Calibration and validation of a general infiltration model     

Surendra Kumar Mishra  Shashi Ranjan Kumar  Vijay P. Singh 《水文研究》1999,13(11):1691-1718

A general infiltration model proposed by Singh and Yu (1990) was calibrated and validated using a split sampling approach for 191 sets of infiltration data observed in the states of Minnesota and Georgia in the USA. Of the five model parameters, f_c (the final infiltration rate), S_o (the available storage space) and exponent ‘n’ were found to be more predictable than the other two parameters: m (exponent) and a (proportionality factor). A critical examination of the general model revealed that it is related to the Soil Conservation Service (1956) curve number (SCS‐CN) method and its parameter S_o is equivalent to the potential maximum retention of the SCS‐CN method and is, in turn, found to be a function of soil sorptivity and hydraulic conductivity. The general model was found to describe infiltration rate with time varying curve number. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

Study of isotopic seasonality to assess the water source of proglacial stream in Chhota Shigri Glaciated Basin,Western Himalaya     

Naveen Kumar  Alagappan Ramanathan  Aman Arora  Mohd Soheb  Arindan Mandal  Parmanand Sharma  Shyam Ranjan 《水文研究》2020,34(5):1285-1300

The impact of surface melt patterns and the Indian summer monsoon (ISM) is examined on the varying contributions of end member (snow, glacier ice, and rain) to proglacial streamflow during the ablation period (June–October) in the Chhota Shigri glaciated basin, Western Himalaya. Isotopic seasonality observed in the catchment precipitation was generally reflected in surface runoff (supraglacial melt and proglacial stream) and shows a shift in major water source during the melt season. Isotopically correlated (δ¹⁸O–δD) high deuterium intercept in the surface runoff suggests that westerly precipitation acts as the dominant source, augmenting the other snow- and ice-melt sources in the region. The endmember contributions to the proglacial stream were quantified using a three-component mixing. Overall, glacier ice melt is the major source of proglacial discharge. Snowmelt is the predominant source during the early ablation season (June) and the peak ISM period (August and September), whereas ice melt reaches a maximum in the peak melt period (July). The monthly contribution of rain is on the lower side and shows a steady rise and decline with onset and retreat of the monsoon. These results are persistent with the surface melt pattern observed in Chhota Shigri glacier, Upper Chandra basin. Moreover, the role of the ISM in Chhota Shigri glacier is unvarying to that observed in other glacierized catchments of Upper Ganga basin. Thus, this study augments the significant role of the ISM in glacier mass balance up to the boundary of the central-western Himalayan glaciated region.  相似文献   

GIS-based weights-of-evidence modelling of rainfall-induced landslides in small catchments for landslide susceptibility mapping   总被引：10，自引：0，他引：10  

Ranjan Kumar Dahal  Shuichi Hasegawa  Atsuko Nonomura  Minoru Yamanaka  Takuro Masuda  Katsuhiro Nishino 《Environmental Geology》2008,54(2):311-324

Landslide susceptibility mapping is a vital tool for disaster management and planning development activities in mountainous terrains of tropical and subtropical environments. In this paper, the weights-of-evidence modelling was applied, within a geographical information system (GIS), to derive landslide susceptibility map of two small catchments of Shikoku, Japan. The objective of this paper is to evaluate the importance of weights-of-evidence modelling in the generation of landslide susceptibility maps in relatively small catchments having an area less than 4 sq km. For the study area in Moriyuki and Monnyu catchments, northeast Shikoku Island in west Japan, a data set was generated at scale 1:5,000. Relevant thematic maps representing various factors (e.g. slope, aspect, relief, flow accumulation, soil depth, soil type, land use and distance to road) that are related to landslide activity were generated using field data and GIS techniques. Both catchments have homogeneous geology and only consist of Cretaceous granitic rock. Thus, bedrock geology was not considered in data layering during GIS analysis. Success rates were also estimated to evaluate the accuracy of landslide susceptibility maps and the weights-of-evidence modelling was found useful in landslide susceptibility mapping of small catchments.  相似文献   

Modeling urban floods and drainage using SWMM and MIKE URBAN: a case study     

Deepak Singh Bisht  Chandranath Chatterjee  Shivani Kalakoti  Pawan Upadhyay  Manaswinee Sahoo  Ambarnil Panda 《Natural Hazards》2016,84(2):749-776

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Macrobenthos of Kakinada Bay in the Godavari delta, East coast of India: comparing decadal changes   总被引：3，自引：0，他引：3  

Dipti Raut  T. Ganesh  N.V.S.S. Murty  A.V. Raman   《Estuarine, Coastal and Shelf Science》2005,62(4):609-620

A one-year study (1995–1996) on the macrobenthos over a spread of (37) hydrographically differing GPS-fixed sites in Kakinada Bay (mean salinity 27.16±0.4) and adjacent mangrove channels (14.78±0.55) in the Godavari delta, one of India's largest estuarine systems, revealed a great preponderance of benthic life. There were 11 diverse taxa represented by 95 species collected through several (303) grab and dredge hauls. Based on Bray-Curtis similarity through hierarchical clustering implemented in PRIMER, it was possible to distinguish the benthos into four assemblages each of which represented sites in the Central and North bay (Paphia textrix – Typhlocarcinus sp. Assemblage), South-East bay (Protankyra similis – Paphia malabarica Assemblage), Mangrove Outlets (Cerithidea cingulata Assemblage) and Mangrove channels (Diopatra neapolitana Assemblage). Benthos densities (mean nos. dredge haul⁻¹) were highest (299 individuals) at sites close to mangrove outlets. Species diversity (Margalef, d; Shannon-Wiener, H′) was low in general (d 1.244 to 2.251 and H′ 0.038 to 1.502). Sediments were mostly clayey-silt in nature except in southeast bay where they are silt-sand. Organic matter (mean) was at or near 1.3%. The observations have revealed marked changes in benthic community structure relative to an earlier investigation held in 1958–1963 in this area. Over the years, species such as Turritella duplicata, Tonna dolium and Placuna placenta found in considerable numbers previously have dwindled. Anomia, Bursa and Atrina and echinoderms, Astropecten indica, Echinodiscus auritus and Temnopleurus toreumaticus and the brachiopod, Lingula sp. of common occurrence in early 60s are absent altogether attributable to long-term natural trends during the intervening years and/or events accompanying human impingement (e.g. industrial and urban growth, port expansion measures, aquaculture, mangrove denudation etc.). Despite such large-scale alterations in benthos community structure, there were no significant changes in “biodiversity” measured through Average Taxonomic Distinctness (AvTD) and Variation in Taxonomic Distinctness (VarTD). The investigation revealed that AvTD (Δ⁺) and VarTD (Λ⁺) for previous years and the present study remained well within the 95% confidence funnel implying taxonomic stability. It was found that species, which had replaced the earlier forms, were drawn from comparable (Linnean) hierarchy i.e. same phylum/class.  相似文献   

Acoustic Doppler current profiler observations of herring movement     

Zedel  Len; Knutsen  Tor; Patro  Ranjan 《ICES Journal of Marine Science》2003,60(4):846-859

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First Observations from the Multi-Application Solar Telescope (MAST) Narrow-Band Imager     

Shibu K. Mathew  Ankala Raja Bayanna  Alok Ranjan Tiwary  Ramya Bireddy  Parameswaran Venkatakrishnan 《Solar physics》2017,292(8):106

The Multi-Application Solar Telescope is a 50 cm off-axis Gregorian telescope recently installed at the Udaipur Solar Observatory, India. In order to obtain near-simultaneous observations at photospheric and chromospheric heights, an imager optimized for two or more wavelengths is being integrated with the telescope. Two voltage-tuneable lithium-niobate Fabry–Perot etalons along with a set of interference blocking filters have been used for developing the imager. Both of the etalons are used in tandem for photospheric observations in Fe i 6173 Å and chromospheric observation in H\(\alpha\) 6563 Å spectral lines, whereas only one of the etalons is used for the chromospheric Ca II line at 8542 Å. The imager is also being used for spectropolarimetric observations. We discuss the characterization of the etalons at the above wavelengths, detail the integration of the imager with the telescope, and present a few sets of observations taken with the imager set-up.  相似文献   

Scanning sky monitor (SSM) onboard AstroSat     

M. C. Ramadevi  S. Seetha  Dipankar Bhattacharya  B. T. Ravishankar  N. Sitaramamurthy  G. Meena  M. Ramakrishna Sharma  Ravi Kulkarni  V. Chandra Babu  Kumar  Brajpal Singh  Anand Jain  Reena Yadav  S. Vaishali  B. N. Ashoka  Anil Agarwal  K. Balaji  G. Nagesh  Manoj Kumar  Dhruti Ranjan Gaan  Prashanth Kulshresta  Pankaj Agarwal  Mathew Sebastian  A. Rajarajan  D. Radhika  Anuj Nandi  V. Girish  Vivek Kumar Agarwal  Ankur Kushwaha  Nirmal Kumar Iyer 《Experimental Astronomy》2017,44(1):11-23

Scanning Sky Monitor (SSM) onboard AstroSat is an Xray sky monitor in the soft X-ray band designed with a large field of view to detect and locate transient X-ray sources and alert the astronomical community about interesting phenomena in the X-ray sky. SSM comprises position sensitive proportional counters with 1D coded mask for imaging. There are three detector units mounted on a platform capable of rotation which helps covering about 50% of the sky in one full rotation. This paper discusses the elaborate details of the instrument and few immediate results from the instrument after launch.  相似文献   

Analytical expressions for determining the stability of cohesionless soil slope under generalized seismic conditions     

Sahoo Pragyan Pradatta  Shukla Sanjay Kumar  Mohyeddin Alireza 《山地科学学报》2018,15(7):1559-1571

In recent major earthquakes, the researchers have found the need for consideration of vertical seismic acceleration for the stability analysis of the man-made and natural slopes. However, in most past studies, the performance of slopes has been assessed by accounting only the horizontal seismic component of the ground motion, without giving due weightage to the effect of vertical component. In the present study, analytical expressions are derived to determine the factor of safety, yield seismic coefficient and consequently the seismic displacement of cohesionless soil slope under combined horizontal and vertical components of the ground motion. The derivation uses the Newmark’s sliding block approach, in which the soil slope with a planar failure surface within the framework of conventional pseudo-static analysis is assumed to follow the Mohr-Coulomb failure criterion. The effects of vertical seismic coefficient on the stability of cohesionless slope have been studied through a set of graphical presentations for a specific range of soil parameters. It is observed that overlooking the effect of the vertical component of the ground motion on factor of safety and the displacement while designing the slope may be detrimental, resulting in the slope failure. The general expressions presented in this paper may be highly useful in the field of earthquake geotechnical engineering practice for designing the cohesionless soil slopes under combined horizontal and vertical seismic loads.  相似文献   

Evaluation of time scale of meteorological,hydrological and agricultural drought indices     

Prajapati  V. K.  Khanna  M.  Singh  M.  Kaur  R.  Sahoo  R. N.  Singh  D. K. 《Natural Hazards》2021,109(1):89-109

Natural Hazards - The present study was carried out to characterize drought in the Marathwada region of Maharashtra, which experiences recurring droughts, through meteorological, hydrological and...  相似文献