Where does all the gravel go? Tracking landslide sediment from the 2015 Gorkha earthquake along the Kosi River, Nepal

2020 ◽  
Author(s):  
Emma Graf ◽  
Hugh Sinclair ◽  
Mikael Attal
Keyword(s):  
Large Scale ◽  
Size Fraction ◽  
Sediment Supply ◽  
Gorkha Earthquake ◽  
Gangetic Plain ◽  
Gangetic Plains ◽  
2015 Gorkha Earthquake ◽  
Channel Aggradation ◽  
The Impact ◽  
The Himalaya

<p>Rivers draining the Himalaya and feeding the Indo-Gangetic plain support around 10% of the world’s population. However, these rivers are also prone to frequent and often devastating floods such as the 2008 Kosi floods which displaced more than 2.5 million people. Changes in sediment supply from the Himalaya influence the magnitude and distribution of floods through changing capacity and routing respectively. Widespread landsliding following the 2015 Gorkha (Nepal) earthquake increased suspended sediment supply to the river network and is expected to result in some degree of coarse bedload aggradation and increased rates of channel migration at the mountain front. Given the significant amounts of channel aggradation observed in the aftermath of similar events, understanding the timescales of sediment transport following the 2015 Gorkha earthquake and the impact of any resulting sediment wave on flooding in the Gangetic plains is crucial. We track the gravel size fraction of the landslide sediment along the Kosi River (East Nepal) by mapping zones of sediment input from optical satellite imagery and constructing a time series of high-resolution channel cross-sections using an Acoustic Doppler Current Profiler (ADCP) in the years following the earthquake. We use these datasets to identify zones of channel aggradation and migrating sediment, and test whether the changes are consistent with the location of sediment sources (landslides) and magnitude of the monsoon floods with the aid of landslide inventories and flow data. While initial results show a marked increase in coarse sediment following the 2015 monsoon, we see little evidence of large-scale downstream migration of any sediment pulse, indicating the Gorkha landslides may have less of an impact on flood and sediment dynamics on the Indo-Gangetic plains than expected from comparison with similar events. We suggest that the Gorkha landslides may not be connected to the fluvial system to the same extent as for similar events and revegetated rapidly, and therefore did not release significant amounts of sediment into channels after the initial post-2015 monsoon pulse.</p>

scholarly journals Comparison of Earthquake-Triggered Landslide Inventories: A Case Study of the 2015 Gorkha Earthquake, Nepal

Geosciences ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 437 ◽  
Author(s):  
Meena ◽  
Tavakkoli Piralilou
Keyword(s):  
Risk Mitigation ◽  
Landslide Susceptibility Mapping ◽  
Gorkha Earthquake ◽  
Area Distribution ◽  
2015 Gorkha Earthquake ◽  
The World ◽  
Mapping Techniques ◽  
Event Based ◽  
The Impact

Despite landslide inventories being compiled throughout the world every year at different scales, limited efforts have been made to critically compare them using various techniques or by different investigators. Event-based landslide inventories indicate the location, distribution, and detected boundaries of landslides caused by a single event, such as an earthquake or a rainstorm. Event-based landslide inventories are essential for landslide susceptibility mapping, hazard modeling, and further management of risk mitigation. In Nepal, there were several attempts to map landslides in detail after the Gorkha earthquake. Particularly after the main event on 25 April 2015, researchers around the world mapped the landslides induced by this earthquake. In this research, we compared four of these published inventories qualitatively and quantitatively using different techniques. Two principal methodologies, namely the cartographical degree of matching and frequency area distribution (FAD), were optimized and applied to evaluate inventory maps. We also showed the impact of using satellite imagery with different spatial resolutions on the landslide inventory generation by analyzing matches and mismatches between the inventories. The results of our work give an overview of the impact of methodology selection and outline the limitations and advantages of different remote sensing and mapping techniques for landslide inventorying.

Geodynamic evolution of the East Carpathian Foreland Basin since the Middle Miocene: Implications for sediment supply to the Black Sea and Dacian Basin

2020 ◽  
Author(s):  
Arjan de Leeuw ◽  
Stephen Vincent ◽  
Anton Matoshko ◽  
Andrei Matoshko ◽  
Marius Stoica ◽  
...  
Keyword(s):  
Black Sea ◽  
Large Scale ◽  
Drainage System ◽  
Foreland Basin ◽  
Continental Collision ◽  
Sediment Supply ◽  
The Black Sea ◽  
Accretionary Wedge ◽  
Sedimentary Architecture ◽  
The Impact

<p>The Carpathian orogen is part of the Alpine-Himalayan collision zone and formed as the result of the collision of the Tisza-Dacia and ALCAPA mega-units with the European southern margin, following a protracted phase of subduction, slab roll-back and accretionary wedge formation. The foreland basin of the East Carpathians is 800 km long and stretches out across Poland, Ukraine, Moldova and Romania. We use the results of our intensive field research to unravel the sedimentary architecture of this basin and reveal how it responded to the final phases of foreland vergent thrusting, continental collision and subsequent slab detachment. We discuss the asymmetry in the basins evolution and eventual inversion and relate this to the diachronous evolution of the Carpathian orogen. We also address the impact of changing subsidence patterns and base-level changes on connectivity with the Central and Eastern Paratethys, important for faunal exchange and patterns of endemism. We finally show that continental collision led to the establishment of a Late Miocene NW-SE prograding axial drainage system in the foreland supplying abundant sediment to the NW Black Sea, thus triggering large-scale shelf edge progradation.</p>

scholarly journals Modeling of Regional Hydroclimate Change over the Indian Subcontinent: Impact of the Expanding Thar Desert

2011 ◽  
Vol 24 (12) ◽  
pp. 3089-3106 ◽  
Author(s):  
Massimo Bollasina ◽  
Sumant Nigam
Keyword(s):  
Summer Monsoon ◽  
Large Scale ◽  
Asian Summer Monsoon ◽  
Vegetation Type ◽  
Indian Subcontinent ◽  
Monsoon Circulation ◽  
Thar Desert ◽  
South Asian Summer Monsoon ◽  
Gangetic Plain ◽  
The Impact

Abstract The Thar Desert between northwestern India and Pakistan is the most densely populated desert region in the world, and the vast surrounding areas are affected by rapid soil degradation and vegetation loss. The impact of an expanded desert (implemented by changing vegetation type and related greenness fraction, albedo, surface roughness length, emissivity, among others) on the South Asian summer monsoon hydroclimate is investigated by means of 7-month, 4-member ensemble sensitivity experiments with the Weather Research and Forecasting model. It is found that extended desertification significantly affects the monsoon at local and large scales. Locally, the atmospheric water cycle weakens because precipitation, evaporation, and atmospheric moisture convergence all decrease; soil moisture and runoff reduce too. Air temperature cools because of an increase in albedo (the desert makes the area brighter) and a reduction of surface turbulent fluxes; the cooling is partially offset by adiabatic descent, generated to maintain thermodynamic balance and originating at the northern flank of the low-level anticyclone forced by desert subsidence. Regionally, an anomalous northwesterly flow over the Indo-Gangetic Plain weakens the monsoon circulation over northeastern India, causing precipitation to decrease and the formation of an anomalous anticyclone in the region. As a result, the middle troposphere cools because of a decrease in latent heat release, but the ground heats up because of a reduction in cloudiness. At larger scale, the interaction between the anomalous circulation and the mountains leads to an increase in precipitation over the eastern Himalayas and Indochina. The findings of this study reveal that the expansion of the Thar Desert can lead to a pronounced and large-scale impact on summer monsoon hydroclimate, with a potential to redistribute precious water over South Asia.

scholarly journals On the impact of earthquake-induced landslides on Red Panda Ailurus fulgens (Mammalia: Carnivora: Ailuridae) habitat in Langtang National Park, Nepal

2021 ◽  
Vol 13 (9) ◽  
pp. 19191-19202
Author(s):  
Yogesh Rana Magar ◽  
Man Kumar Dhamala ◽  
Ajay Mathema ◽  
Raju Chauhan ◽  
Sijar Bhatta
Keyword(s):  
National Park ◽  
Geographical Information ◽  
Infrastructure Development ◽  
Gorkha Earthquake ◽  
Potential Habitat ◽  
2015 Gorkha Earthquake ◽  
Red Panda ◽  
Average Size ◽  
The Impact ◽  
Panda Habitat

In addition to the threats of human encroachment, infrastructure development, tourism activities, habitat fragmentation, and human-wildlife interactions, natural disasters also pose a threat to the habitat of endangered species such as the Red Panda. This study aims to assess the impact of the 2015 Gorkha earthquake-induced landslides on the Red Panda’s habitat in Langtang National Park (LNP), central Nepal Himalaya. Remote sensing and geographical information system were applied to estimate the potential and core habitats of the Red Panda, and collect information on earthquake-induced landslides. Field sampling and verification of remotely collected data were done within a year of the earthquake. Considering preferred vegetation types, elevation range, aspects, distance from water sources, and Red Panda presence points, an area of 214.34 km2 was estimated as the potential habitat of Red Panda in the Park. Thirty-nine landslides were identified in LNP triggered by the Gorkha earthquake, 14 of which occurred in the core Red Panda habitat. As a result of the earthquake-induced landslides, a significant decrease in tree density was observed in the areas affected by the landslides. Similarly, the bamboo cover was observed to be significantly lower in the areas affected by landslides compared to the unaffected adjacent areas. The average size of the landslide, causing damage to the Red Panda habitat was 0.8 ha. The potential habitat damaged by the earthquake-induced landslide was estimated to be 11.20 ha which is equivalent to the habitat required by one Red Panda. The findings could be useful in initiating restoration of the damaged Red Panda habitat in LNP. 

Seismic Assessment of RC Arch Bridge: A Case of 2015 Gorkha Earthquake

2019 ◽  
Vol 15 (1) ◽  
pp. 47-53
Author(s):  
Prakash Gaire ◽  
Ma Hongwang
Keyword(s):  
Ground Motion ◽  
Time History ◽  
Time History Analysis ◽  
Nonlinear Time History Analysis ◽  
Gorkha Earthquake ◽  
Arch Bridge ◽  
History Analysis ◽  
2015 Gorkha Earthquake ◽  
Seismic Force ◽  
The Impact

Nepal Himalayas is one of the most seismic vulnerable zones. The active tectonic action impels the assessment of structures in possible seismic hazards including the bridge structures. This paper presents the impact of the 2015 Gorkha earthquake on the existing reinforced concrete arch bridge at Chobhar, Nepal. A three-dimensional model of the bridge is constructed using Open Sees platform. Nonlinear pushover analysis was performed to find the displacement capacity of the bridge. Ground motion from the main shock of the 2015 Gorkha earthquake is used in this study. Nonlinear time history analysis is performed with three orthogonal ground motions applied in the transverse, longitudinal and vertical direction of the bridge. The study investigates the safety of the bridge scaling up the ground motion to potential PGA in Nepal Himalayas; the result demonstrated the necessity of retrofit to ensure the safety level. Moreover, the horizontal seismic force obtained from the time history analysis is compared with the force obtained from the design code of the bridge. Also, the design force as per the present code (revised code) is presented.

scholarly journals Impact of Snow-Darkening by Deposition of Light-Absorbing Aerosols on Snow Cover in the Himalaya-Tibetan-Plateau and Influence on the Asian Monsoon: A Possible Mechanism for the Blanford Hypothesis 

2018 ◽  
Author(s):  
William K. Lau ◽  
Kyu-Myong Kim
Keyword(s):  
Tibetan Plateau ◽  
Snow Cover ◽  
Asian Monsoon ◽  
The Tibetan Plateau ◽  
Surface Solar Radiation ◽  
Gangetic Plain ◽  
Northern India ◽  
Absorbing Aerosols ◽  
The Impact ◽  
The Himalaya

The impact of snow darkening by deposition of light absorbing aerosols (LAAs) on snow cover over the Himalaya-Tibetan-Plateau (HTP) and influence on the Asian monsoon are investigated using the NASA Goddard Earth Observing System Model Version 5 (GEOS-5). We find that during April-May-June, deposition of LAAs on snow leads to a reduction in surface albedo, initiating a sequence of feedback processes, starting with increased surface solar radiation, rapid snowmelt in HTP and warming of the surface and upper troposphere, followed by enhanced low-level southwesterlies and increased dust loading over the Himalayas-Indo-Gangetic Plain. The warming is amplified by increased dust aerosol heating, and subsequently amplified by latent heating from enhanced precipitation over the Himalaya foothills and northern India, via the Elevated Heat Pump (EHP) effect during June-July-August. The reduced snow cover in the HTP anchors the enhanced heating over the Tibetan Plateau and its southern slopes, in conjunction with an enhancement of the Tibetan Anticyclone, and the development of an anomalous Rossby wavetrain over East Asia, leading to weakening of the subtropical westerly jet, and northward displacement and intensification of the Mei-Yu rainbelt. Our results suggest that atmosphere-land heating by LAAs, particularly desert dust play a fundamental role in physical processes underpinning the snow-monsoon relationship proposed by Blandford more than a century ago.

scholarly journals Deposition of light-absorbing particles in glacier snow of the Sunderdhunga Valley, the southern forefront of Central Himalaya

2020 ◽  
Author(s):  
Jonas Svensson ◽  
Johan Ström ◽  
Henri Honkonen ◽  
Eija Asmi ◽  
Nathaniel B. Dkhar ◽  
...  
Keyword(s):  
Large Scale ◽  
Anthropogenic Activities ◽  
Central Himalaya ◽  
Snow Layer ◽  
Gangetic Plain ◽  
Central Himalayas ◽  
Indo Gangetic Plain ◽  
The Himalaya ◽  
Very High ◽  
Fractional Absorption

Abstract. Anthropogenic activities on the Indo-Gangetic Plain emit vast amounts of light-absorbing particles (LAP) into the atmosphere, modifying the atmospheric radiation scheme. With transport to the nearby Himalayan mountains and deposition to its surfaces the particles contribute to glacier and snowmelt via darkening of the highly reflective snow. The Central Himalayas have been identified as a region where LAP are especially pronounced in glacier snow, but still remain a region where measurements of LAP in the snow are scarce. Here we study the deposition of LAP in five snow pits sampled in 2016 (and one from 2015) from two glaciers in the Sunderdhunga valley, state of Uttarakhand, India, Central Himalaya. The snow pits display a distinct melt layer interleaved by younger snow above, and older snow below. The LAP exhibit a large vertical distribution in these different snow layers. For the analyzed elemental carbon (EC), the younger snow layers in the different pits show similarities, and can be characterized by a deposition constant of about 50 µg m−2 mm−1 while the old snow layers also indicate similar values, and can be described with deposition constant of roughly 150 µg m−2 mm−1. The melt layer, contrarily, display no similar trends between the pits. Instead, it is characterized by very high amounts of LAP, and differ in orders of magnitude for concentration between the pits. The melt layer is likely a result of strong melting that took place during the summers of 2015 and 2016. The mineral dust fractional absorption is slightly below 50 % for the young and old snow layer, whereas in the melt layer is the dominating light absorbing constituent, thus, highlighting the importance of dust in the region. Our results indicate the problems with complex topography in the Himalaya, but nonetheless, can be useful in large-scale assessments of LAP in Himalayan snow.

scholarly journals Response of Zero Tillage Technique on Wheat Production in the Middle Indo-Gangetic Plains of Nalanda (Bihar)

2020 ◽  
pp. 76-82
Author(s):  
V. K. Singh ◽  
Abhishek Pandey ◽  
V. Y. Deshpande ◽  
B. Shivarudrappa
Keyword(s):  
Large Scale ◽  
Growth Yield ◽  
Zero Tillage ◽  
Gangetic Plain ◽  
Gangetic Plains ◽  
Wheat Production ◽  
Significant Difference ◽  
Economic Parameters ◽  
Monetary Return ◽  
Tillage Method

The present study was undertaken to compare the response of zero tillage method and conventional method on wheat production with respect to various growth, yield and economic parameters in the middle Indo-Gangetic Plains of Nalanda district of Bihar. The study was conducted during Rabi seasons of 2017-18 and 2018-19. Fourteen farmers were selected for the study, 7 of whom sowed with zero tillage machine and 7 followed broadcasting method. Four observation from each plot were taken, therefore, total 56 observations were taken for both the methods. Results showed that higher mean plant height was recorded by Zero Tillage (ZT) method (83.07±128 cm) followed by broadcasting method (79.57±187 cm) that shows significant difference. Significantly mean higher no. of tillers per square meters was recorded by ZT method (556.57±21.28) as compared to broadcasting method (501.07±13.48). Mean spike length was significantly higher in case of ZT method (11.96±0.53 cm) compared to broadcasting method (11.03±0.22 cm). Significantly higher mean no. of grains per spike was recorded in ZT method (45.42±0.93) compared to broadcasting method (42.46±1.03). Significantly higher mean 1000- grain weight (g) were recorded in ZT method (42.07±0.61) compared to broadcasting method (40.03±0.67). Highly significant difference was recorded in grain yield (tonnes/ha) between ZT (3.82±0.03) and broadcasting method (3.68±0.04). Also, there were highly significant difference recorded in all the economic parameters between ZT and broadcast method. Cost of cultivation (Rs. /ha), gross monetary return (Rs. /ha), net monetary return (Rs. /ha) and BCR for ZT method are 37564±289, 70657±620, 33093±677 and 1.88±0.02. Corresponding values for broadcasting method are 40427±256, 68087±728, 27659±759 and 1.68±0.02. From the two years on farm research study it is concluded that the Zero tillage method of wheat cultivation is cost saving, more remunerative with timely sowing and helpful for areas where burning of paddy straw after paddy harvesting is widely prevalent. This method can be promoted among the farmers in Bihar and other middle Indo- Gangetic Plain regions for large scale adoption.

scholarly journals Dynamics of Domestic Water Consumption in the Urban Area of the Kathmandu Valley: Situation Analysis Pre and Post 2015 Gorkha Earthquake

Water ◽  
2017 ◽  
Vol 9 (3) ◽  
pp. 222 ◽  
Author(s):  
Sadhana Shrestha ◽  
Yoko Aihara ◽  
Arun Prasad Bhattarai ◽  
Niranjan Bista ◽  
Sudarshan Rajbhandari ◽  
...  
Keyword(s):  
Water Supply ◽  
Water Use ◽  
Water Consumption ◽  
Kathmandu Valley ◽  
Domestic Water ◽  
Wealth Status ◽  
Gorkha Earthquake ◽  
2015 Gorkha Earthquake ◽  
Domestic Water Consumption ◽  
The Impact

Information regarding domestic water consumption is vital, as the Kathmandu Valley will soon be implementing the Melamchi Water Supply Project; however, updated information on the current situation after the 2015 Gorkha Earthquake (GEQ) is still lacking. We investigated the dynamics of domestic water consumption pre- and post-GEQ. The piped water supply was short, and consumption varied widely across the Kathmandu Upatyaka Khanepani Limited (KUKL) branches and altitude. The reduction in piped, ground, and jar water consumption and the increase in tanker water consumption post-GEQ appeared to be due to the impact of the GEQ. However, the impact did not appear to be prominent on per capita water consumption, although it was reduced from 117 to 99 L post-GEQ. Piped, ground, and tanker water use were associated with an increase and jar water use was associated with a decrease in water consumption. Despite improvements in quantity, inequality in water consumption and inequity in affordability across wealth status was well established. This study suggests to KUKL the areas of priority where improvements to supply are required, and recommends an emphasis on resuming performance. Policy planners should consider the existing inequity in affordability, which is a major issue in the United Nations Sustainable Development Goals.

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