scholarly journals Secondary Geomorphic Processes and their Influence on Alluvial Fan Morphology, Channel Behaviour and Flood Hazards

2021 ◽  
Author(s):  
Lauren Vincent ◽  
Brett C Eaton ◽  
Anya S Leenman ◽  
Matthias Jakob
Keyword(s):  
Alluvial Fan ◽  
Flood Hazards ◽  
Geomorphic Processes

scholarly journals Exploring Geomorphic Processes and Martian Gale Crater Topography on Mars using CTX and HiRISE Express Image Dataset

2019 ◽  
Author(s):  
Pavan Kumar ◽  
Jiwan Singh Rawat ◽  
Sufia Rehman ◽  
Haroon Sajjad ◽  
Meenu Rani ◽  
...  
Keyword(s):  
Alluvial Fan ◽  
Martian Surface ◽  
Laser Altimeter ◽  
Gale Crater ◽  
Topographic Features ◽  
Geomorphic Features ◽  
Imaging Science ◽  
Resolution Imaging ◽  
Orbital Data ◽  
Geomorphic Processes

Abstract. Exploration of Martian surface and the crater deposition has recently attracted scientific community. We hypothesized the existence of momentous topographic features of different origin on the Martian surface. It was observed that Gale Crater has a thick sediment deposition mainly of fluvial and aeolian origin. This study has utilized spatially referenced topographic dataset Context Camera images acquired from Mars reconnaissance orbiter for exploring the geomorphic processes and topography of Gale Crater. A base map was prepared by mosaicking all imagesfor preparing geomorphologic map of the crater. Surface map of the topography of the Crater was prepared using Mars Orbiter Laser Altimeter (MOLA) data. HiRISE images were used to examine the identified geomorphic features. Results revealed that the presence of both fluvial and aeolian processes and their respective associated landforms in the Crater. Depositional landforms such as alluvial fan, inverted channel and mound and erosional landform namely canyons were distinctly identified on the image. Yardangs produced by erosional and ripple and dunes formed by the depositional work of wind were also identified in the Crater. The fluvial channel, inverted channels and fan shaped deposits further signifies ongoing aqueous activity on the Gale Crater. Sinuous ridges are the common features present on the floor of Crater. Rock particles, sand and silt in the crater were found to have been transported and deposited by flowing water on its floor. Presence of different sedimentary structures and valley revealed ancient sedimentary deposition due to water action. Significant ejecta morphologies were also identified on Martian surface. Our study confirms the previous studies that presence of H2O sub surface volatiles. Concentrations of volatiles have produced double layer ejecta morphology. The concept and findings of this study will escalate knowledge about the surface features on Gale Crater. However, more coherent investigation is needed for modelling and understanding the processes and landforms of the crater. Context Camera (CTX) and High-Resolution Imaging Science Experiment (HiRISE) images have proved useful for geomorphic and topographic mapping of the Mars planet. The dataset used in this study can be accessed on Mars Orbital Data Explorer (https://ode.rsl.wustl.edu/mars/indexproductsearch.aspx).

scholarly journals Glacier-Induced Alluvial Fan Development on the Northeast Tibetan Plateau Since the Late Pleistocene

2021 ◽  
Vol 9 ◽  
Author(s):  
Fuyuan An ◽  
BadingQiuying ◽  
Shanlu Li ◽  
Donglin Gao ◽  
Tianyuan Chen ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Late Pleistocene ◽  
Drainage Basin ◽  
Alluvial Fan ◽  
Alluvial Fans ◽  
Alluvial Sediments ◽  
Mis 3 ◽  
Last Glaciation ◽  
Mis 5 ◽  
Geomorphic Processes

The origin of alluvial fans at the drainage basin or the margins of the arid sedimentary basin on the northeastern Tibetan Plateau (NETP) has been a focus of debate among scientific communities. Extensive alluvial fans had developed in the mountain-basin systems of this region during the late Pleistocene. Based on geomorphic/stratigraphic studies and the optically stimulated luminescence (OSL) chronology, we investigated numerous alluvial sequences in the drainage basin of the coupled mountain-basin system on the NETP. Sedimentologic analyses showed that these alluvial sediments mainly comprise crudely meter and decimeter beds of fanglomerate and sandy lenticles, which occasionally contain boulders in the thinner layers. OSL dating results showed that the alluvial sediments were mainly developed during the late MIS 5, MIS 3, and Last Glaciation and Deglaciation (maximum aggradations), while little had occurred during the early Holocene. Comparing our ages and their probability density curves with those of glacial advances from the northeastern/eastern TP, the consistency of both records during different stages since the late Pleistocene suggested that the development of alluvial fans was driven by glacier activities, which yielded abundant outwash, feeding alluvial aggradations. Based on this finding, together with results of previous studies, we argued that the dynamics of alluvial geomorphic processes had a paleoclimatic origin rather than surface uplifts. Further studies indicated that the precipitation of glaciations originated from the ISM northward intrusion during the late MIS 5, MIS 3, and Holocene; however, it was mainly influenced by the westerlies during the Last Glaciation and Deglaciation. Therefore, the development of alluvial fans on the NETP represents coupling signals of the ISM and the westerlies on the interglacial–glacial cycle timescales. The coupling evolution of glacier activities and alluvial aggradations in the drainage basins of mountain-basin systems on the NETP provides a model for assessing the linkages between regional geomorphic processes and atmospheric circulations on hemispheric scales.

scholarly journals Hydrological assessment of flash flood hazards and the constructed mitigation measures in Wadis affecting Ain Al Soukhna, Northwest Gulf of Suez, Egypt

2021 ◽  
Author(s):  
Hanaa Megahed ◽  
Mohammed El Bastawesy
Keyword(s):  
Flash Flood ◽  
Flow Direction ◽  
Anthropogenic Activities ◽  
Flash Floods ◽  
Alluvial Fan ◽  
Mitigation Measures ◽  
Optical Remote Sensing ◽  
Gulf Of Suez ◽  
Flood Hazards ◽  
Industrial Zone

Considerable stretches of barren coastal areas of the Gulf of Suez and the Red Sea have been covered by various anthropogenic activities during the past few decades. Several dykes have been erected on the wadi beds constituting the catchment of Wadi Ghuwaiba, which encloses the industrial zone of Ain Al Soukhna on its large alluvial fan. The multitude of optical remote sensing data, Digital Elevation Model (DEM) and thematic geological data have been integrated into Geographic Information System (GIS) to estimate the hydrological parameters of flash floods, pathways and storage capabilities of the constructed dykes upstream of the industrial zone. Due to the absence of rainfall/runoff data for these ungagged wadis, a semi-distributed hydrological model was developed using the extracted morphometric parameters from the DEM from the analyses of satellite images. Manning equation was used to compute the open channel flow velocities, and the spatial functionalities into GIS were used to estimate the cumulative flow times. Next, the catchments were subdivided into cascading time-area zones using the derivatives of flow direction, accumulation and length from the DEM. Then, the spatially distributed unit hydrograph was computed using a hypothetical rainfall distribution and runoff coefficients, and the obtained time-area zones. The dykes have been visited in the field to measure the distribution of entrapped sediment loads due to the accumulation of torrential flows in these specific areas. The magnitudes of flash floods developed from an effective rainfall of 20 mm will not be fully contained in the storage areas of these dykes and overflows will reach the industrial zone via uncontrolled pathways, thus the area is prone to flash flood vulnerability and additional mitigation measures are still needed. The slack deposits are accumulating with notable rates and have reached 60 cm in some areas. It is strongly recommended to construct a conveying channel downstream of the dykes to collect the surplus overflow and discharge it into the Gulf of Suez via a well-defined channel-pathway

scholarly journals Experimental measurements of flood-induced impact forces on exposed elements

2018 ◽  
Vol 40 ◽  
pp. 05005 ◽  
Author(s):  
Michael Sturm ◽  
Bernhard Gems ◽  
Florian Keller ◽  
Bruno Mazzorana ◽  
Sven Fuchs ◽  
...  
Keyword(s):  
Force Measurement ◽  
Flow Patterns ◽  
Building Envelope ◽  
Alluvial Fan ◽  
Scale Model ◽  
Experimental Measurements ◽  
Alluvial Fans ◽  
Flood Hazards ◽  
Impact Forces ◽  
The Impact

Torrential flood hazards are a major threat for inhabited alluvial fans. They have the potential to relocate large amounts of sediment from the upper catchments to settlement areas on the alluvial fans where typically distributary processes take place. The approaching water-sediment-mixture impacting on building walls are part of a set of damage-generating mechanisms and may cause severe damages to buildings and infrastructure. It is difficult to predict the magnitude and temporal forces on buildings due to the complex flow patterns and sediment deposition processes around obstacles on the floodplain. Our work focuses on experimental measurements of impact forces of flood events on buildings at a 1:30 scale model. It covers the alluvial fan of the Schnannerbach torrent (Austria) with a set of building structures which are equipped with force measurement devices. The measured impact forces are correlated to the approaching flow heights. Influencing factors on the impacts forces such as surrounding buildings on the floodplain and the presence of openings in the building envelope are also analysed. The influence of different hydraulic flow patterns on the impact forces and regression analyses for an estimation of impact forces are presented.

Design flood estimates in mountain streams – the need for a geomorphic approach

2001 ◽  
Vol 28 (3) ◽  
pp. 425-439 ◽  
Author(s):  
Matthias Jakob ◽  
Peter Jordan
Keyword(s):  
Debris Flows ◽  
Regional Analysis ◽  
Landslide Dam ◽  
Flood Frequency ◽  
Flood Hazards ◽  
Design Flood ◽  
Rainfall Frequency ◽  
Outburst Floods ◽  
Streamflow Data ◽  
Geomorphic Processes

Estimates of design flood frequencies are routinely required for engineering purposes on ungauged streams and streams with a limited period of streamflow record. In these cases, the design flood is determined either by rainfall frequency–duration analysis, regional analysis of streamflow data, or by extrapolation of a short record from a gauged stream. Although these types of analyses are valuable in a first approximation of peak discharges for different return periods, there is increasing evidence that geomorphic processes such as debris flows, landslide dam failures, glacial outburst floods, and even snow avalanches in the watershed can significantly exceed these estimates. This paper highlights the problem of a purely hydrologic approach for design flood estimates using several case studies, and suggests procedures to routinely include geomorphic processes in standard flood frequency studies.Key words: debris flows, debris floods, landslide dams, flood hazards, outburst floods, frequency analysis.

scholarly journals Characteristics of Flood Flow with Active Sediment Transport in the Sozu River Flood Hazards at the Severe Rainfall Event in July 2018

2019 ◽  
Vol 14 (6) ◽  
pp. 886-893
Author(s):  
Daisuke Harada ◽  
◽  
Naoko Nagumo ◽  
Yousuke Nakamura ◽  
Shinji Egashira
Keyword(s):  
Sediment Transport ◽  
Flow Characteristics ◽  
Alluvial Fan ◽  
Flood Hazards ◽  
Field Surveys ◽  
Flood Peak ◽  
River Flood ◽  
Flood Peaks ◽  
Flood Flow ◽  
Second Peak

This study reveals the characteristics of flood flow with active sediment transport that caused the Sozu River flood disaster in July 2018. The results of field surveys revealed that the basin contains steep mountains and flat areas, facilitating the rapid transport of sediment produced in the mountains to downstream areas during the disaster. Two-dimensional numerical simulations of flood flow with sediment transport are conducted to realize the flood flow characteristics. As a result of the simulation, a huge amount of sediment deposition in the channel near the top of the alluvial fan increases the inundation damage at downstream areas. The results indicate that within two flood peaks during the disaster, the inundation in the second flood peak is more severe than that in the first peak, whereas the discharge of the second peak is much less than that in the first peak, caused by the reduction in the capacity of the original channel owing to the sand deposition during the first and second flood peaks.

scholarly journals Enhancing flood hazard estimation methods on alluvial fans using an integrated hydraulic, geological and geomorphological approach

2018 ◽  
Vol 18 (4) ◽  
pp. 1159-1171 ◽  
Author(s):  
Zeinab Mollaei ◽  
Kamran Davary ◽  
Seyed Majid Hasheminia ◽  
Alireza Faridhosseini ◽  
Yavar Pourmohamad
Keyword(s):  
Flood Hazard ◽  
Cost Effective ◽  
Developed Countries ◽  
The United States ◽  
Alluvial Fan ◽  
Geographical Information ◽  
Estimation Methods ◽  
Alluvial Fans ◽  
Flood Hazards ◽  
2D Model

Abstract. Due to the uncertainty concerning the location of flow paths on active alluvial fans, alluvial fan floods could be more dangerous than riverine floods. The United States Federal Emergency Management Agency (FEMA) used a simple stochastic model named FAN for this purpose, which has been practiced for many years. In the last decade, this model has been criticized as a consequence of development of more complex computer models. This study was conducted on three alluvial fans located in northeast and southeast Iran using a combination of the FAN model, the hydraulic portion of the FLO-2D model, and geomorphological information. Initial stages included three steps: (a) identifying the alluvial fans' landforms, (b) determining the active and inactive areas of alluvial fans, and (c) delineating 100-year flood within these selected areas. This information was used as an input in the mentioned three approaches of the (i) FLO-2D model, (ii) geomorphological method, and (iii) FAN model. Thereafter, the results of each model were obtained and geographical information system (GIS) layers were created and overlaid. Afterwards, using a scoring system, the results were evaluated and compared. The goal of this research was to introduce a simple but effective solution to estimate the flood hazards. It was concluded that the integrated method proposed in this study is superior at projecting alluvial fan flood hazards with minimum required input data, simplicity, and affordability, which are considered the primary goals of such comprehensive studies. These advantages are more highlighted in underdeveloped and developing countries, which may well lack detailed data and financially cannot support such costly projects. Furthermore, such a highly cost-effective method could be greatly advantageous and pragmatic for developed countries.

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