Climate change,the monsoon,and rice yield in India   总被引：4，自引：1，他引：3  

Maximilian Auffhammer  V. Ramanathan  Jeffrey R. Vincent 《Climatic change》2012,111(2):411-424

Recent research indicates that monsoon rainfall became less frequent but more intense in India during the latter half of the Twentieth Century, thus increasing the risk of drought and flood damage to the country’s wet-season (kharif) rice crop. Our statistical analysis of state-level Indian data confirms that drought and extreme rainfall negatively affected rice yield (harvest per hectare) in predominantly rainfed areas during 1966–2002, with drought having a much greater impact than extreme rainfall. Using Monte Carlo simulation, we find that yield would have been 1.7% higher on average if monsoon characteristics, especially drought frequency, had not changed since 1960. Yield would have received an additional boost of nearly 4% if two other meteorological changes (warmer nights and lower rainfall at the end of the growing season) had not occurred. In combination, these changes would have increased cumulative harvest during 1966–2002 by an amount equivalent to about a fifth of the increase caused by improvements in farming technology. Climate change has evidently already negatively affected India’s hundreds of millions of rice producers and consumers.  相似文献   

Suspended sediment dynamics in the meltwater of Chhota Shigri glacier,Chandra basin,Lahaul-Spiti valley,India     

Virendra Bahadur Singh  AL. Ramanathan 《山地科学学报》2018,15(1):68-81

Present study shows suspended sediment dynamics in the meltwater of Chhota Shigri glacier, Himachal Pradesh, India for different melt seasons during the period 2011-2014. Maximum suspended sediment concentration in the meltwater was found during the month of July 2011, 2012 and 2014 constituting to 55.2%, 48.3% and 46.9%, respectively. Whereas in 2013, maximum suspended sediment concentration was observed in August accounting for 46.1% of the total. On the other hand, maximum suspended sediment load was monitored in the month of July 2011, 2012 and 2014 constituting 59.5%, 63% and 55.7% of the total, respectively. Whereas in 2013, maximum suspended sediment load was observed in the month of August accounting for 49.8% of the total suspended sediment load. Annual distribution of suspended sediment concentration (SSC) and suspended sediment load (SSL) in the Chhota Shigri glacier shows higher value of SSC and SSL during the study period 2012 and 2013, which may be due to the presence of high glacial runoff and negative mass balance of the studied area during these time periods. Marked diurnal variation has been observed in the SSC of meltwater. Strong correlation was observed between SSC and SSL with discharge. On the other hand, SSC and SSL also showed strong exponential correlation with air temperature of the studied area. Sediment yield from the catchment of Chhota Shigri glacier is high during the peak melt season (July and August) and low during the late melt season (September and October). The average value of erosion rate for Chhota Shigri glacier basin during the study period 2011-2014 was calculated to be 1.1 mm/yr, which is lower than the average erosion rate of other Himalayan glaciers such as Rakiot, Chorabari and Gangotri glaciers, which may be caused by its geological setting containing high erosion resistant rocks such as granite, granite gneiss and porphyritic granite.  相似文献   

A study on the high fluoride concentration in the magnesium-rich waters of hard rock aquifer in Krishnagiri district, Tamilnadu, India     

S. Manikandan  S. Chidambaram  AL. Ramanathan  M. V. Prasanna  U. Karmegam  C. Singaraja  P. Paramaguru  I. Jainab 《Arabian Journal of Geosciences》2014,7(1):273-285

Excess fluoride in groundwater affects the human health and results in dental and skeletal fluorosis. Higher concentration of fluoride was noted in hard rock terrain of the south India, in the Krishnagiri district of Tamilnadu. The region has a complex geology ranging from ultra basic to acid igneous rocks, charnockite and gneissic rocks. Thirty-four groundwater samples were collected from this study area and analysed for major cations and anions along with fluoride. The order of dominance of cations is Na⁺?>?Mg²⁺?>?Ca²⁺?>?K⁺ and the anions in the following order HCO₃ ^??>?Cl^??>?NO₃ ^??>?SO₄ ^2?. It is found that nearly 58 % of the samples have more fluoride ranging from 1 to 3 mg/L. It is also noted that high fluoride waters correspond to magnesium water types. This is due to the release of fluoride from the magnesium-bearing minerals like, biotite, hornblende, etc., or weathering of apatite/hydroxyapatites found in charnockites.  相似文献   

Hydrogeochemical assessment of groundwater in Neyveli Basin, Cuddalore District, South India     

M. V. Prasanna  S. Chidambaram  G. Senthil Kumar  AL Ramanathan  H. C. Nainwal 《Arabian Journal of Geosciences》2011,4(1-2):319-330

In the light of progressive depletion of groundwater reservoir and water quality deterioration of the Neyveli basin, an investigation on dissolved major constituents in 25 groundwater samples was performed. The main objective was detection of processes for the geochemical assessment throughout the area. Neyveli aquifer is intensively inhabited during the last decenniums, leading to expansion of the residential and agricultural area. Besides semi-aridity, rapid social and economic development stimulates greater demand for water, which is gradually fulfilled by groundwater extraction. Groundwaters of the study area are characterized by the dominance of Na?+?K over Ca?+?Mg. HCO₃ was found to be the dominant anion followed by Cl and SO₄. High positive correlation was obtained among the following ions: Ca–Mg, Cl–Ca,Mg, Na–K, HCO₃–H₄SiO₄, and F–K. The hydrochemical types in the area can be divided into two major groups: the first group includes mixed Ca–Mg–Cl and Ca–Cl types. The second group comprises mixed Ca–Na–HCO₃ and Ca–HCO₃ types. Most of the groundwater samples are within the permissible limit of WHO standard. Interpretation of data suggests that weathering, ion exchange reactions, and evaporation to some extent are the dominant factors that determine the major ionic composition in the study area.  相似文献   

A study on the factors affecting the stable isotopic composition in precipitation of Tamil Nadu,India     

S. Chidambaram  M. V. Prasanna  A. L. Ramanathan  K. Vasu  S. Hameed  U. K Warrier  K. Srinivasamoorthy  R. Manivannan  K. Tirumalesh  P. Anandhan  G. Johnsonbabu 《水文研究》2009,23(12):1792-1800

Stable isotope measurements in precipitation help us to form the basic inference about the origin and the state of water in different environments. The precipitation samples collected during the South West Monsoon (SWM) during August 2007 from 37 different locations in the state help in deriving the first preliminary local meteoric water line (LMWL) for the Tamil Nadu State. The study reveals that there are three main sources of water vapours, namely South East Arabian Sea (SEAS), Indian Ocean (IO) and evaporation from local water bodies. There are wide variations in the altitude and amount of rainfall received in the state. It is also noted that there is a significant variation in the latitude and the distance from the coast. Hence, an attempt is made in this paper to study the factors controlling the composition of stable isotopes in precipitation with reference to amount of rainfall, latitude, altitude and the continental effect. The altitude and continental effect shows good correlation to the variations in stable isotope composition. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Geobiology and geomicrobiology: Frontier areas in Earth System Science     

Ramanathan Baskar 《Journal of the Geological Society of India》2013,81(1):147-148

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Conservative models: parametric entropy vs. temporal entropy in outcomes     

Huang L  Ritzi RW  Ramanathan R 《Ground water》2012,50(2):199-206

The geologic architecture in aquifer systems affects the behavior of fluid flow and the dispersion of mass. The spatial distribution and connectivity of higher-permeability facies play an important role. Models that represent this geologic structure have reduced entropy in the spatial distribution of permeability relative to models without structure. The literature shows that the stochastic model with the greatest variance in the distribution of predictions (i.e., the most conservative model) will not simply be the model representing maximum disorder in the permeability field. This principle is further explored using the Shannon entropy as a single metric to quantify and compare model parametric spatial disorder to the temporal distribution of mass residence times in model predictions. The principle is most pronounced when geologic structure manifests as preferential-flow pathways through the system via connected high-permeability sediments. As per percolation theory, at certain volume fractions the full connectivity of the high-permeability sediments will not be represented unless the model is three-dimensional. At these volume fractions, two-dimensional models can profoundly underrepresent the entropy in the real, three-dimensional, aquifer system. Thus to be conservative, stochastic models must be three-dimensional and include geologic structure.  相似文献   

Fenton‐Type Oxidative Degradation of N,N‐Diethyl‐p‐phenylenediamine by a Mesoporous Wormhole Structured FeTUD‐1 Catalyst          下载免费PDF全文

Muthusamy Poomalai Pachamuthu  Sekar Karthikeyan  Ganesan Sekaran  Rajamanickam Maheswari  Anand Ramanathan 《洁净——土壤、空气、水》2015,43(3):375-381

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Geospatial Human‐environment Simulation through Integration of Massive Multiplayer Online Games and Geographic Information Systems     

Ola Ahlqvist  Thomas Loffing  Jay Ramanathan  Austin Kocher 《Transactions in GIS》2012,16(3):331-350

This article reports on the initial development of a generic framework for integrating Geographic Information Systems (GIS) with Massive Multi‐player Online Gaming (MMOG) technology to support the integrated modeling of human‐environment resource management and decision‐making. We review Web 2.0 concepts, online maps, and games as key technologies to realize a participatory construction of spatial simulation and decision making practices. Through a design‐based research approach we develop a prototype framework, “GeoGame”, that allows users to play board‐game‐style simulations on top of an online map. Through several iterations we demonstrate the implementation of a range of design artifacts including: real‐time, multi‐user editing of online maps, web services, game lobby, user‐modifiable rules and scenarios building, chat, discussion, and market transactions. Based on observational, analytical, experimental and functional evaluations of design artifacts as well as a literature review, we argue that a MMO GeoGame‐framework offers a viable approach to address the complex dynamics of human‐environmental systems that require a simultaneous reconciliation of both top‐down and bottom‐up decision making where stakeholders are an integral part of a modeling environment. Further research will offer additional insight into the development of social‐environmental models using stakeholder input and the use of such models to explore properties of complex dynamic systems.  相似文献   

Age of Saurashtra miliolites by U-Th decay series methods: possible implications to their origin     

N Hussain  N Bhandari  K R Ramanathan  B L K Somayajulu 《Journal of Earth System Science》1980,89(2):276-276

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