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1.
Water quality is often highly variable both in space and time, which poses challenges for modelling the more extreme concentrations. This study developed an alternative approach to predicting water quality quantiles at individual locations. We focused on river water quality data that were collected over 25 years, at 102 catchments across the State of Victoria, Australia. We analysed and modelled spatial patterns of the 10th, 25th, 50th, 75th and 90th percentiles of the concentrations of sediments, nutrients and salt, with six common constituents: total suspended solids (TSS), total phosphorus (TP), filterable reactive phosphorus (FRP), total Kjeldahl nitrogen (TKN), nitrate-nitrite (NOx), and electrical conductivity (EC). To predict the spatial variation of each quantile for each constituent, we developed statistical regression models and exhaustively searched through 50 catchment characteristics to identify the best set of predictors for that quantile. The models predict the spatial variation in individual quantiles of TSS, TKN and EC well (66%–96% spatial variation explained), while those for TP, FRP and NOx have lower performance (37%–73% spatial variation explained). The most common factors that influence the spatial variations of the different constituents and quantiles are: annual temperature, percentage of cropping land area in catchment and channel slope. The statistical models developed can be used to predict how low- and high-concentration quantiles change with landscape characteristics, and thus provide a useful tool for catchment managers to inform planning and policy making with changing climate and land use conditions. 相似文献
2.
Abstract The rates of the accumulated and continuous displacement of solifluction lobes in the Kangchenjunga area, eastern Nepal Himalaya, were determined using glass fiber tubes and a strain probe. Ground temperature, precipitation and soil moisture were monitored at two sites, whose altitude differed by approximately 100 m, to understand the solifluction process. The average movement rate of the glass fiber tubes on a 31° slope at altitudes of 5412–5414 m a.s.l. was approximately 11 mm/year, being almost threefold greater than that observed on a 22° slope at 5322–5325 ma.s.l. There was no significant difference in the depth of displacement at these sites. The continuous displacement measurement near the ground surface at 5414 m showed permanent downslope movement from early July. Such movement may be attributed to additional moisture supply during the monsoon season. The amplitude of the displacement cycle was highest at the ground surface, and decreased to virtually zero at and below 20 cm in depth. Probable factors leading to the relatively slow rates of downslope displacement at the surface and depth at the studied altitudes are the lack of concurrence of the freeze–thaw cycles and the high moisture condition in the soil, and the low moisture retention capacity of the soil because of steep slopes and superficial desiccation. The rate of displacement may be more pronounced at altitudes above 5600 m because of the freeze–thaw cycles during the summer season. 相似文献
3.
Prabhin Sukumaran Dhananjay A. Sant K. Krishnan Govindan Rangarajan 《Journal of the Geological Society of India》2012,79(1):41-52
A high resolution quantitative granulometric record for site Uchediya [21°43′2.22″ N, 73° 6′26.22″ E; 10 m a. s. l.] gives
understanding towards accretion history of the late Holocene flood plain in the lower reaches of Narmada River. Two sediment
facies (sandy and muddy) and seven subfacies (sandy subfacies: StMS+FS+CS, SmFS+MS, SlFS+VFS, and StMS + CS; muddy subfacies: FmSILT+VFS+FS, FmSILT+VFS (O) and FmSILT+VFS (T)) are identified based on cluster analysis supplemented with sedimentary structures observed in field and other laboratory
data. Changes in hydrodynamics are further deduced based on various sedimentological parameters and their ratios leading to
arrive at a depositional model. 相似文献
4.
Prabhin Sukumaran C. Rajshekhar Dhananjay A. Sant K. Krishnan 《Journal of the Geological Society of India》2012,80(3):403-408
Storms from the Arabian Sea are the most significant meteorological feature in western India that brings extreme rainy days together with catastrophic flooding. The present study reports two such palaeo-storm horizons at 1.16 m and 3.2 m above the present day water level in the Narmada channel, 56 km inland based on sedimentology and foraminiferal records. Both the horizons show similar sediment facies and foraminiferal assemblage. The present findings instigate to look for such new sites and build palaeo-storm records for western India. 相似文献
5.
Dhananjay A. Sant Sudesh K. Wadhawan Rajinder K. Ganjoo Nathani Basavaiah Prabhin Sukumaran Sourabh Bhattacharya 《Journal of the Geological Society of India》2011,78(2):147-156
The paraglacial sequence in the Leh valley, Ladakh Himalaya preserves imprints of various processes active during deglaciation
in the late phase of Last Glacial. In present work, a high resolution sedimentological record generated for Spituk is presented
identifying aeolian episodes, mudflow events from Ladakh Range and debris flows extending from Zanskar Range across present
Indus River. Two temporal phases of water ponding within Spituk Sequence are also identified. The seismites recorded at various
stratigraphic depths and their association with the sediment facies signifies gravity induced process besides possible seismic
activity as an added phenomena. Linkage between paraglacial processes since Last Glacial to Recent is tracked and evaluated. 相似文献
6.
7.
Divya Prakash Dhananjay Kumar Patel Suparna Tewari Manoj Kumar Yadav Roopali Yadav 《Journal of the Geological Society of India》2017,89(2):139-144
The pelitic schists of the area around Kandra, Singhbhum district, Jharkhand belong to the Chaibasa Formation of the Singhbhum Group, which constitute a part of the youngest Precambrian orogenic cycle of the Singhbhum region. Structurally, the area represents the Singhbhum anticlinorium and is overlain by Dalma traps which form the synclinorium towards the north of the area around Kandra. This area mainly consists of medium to high grade rocks belonging to greenschist and amphibolite facies. These rocks are folded in the E-W trending doubly plunging folds (F1) overturned towards the south with low plunges and superposed by cross-folds (F2). The spatial distribution of the index minerals in the pelitic schists of the area shows Barrovian type of metamorphism. Four isograds, viz. biotite, garnet, staurolite and sillimanite have been delineated by the first appearance of the index minerals and also by isograd reactions. The textural relation suggests that sillimanite is formed from staurolite consumption reaction instead of kyanite consumption. 相似文献
8.
Dhananjay A. Sant Sudesh K. Wadhawan Rajinder K. Ganjoo Nathani Basavaiah Prabhin Sukumaran Sourabh Bhattacharya 《Journal of the Geological Society of India》2011,77(6):499-510
In the present paper we study morphology, occurrence and mutual interrelationship of erosional (amphitheaters) and depositional
landforms belonging to glacial (moraines), fluvio-glacial (glacial out wash), mass wasting (alluvial fans), aeolian (obstacle
dune and sand sheets) and lacustrine (palaeo-lake sediments) processes within the Leh valley. These landforms are the geomorphic
expression of past deglaciation grouped into five Formative Stages of Landform (FSL 1 to FSL 5) development in the Leh valley.
The broad age bracket for the formative stages are based on the empirical relationship of the landforms, available chronology
and their correlation with comparable climate phases. The retreat of glaciers in the Leh valley, along the southern slopes
of Ladakh hill range and their retention over the northern slopes and Karakoram is further explained. 相似文献
9.
Özcan Bektaş Dhananjay Ravat Aydin Büyüksaraç Funda Bilim Abdullah Ateş 《Pure and Applied Geophysics》2007,164(5):975-998
East Anatolia is a region of high topography made up of a 2-km high plateau and Neogene and Quaternary volcanics overlying
the subduction-accretion complex formed by the process of collision. The aeromagnetic and gravity data surveyed by the Mineral
Research and Exploration (MTA) of Turkey have been used to interpret qualitatively the characteristics of the near-surface
geology of the region. The residual aeromagnetic data were low-pass filtered and analyzed to produce the estimates of magnetic
bottom using the centroid method and by forward modelling of spectra to evaluate the uncertainties in such estimates. The
magnetic bottom estimates can be indicative of temperatures in the crust because magnetic minerals lose their spontaneous
magnetization at the Curie temperature of the dominant magnetic minerals in the rocks and, thus, also are called Curie point
depths (CPDs). The Curie point depths over the region of Eastern Anatolia vary from 12.9 to 22.6 km. Depths computed from
forward modelling of spectra with 200–600 km window sizes suggest that the bottom depths from East Anatolia from the magnetic
data may have errors exceeding 5 km; however, most of the obtained depths appear to lie in the above range and indicate that
the lower crust is either demagnetized or non-magnetic. In the interpretation of the magnetic map, we also used reduction-to-pole
(RTP) and amplitude of total gradient of high-pass filtered anomalies, which reduced dipolar orientation effects of induced
aeromagnetic anomalies. However, the features of the RTP and the total gradient of the high-pass filtered aeromagnetic anomalies
are not highly correlated to the hot spring water locations. On the other hand, many high-amplitude features seen on the total
gradient map can be correlated with the ophiolitic rocks observed on the surface. This interpretation is supported by Bouguer
gravity data. In this paper, we recommend that the sources of the widespread thermal activity seen in East Anatolia must be
investigated individually by means of detailed mapping and modelling of high resolution geophysical data to assess further
the geothermal potential of the region. 相似文献
10.
Dhananjay K. Deshmukh Manas Kanti Deb Ying I. Tsai Stelyus L. Mkoma 《Journal of Atmospheric Chemistry》2010,66(1-2):81-100
This study elucidates the characteristics of ambient PM2.5 (fine) and PM1 (submicron) samples collected between July 2009 and June 2010 in Raipur, India, in terms of water soluble ions, i.e. Na+, NH 4 + , K+, Mg2+, Ca2+, Cl?, NO 3 ? and SO 4 2? . The total number of PM2.5 and PM1 samples collected with eight stage cascade impactor was 120. Annual mean concentrations of PM2.5 and PM1 were 150.9?±?78.6 μg/m3 and 72.5?±?39.0 μg/m3, respectively. The higher particulate matter (PM) mass concentrations during the winter season are essentially due to the increase of biomass burning and temperature inversion. Out of above 8 ions, the most abundant ions were SO 4 2? , NO 3 ? and NH 4 + for both PM2.5 and PM1 aerosols; their average concentrations were 7.86?±?5.86 μg/m3, 3.12?±?2.63 μg/m3 and 1.94?±?1.28 μg/m3 for PM2.5, and 5.61?±?3.79 μg/m3, 1.81?±?1.21 μg/m3 and 1.26?±?0.88 μg/m3 for PM1, respectively. The major secondary species SO 4 2? , NO 3 ? and NH 4 + accounted for 5.81%, 1.88% and 1.40% of the total mass of PM2.5 and 11.10%, 2.68%, and 2.48% of the total mass of PM1, respectively. The source identification was conducted for the ionic species in PM2.5 and PM1 aerosols. The results are discussed by the way of correlations and principal component analysis. Spearman correlation indicated that Cl? and K+ in PM2.5 and PM1 can be originated from similar type of sources. Principal component analysis reveals that there are two major sources (anthropogenic and natural such as soil derived particles) for PM2.5 and PM1 fractions. 相似文献