Assessing and monitoring the human influence on water quality in response to land transformation within Wular environs of Kashmir Valley     

Tariq Ahmad Ganaie  Mehebub Sahana  Haseena Hashia 《GeoJournal》2018,83(5):1091-1113

Wular Lake is the largest freshwater lake of India located in north western Himalayas of Kashmir Valley which has got deteriorated over the period of time due to the enough human interference within its catchment areas. The purpose of the present research study is to identify the changes in land use and land cover in the Wular catchment as well as its transformation into other classes and its impact on the overall water quality of the lake. For the present study Landsat (TM) image of 1992 and Landsat-8 (OLI) of 2015 have been used for assessing the changes in land use/land cover. Supervised classification technique was used to generate LULC maps of different categories pertaining to study area for years 1992 and 2015. Regarding water quality, water samples were collected from five different spots of the lake in four different seasons of the year—from December 2014 to September 2015. The sites from which samples were collected are Vintage Park, Ashtungo, Watlab, Makhdomyari and Ningal as site 1, 2, 3, 4, and 5 respectively. Some parameters of water like temperature, transparency, depth, conductivity and pH were examined on the spot during the sample collection by their respective measuring instruments. The rest of the parameters were examined in hydrological laboratory within 24 h after collection following the standard methods of APHA (Standard methods for the examination of water and wastewater, 21st edn. American Public Health Association, Washington, DC, 2005). The relationship between the LULC classes and water quality parameters has been calculated with the help of SHDI which has shown both positive and as well as negative results.  相似文献   

Seasonal changes of water properties and current in the northernmost gulf of aqaba,red sea     

Riyad Manasrah  Mohammad Zibdah  Firas Al-Ougaily  Najim Yusuf  Tariq Al-Najjar 《Ocean Science Journal》2007,42(2):103-116

Seasonal changes of tide signal(s), temperature, salinity and current were studied during the years 2004-2005 in the northernmost Gulf of Aqaba, which is under developmental activities, to obtain scientific bases for best management and sustainability. Spectrum analysis revealed permanent signals of tide measurements during all seasons, which represented semidiurnal and diurnal barotropic tides. The other signal periods of 8.13, 6.10-6.32, 4.16 and 1.02-1.05 h were not detected in all seasons, which were related to shallow water compound and overtides of principle solar and lunar constituent and to seiches generated in the Red Sea and the Gulf of Aqaba. Spatial and temporal distribution of temperature, salinity and density showed significant differences between months in the coastal and offshore region and no significant differences among the coastal sites, between the surface and bottom waters and between coastal and offshore waters. Therefore, the temporal and spatial variation of water properties in the northernmost Gulf of Aqaba behave similarly compared to other parts. The coastal current below 12 m depth was weak (3-6 cms^-1) and fluctuated from east-northeastward to west-southwestward (parallel to the shoreline), which may be related to the effect of bottom topography and/or current density due to differential cooling between eastern and western parts in the study area, and windinduced upwelling and downwelling in the eastern and western side, respectively. The prevailing northerly winds and stratification conditions during summer were the main causes of the southward current at 6 and 12 m depths with average speed of 28 and 12 cms^-1, respectively.  相似文献   

Sediment yield assessment and identification of check dam sites for Rawal Dam catchment     

Nida Samad  Muhammad Hamid Chauhdry  Muhammad Ashraf  Muhammad Saleem  Qudsia Hamid  Umair Babar  Hassan Tariq  Muhammad Shahid Farid 《Arabian Journal of Geosciences》2016,9(6):466

Sediment yield is the amount of erosional debris from drainage basin deposited in reservoirs. The economic life of storage reservoir depends upon the estimation of the time it takes for the reservoir to be filled with the deposition of sediments. This research is based on assessing the sediment yield in Rawal Dam catchment by using Soil and Water Assessment Tool (SWAT) model. Digital Elevation Model (DEM), land use maps, soil maps, and weather data of the study watershed were used as input to SWAT model. Monthly sedimentation data of year 2010 and discharge data from 1998 to 2005 is being used for model calibration and validation, respectively. Whereas simulations are being generated from 1998 to 2011 for both sedimentation and discharge. Modified Universal Soil Loss Equation (MUSLE) was used for the estimation of sediment yield. The Nash and Sutcliffe coefficient of the model was found to be 0.79 which depicts its effectiveness. After the estimation of the sediment yield and discharge by using SWAT model, double mass curve was used to evaluate the sedimentation rate. The rate of sediment transport can be reduced by the construction of check dams. Various sites have also been proposed for check dams construction to prevent the sediments transported into the Rawal Catchment.  相似文献   

Migration velocity analysis using pre‐stack wave fields          下载免费PDF全文

Tariq Alkhalifah  Zedong Wu 《Geophysical Prospecting》2017,65(3):639-649

Using both image and data domains to perform velocity inversion can help us resolve the long and short wavelength components of the velocity model, usually in that order. This translates to integrating migration velocity analysis into full waveform inversion. The migration velocity analysis part of the inversion often requires computing extended images, which is expensive when using conventional methods. As a result, we use pre‐stack wavefield (the double‐square‐root formulation) extrapolation, which includes the extended information (subsurface offsets) naturally, to make the process far more efficient and stable. The combination of the forward and adjoint pre‐stack wavefields provides us with update options that can be easily conditioned to improve convergence. We specifically use a modified differential semblance operator to split the extended image into a residual part for classic differential semblance operator updates and the image (Born) modelling part, which provides reflections for higher resolution information. In our implementation, we invert for the velocity and the image simultaneously through a dual objective function. Applications to synthetic examples demonstrate the features of the approach.  相似文献   

Research Note: The sensitivity of surface seismic P‐wave data in transversely isotropic media to reflector depth          下载免费PDF全文

Tariq Alkhalifah 《Geophysical Prospecting》2017,65(5):1398-1406

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Full waveform inversion using oriented time‐domain imaging method for vertical transverse isotropic media          下载免费PDF全文

Zhen‐dong Zhang  Tariq Alkhalifah 《Geophysical Prospecting》2017,65(Z1):166-180

Full waveform inversion for reflection events is limited by its linearised update requirements given by a process equivalent to migration. Unless the background velocity model is reasonably accurate, the resulting gradient can have an inaccurate update direction leading the inversion to converge what we refer to as local minima of the objective function. In our approach, we consider mild lateral variation in the model and, thus, use a gradient given by the oriented time‐domain imaging method. Specifically, we apply the oriented time‐domain imaging on the data residual to obtain the geometrical features of the velocity perturbation. After updating the model in the time domain, we convert the perturbation from the time domain to depth using the average velocity. Considering density is constant, we can expand the conventional 1D impedance inversion method to two‐dimensional or three‐dimensional velocity inversion within the process of full waveform inversion. This method is not only capable of inverting for velocity, but it is also capable of retrieving anisotropic parameters relying on linearised representations of the reflection response. To eliminate the crosstalk artifacts between different parameters, we utilise what we consider being an optimal parametrisation for this step. To do so, we extend the prestack time‐domain migration image in incident angle dimension to incorporate angular dependence needed by the multiparameter inversion. For simple models, this approach provides an efficient and stable way to do full waveform inversion or modified seismic inversion and makes the anisotropic inversion more practicable. The proposed method still needs kinematically accurate initial models since it only recovers the high‐wavenumber part as conventional full waveform inversion method does. Results on synthetic data of isotropic and anisotropic cases illustrate the benefits and limitations of this method.  相似文献   

Assessing Metal Content in Halophila stipulacea Seagrass as an Indicator of Metal Pollution in the Northern Gulf of Aqaba,Red Sea     

Al-Najjar  Tariq  Wahsha  Mohammad  Al-Khushman  Mwaffaq  Khalaf  Maroof  Hardage  Kyle  Hayek  Wissam  Khadra  Khalid Abu  Paytan  Adina 《Ocean Science Journal》2021,56(4):364-377

Ocean Science Journal - To assess the utility of the seagrass (Halophila stipulacea) for biomonitoring of metal pollution, seagrass samples were collected from four sites along the Jordanian coast...  相似文献   

Photo-induced degradation of emamectin benzoate: effect of iron amendments and solvent system     

Saadia Rashid Tariq  Nazia Rafique  Sana Kiran  Abdul Muqeet Khan 《Environmental Earth Sciences》2014,72(4):983-988

Photodegradation is the major dissipation pathway for emamectin benzoate (EB) in water. Therefore, the photolysis of EB was studied in distilled water (DW) and methanol under different irradiation conditions such as natural sunlight, UV tube, and artificially stimulated light (mercury lamp 125 W). The results of the study showed that EB degrades rapidly in DW than in methanol as evidenced by a photodegradation efficiency of about 75 % achieved in DW, after 24 h of irradiation with UV light, while in methanol, it was only 59.3 %. The addition of iron to EB solution in DW further enhanced its photodegradation. The rate of photodegradation of EB was recorded to be increased from 5.5 × 10^?2 to 1.0 × 10^?1 k/h after amendment with iron. The order for the rate of photodegradation of EB was DW + Fe > DW > methanol, with their respective t _1/2 values of 6.5, 12.6, and 18.7 h. Fe amendment was also found to enhance the degradation efficiency of EB even in the absence of any light (dark).  相似文献   

Effect of Fe2+ amendment on photodegradation kinetics of imidacloprid in moist soil     

Nazia Rafique  Saadia R. Tariq  Mateen Abbas 《Environmental Earth Sciences》2014,71(6):2869-2874

The present study deals with the effect of Fe²⁺ on degradation kinetics of imidacloprid in moist soil under UV system. The moist soil samples were spiked with imidacloprid and irradiated in specially designed UV-photoreactor. The analysis of imidacloprid was carried out by using HPLC–DAD system. UV irradiation caused about ten fold increase in photodegradation rate of the pesticide. Amendment of soil with Fe²⁺ at concentrations of 30 mg/kg led to a further increase in the rate of photodegradation, i.e., a 98 % degradation of imidacloprid was observed in the presence of iron after 32 days of irradiation. Moreover, the half-life of imidacloprid in Fe²⁺ -amended soil was observed to be reduced to 7 days that in the absence of Fe²⁺ was recorded to be 21 days. Iron was also observed to affect the half-life of imidacloprid in dark. When compared with unsterilized Fe²⁺-amended batch treatments, the t _1/2 in sterilized Fe²⁺-amended batch treatments increased from 58 to 96 days. Imidacloprid-urea was detected by HPLC as the only stable photodegradation byproduct of imidacloprid in the soil.  相似文献   

Traveltime approximations for inhomogeneous transversely isotropic media with a horizontal symmetry axis     

Tariq Alkhalifah 《Geophysical Prospecting》2013,61(3):495-503

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