Modelling soil water dynamics considering measurement uncertainty          下载免费PDF全文

Isaya Kisekka  K. W. Migliaccio  R. Muñoz‐Carpena  B. Schaffer  Y. Khare 《水文研究》2015,29(5):692-711

In shallow water table‐controlled environments, surface water management impacts groundwater table levels and soil water dynamics. The study goal was to simulate soil water dynamics in response to canal stage raises considering uncertainty in measured soil water content. Water and Agrochemicals in the soil, crop and Vadose Environment (WAVE) was applied to simulate unsaturated flow above a shallow aquifer. Global sensitivity analysis was performed to identify model input factors with the greatest influence on predicted soil water content. Nash–Sutcliffe increased and Root Mean Square Error reduced when uncertainties in measured data were considered in goodness‐of‐fit calculations using measurement probability distributions and probable asymmetric error boundaries, implying that appropriate model performance evaluation should be carried out using uncertainty ranges instead of single values. Although uncertainty in the experimental measured data limited evaluation of the absolute predictions by the model, WAVE was found a useful exploratory tool for estimating temporal variation in soil water content. Visual analysis of soil water content time series under proposed changes in canal stage management indicated that sites with land surface elevation of less than 2.0‐m NGVD29 were predicted to periodically experience saturated conditions in the root zone and shortening of the growing season if canal stage is raised more than 9 cm and maintained at this level. The models developed could be combined with high‐resolution digital elevation models in future studies to identify areas with the greatest risk of experiencing saturated root zone. The study also highlighted the need to incorporate measurement uncertainty when evaluating performance of unsaturated flow models. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Environmental implication on chamber accretion of <Emphasis Type="Italic">Neogloboquadrina pachyderma</Emphasis> (Ehrenberg) in southern Indian Ocean     

N. Khare  A. Mazumder  P. Govil  V. P. Singh 《Journal of the Geological Society of India》2009,73(3):379-385

Morphological variations with respect to the number of chambers in Neogloboquadrina pachyderma (Ehrenberg) were investigated in 25 surficial sediments of Indian Ocean taken along the N-S transect between 9.69° N and 55.01° S latitude and 80° E and 40° E longitude. The number of chamber was counted for at least 40 specimens picked for each sample. The average number of chamber was correlated with the average temperature and salinity along the changing latitude. The results showed a high correlation between the number of chambers and temperature and salinity. It was noted that number of chambers decreases from equatorial to polar region. The carbonate saturation and nutrient availability could possibly be other causes for the change in number of chambers. The results of this study, if applied on the subsurface marine sediments, will bear implications on paleoclimatic condition in the Indian Ocean region.  相似文献   

Future changes in rainfall,temperature and reference evapotranspiration in the central India by least square support vector machine     

Sananda Kundu  Deepak Khare  Arun Mondal 《地学前缘(英文版)》2017,8(3):583-596

Climate change affects the environment and natural resources immensely. Rainfall, temperature and evapotranspiration are major parameters of climate affecting changes in the environment. Evapotranspiration plays a key role in crop production and water balance of a region, one of the major parameters affected by climate change. The reference evapotranspiration or ET₀ is a calculated parameter used in this research. In the present study, changes in the future rainfall, minimum and maximum temperature, and ET₀ have been shown by downscaling the HadCM3 (Hadley Centre Coupled Model version 3) model data. The selected study area is located in a part of the Narmada river basin area in Madhya Pradesh in central India. The downscaled outputs of projected rainfall, ET₀ and temperatures have been shown for the 21st century with the HADCM3 data of A2 scenario by the Least Square Support Vector Machine (LS-SVM) model. The efficiency of the LS-SVM model was measured by different statistical methods. The selected predictors show considerable correlation with the rainfall and temperature and the application of this model has been done in a basin area which is an agriculture based region and is sensitive to the change of rainfall and temperature. Results showed an increase in the future rainfall, temperatures and ET₀. The temperature increase is projected in the high rise of minimum temperature in winter time and the highest increase in maximum temperature is projected in the pre-monsoon season or from March to May. Highest increase is projected in the 2080s in 2081–2091 and 2091–2099 in maximum temperature and 2091–2099 in minimum temperature in all the stations. Winter maximum temperature has been observed to have increased in the future. High rainfall is also observed with higher ET₀ in some decades. Two peaks of the increase are observed in ET₀ in the April–May and in the October. Variation in these parameters due to climate change might have an impact on the future water resource of the study area, which is mainly an agricultural based region, and will help in proper planning and management.  相似文献   

Analyzing and modeling of a large river basin dynamics applying integrated cellular automata and Markov model     

Brij Kishor Pandey  Deepak Khare 《Environmental Earth Sciences》2017,76(22):779

Historical and exact information about the land use/land cover change is very important for regional sustainable development. The aim of this paper is to determine the rapid changes in land use/land cover (LULC) pattern due to agriculture expansion, environmental calamities such as flood and government policies over Upper Narmada basin, India. Multi-temporal Landsat satellite images for years 1990, 2000, 2010 and 2015 were used to analyze and monitor the changes in LULC with an overall accuracy of more than 85%. Results revealed a potential decrease in natural vegetation (? 9.52%) due to the expansion of settlement (+ 0.52%) and cropland (+ 9.43%) from 1990 to 2015. In the present study, Cellular Automata and Markov (CA–Markov), an integrated tool was used to project the short-term LULC map of year 2030. The projected LULC (2030) indicated the expansion of built-up area along with the cropland and degradation in the vegetation area. The outcomes from the study can help as a guiding tool for protection of natural vegetation and the management of the built-up area. Additionally, it will help in devising the strategies to utilize every bit of land in the study area for decision makers.  相似文献   

Experimental impact shock chemistry on planetary icy satellites     

Delphine Nna-Mvondo  Bishun Khare  Tomoko Ishihara  Christopher P. McKay 《Icarus》2008,194(2):822-835

We present new experimental results on impact shock chemistry into icy satellites of the outer planets. Icy mixtures of pure water ice with CO₂, Na₂CO₃, CH₃OH, and CH₃OH/(NH₄)₂SO₄ at 77 K were ablated with a powerful pulsed laser—a new technique used to simulate shock processes which can occur during impacts. New products were identified by GC-MS and FTIR analyses after laser ablation. Our results show that hydrogen peroxide is formed in irradiated H₂O/CO₂ ices with a final concentration of 0.23%. CO and CH₃OH were also detected as main products. The laser ablation of frozen H₂O/Na₂CO₃ generates only CO and CO₂ as destruction products from the salt. Pulsed irradiation of water ice containing methanol leads also to the formation of CO and CO₂, generates methane and more complex molecules containing carbonyl groups like acetaldehyde, acetone, methyl formate, and a diether, dimethyl formal. The last three compounds are also produced when adding ammonium sulfate to H₂O/CH₃OH ice, but acetone is more abundant. The formation of two hydrocarbons, CH₄ and C₂H₆ is observed as well as the production of three nitrogen compounds, nitrous oxide, hydrogen cyanide, and acetonitrile.  相似文献   

Magnetostatic models filled with dust and disordered radiation     

Raj Bali  Deepak Raj Jain 《Astrophysics and Space Science》1991,175(1):89-100

Magnetostatic models filled with dust and disordered radiation in which the distribution is that of perfect fluid, are obtained. Some physical and geometrical aspects of the models are investigated. In the last section of the paper, the Newtonian analogues of forces are also obtained.  相似文献   

GIS application to determine the effect of topography on landuse in Ashwani Khad watershed     

Sudhir Mahajan  Pankaj Panwar  Deepak Kaundal 《Journal of the Indian Society of Remote Sensing》2001,29(4):243-248

The landuse status of Ashwani Khad watershed has been obtained using 1RS-ID satellite data for 1999 and further topographic analysis has been carried out using GIS software-ARC/ INFO and ARCVIEW. It has been found that of the total geographical area (85.30 sq. km) of the Ashwani Khad watershed which lies between 30°50′ to 31°N latitude and 77°05′ to 77° 15′E longitude in Himachal Pradesh, 54.53 % constituted wasteland, 33.55% agriculture and least 11.92 % forest. The altitude, aspect and slope have exhibited marked effect on land utilization. Agriculture and wasteland have been found maximum in mid altitude (1300-1500 m) and moderate slopes (13.2-26.4 degree), whereas, agriculture and forest have been maximum in flat and north aspect.  相似文献   

Redox-linked conformation change and electron transfer between monoheme c-type cytochromes and oxides     

Nidhi Khare  Carrick M. Eggleston  Michael Swenson 《Geochimica et cosmochimica acta》2006,70(17):4332-4342

Electron transfer between redox active proteins and mineral oxides is important in a variety of natural as well as technological processes, including electron transfer from dissimilatory metal-reducing bacteria to minerals. One of the pathways that could trigger electron transfer between proteins and minerals is redox-linked conformation change. We present electrochemical evidence that mitochondrial cytochrome c (Mcc) undergoes significant conformation change upon interaction with hematite and indium-tin oxide (ITO) surfaces. The apparent adsorption-induced conformation change causes the protein to become more reducing, which makes it able to transfer electrons to the hematite conduction band. Although Mcc is not a protein thought to be involved in interaction with mineral surfaces, it shares (or can be conformed so as to share) some characteristics with multiheme outer-membrane cytochromes thought to be involved in the transfer of electrons from dissimilatory iron-reducing bacteria to ferric minerals during respiration. We present evidence that a 10.1 kDa monohoeme cytochrome isolated and purified from Acidiphilium cryptum, with properties similar to those of Mcc, also undergoes conformation change as a result of interaction with hematite surfaces.  相似文献   

Phosphate bonding configuration on ferrihydrite based on molecular orbital calculations and XANES fingerprinting     

Nidhi Khare  James D. Martin 《Geochimica et cosmochimica acta》2007,71(18):4405-4415

Sorption of phosphate by Fe(III)- and Al(III)-(hydr)oxide minerals regulates the mobility of this potential water pollutant in the environment. The objective of this research was to determine the molecular configuration of phosphate bound on ferrihydrite at pH 6 by interpreting P K-edge XANES spectra in terms of bonding mode. XANES and UV-visible absorption spectra for aqueous Fe(III)-PO₄ solutions (Fe/P molar ratio = 0-2.0) provided experimental trends for energies of P(3p)-O(2p) and Fe(3d)-O(2p) antibonding molecular orbitals. Molecular orbitals for Fe(III)-PO₄ or Al(III)-PO₄ complexes in idealized monodentate or bidentate bonding mode were generated by conceptual bonding arguments, and Extended-Hückel molecular orbital computations were used to understand and assign XANES spectral features to bound electronic states. The strong white line at the absorption edge in P K-edge XANES spectra for Fe-PO₄ or Al-PO₄ systems is attributable to an electronic transition from a P 1s atomic orbital into P(3p)-O(2p) or P(3p)-O(2p)-Al(3p) antibonding molecular orbitals, respectively. For Fe-PO₄ systems, a XANES peak at 2-5 eV below the edge was assigned to a P 1s electron transition into Fe(4p)-O(2p) antibonding molecular orbitals. Similarly, a shoulder on the low-energy side of the white line for variscite corresponds to a transition into Al(3p)-O(2p) orbitals. In monodentate-bonded phosphate, Fe-O bonding is optimized and P-O bonding is weakened, and the converse is true of bidentate-bonded phosphate. These differences explained an inverse correlation between energies of P(3p)-O(2p) and Fe(3d)-O(2p) antibonding molecular orbitals consistent with a monodentate-to-bidentate transition in aqueous Fe(III)-PO₄ solutions. The intensity of the XANES pre-edge feature in Fe(III)-bonded systems increased with increasing number of Fe(III)-O-P bonds. Based on the similarity of intensity and splitting of the pre-edge feature for phosphate sorbed on ferrihydrite at 750 mmol/kg at pH 6 and aqueous Fe-PO₄ solutions containing predominantly bidentate complexes, XANES results indicated that phosphate adsorbed on ferrihydrite was predominantly a bidentate-binuclear surface complex.  相似文献   

Multi-scale assessment of invasive plant species diversity using Pléiades 1A,RapidEye and Landsat-8 data     

Siddhartha Khare  Hooman Latifi  Sanjay Kumar Ghosh 《国际地球制图》2018,33(7):681-698

We used a full remote sensing-based approach to assess plant species diversity in large and inaccessible areas affected by Lantana camara L., a common invasive species within the deciduous forests of Western Himalayan region of India, using spectral heterogeneity information extracted from optical data. The spread of L. camara was precisely mapped by Pléiades 1A data, followed by comparing Pléiades 1A, RapidEye and Landsat-8 OLI – assessed plant species diversities in invaded areas. The single plant species analysis was improved by Pléiades 1A-based diversity analysis, and higher species diversity values were observed for mixed vegetation cover. Furthermore, lower Coefficient of Variation and Renyi diversity values were observed where L. camara was the only species, while higher variations were observed in areas with a mixed spectral reflectance. This study was concluded to add a crucial baseline to the previous studies on remote sensing-based solutions for rapid estimation of biodiversity attributes.  相似文献