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991.
Investigation of four edible fishes(Etroplus suratensis, Oreochromis mossambicus, Lates calcarifer, Chanos chanos)collected from a fish landing center along Cochin Backwaters has done for caligid infestation. Of these, caligids were detected only from Etroplus suratensis and was identified to be Caligus rotundigenitalis. Parasites were attached to the inner side of operculum of host which indicates strong site preference. The annual observation of prevalence, mean intensity and abundance were fo... 相似文献
992.
FAO 56 Model and Remote Sensing for the Estimation of Crop-Water Requirement in Main Branch Canal of the Bhadra Command area, Karnataka State 总被引:1,自引:0,他引:1
S. N. A. Abdul Karim S. A. Ahmed V. Nischitha Surabhi Bhatt S. Kiran Raj K. N. Chandrashekarappa 《Journal of the Indian Society of Remote Sensing》2013,41(4):883-894
Remote sensing and FAO 56 crop water model are used for estimating crop water requirement for paddy crop located in the main branch canal of Bhadra Command Area in Karnataka, India. The estimation of crop-water requirement depends on the meteorological factors, soil type and crop coefficients. The result obtained showed that water requirements of rabi crops higher than those of the kariff crops. The total irrigated area estimated from the IRS image is 29,353 ha. It is found that the total paddy crop acreage is 18,257 ha covering 62 % in the total irrigated area of the command area, Arecanut 20 %, coconut 15 % and sugarcane with other crops 3 %. The water requirement for paddy is 1180.4 mm for its entire growth period. The total water requirement for irrigation supply for crops in the entire command area is 5,790 at a demand of 0.10501 cusecs per ha. 相似文献
993.
994.
Most stochastic modelling techniques neglect the correlations among the raw un-differenced observations when forming the variance–covariance matrix of the Global Navigation Satellite System (GNSS) observations. Some methods were developed to model these correlations. One such method is the Minimum Norm Quadratic Unbiased Estimator (MINQUE). Studies have shown that MINQUE improves ambiguity resolution, and ultimately, the positioning solution in short baselines. However, its effect in cases of processing with longer baselines and on the estimation of zenith wet delay (ZWD) is somewhat unknown. In this paper, a comparison between the impact of neglecting the correlations among the observations using an elevation-angle-dependent model (EADM) and modelling the correlations using MINQUE on height determination and ZWD for medium and long baselines is carried out. The initial testing was carried out across two Australian GNSS stations with a medium-length baseline throughout a three-week campaign. The results showed that using MINQUE did not resolve the coordinate, height and wet delay components as accurately as the EADM. The results were further verified with two long-baseline campaigns whereby EADM was also able to provide better wet delay estimates. The coordinate results were, however, mixed. Overall, the study concluded that the inclusion of the correlations among the observations, in general, do not improve the resolution of the coordinate and wet delay estimates. 相似文献
995.
Inos Dhau Elhadi Adam Onisimo Mutanga Kwabena Ayisi Elfatih Mohamed Abdel-Rahman John Odindi 《国际地球制图》2013,28(11):1223-1236
AbstractIn this study, we tested whether GLS field symptoms on maize can be detected using hyperspectral data re-sampled to WorldView-2, Quickbird, RapidEye and Sentinel-2 resolutions. To achieve this objective, Random Forest algorithm was used to classify the 2013 re-sampled spectra to represent the three identified disease severity categories. Results showed that Sentinel-2, with 13 spectral bands, achieved the highest overall accuracy and kappa value of 84% and 0.76, respectively, while the WorldView-2, with eight spectral bands, yielded the second highest overall accuracy and kappa value of 82% and 0.73, respectively. Results also showed that the 705 and 710 nm red edge bands were the most valuable in detecting the GLS for Sentinel-2 and RapidEye, respectively. On the re-sampled WorldView 2 and Quickbird sensor resolutions, the respective 608 and 660 nm in the yellow and red bands were identified as the most valuable for discriminating all categories of infection. 相似文献
996.
Javed Mallick Yasser Alashker Shams Al-Deen Mohammad Mohd Ahmed Mohd Abul Hasan 《国际地球制图》2013,28(8):915-940
Soil erosion is the most important factor in land degradation and influences desertification in semi-arid areas. A comprehensive methodology that integrates revised universal soil loss equation (RUSLE) model and GIS was adopted to determine the soil erosion risk (SER) in semi-arid Aseer region, Saudi Arabia. Geoenvironmental factors viz. rainfall (R), soil erodibility (K), slope (LS), cover management and practice factors were computed to determine their effects on average annual soil loss. The high potential soil erosion, resulting from high denuded slope, devoid of vegetation cover and high intensity rainfall, is located towards the north western part of the study area. The analysis is investigated that the SER over the vegetation cover including dense vegetation, sparse vegetation and bushes increases with the higher altitude and higher slope angle. The erosion maps generated with RUSLE integrated with GIS can serve as effective inputs in deriving strategies for land planning/management in the environmentally sensitive mountainous areas. 相似文献
997.
A method is described for the detection and identification of dissolved organic compounds (DOCs) in various water samples. Acid treated active silica gel sorbent (pH 3) was packed into a micro‐column and used as a solid‐phase extraction medium for adsorption of DOCs. Silica particles‐adsorbed‐organic species were then divided into equal portions followed by suspension into various organic solvents of different polarities such as methanol, acetone, ethyl acetate, and toluene. Suspended silica‐adsorbed‐organic species were shaken for 1 h at room temperature and the organic extracts were subjected to GC–MS analysis under temperature programming conditions for qualitative detection and identification of these species. Blank solvents and silica samples were also subjected to the same extraction procedures and GC–MS analysis for comparison. The mass spectrum of each eluted chromatographic peak was library searched or manually interpreted to identify the compound. 相似文献
998.
Fast economic growth of a country contributes to the increase of activities that can also bring negative impacts on the rivers. Contamination of rivers, sedimentation, coastal erosion, decrease of aquatic life, and also flooding are some of these universal impacts. There are several rivers around the world, which are categorized as very polluted and require cleaning‐up operations. Several factors have been identified to be influencing factors in the success or otherwise of the implementation and operation of these projects. This study examined the factors related to the steps taken to clean‐up and rehabilitate these rivers and deduce by utilizing factor analysis the most critical success factors from the results obtained. A responsible river community is by far the most effective way to keep a river basin clean. Very often, however, cleaning‐up operations are necessary to revive and maintain the quality of the river so that it can be save to use as an important source of water for human consumption. It was found that community awareness was the most critical cluster of factors determining the success of the clean‐up work. 相似文献
999.
Abstract Rainfall simulators have often been used to mimic natural rainfall for studies of various land-surface and water interaction processes. The characteristics of the simulated rainfall are the main indicators used to judge the performance of the rainfall simulators. The aim of this study is to investigate the potential of piezoelectric transducers for measuring and evaluating a dripper-type simulated rainfall drop-size distribution (DSD) and kinetic energy (KE). The directly measured KE was significantly correlated with the estimated KE using the drop-size distribution and empirical rain drop fall velocity relationships. This result emphasizes the potential use of the piezoelectric sensor to directly measure and evaluate rainfall kinetic energy. Also, the relationship between rainfall intensity and KE showed good patterns of agreement between simulated rainfall and natural rainfall. Citation Abd Elbasit, M. A. M., Yasuda, H. & Salmi, A. (2011) Application of piezoelectric transducers in simulated rainfall erosivity assessment. Hydrol. Sci. J. 56(1), 187–194. 相似文献
1000.
ABSTRACTWhen discharge measurements are not available, design of water structures relies on using frequency analysis of rainfall data and applying a rainfall–runoff model to estimate a hydrograph. The Soil Conservation Service (SCS) method estimates the design hydrograph first through a rainfall–runoff transformation and next by propagating runoff to the basin outlet via the SCS unit hydrograph (UH) method. The method uses two parameters, the Curve Number (CN) and the time of concentration (Tc). However, in data-scarce areas, the calibration of CN and Tc from nearby gauged watersheds is limited and subject to high uncertainties. Therefore, the inherent uncertainty/variability of the SCS parameters may have considerable ramifications on the safety of design. In this research, a reliability approach is used to evaluate the impact of incorporating the uncertainty of CN and Tc in flood design. The sensitivity of the probabilistic outcome against the uncertainty of input parameters is calculated using the First Order Reliability Method (FORM). The results of FORM are compared with the conventional SCS results, taking solely the uncertainty of the rainfall event. The relative importance of the uncertainty of the SCS parameters is also estimated. It is found that the conventional approach, used by many practitioners, might grossly underestimate the risk of failure of water structures, due to neglecting the probabilistic nature of the SCS parameters and especially the Curve Number. The most predominant factors against which the SCS-CN method is highly uncertain are when the average rainfall value is low (less than 20 mm) or its coefficient of variation is not significant (less than 0.5), i.e. when the resulting rainfall at the design return period is low. A case study is presented for Egypt using rainfall data and CN values driven from satellite information, to determine the regions of acceptance of the SCS-CN method.
EDITOR D. Koutsoyiannis; ASSOCIATE EDITOR A. Efstratiadis 相似文献