Modeling regional landslide susceptibility using dynamic soil moisture profiles     

Ram L. Ray  Jennifer M. Jacobs  Ellen M. Douglas 《山地科学学报》2018,15(8):1807-1824

A landslide susceptibility mapping study was performed using dynamic hillslope hydrology. The modified infinite slope stability model that directly includes vadose zone soil moisture (SM) was applied at Cleveland Corral, California, US and Krishnabhir, Dhading, Nepal. The variable infiltration capacity (VIC-3L) model simulated vadose zone soil moisture and the wetness index hydrologic model simulated groundwater (GW). The GW model predictions had a 75% NASH-Sutcliffe efficiency when compared to California’s in-situ GW measurements. The model performed best during the wet season. Using predicted GW and VIC-3L vadose zone SM, the developed landslide susceptibility maps showed very good agreement with mapped landslides at each study region. Previous quasi-dynamic model predictions of Nepal’s hazardous areas during extreme rainfall events were enhanced to improve the spatial characterization and provide the timing of hazardous conditions.  相似文献   

Evidence of melt/rock interaction in the Cr-spinel bearing wehrlite rocks of Bangriposi,India: Implications for nature of the metasomatic agent     

Tushar Mouli Chakraborti  Arijit Ray  Gautam Kumar Deb 《地学前缘(英文版)》2018,9(4):1213-1227

Cr-spinel bearing wehrlite rocks of Bangriposi are found within the multiply deformed metasedimentary rocks of Singhbhum Group belonging to North Singhbhum Mobile Belt of eastern India. Detailed mineralogical and geochemical studies reveal that these rocks have suffered a two-stage alteration involving a deeper level modal and cryptic metasomatism and a subsequent shallower depth pervasive hydrothermal alteration. Cryptic metasomatism is defined by elevated LREE contents of the wehrlite and its clinopyroxne grains. Metasomatism induced changes in the modal mineralogy of the rocks include the absence of primary orthopyroxene grains, presence of secondary diopside-phlogopite(now present as vermiculite) defining disequilibrium reaction textures and secondary orthopyroxene rims around serpentinized olivine. The mineralogical and geochemical changes due to the metasomatic event present a contrasting picture in regard to the metasomatic history of the rocks. Possible scenarios involving a single stage or multiple stage metasomatism events have been discussed while explaining the metasomatic reactions that took place. An attempt has been made to estimate the REE concentrations of the final equilibrating melt from REE contents of clinopyroxene grains of the wehrlite. The possibility of the LREE-enriched equilibrating melt of the wehrlite rocks(the deeper level metasomatic agent) being similar to residual melts from the E-MORB type parental melts of nearby gabbro suite has been ruled out by geochemical modeling. REE abundance patterns of several natural enriched melts have been compared with REE pattern of calculated LREE-enriched equilibrating melt of the wehrlite and most resemblance has been observed with calcic and potassic melts. It is therefore suggested that the Cr-spinel bearing wehrlite rocks of Bangriposi has been affected by a calcio-potassic melt in deeper level, prior to the shallow level serpentinization event.  相似文献   

Numerical modelling of rheological properties of landslide debris     

Ray  Arunava  Verma  Harshal  Bharati  Ashutosh Kumar  Rai  Rajesh  Koner  Radhakanta  Singh  Trilok Nath 《Natural Hazards》2022,110(3):2303-2327

Debris flow has caused severe human casualties and economic losses in landslide-prone areas around the globe. A comprehensive understanding of the morphology and deposition mechanisms of debris flows is crucial to delineate the extent of a debris flow hazard. However, due to inherent complex field topography and varying compositions of the flowing debris, coupled with a lack of fundamental understanding about the factors controlling the geomaterial flow, interparticle interactions and its final settlement resulted in a limited understanding of the flow behaviour of the landslide debris. In this study, a physical model was set up in the laboratory to simulate and calibrate the debris flow using PFC, a distinct element modelling-based software. After calibration, a case study of the Varunavat landslide was taken to validate the developed numerical model. Following validation with an acceptable level of confidence, several models were generated to evaluate the effect of slope height, slope angle, slope profile, and grain size distribution of the dislodged geomaterial in the rheological properties of debris flow. Both qualitative and quantitative analysis of the landslide debris flow was performed. Finally, the utility of retaining wall and their effect on debris flow is also studied with different retaining wall positions along the slope surface.

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40Ar/39Ar geochronology of subaerial lava flows of Barren Island volcano and the deep crust beneath the Andaman Island Arc,Burma Microplate     

Jyotiranjan S. Ray  Kanchan Pande  Rajneesh Bhutani 《Bulletin of Volcanology》2015,77(6):1-10

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Disseminated sulphides in basalts from the northern Central Indian Ridge: implications on late-stage hydrothermal activity     

Ranadip Banerjee  Dwijesh Ray 《Geo-Marine Letters》2015,35(2):91-103

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Estimation of flood damage functions for river basin planning: a case study in Bangladesh     

Y. C. Ethan Yang  Patrick A. Ray  Casey M. Brown  Abedalrazq F. Khalil  Winston H. Yu 《Natural Hazards》2015,75(3):2773-2791

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On the possible origin of troilite‐metal nodules in the Katol chondrite (L6‐7)          下载免费PDF全文

Dwijesh Ray  S. Ghosh  S.V.S. Murty 《Meteoritics & planetary science》2017,52(1):72-88

Microtextural study of a single troilite‐metal nodule (TMN) from the Katol L6‐7 chondrite, a recent fall (May, 2012) in India suggests that the TMN is primarily an aggregate of submicron‐scale intergrowth of troilite and kamacite (mean Ni: 6.18 wt%) juxtaposed with intensely fractured silicates, mainly olivine (Fa: 25 mole%), low‐Ca pyroxene (Fs: 21.2 mole%), and a large volume of maskelynite. Evidence of shock textures in the TMN indicates a high degree of shock metamorphism that involves plagioclase‐maskelynite and olivine‐wadsleyite/ringwoodite transformations and formation of quenched metal‐sulfide melt textures due to localized shear‐induced frictional melting. It is inferred that the TMN formation is an independent, localized event by a high energy impact and its subsequent incorporation in the ejected chondritic fragment of the parent body. Katol chondrite has been calibrated with a peak shock pressure of S5 (~45 GPa) after Stöffler et al. (1991), whereas peak shock pressure within the TMN exceeds the shock facies S6 (>45 GPa) following Bennett and McSween (1996) and Stöffler et al. (1991). Overall, the shock‐thermal history of the Katol TMN is dissimilar as compared to the host chondrite.  相似文献   

New insights on petrography and geochemistry of impactites from the Lonar crater,India          下载免费PDF全文

Dwijesh Ray  Dewashish Upadhyay  Saumitra Misra  Horton E. Newsom  Sambhunath Ghosh 《Meteoritics & planetary science》2017,52(8):1577-1599

The Lonar impact crater, India, is one of the few known terrestrial impact craters excavated in continental basaltic target rocks (Deccan Traps, ~65 Ma). The impactites reported from the crater to date mainly include centimeter‐ to decimeter‐sized impact‐melt bombs, and aerodynamically shaped millimeter‐ and submillimeter‐sized impact spherules. They occur in situ within the ejecta around the crater rim and show schlieren structure. In contrast, non–in situ glassy objects, loosely strewn around the crater lake and in the ejecta around the crater rim do not show any schlieren structure. These non–in situ fragments appear to be similar to ancient bricks from the Daityasudan temple in the Lonar village. Synthesis of existing and new major and trace element data on the Lonar impact spherules show that (1) the target Lonar basalts incorporated into the spherules had undergone minimal preimpact alteration. Also, the paleosol layer as preserved between the top‐most target basalt flow and the ejecta blanket, even after the impact, was not a source component for the Lonar impactites, (2) the Archean basement below the Deccan traps were unlikely to have contributed material to the impactite parental melts, and (3) the impactor asteroid components (Cr, Co, Ni) were concentrated only within the submillimeter‐sized spherules. Two component mixing calculations using major oxides and Cr, Co, and Ni suggest that the Lonar impactor was a EH‐type chondrite with the submillimeter‐sized spherules containing ~6 wt% impactor components.  相似文献   

A Global Synthesis of Managing Groundwater Dependent Ecosystems Under Sustainable Groundwater Policy   总被引：1，自引：0，他引：1       下载免费PDF全文

Melissa M. Rohde  Ray Froend  Jeanette Howard 《Ground water》2017,55(3):293-301

Groundwater is a vital water supply worldwide for people and nature. However, species and ecosystems that depend on groundwater for some or all of their water needs, known as groundwater dependent ecosystems (GDEs), are increasingly becoming threatened worldwide due to growing human water demands. Over the past two decades, the protection and management of GDEs have been incorporated into several water management policy initiatives worldwide including jurisdictions within Australia, the European Union, South Africa, and the United States. Among these, Australia has implemented the most comprehensive framework to manage and protect GDEs through its water policy initiatives. Using a science‐based approach, Australia has made good progress at reducing uncertainty when selecting management thresholds for GDEs in their water management plans. This has been achieved by incorporating appropriate metrics for GDEs into water monitoring programs so that information gathered over time can inform management decisions. This adaptive management approach is also accompanied by the application of the “Precautionary Principle” in cases where insufficient information on GDEs exist. Additionally, the integration of risk assessment into Australia's approach has enabled water managers to prioritize the most valuable and vulnerable ecologic assets necessary to manage GDEs under Australia's national sustainable water management legislation. The purpose of this paper is to: (1) compare existing global policy initiatives for the protection and management of GDEs; (2) synthesize Australia's adaptive management approach of GDEs in their state water plans; and (3) highlight opportunities and challenges of applying Australia's approach for managing GDEs under other water management policies worldwide.  相似文献   

Breaking walls towards fully open source hydrological modeling     

Kazi Rahman  Nicolas Ray  Grégory Giuliani  Chetan Maringanti  Chris George  Anthony Lehmann 《Water Resources》2017,44(1):23-30

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