On Simulation and Analysis of Variable‐Rate Pumping Tests     

Phoolendra Kumar Mishra  Velimir Vessilinov  Hoshin Gupta 《Ground water》2013,51(3):469-473

Analytical solutions for constant‐rate pumping tests are widely used to infer aquifer properties. In this note, we implement a methodology that approximates the time‐varying pumping record as a series of segments with linearly varying pumping rates. We validate our approach using an analytical solution for a sinusoidally varying pumping test. We also apply our methodology to analyze synthetic test data and compare the results with those from a commonly used method where rate variations are represented by a series of constant‐rate steps.  相似文献   

Dynamic,Mechanistic, and Thermodynamic Modeling of Zn(II) Ion Biosorption onto Zinc Sequestering Bacterium VMSDCM     

Vishal Mishra  Chandrajit Balomajumder  Vijay K. Agarwal 《洁净——土壤、空气、水》2013,41(9):883-889

The surface of the bacterial cells before the biosorption of Zn(II) ion has been found rough, heterogeneous, and non‐crystalline together with tremendous protrusions and negatively charged functional groups. The bacterium was characterized as rod shaped with Gram‐negative type of cell wall structure. In reaction dynamics, pseudo‐second‐order kinetics with higher linear correlation coefficient (R²) ranging between 0.97 and 0.99, lower sum of square errors (SSE) (0.035–0.081) and chi (χ²) (0.0013–0.009) provided a better explanation of sorption of Zn(II) ion on bacterium surface as compared to pseudo‐first‐order model. The removal of Zn(II) was governed by both film and intra‐particle diffusion at onset and later stage of sorption of metal ion on the surface of bacterial cells. The R² (0.92–0.94) for intra‐particle diffusion model was quite higher with lower values of SSE (9.56–16.33) and chi (χ²) (11.26–19.65) against the Bangham's model. The positive value of ΔH (16.628 × 10^?6 kJ/mol) and ΔS (5320.90 kJ/mol/K) showed that the biosorption of Zn(II) ion across liquid phase on bacterial surface was endothermic with increased randomness at solid–liquid interface. The negative values of ΔG demarcated the whole process as spontaneous in nature. In the present work, the distribution coefficient was found to be > 0.5 at various temperature ranges. At the attainment of equilibrium, the residual concentration of Zn(II) ion in liquid phase was around 0.6 mg/L, which was much below the limit described by United States Environmental Protection Agency (USEPA), i.e. 5 mg/L.  相似文献   

Plume and bloom: effect of the Mississippi River diversion on the water quality of Lake Pontchartrain     

Deepak R. Mishra  Sachidananda Mishra 《国际地球制图》2013,28(7):555-568

The opening of the Bonnet Carré spillway to prevent flood threat to New Orleans in April 2008 created a sediment plume in the Lake Pontchartrain. The nutrient rich plume triggered a massive algal bloom in the lake. In this article, we have quantified the spatio-temporal distribution of the plume (suspended solids) and the bloom (chlorophyll-a (chl-a)) in the lake using remotely-sensed data. We processed the Moderate-resolution Imaging Spectroradiometer satellite data for mapping the total suspended solids (TSS) and chl-a concentrations. An existing algorithm was used for estimating TSS whereas a novel slope model was developed to predict the per-pixel chl-a concentration. Both algorithms were successful in capturing the spatio-temporal trend of TSS and chl-a concentrations, respectively. Algal growth was found to be inversely related to TSS concentrations and a time lag of ～45 days existed between the spillway opening and the appearance of the first algal bloom at an observation location.  相似文献   

Study of seasonal variation of PM2.5 concentration associated with meteorological parameters at residential sites in Delhi,India     

Singh  Bhupendra Pratap  Singh  Deepak  Kumar  Krishan  Jain  Vinod Kumar 《Journal of Atmospheric Chemistry》2021,78(3):161-176

The seasonal variation of particulate matter and its relationship with meteorological parameters were measured at five different residential sites in Delhi. Sampling was carried out for one year including all three seasons (summer, monsoon, and winter). The yearly average concentration of particulate matter (PM_2.5) was 135.16 ± 41.34 µg/m³. The highest average values were observed in winter (208.44 ± 43.67 µg/m³) and the lowest during monsoon season (80.29 ± 39.47 µg/m³). The annual average concentration of PM_2.5 was found to be the highest at the Mukherjee Nagar site (242.16 µg/m³ ) during the winter and lowest at (Jawaharlal Nehru University) JNU (35.65 µg/m³) during the monsoon season. The strongest correlation between PM mass and a meteorological parameter was a strong negative correlation with temperature (R2=0.55). All other parameters were weakly correlated (R2<0.2) with PM mass.

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Analysis and farmers’ perception of climate change in the Kashmir Valley,India     

Mahdi  S. Sheraz  Dhekale  B. S.  Jan  Rukhsana  Bhat  M. Anwar  Hussain  Ashaq  Jehangir  Intikhab Aalum  Sofi  Najeebul Rehman  Ahmed  Latief  Qureshi  Asif M. Iqbal  Aezum  Aziz Mujtaba  Bangroo  Shabir A.  Wani  Owais Ali  Bahar  F. A.  Mishra  S. K. 《Theoretical and Applied Climatology》2022,149(1-2):727-741

Theoretical and Applied Climatology - Analysis of climatic variables is important for the detection and attribution of climate change trends and has received considerable attention from researchers...  相似文献   

Mapping of seawater inundation along Nagapattinam based on field observations   总被引：1，自引：1，他引：0  

M. V. Ramana Murthy  N. T. Reddy  Y. Pari  Tune Usha  P. Mishra 《Natural Hazards》2012,60(1):161-179

Nagapattinam, in the east coast of India, was severely affected during the deadliest Indian Ocean tsunami of December 26, 2004. The tsunami caused heavy damage to life and property, and the death toll was about 3,378 in Nagapattinam taluk. Certain villages along the coast witnessed large inundation while adjacent villages were protected from the fury of the tsunami waves. This study was carried out to examine the underlying causes for the vulnerability along Nagapattinam coast with the help of field observations, remote sensing, and geographical information system as tools. Coastal areas with high sand dunes have been protected from tsunami, and areas adjacent to backwaters were inundated. Realtime Kinematic Global Positioning System and high-resolution satellite data were used to map the topographic information and maximum extent of inundation. Thematic maps on land use, land cover, and coastal geomorphology were generated using remote sensing and field data. Using field data as the primary source of information, tsunami hazard maps have been generated for Nagapattinam.  相似文献   

One-Dimensional Consolidation of Sedimented Stowed Pond Ash     

Devi Prasad Mishra  Samir Kumar Das 《Geotechnical and Geological Engineering》2012,30(4):685-695

Use of fly ash locked in the ash ponds in geotechnical applications such as stowing or backfilling of the mines is an attractive alternative to solve the disposal problem. Before it is used as a stowing or backfilling material, the response of the fly ash?to imposed load must be determined in order to assess its load taking ability. The present study examines the effect of time and incremental load on the consolidation characteristics of the sedimented stowed pond ash using a fixed ring consolidometer. The important parameters, viz. rate of settlement, consolidation coefficients and void ratio, etc. of the hydraulically stowed pond ash collected after 7, 14, 21, 28 and 35?days of stowing under step incremental loads are determined. The study revealed that 60.42–84.87% settlement of the sedimented stowed pond ash takes place in the initial 1?min of the loading. In addition, it is observed that the coefficient of consolidation of the sedimented stowed pond ash, which varies in the range of 0.0195–0.1882?cm²/min, is comparatively low and decreases with the increment of applied load and time. This indicates that the structures lying above the stowed pond ash mass will undergo gradual settling and not suffer large deformation.  相似文献   

Identification of trends in rainfall,rainy days and 24 h maximum rainfall over subtropical Assam in Northeast India     

Deepak Jhajharia  Brijesh K. Yadav  Sunil Maske  Surajit Chattopadhyay  Anil K. Kar 《Comptes Rendus Geoscience》2012,344(1):1-13

Trends in rainfall, rainy days and 24 h maximum rainfall are investigated using the Mann-Kendall non-parametric test at twenty-four sites of subtropical Assam located in the northeastern region of India. The trends are statistically confirmed by both the parametric and non-parametric methods and the magnitudes of significant trends are obtained through the linear regression test. In Assam, the average monsoon rainfall (rainy days) during the monsoon months of June to September is about 1606 mm (70), which accounts for about 70% (64%) of the annual rainfall (rainy days). On monthly time scales, sixteen and seventeen sites (twenty-one sites each) witnessed decreasing trends in the total rainfall (rainy days), out of which one and three trends (seven trends each) were found to be statistically significant in June and July, respectively. On the other hand, seventeen sites witnessed increasing trends in rainfall in the month of September, but none were statistically significant. In December (February), eighteen (twenty-two) sites witnessed decreasing (increasing) trends in total rainfall, out of which five (three) trends were statistically significant. For the rainy days during the months of November to January, twenty-two or more sites witnessed decreasing trends in Assam, but for nine (November), twelve (January) and eighteen (December) sites, these trends were statistically significant. These observed changes in rainfall, although most time series are not convincing as they show predominantly no significance, along with the well-reported climatic warming in monsoon and post-monsoon seasons may have implications for human health and water resources management over bio-diversity rich Northeast India.  相似文献   

Wet and dry spell analysis of Global Climate Model-generated precipitation using power laws and wavelet transforms   总被引：2，自引：2，他引：0  

Ashok K. Mishra  Mehmet ?zger  Vijay P. Singh 《Stochastic Environmental Research and Risk Assessment (SERRA)》2011,25(4):517-535

Climate model simulations for the twenty-first century point toward changing characteristics of precipitation. This paper investigates the impact of climate change on precipitation in the Kansabati River basin in India. A downscaling method, based on Bayesian Neural Network (BNN), is applied to project precipitation generated from six Global Climate Models (GCMs) using two scenarios (A2 and B2). Wet and dry spell properties of monthly precipitation series at five meteorologic stations in the Kansabati basin are examined by plotting successive wet and dry durations (in months) against their number of occurrences on a double-logarithmic paper. Straight-line relationships on such graphs show that power laws govern the pattern of successive persistent wet and dry monthly spells. Comparison of power-law behaviors provides useful interpretation about the temporal precipitation pattern. The impact of low-frequency precipitation variability on the characteristics of wet and dry spells is also evaluated using continuous wavelet transforms. It is found that inter-annual cycles play an important role in the formation of wet and dry spells.  相似文献