the wind speed and direction. The model takes a logistic activation function and the loss function is optimized using the Mean Squared Errors and the Mean Absolute Error. The choice of the activation function and the optimizer is the result of running several combinations of optimization functions with different activation functions. Once the best fit was chosen, the sigmoid with a SGD (Stochastic Gradient Descent) optimizer was chosen, and when training the model for 120 cycles, Shimabara station and the XRain data shows an error < 4 mm rainfall, while at the Unzen summit, even after 300 cycles, the validation error remained at 8 mm while the training loss was < 4mm. This shows that location specific functions might be necessary for each location, not only taking into account the weather data, but also the local topographic variability and the topographic position on slopes. Finally, neither the raingage, nor the Xrain are “true data” and the remaining error can also be the result of an error existing in any of the two dataset. Furthermore, the X-Rain data are spatialized data over an area, whereas the raingage is very limited in terms of spatial representativity.

  • Open access
  • 18 Reads
Ecohydrological analysis in watersheds of mountain areas of São Paulo coastal, Brazil

In the Brazilian state of São Paulo, the coastal municipalities have watersheds in mountains with active relief evolution (Serra do Mar). The coastal regions are more vulnerable to flooding and landslides. A large number of people live on the slopes of Serra do Mar, these places are more vulnerable to landslides, which causes biodiversity loss and tragedies. This study seeks to present an ecohydrological analysis to categorize coastal watersheds into clusters considering the spatial characteristics of NDVI, DTM, soil depth, climate, and Soil Organic Carbon (SOC) and identify areas' susceptibility to landslides in the coastal watersheds of the State of São Paulo. The findings show that vegetation cannot prevent landslides from happening on its own. The higher altitude regions, where the tropical forest is still present, are those most prone to landslides, designated as cluster 2.

  • Open access
  • 29 Reads
The geosite of travertine waterfall of El ksiba (Morocco), a heritage to enhancement and preserve
Published: 16 December 2022 by MDPI in The 4th International Electronic Conference on Geosciences session Geoheritage

The travertines of El Ksiba forming cliffs with an extension of about 8 km and a variable height that can reach about thirty meters. They are developed on lacustrine limestones and conglomerates of Early Quaternary age. The results reveal the high scientific (≃0.88) and aesthetic (≃0.88) values related to the strong representativeness of the regional geological phenomena. The assessment also shows the high economic value (≃0.75) and cultral (≃0.81). In this work, we presented the strategies of valorization and protection of this heritage in the framework of rural socio-economic development through activities related to geo-tourism and geo-education.

  • Open access
  • 31 Reads
Inventory and enhancement of geological heritage in the Ouzoud syncline (M'Goun UNESCO Geopark, Central High Altas, Morocco): first step for promoting geotourism and sustainable development
Published: 19 December 2022 by MDPI in The 4th International Electronic Conference on Geosciences session Geoheritage

The Ouzoud syncline, in central Morocco, is one of the wealthiest areas of natural and cultural heritage in the kingdom. The diversity of its landscapes and geological sites is interesting to explain the evolution of geological history of the central High Atlas (CHA) of Morocco and paleoclimate changes. This syncline also has great potential for geotourism development, it contains the Ouzoud waterfalls, one of the most coveted tourist attractions, which are part of the geosites listed in the Unesco M'Goun Geopark. The abundance of resurgences, waterfalls, travertine, caves, magmatic rocks, exceptional geomorphological forms and fascinating panoramic views make this territory a suitable tourist destination for excursions, hiking and climbing, and a good support for understanding the post-Hercynian sedimentary evolution of CHA. The dense and diversified vegetation cover offers a habitat for various animals (magot monkeys, bats, birds...) which attracts more nature-loving tourists. This exceptional biodiversity and the cultural wealth (traditional mills and the Zaouïa of Tanaghmelt) contribute to accentuate the importance of this syncline. Despite all these opportunities, this heritage remains unknown to the general public and not well exploited by managers, although it constitutes a lever for local socioeconomic development. To overcome this gap, an inventory and assessment of sites of interest was carried out in order to provide a database that would support decision makers in any geoheritage promotion projects. Thus, about twenty highly attractive geosites were inventoried, eight of which (the most important ones) were selected for evaluation using the Reynard (2016) methodology. This approach takes into account the scientific value, the additional values and the use and management values of sites. Also, a geoitinarery has been proposed to promote this heritage wealth. Such promotion can popularise the geosciences and create income-generating activities, which will improve the economic situation of the local population.

  • Open access
  • 38 Reads
Line of sight glacier velocity estimation of transboundary glaciers in Eastern Himalayas using high-resolution TerraSAR-X data.

Glacier velocity is one of the critical parameters for understanding the current health status of a glacier. According to the momentum law, mass is inversely proportional to velocity. Higher velocity may indicate lesser mass. Fifteen transboundary glaciers from the eastern Himalayas in the vicinity of India, Nepal, Bhutan, and China are chosen for the estimation of glacier velocity. These glaciers are Changshang, Rathong, South Lhonak, South Simvo, Talung, Tongshiong, Yalung, Zemu, Glacier 2, Glacier 3, Kaer, Ktr Gr 193, Middle Lhonak, North Lhonak, and Ktr Gr 171 (Lhonak Nepal) covering total area of 440.92 km2. A remote sensing and GIS-based approach is considered for the study. High-resolution Synthetic Aperture Radar data of TerraSAR-X was acquired from the German Aerospace Center (DLR) by European Space Agency for study area in the year 2020-2021. Satellite data are preprocessed using radiometric calibration and multi-look for speckle noise reduction. These datasets are co-registered using SRTM Digital Elevation Model. Offset Tracking is applied to estimate the glacier velocity. The maximum velocity in all glaciers ranged from 14.31-84.26ma-1. The average velocity ranged from 1.78-7.09ma-1. The glacier having highest average velocity is South Lhonak glacier. This glacier is melting rapidly in the last few decades. Near the snout of this glacier lies a glacial lake made up of a moraine dam. For quality assessment, latest field-based results of 2018 and observed results of 2021 were compared. It has been noticed that there is a variation of approximately 10%.

  • Open access
  • 40 Reads
Petrophysical characteristics of hydrothermally altered volcaniclastic-rich sedimentary rocks on the Naturaliste Plateau, offshore southwestern Australia (IODP Site U1513)

Drilling at Site U1513 recovered the Lower Cretaceous volcaniclastic-rich sedimentary sequence on the Naturaliste Plateau and Mentelle Basin, offshore southwestern Australia. The sequence exhibits distinct lithologic characteristics, attributed to volcanism and subsidence occurred during the breakup between Greater India and Australia-Antarctica. It consists of sandstones, siltstones, and silty claystones with abundant volcanic clasts, lithics, and hydrothermal alteration. This study characterizes petrophysical properties of the sequence and correlate them with lithologic and mineralogical features. The properties show noticeable variations. Our results confirm that the petrophysical characteristics are associated with grain size, volcanic matter, organic content, as well as hydrothermal alteration minerals.

  • Open access
  • 21 Reads
The Four Principal Megabiases in the Known Fossil Record: Taphonomy, Rock Preservation, Fossil Discovery and Fossil Study

The Known Fossil Record represents museum collections and the published literature, and it is subject to multiple large-scale megabiases grouped into four major categories: (1) taphonomy; (2) rock preservation; (3) fossil discovery; and (4) fossil study. Taphonomic megabiases are largescale patterns in the quality of the fossil record that affect paleobiologic analysis at provincial to global levels and at timescales usually exceeding ten million years. Taphonomic megabiases are intrinsic (form and behavior) and extrinsic (biotic and abiotic controls on preservation). Other megabiases are the preservation and exposure of rock strata, kyreonomy (discovery) and concipionomy (study). Kyreonomy megabiases include location of fossil sites, mineral evaluation, mineral extraction and colonialism. Concipionomy megabiases include the Taxophile Effect, language and development and distribution of technology.

  • Open access
  • 26 Reads
A giant slide within the upper Cretaceous limestones as an indicator for fault activity dating and basin evolution.

The studied section, up to 10m thick with 17 different carbonate beds, showed the interaction between a giant slide and the pre-existing normal faults, during the upper Cretaceous time. There are three major points in the studied section: 1. The presence of two slump horizons, up to 1m thick each, within the stratigraphic column, related with the basin floor instability due to normal listric faults activity. 2. The presence of many normal with listric geometry faults, with a ESE-WNW direction, and mostly west dipping. These faults, acted during the sedimentation processes, produced the basin floor inclination for the slumping, when still the sediments were unconsolidated. This tectonic activity seems to terminate in the upper part of the stratigraphic column. 3. After the development of the slumps and the normal fault activity, that produced a displacement up to 30cm, a new event was characterized the region. The completely studied block rotated to the west and the instability of the sediments produced a giant slide, with up to 7m thick and movement up to 0.9m, cutting the pre-existing normal faults. According to the knowledge of the regional evolution, as it represents the Apulian Platform Margins, with extensional tectonic during Jurassic to early Miocene, that was inverted to compressional regime, during middle Miocene, and the presence of a major fault along the studied section, with a NNW-SSE direction, it seems that the studied section was situated on the hangingwall of the fault, the downthrown block, during the extensional regime.

  • Open access
  • 15 Reads
Cascading effects of major natural hazards in Greece

When a disaster occurs, the society in risk is not only threatened by the consequences of this event. Stable and trigger factors generate a natural hazard, which in turn induces changes in some trigger factors and thereby these changes can induce another natural hazard. Furthermore, natural hazards are characterized by interactions, which consist of various types, such as the triggering (cascading) interrelations. The purpose of this research is to identify, through a review process, the cascading effects of major natural hazards that occurred in Greece and had a significant impact on society.

  • Open access
  • 22 Reads
Cities resilient to climate change through natural heritage: a bibliometric review
Published: 09 January 2023 by MDPI in The 4th International Electronic Conference on Geosciences session Others

Natural heritage is the composition between biodiversity and geodiversity; therefore, it is also a primary source of ecosystem services and geosystem services that have multiple benefits such as adaptation to climate change. However, it is mainly found in natural environments. On the other hand, due to climate change, there are cities around the world with extreme conditions such as heat or cold waves. The objective of this article is to analyses climate change mitigations through ecosystem and geosystem services in urban planning of cities using mapping science tools to take advantage of the benefits of natural heritage in cities. The methods are indicated in a) selection of the topic, keywords and scientific databases; b) pre-processing, merging of databases, and data processing using Bibliometrix-RStudio; and c) analysis and interpretation of results. A total of 1361 records were found in Scopus and 940 in the Web of Science, and the countries contributing to the subject are China, the United States, Germany, Italy and the United Kingdom. In addition, the processing of the unified database made it possible to recognize i) conceptual and intellectual structure, research trends over time. Finally, geosystem services and ecosystem services help mitigate climate change through green infrastructure, blue infrastructure, and their adaptability to gray infrastructure, contributing to sustainable development goals: sustainable cities and communities and climate action.

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