Morpho‐sedimentary records at the Brahmaputra River exit,NE Himalaya: climate–tectonic interplay during the Late Pleistocene–Holocene     

Pradeep Srivastava  Surendra S. Bhakuni  Khayingshing Luirei  Dileep K. Misra 《第四纪科学杂志》2009,24(2):175-188

Morphological and sedimentary records at the exit of Brahmaputra River at Pasighat in the NE Himalaya inform about the climate–tectonic interplay during the past ca. 15 ka. The geomorphology of the area comprises (1) fan terrace T₃, (2) a high‐angle fan (3) terrace T₂, (4) terrace T₁ and (5) a low‐angle fan. Geomorphic consideration suggests that the fan terrace T₃ and high‐angle fans are the oldest units and were coeval. The low‐angle fan is the youngest geomorphic unit. Sedimentological studies and optically stimulated luminescence chronology suggest that (i) fan terrace T₃ formed between 13 and 10.5 ka and comprised multiple events of debris flows separated by the aggradation as channel bars in a braided river environment; (ii) the high‐angle fan formed during 15–10 ka and comprises channel bar aggradation in braided river conditions; (iii) terrace T₂ formed during 10–8 ka due to aggradation in a braided channel environment with lesser events of debris flows; (iv) terrace T₁ formed during <7 and 3 ka took place as bars of the braided river. Sudden coarsening of the sediment indicated a tectonic rejuvenation in the provenance region between 7 and 3 ka; and (v) the low‐angle fans dated to <3 ka formed due to aggradation in a small tributary joining the Brahmaputra River. This implies a phase when the main channel of the Brahmaputra did not flood regularly and the tributaries were actively aggrading. The sedimentation style and incision of these geomorphic units responded to contemporary climatic changes and uplift in the Siwalik range along the Himalayan Frontal Fault. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Hydrogeologic framework of the Deccan terrain of the Koyna River basin, India     

Pradeep K. Naik  Arun K. Awasthi  A. Anand  Prakash C. Mohan 《Hydrogeology Journal》2001,9(3):243-264

The Koyna River basin in India drew the attention of geoscientists after an earthquake (magnitude 7) in 1967. Since then, detailed geological, tectonic, and seismic investigations of this river basin have been carried out by several workers. However, very little study has been done on its hydrogeological framework. The present work aims at filling this gap. Basalts, laterites, alluvium, soils, and talus deposits form shallow unconfined aquifers, with transmissivity of 27–135 m²/d and a regional specific yield of 0.012. In shallow basaltic aquifers, the lower part of the highly weathered and highly jointed horizon above, and the poorly weathered and highly jointed horizon below, form the most potential zone for groundwater occurrence. Well yields in the deeper basaltic aquifers are directly related to the occurrence of lineaments, whereas at a shallower level they are related to geomorphic features. Spring discharges are highly dependent on their source aquifers and areas of recharge. They have a mean winter discharge of 46 m³/d and a summer discharge of 28 m³/d. Chemically, groundwaters are dominated by alkaline earths (Ca²⁺, Mg²⁺) and weak acids (HCO₃ ^–, CO₃ ^–); they are calcium-bicarbonate type (53%) and calcium-magnesium-bicarbonate type (27%) at shallower levels; and calcium-magnesium-bicarbonate type (29%), sodium-bicarbonate type (24%), calcium-bicarbonate type (19%), and calcium-magnesium-sodium-bicarbonate type (19%) in deeper aquifers. The Koyna River basin is characterized by both scarcity and abundance of groundwater. In the water-scarce areas in the dissected plateaus, artificial recharge of aquifers through construction of several recharge structures at suitable locations is highly recommended. In the water-abundant areas in the central valley, on the other hand, expanded consumptive use of water resources is encouraged. Electronic Publication  相似文献   

Stress distribution near lake Jocassee,South Carolina     

Pradeep Talwani 《Pure and Applied Geophysics》1977,115(1-2):275-281

Seven months of seismic monitoring near Jocassee reservoir (impounded 1974) resulted in the detection of four clusters of earthquake activity. Composite fault plane solutions (CFPS) for each cluster indicate strike slip faulting for shallow earthquakes (<1.0 km) on the shores of the reservoir and normal faulting for deeper events (1–3 km) in the middle of the reservoir. The directions of the axes of maximum and minimum compression inferred from the CFPS were found to be NW and NE respectively and contrast with the NE and NW directions obtained by hydrofracture in a shallow well (230 m) at Bad Creek, about 10 km from the epicentral region.  相似文献   

Geochemical approach to estimate the quality of water entering abandoned underground coalmines     

Pradeep?Mugunthan  Kathleen?M.?McDonough  David?A.?DzombakEmail author 《Environmental Geology》2004,45(6):769-780

Geochemical modeling was employed to estimate the chemistry of water infiltrating into abandoned underground flooded and unflooded coalmines of the Uniontown syncline, Fayette County, Pennsylvania. This was done to help evaluate factors governing the long-term evolution of coalmine discharge water quality in the Uniontown syncline area. The subsurface structure and lithology was delineated using borehole, mine shaft, and stratigraphic information. Hydrogeologic analyses indicated that most of the recharge to mine voids occurs in the zones of shallow overburden cover of less than 20 m in thickness. The water–rock contact period in the recharge areas of the overburden was estimated to be 5 days or greater for the flooded mines, and a day or less for the unflooded mines. Flow-through reaction-path models were applied to the topsoil and shale–sandstone lithological units identified in the recharge areas. The model predicted water entering the flooded mines at a pH of 6.65, alkalinity of 6.92 mequiv. l^–1 and a total sulfate concentration of 7.33 mM, and the unflooded mines at a pH of 6.68, alkalinity of 6.99 mequiv. l^–1 and a total sulfate concentration of 3.08 mM. The model predictions for the flooded and unflooded mines are consistent with groundwater data from the study site, indicating the usefulness of this approach in evaluating the contribution of overburden chemistry to the evolution of mine discharge quality.  相似文献   

Remote sensing techniques to locate ground water potential zones in upper Urmil River Basin, district Chhatarpur — Central India     

Pradeep K Jain 《Journal of the Indian Society of Remote Sensing》1998,26(3):135-147

In the present study efforts have been made to locate favourable zones for ground water targeting using IRS-USS-II data, Hydromorphogeological lineament, lineament density and ground water prospect maps have been prepared through visual interpretation of geocoded images on 1:50,000 scale and Survey of India topographical maps of the same scale. The resulting base line information has been integrated for evaluating ground water potential of mapping units. The alluvial plain, flood plain, infilled valley and deeply buried pediplain ace the prospective zones of ground water exploration and development. Fractures and faults parallel to drainage courses constitute priority zones for ground water targetting.  相似文献   

Evaluation of Batch Leaching Procedures for Estimating Metal Mobility in Glaciated Soils     

Jeffrey A. Lackovic  Nikolaos P. Nikolaidis  Pradeep Chheda  Robert J. Carley  Elsie Patton 《Ground Water Monitoring & Remediation》1997,17(3):231-240

Batch leaching methods have been used for several decades to estimate the potential release of contaminants from soils. Four batch leaching procedures (toxicity characteristic leaching procedure, synthetic precitation leaching procedure, deionized water leaching procedure, and California waste extraction test) were evaluated for their ability to realistically quantify the mobility of metals from previously contaminated glaciated soils. The study was conducted using soils from four different sites (three in Connecticut and one in Maine). The results of the batch leaching procedures were compared with a set of continuous column leaching experiments performed at two different flowrates and two influent pH values. The results suggested that the synthetic precipitation leaching procedure (SPLP) was more realistic than the toxicity characteristic leaching procedure (TCLP), but still a conservative leaching estimate for evaluating the potential for metal mobility in glaciated soils. This study suggests that using SPLP as a test for estimating metal cleanup levels will result in lower remediation costs relative to TCLP or waste extraction test (WET), but still maintain a high level of confidence in the protection of ground water quality.  相似文献   

Monsoonal impact on circulation pathways in the Indian Ocean     

Priyantha Jinadasa Sinhalage Uday  Pathirana Gayan  Ranasinghe Pradeep Nalak  Centurioni Lu  Hormann Verena 《海洋学报(英文版)》2020,39(3):103-112

Monsoon driven water mass exchange between the Bay of Bengal(Bo B) and Arabian Sea(AS) is the common experience. However, it is not yet firmly confirmed that the exchange pathway is either passing through southern tip of Sri Lanka or Palk Strait. Local circulation patterns impact the pathways followed by the East Indian Coastal Currents(EICC) that drive exchange, thereby modulating mixing and water mass transformation in the Bay of Bengal around Sri Lanka. In this study, observations from surface drifters were incorporated with the satellite derived data to understand the monsoonal impact on circulation patterns in the Indian Ocean. This was the first multi-national scientific effort which was conducted in the Bo B and AS during 2013 to 2015 to understand the monsoonal impact on circulation patterns in the complex region. The results indicated that seasonally reversing monsoonal currents of southern Sri Lanka, traced by the wintertime freshwater export pathways of the EICC. The deflection of monsoon currents running along the east coast of Sri Lanka by forming cyclonic and anti-cyclonic eddies, which influence the mixing and stirring associated with these flows. Results further indicate the low salinity cold water flows from the Bo B to AS along the western boundary of the Bo B during northeast monsoon. In the same way, reverses the phenomena during southwest monsoon, transporting high salinity warm water from AS to the Bo B. This maintain the bay status which occurred due to freshwater influx from large rivers and high saline water from AS. However, no evidences were observed for the exchange through Palk Strait during the study.Also, there are some mis-matches in in-situ and remotely sensed measurements which imply the necessity of systematic observation system for the complex region as an alternative approach.  相似文献   

Climate and Rural Income   总被引：3，自引：0，他引：3  

Robert Mendelsohn  Alan Basist  Pradeep Kurukulasuriya  Ariel Dinar 《Climatic change》2007,81(1):101-118

This paper tests whether climate has an impact on per capita rural income. The study finds that total (agricultural and nonagricultural) income in rural counties and municipios in the US and Brazil are affected by climate. The study demonstrates that this income effect is due to changes in the net value of agriculture. Regions with better climates for agriculture support higher rural incomes and regions with poor climates have more rural poverty. The results also suggest that global warming will likely increase rural poverty.  相似文献   

Major ion chemistry of two cratonic rivers in the tropics: Weathering rates and their controlling factors     

Anupam Samanta  Gyana Ranjan Tripathy  Aswin T. Pradeep  Anirban Mandal 《水文研究》2021,35(2):e14035

Continental weathering plays a dominant role in regulating the global carbon cycle, soil chemistry and nutrient supply to oceans. The CO₂-mediated silicate weathering acts as a major CO₂ sink, whereas sulphuric acid-mediated carbonate dissolution releases CO₂ to the atmosphere–ocean system. In this study, dissolved major ions and silica concentrations of two tropical (Damodar and Subarnarekha) river systems from India have been measured to constrain the type and rate of chemical weathering for these basins. The total dissolved solids (TDS) of these rivers, a measure of total solute supply from all possible sources, are about 2–3 times higher than that of the global average for rivers. Mass balance calculations involving inverse modelling estimate that 63 ± 11% of total cations are derived from rock weathering, of which 27 ± 7% of cations are supplied through silicate weathering. The sulphide-S concentrations are estimated by comparing the water chemistry of these two rivers with that of a nearby river (Brahmani) with similar lithology but no signatures of sulphide oxidation. The outflows of Damodar and Subarnarekha rivers receive 17% and 55% of SO₄ through sulphide oxidation, respectively. The sulphide oxidation fluxes from the ore mining areas, such as upper Damodar (0.52 × 10⁹ mol/yr) and lower Subarnarekha (0.66 × 10⁹ mol/yr) basins, are disproportionally (~9 times) higher compared to their fractional areal coverage to the global drainage area. The corresponding CO₂ release rate (2.84 × 10⁴ mol/km²/yr) for the Damodar basin is lower by five times than its CO₂ uptake rate (1.38 × 10⁵ mol/km²/yr). The outcomes of this study underscore the dominance of sulphide oxidation in controlling the dissolved chemical (cationic and sulphur) fluxes.  相似文献   

Modelling of stream run-off and sediment output for erosion hazard assessment in Lesser Himalaya: need for sustainable land use plan using remote sensing and GIS: a case study     

Pradeep K. Rawat  P. C. Tiwari  C. C. Pant  A. K. Sharama  P. D. Pant 《Natural Hazards》2011,59(3):1277-1297

Assessment and inventory on soil erosion hazard are essential for the formulation of successful hazard mitigation plans and sustainable development. The objective of this study was to assess and map soil erosion hazard in Lesser Himalaya with a case study. The Dabka watershed constitutes a part of the Kosi Basin in the Lesser Himalaya, India, in district Nainital has been selected for the case illustration. The average rate of erosion hazard is 0.68 mm/year or 224 tons/km²/year. Anthropogenic and geo-environmental factors have together significantly accelerated the rate of erosion. This reconnaissance study estimates the erosion rate over the period of 3 years (2006–2008) as 1.21 mm/year (398 tons/km²/year) in the barren land having geological background of diamictite, siltstone and shale rocks, 0.92 mm/year (302 tons/km²/year) in the agricultural land with lithology of diamictite, slates, siltstone, limestone rocks, while in the forest land, it varies between 0.20 mm/year (66 tons/km²/year) under dense forest land having the geology of quartzwacke and quartrenite rocks and 0.40 mm/year (132 tons/km²/year) under open forest/shrubs land having geological setup of shale, dolomite and gypsum rocks. Compared to the intensity of erosion in the least disturbed dense forest, the erosion rate is about 5–6 times higher in the most disturbed agricultural land and barren land, respectively. The erosion hazard zones delineated following scalogram modelling approach. Integrated scalogram modelling approach resulted in severe classes of soil erosion hazard in the study area with numerical values of Erosion Hazard Index (EHI) ranging between 01 (very low hazard) and 5 (very high hazard).  相似文献