Thousands of Potholes in the Mekong River and Giant Pedestal Rock from North-eastern Thailand: Introduction to a Future Geological Heritage Site

Udomsak, Sirawat; Choowong, Nutcha; Choowong, Montri; Chutakositkanon, Vichai

doi:10.1007/s12371-020-00524-w

Cited by 5 publications

(5 citation statements)

References 15 publications

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“…Zone 1 has many potholes with low strength and slakes durability index, meaning that this zone is more easily eroded than zones 2 and 3 by flowing water. Furthermore, zone 1 had high absorption and porosity, which caused rocks to absorb much water during the rainy season, while in the dry season, water in the rocks evaporates dissolving some matrix, hence secondary porosity is created which results in enhanced erosion (Udomsak et al, 2021). Bedrocks of zone 2 have greater strength and a higher slake durability index with lower water absorption and porosity, while zone 3 is on the river bank and lacks potholes, although it has a low strength and slake durability index with high water absorption and porosity.…”

Section: Discussion On Pothole Origin and Geotourism Developmentmentioning

confidence: 99%

“…These potholes occur in the centre of the large syn- cline in subhorizontally bedded sandstones. Formation of the Sam Phan Bok is primarily related to the fact that the stream eroded the rocks, breaking them down to sand faction and polishing them until becoming a pothole (Udomsak et al, 2021). Therefore, there is a strong need to understand the relationship between pothole occurrence and rock properties, which ultimately will help provide better data to tourists and local people and local guides in the Phetchabun geopark alike.…”

Section: Introductionmentioning

confidence: 99%

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Characterisation of potholes formed on bedrock sandstones at Loei Dun, Phetchabun Geopark, Thailand

Singtuen

Junjuer

2022

Geologos

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Phetchabun National Geopark comprises varied geosites; one of the fluvial bedrock landforms distinguished here is Loei Dun. This shows many potholes in Mesozoic sandstone of the Nam Phong Formation (Khorat Group). A genetic study of the occurrence of the Loei Dun potholes lends it a higher geoheritage value. For the present study we did fieldwork and carried out petrographical and geotechnical analyses so as to classify and characterise the potholes and consider geotourism potentials. Petrographically, the bedrock sandstone is a lithic arenite which consists of 82-96 percent very fine to coarse, well-sorted subangular sand with low sphericity and calcite cementation. Our geotechnical analysis of the bedrock sandstone suggests that pothole occurrence may be linked to low rock strength and slake durability index with high rock absorption and porosity at Loei Dun. Field studies confirmed the impact of other factors such as joints/faults, fluvial conditions and biological weathering. There are five types of pothole, viz., simple ones, potholes with external furrows, compound potholes, breached potholes and lateral ones. The present study adds educational value to the Loei Dun geosite at Phetchabun Geoparks and cultural and economic aspects can be further strengthened through the development of geotourism in the area.

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Section: Discussion On Pothole Origin and Geotourism Developmentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Characterisation of potholes formed on bedrock sandstones at Loei Dun, Phetchabun Geopark, Thailand

Singtuen

Junjuer

2022

Geologos

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“…In the riverbed of the Mekong River (Thailand), Udomsak et al (2021) define multiple pothole types, addressing the action of pebbles and gravel for the enlargement of the cavities. This exploratory study considers the characterization of potholes as sediment traps and the analysis of the trapped sediments in the Loña River (belonging to the Miño-Sil network in Galicia).…”

Section: Introductionmentioning

confidence: 99%

An exploratory study to test sediments trapped by potholes in Bedrock Rivers as environmental indicators (NW Iberian Massif)

Álvarez-Vázquez¹,

Álvarez²

2021

CyG

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The capacity of fluvial potholes to trap sediments, together with the geochemical analysis of their stored sediments for environmental assessment, is an overlooked research topic in small bedrock rivers. The present exploratory study is focused on this issue. It was developed in a small river over rock, in the inland territory of Galicia (NW Iberian Peninsula). The study started from an analysis of the inventoried fluvial potholes to identify suitable forms for sampling, and the collection of sediment samples within them. After this, the determination of the grain texture, mineralogy and content of major and trace elements in sediments were carried out. Potholes with maximum vertical depth from 25 cm to 1 m, located in central and sidewall sectors of the bedrock channel, provided the best conditions for sediment sampling. The sediments collected from six potholes showed predominance of coarse-medium grain size and sand fraction. The rough contents of the major and even trace elements are related with the nature of the more refractory minerals of the bedrock. An adequate sampling strategy, considering grain-size fractions, show potential to use trace elements as environmental indicators.

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“…Only one giant pedestal rock with a vertical crack was preserved. In addition, rock falls were seen in Phachun (Udomsak et al, 2021).…”

Section: Simplified Formation Of the Giant Pedestal Rockmentioning

confidence: 99%

“…Only one giant pedestal rock with a vertical crack was preserved. In addition, rock falls were seen in Phachun (Udomsak et al, 2021) The primary aim of this dissertation is to conduct a comprehensive analysis of the typology and formation of potholes along the Mekong River and erosional remnants in the sandstone of the Khorat Group. The research will focus on understanding the various processes that lead to the formation of these geological features and their characteristics.…”

mentioning

confidence: 99%

Typology and formation of pothole along the Mekong river and erosional remnant in sandstone of Khorat group, Ubon Ratchathani province, northeastern Thailand

Udomsak

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Phachan Samphanbok Geopark showcases fascinating erosional features, such as a multitude of potholes in the Mekong River. Additionally, it is home to the largest pedestal rock in Thailand, located in Ubon Ratchathani province in the northeastern part of the country, near the border between Thailand and Laos PDR. The formation of potholes is attributed to the erosive force of swirling sediment within fractures caused by vortex currents. In this research study on pothole evolution, the potholes in the Mekong River were categorized into two main groups: structural control potholes and non-structural control potholes. These types were further divided into five groups: ovoid potholes, lateral potholes, open lateral potholes, hierarchical potholes, and coalesced potholes. To analyze pothole characteristics, pebbles within sandstone beds were counted, and samples of pothole grinders were collected for composition comparison. The study revealed that a higher proportion of grinders in a pothole increases the likelihood of its occurrence. Stratigraphic columns were constructed in the study area to describe lithofacies and sedimentary structures. Pothole occurrence was found to be related to pebbly sandstone and trough cross bedding, which are associated with hierarchical potholes. A drone was utilized to capture aerial photos in a grid pattern, enabling the estimation of pothole density and categorization into three zones: high-density, moderate-density, and low-density pothole zones. Several factors were identified as controlling pothole occurrence, including horizontal bedding, the narrow width of the river leading to increased flow velocity, and the location situated in the cutbank zone. The formation of the giant pedestal rock is attributed to ancient gullies eroding into vertical fractures during the last tectonic event. The study of lithofacies indicates a paleoenvironment characterized by a braided river, with paleocurrents flowing in a southwest direction. Overall, this research emphasizes the significance of promoting the Phachan Samphanbok Geopark as a world-class geological heritage site. It also provides suggestions for the local communities and recommendations for future risk management in the Phachan and Samphanbok areas.

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Thousands of Potholes in the Mekong River and Giant Pedestal Rock from North-eastern Thailand: Introduction to a Future Geological Heritage Site

Cited by 5 publications

References 15 publications

Characterisation of potholes formed on bedrock sandstones at Loei Dun, Phetchabun Geopark, Thailand

Characterisation of potholes formed on bedrock sandstones at Loei Dun, Phetchabun Geopark, Thailand

An exploratory study to test sediments trapped by potholes in Bedrock Rivers as environmental indicators (NW Iberian Massif)

Typology and formation of pothole along the Mekong river and erosional remnant in sandstone of Khorat group, Ubon Ratchathani province, northeastern Thailand

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