ENSO and IOD analysis on the occurrence of floods in Pakistan     

Asif Iqbal  Syed Ahmad Hassan 《Natural Hazards》2018,91(3):879-890

Different techniques have been used to discuss the existence of significant relation between the El Nino Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD). Various studies present their interaction and influence on the natural disasters (i.e. drought, flood, etc.) over large parts of the globe. This study uses a Markov chain method to investigate the relation between the ENSO and IOD for the period of 62 years (1950–2011) and aggregates their influence on the occurrence of floods in Pakistan. Both data sets show similarities in the formation of transition matrices and expected number of visits from one state to another. The strong values of 2-dimensional correlation and high self-communication of the transition states confirm the existence of a possible relation between ENSO and IOD data. Moreover, significant values of dependency and stationary test endorse the applicability of the Markov chain analyses. The independent analysis shows that strong events of both data sets are co-occurred in the same flood years. During the study period maximum number of floods was observed during summer monsoon season. However, further analysis shows that after 1970, Pakistan observed the highest percentage of floods occurred per year during El Nino, Non-ENSO and positive IOD years. These observations and results demonstrate that climate variability especially ENSO and IOD should be incorporated into disaster risk analyses and policies in Pakistan.  相似文献   

Regional subglacial quarrying and abrasion below hard-bedded palaeo-ice streams crossing the Shield–Palaeozoic boundary of central Canada: the importance of substrate control     

Syed Bukhari  Nick Eyles  Shane Sookhan  Riley Mulligan  Roger Paulen  Maarten Krabbendam  Niko Putkinen 《Boreas: An International Journal of Quaternary Research》2021,50(3):781-805

Three-dimensional surface visualization models derived from high-resolution LiDAR data provide new information about the type and scale of erosional processes below Late Wisconsin palaeo-ice streams traversing the boundary between Canadian Shield crystalline rocks with offlapping Palaeozoic limestones in central Ontario. The hard bed is directly analogous to that found below ice streams in East Antarctica and East Greenland and provides insight into the effects of abrupt changes in substrate type on subglacial processes. Erosion of hard crystalline Canadian Shield rock was largely ineffectual consisting of areal abrasion of rounded whalebacks and local lee side plucking. In contrast, fast flow over the strike of gently dipping well-bedded and jointed Palaeozoic limestones cut large flow-parallel grooves and ridges akin to mega-scale glacial lineations reflecting intense abrasion below narrow streams of subglacial debris dominated by hard crystalline Shield clasts (erodents). Regionally extensive plucking of structurally weak, well-jointed and bedded limestone produced large volumes of rubbly carbonate debris leaving a 25-km-wide belt of uncontrolled hummocky rubble terrain (long known as the Dummer Moraine in Southern Ontario) some 350 km long and locally as much as 10 m thick. Subglacial plucking and abrasion under fast flowing ice were highly effective in stripping limestone cover rocks from Precambrian basement, and over many glacial cycles, may have played a role in the location and excavation of numerous large and deep lake basins around the Shield–Palaeozoic boundary zone in North America.  相似文献   

Isotopic analysis to quantify the role of the Indian monsoon on water resources of selected river basins in the Himalayas     

Ghulam Jeelani  Rouf Ahmad Shah  Rajendrakumar D. Deshpande  Ashok P. Dimri  Suraj Mal  Anupam Sharma 《水文研究》2021,35(11):e14406

Western disturbances (WDs) and Indian summer monsoon (ISM) led precipitation play a central role in the Himalayan water budget. Estimating their contributions to water resource is although a challenging but essential for hydrologic understanding and effective water resource management. In this study, we used stable water isotope data of precipitation and surface waters to estimate the contribution of ISM and WDs to the water resources in three mountainous river basins - Indus, Bhagirathi and Teesta river basins of western, central and Eastern Himalayas. The study reveals distinct seasonality in isotope characteristics of precipitation and surface waters in each river basin is due to changes in moisture source, hydrometeorology and relief. Despite steady spatial variance in the slope and intercept of regression lines from the Teesta to Indus and the Bhagirathi river basins, the slope and intercept are close to the global meteoric water line and reported local meteoric water line of other regions in the Himalayas and the Tibetan Plateau. The two-component end-member mixing method using d-excess as tracer were used to estimate the contribution from ISM and WD led precipitation to surface water in aforementioned river basins. The results suggest that the influence of the ISM on the water resources is high (>72% to annual river flow) in Teesta river basin (eastern Himalayas), while as the WDs led precipitation is dominantly contributing (>70% average annual river flow) to the surface waters in the Indus river basin (western Himalayas). The contribution of ISM and WD led precipitation in Bhagirathi river basin is 60% and 40%, respectively. The findings demonstrate that the unusual changes in the ISM and WD moisture dynamics have the potential to affect the economy and food security of the region, which is dependent on the availability of water resources. The obtained results are of assistance to policy makers/mangers to make use of the information for better understanding hydrologic response amid unusual behaviour of the dual monsoon system over the region.  相似文献   

Parametric study of acoustic emission location using only four sensors     

J. F. Labuz  H. S. Chang  C. H. Dowding  S. P. Shah 《Rock Mechanics and Rock Engineering》1988,21(2):139-148

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Development of a rainwater harvesting system for increasing soil moisture in arid rangelands of Pakistan     

Sheikh Suleman  M. Karl Wood  Bashir Hussain Shah  Leigh Murray   《Journal of Arid Environments》1995,31(4)

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Pre-and post-construction status of panam reservoir and its environs using remotely sensed and ancillary data     

R Nagarajan  S D Shah  V K Yadav 《Journal of the Indian Society of Remote Sensing》1993,21(1):29-35

The success of water-resources projects can be evaluated by using remotely sensed and ancillary data supported by ground-based information. Surficial features in the vicinity of Panam reservoir of the Mahi-Kadana river-valley project, have been demarcated using IRS data of 1991 (post-commission) and 1969 topographic sheet information (prior to commission) and have been evaluated. Observed positive and negative changes indicate that the project maintains its environment-friendly function.  相似文献   

Behaviour of Tl relative to K,Rb, Sr and Ba in mineralized and unmineralized metavolcanics from the Dir area,northern Pakistan     

M. T. Shah  M. Ikramuddin  J. W. Shervais 《Mineralium Deposita》1994,29(5):422-426

Copper mineralization in the Dir area of northern Pakistan is confined to the quartz veins and associated with hydrothermally altered metavolcanics. Chalcopyrite is the main copper-bearing phase with subordinate amounts of bornite, chalcocite, covellite, malachite and azurite. Both mineralized quartz veins and associated unmineralized (least altered) and mineralized (strongly altered) metavolcanics have been analyzed for Cu, Au, Ag, Tl, K, Rb, Ba and Sr. An increase of Cu, Au, Ag, Rb/Sr and Tl/Sr, and a decrease of Sr and K/Rb is observed in both mineralized metavolcanics and mineralized quartz veins. Thallium shows lithophile behaviour in the Dir metavolcanics and no chalcophile behaviour was observed. The Tl/Sr ratio might be an indirect guide for the exploration of volcanic-hosted hydrothermal copper deposits.  相似文献   

Orographic effect on potential gradient     

Syed Nizamuddin 《Pure and Applied Geophysics》1984,122(1):86-88

Potential gradients were measured in the valley of the Simhachalam hills and near the top. They were found to be higher at the top than in the valley, where they increased in the forenoon. It was the reverse at the top of the hills. The valley winds were found to play an important role in the variation of potential gradient.  相似文献   

The Indus-Tsangpo suture zone in Ladakh, northwest Himalaya: Further palaeomagnetic data and implications     

Chris Klootwijk  Madan Lal Sharma  Jozef Gergan  S.K. Shah  Biras Tirkey 《Tectonophysics》1984,106(3-4)

A total of 81 samples (244 specimens) from Upper Cretaceous Indus Molasse and Middle to Upper Cretaceous Dras Flyschoids of the Indus-Tsangpo suture zone in Ladakh (northwest Himalaya) has been studied by thermal demagnetization methods.Both formations showed a characteristic magnetization component indicative for equatorial to low northern palaeolatitudes of acquisition. Similar palaeolatitudes have been obtained before from secondary magnetization components of Early Tertiary age in the Ladakh Intrusives and in the Tibetan Sedimentary Series of central Nepal. The present characteristic components are interpreted likewise as secondary magnetizations which stabilized between 50 and 60 m.y. ago, during Greater India's collision with Asia's southern margin.The Dras Flyschoids show another magnetic component which, in case of primary origin, indicates acquisition at a low southern palaeolatitude. If correct, this interpretation supports recent suggestions for Late Cretaceous obduction of an island arc on Greater India's northern margin.  相似文献   

Reinforced concrete hysteresis model based on the damage concept     

Ming-Liang Wang  Surendra P. Shah 《地震工程与结构动力学》1987,15(8):993-1003

Reinforced concrete members subjected to cyclic inelastic deformation may exhibit both stiffness and strength degradation, depending on the maximum amplitude and the number of cycles experienced by the member. Many of the currently available models do not simulate the cycle-dependent stiffness loss often observed during the experiments. An analytical model based on a damage parameter which is a function of the cumulative cyclic inelastic deformation is proposed. A small-scale reinforced concrete beam–column joint was constructed and subjected to cyclic loading to calibrate the damage parameter. The model is able to approximate the complete hysteretic response and is simple to implement. The sensitivity of the analytical model was examined by comparing the model with several experimental results.  相似文献