Impact of cropping pattern changes on the exploitation of water resources: A remote sensing and GIS approach     

Anil Sood  B. U. Choudhury  S. S. Ray  S. K. Jalota  P. K. Sharma  Shushma Panigrahy 《Journal of the Indian Society of Remote Sensing》2009,37(3):483-491

A remote sensing-based approach was applied to study the impact of changes in cropping system on the exploitation of water resources in two districts namely Ludhiana in central Punjab and Muktsar in South-Western Punjab. Rice-wheat remained dominant rotation in Ludhiana while cottonwheat rotation was replaced partially by rice-wheat in Muktsar within a span of over five years (1998–99 to 2003–04). The solo rice-wheat system in Ludhiana district has resulted in large-scale ground water exploitation as is evident from the faster decline in water table (up to 0.9m year⁻¹) and higher tube-wells density (440 per 1000 ha). As a result, nearly 60 per cent of the total area of Ludhiana district has the water table depth greater than 10m and in some blocks, it has reached to a depth of 22 m. In Muktsar district, corresponding rise in water table is 0.2m per year and tube well density is 114 per 1000 ha. Irrigation water associated with paddy cultivation in Ludhiana and adjoining areas moves laterally through the buried paleo-channels of Sutlaj in the deeper soil profile and gets accumulated in the basin lands of Muktsar and adjoining areas and causes an extra water flux and subsequent rise in water table, recorded at 3 to 7m depth. To minimize the hydrological imbalance of the state, it is suggested to diversify some of the area in the central districts from irrigation water intensive rice-wheat system to less water intensive cropping system.  相似文献   

GPS工程控制网基线解算优化的探讨   总被引：1，自引：0，他引：1  

徐辉  张凯  陶李  李国华 《地理空间信息》2009,7(4):32-34

对GPS基线解算的原理、影响因素和精度指标进行了分析,并结合Trimble Geomatic Office软件的基线解算实例阐述了具体的基线解算优化方法。  相似文献   

Gas hydrates and active mud volcanism on the South Shetland continental margin, Antarctic Peninsula   总被引：1，自引：0，他引：1  

U. Tinivella  F. Accaino  B. Della Vedova 《Geo-Marine Letters》2008,28(2):97-106

During the Antarctic summer of 2003–2004, new geophysical data were acquired from aboard the R/V OGS Explora in the BSR-rich area discovered in 1996–1997 along the South Shetland continental margin off the Antarctic Peninsula. The objective of the research program, supported by the Italian National Antarctic Program (PNRA), was to verify the existence of a potential gas hydrate reservoir and to reconstruct the tectonic setting of the margin, which probably controls the extent and character of the diffused and discontinuous bottom simulating reflections. The new dataset, i.e. multibeam bathymetry, seismic profiles (airgun and chirp), and two gravity cores analysed by computer-aided tomography as well as for gas composition and content, clearly shows active mud volcanism sustained by hydrocarbon venting in the region: several vents, located mainly close to mud volcanoes, were imaged during the cruise and their occurrence identified in the sediment samples. Mud volcanoes, vents and recent slides border the gas hydrate reservoir discovered in 1996–1997. The cores are composed of stiff silty mud. In core GC01, collected in the proximity of a mud volcano ridge, the following gases were identified (maximum contents in brackets): methane (46 μg/kg), pentane (45), ethane (35), propane (34), hexane (29) and butane (28). In core GC02, collected on the flank of the Vualt mud volcano, the corresponding data are methane (0 μg/kg), pentane (45), ethane (22), propane (0), hexane (27) and butane (25).  相似文献   

Trophic position of Calanus finmarchicus (Copepoda, Calanoida) in the Trondheim Fjord     

A. Saage  D. Altin  O. Vadstein  U. Sommer 《Journal of Sea Research》2008,59(3):162-172

The trophic position of Calanus finmarchicus in the Trondheim Fjord in 2004 was determined through stable isotope analyses. Wild specimens were sampled monthly in the fjord and δ¹³C and δ¹⁵N signatures of the developmental stages from CIII to adults were measured. There were statistically significant differences in the δ¹³C and δ¹⁵N signatures of three identified groups: overwintered parental generation, developing new generation and new generation preparing for overwintering. C. finmarchicus individuals raised in a laboratory on a pure algal diet (Dunaliella tertiolecta and Isochrysis galbana) provided stable isotope signatures for purely herbivorous copepods. With these signatures as comparison, the trophic position of C. finmarchicus in the Trondheim Fjord in 2004 was determined as trophic level 2.4, thus indicating omnivory under natural conditions. Additionally, our data suggest that seasonal differences in the δ¹³C signatures of C. finmarchicus are due to the varying lipid content of the different developmental stages.  相似文献   

Heavy metal bioaccumulation and toxicity with special reference to microalgae   总被引：1，自引：0，他引：1  

K. K. I. U. Arunakumara ZHANG Xuecheng 《中国海洋大学学报(英文版)》2008,7(1):60-64

  相似文献   

Die Suche eines Lichtwechsels bei 8 Sternen mit anomalem Heliumgehalt     

B. Vet  W. Schneich  Y. U. S. Rustamov 《Astronomische Nachrichten》1980,301(6):317-326

For eight stars with anomal Helium contents a search for periodic lightvariability was carried out. Three of them HD 178 993, HD 207 538, and HD 209 339 did not show any detectable variability during the period of observations. For HD 184 927, the period, obtained by BOND , LEVATO , was confirmed. For HD 191 980, HD 208 266, and HD 217 833 photometric variability was detected and the periods were obtained. Six of the used comparison stars were shown to be variable too.  相似文献   

现行黄河口水下三角洲海底形貌及不稳定性   总被引：4，自引：0，他引：4  

杨作升  G.H.Keller  陆念祖  D.B.Prior  林天充  B.D.Bornhold  许卫东  L.D.Wright  J.Suhayda  曹立华  W.J.Wisenman 《中国海洋大学学报(自然科学版)》1990,(1)

高分辨力的声学仪器调查表明,现行黄河口水下三角洲海底的形貌十分复杂,由于高浓度巨量黄河泥沙快速沉积的结果,使河口底坡出现了大量的不稳定性现象,如塌陷冲沟,高密度沉积物重力流,切割—充填结构海底,V形水下河谷、滑塌等。根据海底扰动程度作了分区,划分了地形单元,并对不同的海底形态的成因作了分析。比较了1985和1986年两个航次考查结果的变动,分析了原因。  相似文献   

Synchronous variability changes in Alpine temperature and tree-ring data over the past two centuries     

DAVID FRANK  ROBERT WILSON  JAN ESPER 《Boreas: An International Journal of Quaternary Research》2005,34(4):498-505

The understanding of extremes and their temporal distribution is useful in characterizing the behaviour of the climate system, and necessary for understanding their social and economic costs and risks. This task is analogous to the study of pointer years in dendrochronological investigations. Commonly used dendroclimatological methods, however, tend to result in an equalization of variance throughout the record by normalizing variability within moving windows. Here, we analyse a larger network of high-elevation temperature-sensitive tree sites from the European Alps processed to preserve the relative frequency and magnitude of extreme events. In so doing, temporal changes in year-to-year tree-ring width variability were found. These decadal length periods of increased or decreased likelihood of extremes coincide with variability measures from a long-instrumental summer temperature record representative of high-elevation conditions in the Alps. Intervention analysis, using an F-test to identify shifts in variance, on both the tree-ring and instrumental series, resulted in the identification of common transitional years. Based on a well-replicated network of sites reflecting common climatic variation, our study demonstrates that the annual growth rings of trees can be utilized to quantify past frequency and amplitude changes in extreme variability. Furthermore, the approach outlined is suited to address questions about the role of external forcing, ocean-atmosphere interactions, or synoptic scale changes in determining patterns of observed extremes prior to the instrumental period.  相似文献   

Spectroscopic survey of the Galaxy with Gaia– II. The expected science yield from the Radial Velocity Spectrometer     

M. I. Wilkinson  A. Vallenari  C. Turon  U. Munari  D. Katz  G. Bono  M. Cropper  A. Helmi  N. Robichon  F. Thévenin  S. Vidrih  T. Zwitter  F. Arenou  M.-O. Baylac  G. Bertelli  A. Bijaoui  F. Boschi  F. Castelli  F. Crifo  M. David  A. Gomboc  A. Gómez  M. Haywood  U. Jauregi  P. de Laverny  Y. Lebreton  P. Marrese  T. Marsh  S. Mignot  D. Morin  S. Pasetto  M. Perryman  A. Pr&#;a  A. Recio-Blanco  F. Royer  A. Sellier  A. Siviero  R. Sordo  C. Soubiran  L. Tomasella  Y. Viala 《Monthly notices of the Royal Astronomical Society》2005,359(4):1306-1335

  相似文献   

A Late Quaternary lake record from the Qilian Mountains (NW China): lake level and salinity changes inferred from sediment properties and ostracod assemblages   总被引：5，自引：0，他引：5  

S. Mischke  U. Herzschuh  C. Zhang  J. Bloemendal  F. Riedel   《Global and Planetary Change》2005,46(1-4):337

Two sediment cores (length 13.94 and 12.93 m) have been drilled from the small alpine Lake Luanhaizi in the eastern central Qilian Mountains and correlated by means of magnetic susceptibility (MS). This paper focuses on the lithology and chronology of the longer core, on the results of loss on ignition (LOI), element concentration, thermomagnetic as well as magnetic hysteresis loop measurements, and on the ostracod record.The recovered sediments represent three types of depositional environment: a shallow intermittent lake, a deeper permanent lake and a true playa lake. Three stages of a higher lake level and permanence of the water body are reconstructed. The lowermost stage of a permanent lake and inferred favourable environmental conditions occurred probably about 45 ¹⁴C ka BP. The second stage of a deeper permanent lake occurred either shortly before or, more likely, following the LGM. Most favourable environmental conditions and highest water levels were reconstructed for the uppermost stage comprising the Holocene. Considering the lake record, glaciers have not reached the lake site at 3200 m altitude during the LGM, providing further evidence against a large ice sheet on the Tibetan Plateau.  相似文献