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51.
Spur dikes are river training structures that have been extensively used worldwide for towards enhancing flood control and the stability of embankments and riverbanks.However,scour around spur dikes can be a major problem affecting their stability and hydraulic performance.The precise computation of temporal scour depth at spur dikes is very important for the design of economical and safe spur dikes.This study focuses on experimentally assessing the temporal variation of scour depth around a vertical wall spur dike and identifying the parameters,which mostly influence spur dike performance for a channel bed surface comprised of sand-gravel mixtures.In the current study,the authors did physical experiments in a flume based study to obtain new data,aimed at deriving a new predictive model for spur dike scour and comparing its performance to others found in the literature.It was found that the dimensionless temporal scour depth variation increases with an increase in(i)the threshold velocity ratio,(ii)the densimetric Froude number of the bed surface sediment mixture,(iii)the flow shallowness(defined as the ratio of the approach flow depth,y,to the spur dike’s transverse length,l),and(iv)the flow depth-particle size ratio.It is also concluded that the temporal scour depth variation in the sediment mixture is influenced by the non-uniformity of sediment and decreases with an increase in the non-uniformity of the sediment mixture.A new mathematical model is derived for the estimation of temporal scour depths in sand-gravel sediment mixtures.The proposed equation has been calibrated and validated with the experimental data,demonstrating a good predictive capacity for the estimation of temporal scour depth evolution. 相似文献
52.
53.
Application of semi‐distributed hydrological model for basin level water balance of the Ken basin of Central India
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In the present study, a semi‐distributed hydrological model soil and water assessment tool (SWAT) has been employed for the Ken basin of Central India to predict the water balance. The entire basin was divided into ten sub basins comprising 107 hydrological response units on the basis of unique slope, soil and land cover classes using SWAT model. Sensitivity analysis of SWAT model was performed to examine the critical input variables of the study area. For Ken basin, curve number, available water capacity, soil depth, soil evaporation compensation factor and threshold depth of water in the shallow aquifer (GWQ_MN) were found to be the most sensitive parameters. Yearly and monthly calibration (1985–1996) and validation (1997–2009) were performed using the observed discharge data of the Banda site in the Ken basin. Performance evaluation of the model was carried out using coefficient of determination, Nash–Sutcliffe efficiency, root mean square error‐observations standard deviation ratio, percent bias and index of agreement criterion. It was found that SWAT model can be successfully applied for hydrological evaluation of the Ken basin, India. The water balance analysis was carried out to evaluate water balance of the Ken basin for 25 years (1985–2009). The water balance exhibited that the average annual rainfall in the Ken basin is about 1132 mm. In this, about 23% flows out as surface run‐off, 4% as groundwater flow and about 73% as evapotranspiration. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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55.
A. K. Awasthi A. K. Pandey J. Khan 《International Journal of Environmental Science and Technology》2017,14(9):2015-2022
The purpose of this research was to test the ability of selected fungus Trichoderma harzianum for municipal solid waste leachate treatment. The research carried out by inoculating the enzyme produced by T. harzianum with different ratio (10% up to 80% v/v) of solid waste leachate. The findings clearly indicated that the enzymatic addition was effectively acted (86.09% of chemical oxygen demand removed), and the rate of chemical degradation amended treatment enhanced as compared to control. Also, the enzymatic addition excellently reduced the inhibition of germination (35.8 ± 0.7) of seed (Zea mays L.) and improved the environmental quality of treated leachate. Therefore, these results can be use to articulate the preliminary feedstock for pilot to field-scale application. 相似文献
56.
Salt crystallisation is a major problem of deterioration in historic stone buildings, monuments and sculptures. The capillary rise of soil water is one of the primary sources of salts in stone structures, which evaporates leaving the salts behind. It has been noted that the spatial distribution profile of different species of salts crystallised in historic stone buildings is not homogeneous, i.e. different salts crystallise at different locations. The capillary transport and inhomogeneous spatial distribution of different salts in the porous building materials has been considered to be a result of solubility-dependent crystallisation; however, the factors responsible for this phenomenon are not clearly known. This paper aims to investigate the factors influencing the differential distribution of salts during capillary rise of soil water. In this study, the capillary transport of salts was simulated on two different sandstones—Locharbriggs, a Permo–Triassic, red sandstone and Stoke Hall, a Carboniferous, buff sandstone. The experiments were carried out under controlled environmental conditions to eliminate the possibility of evaporation-driven crystallisation of salts depending on their solubilities. The results indicate that fractionation or differential distribution of salts takes place even in the absence of evaporation and crystallisation. The sandstones exhibit properties like an ion exchange column, and ionic species present in the salt solution show differential distribution within the porous network of sandstone. 相似文献
57.
O. P. Pandey Priyanka Tripathi Nimisha Vedanti D. Srinivasa Sarma 《Pure and Applied Geophysics》2016,173(7):2455-2471
58.
In the present investigation, an effort has been made to identify the critical sub-watersheds for the development of best
management plan for a small watershed of Eastern India using a hydrological model, namely, AVSWAT2000. A total of 180 combinations
of various management treatments including crops (rice, maize ground nut and soybean), tillage (zero, conservation, field
cultivator, mould board plough and conventional practices) and fertilizer levels (existing half of recommended and recommended)
have been evaluated. The investigation reveled that rice cannot be replaced by other crops such as groundnut, maize, mungbean,
sorghum and soybean since comparatively these crops resulted in higher sediment yield. The tillage practices with disk plough
have been found to have more impact on sediment yield and nutrient losses than conventional tillage practices for the existing
level of fertilizer. Sediment yield decreased in the case of zero tillage, conservation tillage, field cultivator, moldboard
plough, and conservation tillage as compare to conventional tillage. Lowest NO3–N loss was observed in zero tillage in all the fertilizer treatments, whereas field cultivator, moldboard plough and disk
plough resulted in increase of NO3–N loss. As compared to conventional tillage, the losses of soluble phosphorus were increased in moldboard plough. The losses
of organic nitrogen were also increased as fertilizer dose increased. After zero tillage the conservation tillage preformed
better in all the fertilizer treatments as per loss of organic nitrogen and organic phosphorus is concerned. It can be concluded
that the sediment yield was found to be the highest in the case of disk plough followed by moldboard plough, field cultivator,
conventional tillage, field cultivator and least in zero tillage practices. The nutrient losses were found to be in different
order with tillage practices, resulted highest in disk plough tillage practices. In view of sediment yield and nutrient losses,
the conservation tillage practice was found to be the best as the sediment yield is less than the average soil loss whereas
nutrient loss is within the permissible limit. 相似文献
59.
Field biological and geomorphological observations in certain East Asia coasts permit definition of Mean Sea Level (MSL) with an accuracy of ~10 cm, that is, a vertical geodetic datum, as well as recognition of the MSL of fossil shorelines, up to a few thousand years old, mainly associated with tectonic/seismic effects. Subsidence produced by compaction of nearly-surficial strata seems also to be a usual effect. These data indicate that datum variability is a widespread effect in East Asia, time-dependent even at time scales affecting engineering works, but only in a few cases fully predictable. 相似文献
60.
Seasonal and monthly variations of heat flux have been investigated in this study using the Modular Ocean Model of version 3 (MOM 3) simulations and 52 years Simple Ocean Data Assimilation (SODA) products. These variations of the heat flux in different boxes of the Bay of Bengal (BOB) in different depths show the different behavior of the boxes. It is seen that the model and SODA results are comparable. The basin shows north-south variation in the surface from winter to spring whereas there is east-west variation in the mixed layer throughout the year except winter. The remote effect caused by warm water penetration from Pacific Ocean through the Strait of Malacca and coastal Kelvin waves keeps the basin warm most of the year. This article addresses the mechanisms of the seasonal variation of the vertical structure of the temperature and heat flux components. 相似文献