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Madan M.M.,NHPC Ltd
Water and Energy International | Year: 2015

During tunnel execution encountering of thrust zones, shear zones, fracture zones, fluvioglacial material, sandy, silty or clayey strata, overburden material is very common. This type of strata makes tunnelling extremely challenging. Over and above encountering of seepage water creates flowing ground conditions and makes worst tunnelling conditions for excavation of underground structures. Tunnelling becomes very difficult and slow. By adopting new methods like Ground Freezing, Pre Grouting of Face with New Materials, Fibre Shotcreting with new materials and roof protection the weak strata can be strengthened inherently. The Paper deals with various new methods and new materials for controlling the weak zones and successful tunnelling. © 2015, Central Board of Irrigation and Power. All rights reserved.

Kumar R.,NHPC Ltd
Water and Energy International | Year: 2015

In a span of more than 100 years since the first hydro project was commissioned in India, phenomenon progress has been made on exploitation of water power potential. As a part of national policy on hydro development, renovation, modernization and operation of old hydro power plants is being accorded priority. This being a faster and cheaper way of capacity addition than installing new capacity. As per global experience, 10-15% capacity addition can be achieved by simply encroaching upon overload margins, safety factors. Capacity addition up to 30% is achievable by changing the F-class insulation of the stator and by changing the Hydraulic profile of the runner and capacity addition up to 50% is achievable by changing the complete unit and retaining only embedded parts and some major foundation components of the generator. In India, 150 such hydro schemes with an aggregate capacity of 27000.3 MW having expected benefit of 7282.76 MW already been identified for renovation, modernization and capacity addition. Out of these 95 hydro schemes with an aggregate capacity of 17247.9 MW have been completed providing a benefit of 3317.4 MW, 11 hydro schemes with an aggregate capacity of 1665.9 MW having expected benefit of 965.3 MW is under implementation, 17 hydro schemes with an aggregate capacity of 2981.75 MW having expected benefit of 1319.95 MW is under tendering, 13 hydro schemes with an aggregate capacity of 2225.75 MW having expected benefit of 1206 MW is under DPR preparation/finalization & approval and 10 hydro schemes with an aggregate capacity of 905 MW having expected benefit of 60 MW is under RLA studies. The paper attempts to discuss about the need of renovation, modernization and capacity addition of hydropower units in Indian context. The paper sets an over all attention to highlight major concept in regard to phenomenon leading to renovation, refurbishment and quick capacity addition cost effectively. © 2015, Central Board of Irrigation and Power. All rights reserved.

Sen A.,NHPC Ltd
Water and Energy International | Year: 2013

In view of restricted time-frame and finance, establishing safe and economic hydropower schemes necessitates a planned approach towards a comprehensive investigation program involving both direct and indirect techniques. Besides the involvement of drilling, drifting as well as geological, geotechnical studies and other allied studies, it is important to apply state-of-the-art geophysical techniques during various stages of the project. The paper elaborates planned utility of the prime techniques of engineering geophysics in subsurface exploration and site characterization during Pre-feasibility, Feasibility, Detailed Investigation (DPR) and Pre-construction stages of the project towards minimizing geological uncertainties: The proposed extensive application of engineering geophysics during the various stage, with intent of avoiding the practice of carrying forward the application of geophysics to the Construction stage, shall facilitate the project execution with due level of confidence, within schedule and optimum involvement of direct exploration.

Dabral S.,NHPC Ltd | Bhatt B.,M. S. University of Baroda | Joshi J.P.,M. S. University of Baroda | Sharma N.,M. S. University of Baroda
International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences - ISPRS Archives | Year: 2014

Groundwater quality in Gujarat state is highly variable and due to multiplicity of factors viz. influenced by direct sea water encroachment, inherent sediment salinity, water logging, overexploitation leading to overall deterioration in ground water quality, coupled with domestic and industrial pollution etc. The groundwater scenario in the state is not very encouraging due to imbalance between recharge and groundwater exploitation. Further, the demand for water has increased manifold owing to agricultural, industrial and domestic requirement and this has led to water scarcity in many parts of the state, which is likely to become more severe in coming future due to both natural and manmade factors. Therefore, sustainable development of groundwater resource requires precise quantitative assessment based on reasonably valid scientific principles. Hence, delineation of groundwater potential zones (GWPZ), has acquired great significance. The present study focuses on the integrated Geospatial and Multi-Criteria Decision Making (MCDM) techniques to determine the most important contributing factors that affect the groundwater resources and also to delineate the potential zones for groundwater recharge. The multiple thematic layers of influencing parameters viz. geology, geomorphology, soil, slope, drainage density and land use, weightages were assigned to the each factor according to their relative importance as per subject experts opinion owing to the natural setup of the region. The Analytical Hierarchy Process (AHP) was applied to these factors and potential recharge zones were identified. The study area for the assessment of groundwater recharge potential zones is Mahi-Narmada inter-stream region of Gujarat state. The study shows that around 28% region has the excellent suitability of the ground water recharge.

Glennie K.W.,University of Aberdeen | Fryberger S.G.,Petroleum Development Oman | Hern C.,Royal Dutch Shell | Lancaster N.,Desert Research Institute | And 4 more authors.
Geochronometria | Year: 2011

In the Wahiba Sands of eastern Oman, luminescence dating of sands enables us to relate wind activity to climatic variations and the monsoon cycle. These changes resulted from Polar gla-cial/interglacial cyclicity and changes in global sea levels and wind strengths. Luminescence dates show that development of the Sands began over 230 ka ago when the sand-driving winds were the lo-cally arid, northward-blowing SW Monsoon. During late Quaternary low sea levels, the Tigris-Euphrates river system flowed across the floor of the Persian/Arabian Gulf to the Gulf of Oman SE of the Strait of Hormuz. OSL-dated sands contain-ing calcareous bioclastic fragments deflated from the exposed Gulf floor during glacial low-water pe-riods indicate that during the last glacial cycle, and at least one earlier cycle (~120-200 ka and possi-bly as far back as 291 ka), the floor of the Arabian Gulf was exposed. This is deduced from the pres-ence of aeolian dune sands containing bioclastic detritus on the coastal plain of the Emirates and south into Al Liwa (Abu Dhabi), which were built by northern "Shamal" winds. Those calcareous sands now locally overlie sabkhas formed during interglacial high sea levels. Within the present in-terglacial, marine flooding of the Gulf occurred between about 12 and 6 ka. © 2011 Silesian University of Technology, Gliwice, Poland. All rights reserved.

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