An assessment of the potential impact of climate change on flood risk in Mumbai   总被引：2，自引：1，他引：1  

Nicola Ranger  St��phane Hallegatte  Sumana Bhattacharya  Murthy Bachu  Satya Priya  K. Dhore  Farhat Rafique  P. Mathur  Nicolas Naville  Fanny Henriet  Celine Herweijer  Sanjib Pohit  Jan Corfee-Morlot 《Climatic change》2011,104(1):139-167

Managing risks from extreme events will be a crucial component of climate change adaptation. In this study, we demonstrate an approach to assess future risks and quantify the benefits of adaptation options at a city-scale, with application to flood risk in Mumbai. In 2005, Mumbai experienced unprecedented flooding, causing direct economic damages estimated at almost two billion USD and 500 fatalities. Our findings suggest that by the 2080s, in a SRES A2 scenario, an ??upper bound?? climate scenario could see the likelihood of a 2005-like event more than double. We estimate that total losses (direct plus indirect) associated with a 1-in-100 year event could triple compared with current situation (to $690?C$1,890 million USD), due to climate change alone. Continued rapid urbanisation could further increase the risk level. The analysis also demonstrates that adaptation could significantly reduce future losses; for example, estimates suggest that by improving the drainage system in Mumbai, losses associated with a 1-in-100 year flood event today could be reduced by as much as 70%.,We show that assessing the indirect costs of extreme events is an important component of an adaptation assessment, both in ensuring the analysis captures the full economic benefits of adaptation and also identifying options that can help to manage indirect risks of disasters. For example, we show that by extending insurance to 100% penetration, the indirect effects of flooding could be almost halved. We conclude that, while this study explores only the upper-bound climate scenario, the risk-assessment core demonstrated in this study could form an important quantitative tool in developing city-scale adaptation strategies. We provide a discussion of sources of uncertainty and risk-based tools could be linked with decision-making approaches to inform adaptation plans that are robust to climate change.  相似文献   

Evidences of CO<Subscript>2</Subscript> Leakage During the Last Deglaciation: The Need to Understand Deep-ocean Carbonate Chemistry of the Arabian Sea     

Smita N. Naik  Sushant S. Naik 《Journal of the Geological Society of India》2018,92(4):404-406

It is generally accepted view that the ventilation of Southern Ocean during the last deglaciation was the key factor in atmospheric CO₂ rise. Further, other sites were identified, like the western equatorial Pacific, the Sub-Antarctic Atlantic and the eastern equatorial Pacific. Now there are evidences that CO₂ was also released from the eastern Arabian Sea. The Arabian Sea is unique in characteristic, being land locked from the North and affected by monsoon winds and seasonal reversing circulations. Furthermore, the CO₂ outgassing noticed during deglaciation makes it an interesting region to understand if the outgassing occurred from the deeper waters and hence led to any rise in deepwater \([\rm{CO}_3^{2-}]\).  相似文献   

Day-1 INSAT-3DR Vicarious Calibration Using Reflectance-Based Approach Over Great Rann of Kutch     

Piyushkumar N. Patel  K. N. Babu  R. P. Prajapati  Vikram Sitapara  A. K. Mathur 《Journal of the Indian Society of Remote Sensing》2018,46(6):885-894

This study describes the post-launch calibration for visible (VIS) and shortwave infrared (SWIR) bands of Indian National Satellite System (INSAT)-3DR imager over Great Rann of Kutch (GROK) on Day-1 (15th September 2016), when the first time INSAT-3DR Imager camera was switched on. In order to account the characterization of errors and undetermined post-launch changes in sensor spectral response, this calibration activity was performed and extended for its monitoring to Day-56 (since the Day-1; 09th November 2016). A reflectance based technique is used in the present study. The surface reflectance and atmospheric variables were measured over the site as per solar and viewing geometry of the INSAT-3D scan. Top of atmosphere (TOA) spectral radiances were computed using 6SV (second simulation of the satellite signal in the solar spectrum) radiative transfer code with the in situ measurements as well as spectral response function of each channel. Preliminary results of the Day-1 vicarious calibration yield gain coefficients of 0.974 and 0.820 for VIS and SWIR channels respectively despite the inhomogeneity of the ground target caused by sufficient sub-surface soil moisture. In extension of the present study, the obtained gain coefficients were 1.001 and 0.9887 for VIS and SWIR, respectively, during Day-56 which indicates the performance of sensor is within the range of pre-launch laboratory calibration.  相似文献   

Phosphorus and iron cycling in deep saprolite,Luquillo Mountains,Puerto Rico     

Heather L. Buss  Ryan Mathur  Arthur F. White  Susan L. Brantley 《Chemical Geology》2010,269(1-2):52-61

Rapid weathering and erosion rates in mountainous tropical watersheds lead to highly variable soil and saprolite thicknesses which in turn impact nutrient fluxes and biological populations. In the Luquillo Mountains of Puerto Rico, a 5-m thick saprolite contains high microorganism densities at the surface and at depth overlying bedrock. We test the hypotheses that the organisms at depth are limited by the availability of two nutrients, P and Fe. Many tropical soils are P-limited, rather than N-limited, and dissolution of apatite is the dominant source of P. We document patterns of apatite weathering and of bioavailable Fe derived from the weathering of primary minerals hornblende and biotite in cores augered to 7.5 m on a ridgetop as compared to spheroidally weathering bedrock sampled in a nearby roadcut.Iron isotopic compositions of 0.5 N HCl extracts of soil and saprolite range from about δ⁵⁶Fe = 0 to ? 0.1‰ throughout the saprolite except at the surface and at 5 m depth where δ⁵⁶Fe = ? 0.26 to ? 0.64‰. The enrichment of light isotopes in HCl-extractable Fe in the soil and at the saprolite–bedrock interface is consistent with active Fe cycling and consistent with the locations of high cell densities and Fe(II)-oxidizing bacteria, identified previously. To evaluate the potential P-limitation of Fe-cycling bacteria in the profile, solid-state concentrations of P were measured as a function of depth in the soil, saprolite, and weathering bedrock. Weathering apatite crystals were examined in thin sections and an apatite dissolution rate of 6.8 × 10^? 14 mol m^? 2 s^? 1 was calculated. While surface communities depend on recycled nutrients and atmospheric inputs, deep communities survive primarily on nutrients released by the weathering bedrock and thus are tightly coupled to processes related to saprolite formation including mineral weathering. While low available P may limit microbial activity within the middle saprolite, fluxes of P from apatite weathering should be sufficient to support robust growth of microorganisms in the deep saprolite.  相似文献   

Copper isotope fractionation in acid mine drainage   总被引：4，自引：0，他引：4  

B.E. Kimball  R. Mathur  A.J. Wall  S.L. Brantley 《Geochimica et cosmochimica acta》2009,73(5):1247-1263

We measured the Cu isotopic composition of primary minerals and stream water affected by acid mine drainage in a mineralized watershed (Colorado, USA). The δ⁶⁵Cu values (based on ⁶⁵Cu/⁶³Cu) of enargite (δ⁶⁵Cu = −0.01 ± 0.10‰; 2σ) and chalcopyrite (δ⁶⁵Cu = 0.16 ± 0.10‰) are within the range of reported values for terrestrial primary Cu sulfides (−1‰ < δ⁶⁵Cu < 1‰). These mineral samples show lower δ⁶⁵Cu values than stream waters (1.38‰ ? δ⁶⁵Cu ? 1.69‰). The average isotopic fractionation (Δ_aq-min = δ⁶⁵Cu_aq − δ⁶⁵Cu_min, where the latter is measured on mineral samples from the field system), equals 1.43 ± 0.14‰ and 1.60 ± 0.14‰ for chalcopyrite and enargite, respectively. To interpret this field survey, we leached chalcopyrite and enargite in batch experiments and found that, as in the field, the leachate is enriched in ⁶⁵Cu relative to chalcopyrite (1.37 ± 0.14‰) and enargite (0.98 ± 0.14‰) when microorganisms are absent. Leaching of minerals in the presence of Acidithiobacillus ferrooxidans results in smaller average fractionation in the opposite direction for chalcopyrite (Δ_aq-min^o=-0.57±0.14‰, where min^o refers to the starting mineral) and no apparent fractionation for enargite (Δ_aq-min^o=0.14±0.14‰). Abiotic fractionation is attributed to preferential oxidation of ⁶⁵Cu⁺ at the interface of the isotopically homogeneous mineral and the surface oxidized layer, followed by solubilization. When microorganisms are present, the abiotic fractionation is most likely not seen due to preferential association of ⁶⁵Cu_aq with A. ferrooxidans cells and related precipitates. In the biotic experiments, Cu was observed under TEM to occur in precipitates around bacteria and in intracellular polyphosphate granules. Thus, the values of δ⁶⁵Cu in the field and laboratory systems are presumably determined by the balance of Cu released abiotically and Cu that interacts with cells and related precipitates. Such isotopic signatures resulting from Cu sulfide dissolution should be useful for acid mine drainage remediation and ore prospecting purposes.  相似文献   

Migration patterns in India     

Smita  Chandna RC 《Population geography : a journal of the Association of Population Geographers of India》1991,13(1-2):31-52

"The chief objective of the present paper is to comprehend the broad spatial patterns of internal migrations in India." Aspects considered include data constraints, the magnitude of internal migration, interstate migration, migration to rural and to urban destinations, spatial patterns, and areas of origin and destination.  相似文献   

Development of an eye-wall like structure in a tropical cyclone model simulation   总被引：1，自引：0，他引：1  

Mukut B. Mathur 《Dynamics of Atmospheres and Oceans》1998,27(1-4)

Structural changes during the intensification of a tropical storm into a hurricane in a numerical simulation are examined. A 10 layer primitive equation model that employs a horizontal grid spacing of 20 km over 4400 × 4400 km area is integrated. An elongated band in vertical motion over the storm area intensifies slowly during the first few hours. In the upper troposphere high pressures arise due to condensational heating. Between 8–12 h strong outflow winds develop in the upper troposphere due to the increased pressure gradients. Strong divergence occurs in the outflow wind region, and a large increase in the vertical motion, condensational heating and intensification rate of the storm ensues. Between 12–24 h the elongated band of the storm stage transforms into an eye-wall like structure, and the tropical storm intensifies into a hurricane. Regions with negative moist potential vorticity appear in the high troposphere. Widening of area of condensation and slanting of the convergence area occurs with height in the high level negative moist potential vorticity regions. Results suggest that the formation of anvil clouds in some cases may be due to the development of slantwise convection on the outer periphery of a hurricane's eye-wall.  相似文献   

Exploration potential of Cu isotope fractionation in porphyry copper deposits   总被引：6，自引：0，他引：6  

Ryan Mathur  Spencer TitleyFernando Barra  Susan BrantleyMarc Wilson  Allison PhillipsFrancisco Munizaga  Victor MaksaevJeff Vervoort  Garret Hart 《Journal of Geochemical Exploration》2009

We examined the copper isotope ratio of primary high temperature Cu-sulfides, secondary low temperature Cu-sulfides (and Cu-oxides) as well as Fe-oxides in the leach cap, which represent the weathered remains of a spectrum of Cu mineralization, from nine porphyry copper deposits. Copper isotope ratios are reported as δ⁶⁵Cu‰ = ((⁶⁵Cu/⁶³Cu_sample/⁶⁵Cu/⁶³Cu_{NIST 976 standard}) − 1) ? 10³. Errors for all the analyses are ± 0.14‰ (determined by multiple analyses of the samples) and mass bias was corrected through standard-sample-standard bracketing. The overall isotopic variability measured in these samples range from − 16.96‰ to 9.98‰.  相似文献   

Narrow-line Seyfert 1 galaxies and the evolution of galaxies and active galaxies   总被引：1，自引：0，他引：1  

Smita Mathur 《Monthly notices of the Royal Astronomical Society》2000,314(4):L17-L20

Narrow Line Seyfert 1 galaxies (NLS1s) are intriguing owing to their continuum as well as emission-line properties. The observed peculiar properties of the NLS1s are believed to be as a result of an accretion rate close to the Eddington limit. As a consequence of this, for a given luminosity, NLS1s have smaller black hole (BH) masses compared with normal Seyfert galaxies. Here we argue that NLS1s might be Seyfert galaxies in their early stage of evolution and as such may be low-redshift, low-luminosity analogues of high-redshift quasars. We propose that NLS1s may reside in rejuvenated, gas-rich galaxies. We also argue in favour of collisional ionization for production of Fe  ii in active galactic nuclei.  相似文献   

Update on g‐mode research     

R.A. García  A. Jimnez  S. Mathur  J. Ballot  A. Eff‐Darwich  S. J. Jimnez‐Reyes  P. L. Pall  J. Provost  S. Turck‐Chize 《Astronomische Nachrichten》2008,329(5):476-484

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