Review: Assessment and modeling of seawater intrusion in coastal aquifers of the Arabian Peninsula     

Akhtar  Javed  Sana  Ahmad  Tauseef  Syed Mohammed 《Hydrogeology Journal》2023,31(5):1121-1145

Hydrogeology Journal - Significant urbanization and industrialization, combined with strong population growth, have been witnessed in the Arabian Peninsula (Oman, United Arab Emirates, Saudi...  相似文献   

Comparative study of multilayer perceptron-stochastic gradient descent and gradient boosted trees for predicting daily suspended sediment load: The case study of the Mississippi River,U.S.     

Sadra Shadkani  Akram Abbaspour  Saeed Samadianfard  Sajjad Hashemi  Amirhosein Mosavi  Shahab S.Band 《国际泥沙研究》2021,36(4):512-523

Monitoring sediment transport is essential for managing and maintaining rivers.Estimation of the sediment load in rivers is fundamental for the study of sediment movement,erosion,and flood control.In the current study,three machine learning models-multi-layer perceptron(MLP),multi-layer perceptron-stochastic gradient descent(MLP-SGD),and gradient boosted tree(GBT)-were utilized to estimate the suspended sediment load(SSL)at the St.Louis(SL)and Chester(CH)stations on the Mississippi River,U.S.Four evaluation criteria including the Correlation Coefficient(CC),Nash Sutcliffe Efficiency(NSE),Scatter Index(SI),and Willmott’s Index(WI)were utilized to evaluate the performance of the used models.A sensitivity analysis of the models to the input variables revealed that the current day discharge variable had the most effect on the SSL at both stations,but in the absence of current-day discharge data(Qt),a combination of input parameters including SSL_t-3,SSL_t-2,SSL_t-1,Q_t-3,Q_t-2,Q_t-1 can be used to estimate the SSL.The comparative outcomes indicated the high accuracy of MLP-SGD-5 model with a CC of 0.983,SI of 0.254,WI of 0.991,and NSE of 0.967 at station CH and the MLP-SGD-6 model with a CC of 0.933,SI of 0.576,WI of 0.961,and NSE of 0.867,respectively,at station SL.The results of MLP models were improved by SGD optimization.Therefore,the MLP-SGD method is recommended as the most accurate model for SSL estimation.  相似文献   

Geomorphology and landscape evolution of bharatpur district, rajasthan     

Iqbaluddin  Saif Ud Din  Akram Javed 《Journal of the Indian Society of Remote Sensing》1997,25(3):177-186

The morphometric analysis of the surface drainage has been carried out for the four micro-watersheds of Bharatpur district, Rajasthan to quantify the drainage morphometry of the district. The morphochronology of landseape evolution has been described. Banaganga represents anomalous drainage, which causes large scale inundation during rainy season. The strain of post-collision Himalayan tectonics resulted in slope mulation in Bharatpur district which changed slope from westerly to easterly. The landform characteristics of Bharatpur district have been arehieved at the National Informatics Center, District Data Base, Bharatpur is alpha numeric mode.  相似文献   

Debris flow susceptibility analysis based on the combined impacts of antecedent earthquakes and droughts: a case study for cascade hydropower stations in the upper Yangtze River,China     

Gui-sheng Hu  Ning-sheng Chen  Javed Iqbal Tanoli  Mei Liu  Rong-Kun Liu  Kun-Ting Chen 《山地科学学报》2017,14(9):1712-1727

The upper Yangtze River region is one of the most frequent debris flow areas in China. The study area contains a cascade of six large hydropower stations located along the river with total capacity of more than 70 million kilowatts. The purpose of the study was to determine potential and dynamic differences in debris flow susceptibility and intensity with regard to seasonal monsoon events. We analyzed this region’s debris flow history by examining the effective peak acceleration of antecedent earthquakes, the impacts of antecedent droughts, the combined effects of earthquakes and droughts, with regard to topography, precipitation, and loose solid material conditions. Based on these factors, we developed a debris flow susceptibility map. Results indicate that the entire debris flow susceptibility area is 167,500 km², of which 26,800 km² falls within the high susceptibility area, with 60,900 km² in medium and 79,800 km² are in low susceptibility areas. Three of the six large hydropower stations are located within the areas with high risk of debris flows. The synthetic zonation map of debris flow susceptibility for the study area corresponds with both the investigation data and actual distribution of debris flows. The results of debris flow susceptibility provide base-line data for mitigating, assessing, controlling and monitoring of debris flows hazards.  相似文献   

Rock Mass Characterization and Support Assessment along Power Tunnel of Hydropower in Kohistan Area,KPK, Pakistan     

Mian Sohail Akram  Muhammad Zeeshan 《Journal of the Geological Society of India》2018,91(2):221-226

This paper encompasses the engineering geological properties of rock mass along the power tunnel of hydropower in Kohistan, Khayber Pakhtun Khawa (KPK), Pakistan. The major geological units of the study area are Chilas complex (CC) and Gilgit complex (GC) that consists mostly of igneous and metamorphic rocks. Discontinuity surveys were conducted to classify the rock mass by utilizing rock mass rating (RMR) and tunneling quality index (Q) classification systems. RMR system involves collection of data for parameters of rock strength, RQD, spacing of discontinuities, condition of discontinuities, groundwater condition and Q system involves rock quality designation (RQD), joint roughness (J_r), joint sets (J_s), joint alteration (J_a), stress reduction factor (SRF) and joint water reduction (J_w). RMR values ranges from 46 to 66 (fair to good) for rock unit of Chilas complex (CC) and 50 to 58 (fair) for rock unit of Gilgit complex (GC). The evaluated values of tunnel quality by Q-system are 1.55 to 6.4 (poor to fair) for Chilas complex (CC) and 1.35 to 1.84 (poor) for Gilgit complex (GC). The required support along the tunnel route is also estimated by both classification systems. Unwedge program is used to analyze the unstable zones due to the intersection of different joint sets. Total 14 cases are analyzed in Unwedge from which 3 cases have failure potential with FOS less than 1. These failure potential blocks can become stable by applying further support of rock bolting and shotcrete layer.  相似文献   

Transition in Late Quaternary Paleoclimate in Schirmacher Region,East Antarctica as Revealed from Lake Sediments     

Hari B. Srivastava  Prakash K. Shrivastava  Sandip K. Roy  M. Javed Beg  Rajesh Asthana  Pawan Govil  Kamlesh Verma 《Journal of the Geological Society of India》2018,91(6):651-663

The lacustrine sediments are one of the best sources to provide information on climate change, specially in peri-glacial climatic region. Schirmacher Oasis, located on the Princess Astrid Coast in Queen Maud Land, is one of the few areas in East Antarctica that provides valuable information on paleoclimate of the region with various depositional features formed due to deglaciation process. This Oasis is dotted with more than 100 lakes of proglacial, land-locked and epi-shelf type. The multi-proxy sedimentological data, generated from the sediment cores from land-locked lakes and grab sample from a proglacial lake, lying in the same drainage line in the central part of Schirmacher region has provided better insight into the paleoclimatic evolution of the region. The immature and chemically unaltered lake sediments have shown restricted drainage pattern. Different phases of warmer and cooler intervals are highlighted by the patterns of fluctuations in different sedimentological and statistical parameters. The dominance of glacial signatures is very clear on the lake sediments as revealed by the surface textures of quartz grains. Physical weathering has mainly controlled the overall sediments and the composition of clay fraction. The clay minerals indicate a gradual shift in the weathering regime and therewith in climate from strongly glacial to fluvioglacial specially around 42 ka. This indicates beginning of warming of the area much before the LGM. But the warm period is not strong enough to alter the overall clay chemistry. Proxy records indicate short-period climatic oscillations during late Quaternary.  相似文献   

Assessment of Reservoir Rock Properties from Rock Physics Modeling and Petrophysical Analysis of Borehole Logging Data to Lessen Uncertainty in Formation Characterization in Ratana Gas Field,Northern Potwar,Pakistan     

Nisar Ahmed  Tayyaba Kausar  Perveiz Khalid  Sohail Akram 《Journal of the Geological Society of India》2018,91(6):736-742

Petrophysical evaluation and rock physics analysis are the important tools to relate the reservoir properties like porosity, permeability, pore fluids with seismic parameters. Nevertheless, the uncertainties always exist in the quantification of elastic and seismic parameters estimated through wireline logs and rock physics analysis. A workflow based on statistical relationships of rock physics and logs derived elastic and seismic parameters with porosity and the percentage error exist between them is given. The statistical linear regressions are developed for early Eocene Chorgali Formation between various petrophysically factors determined from borehole logging of well Ratana–03 drilled in tectonically disturbed zone and the seismic and elastic parameters estimated through rock physics modeling. The rock physics constraints such as seismic velocities, effective density and elastic moduli calculated from Gassmann fluid substation analysis are in harmony and close agreement to those estimated from borehole logs. The percentage errors between well logs and rock physics computed saturated bulk modulus (K _sat ), effective density (ρ _eff ), compressional and shear wave velocities (V _P and _V S) are 1.31%, 4.23 %, 5.25% and 4.01% respectively. The permeability of reservoir intervals show fairly strong linear relationship with the porosity, indicating that the reservoir interval of the Chorgali Formation is permeable and porous thus having large potential of hydrocarbon accumulation and production.  相似文献   

GIS-based landslide susceptibility evaluation using fuzzy-AHP multi-criteria decision-making techniques in the Abha Watershed,Saudi Arabia     

Javed Mallick  Ram Karan Singh  Mohammed A. AlAwadh  Saiful Islam  Roohul Abad Khan  Mohamed Noor Qureshi 《Environmental Earth Sciences》2018,77(7):276

Landslides are natural geological disasters causing massive destructions and loss of lives, as well as severe damage to natural resources, so it is essential to delineate the area that probably will be affected by landslides. Landslide susceptibility mapping (LSM) is making increasing implications for GIS-based spatial analysis in combination with multi-criteria evaluation (MCE) methods. It is considered to be an effective tool to understand natural disasters related to mass movements and carry out an appropriate risk assessment. This study is based on an integrated approach of GIS and statistical modelling including fuzzy analytical hierarchy process (FAHP), weighted linear combination and MCE models. In the modelling process, eleven causative factors include slope aspect, slope, rainfall, geology, geomorphology, distance from lineament, distance from drainage networks, distance from the road, land use/land cover, soil erodibility and vegetation proportion were identified for landslide susceptibility mapping. These factors were identified based on the (1) literature review, (2) the expert knowledge, (3) field observation, (4) geophysical investigation, and (5) multivariate techniques. Initially, analytical hierarchy process linked with the fuzzy set theory is used in pairwise comparisons of LSM criteria for ranking purposes. Thereafter, fuzzy membership functions were carried out to determine the criteria weights used in the development of a landslide susceptibility map. These selected thematic maps were integrated using a weighted linear combination method to create the final landslide susceptibility map. Finally, a validation of the results was carried out using a sensitivity analysis based on receiver operator curves and an overlay method using the landslide inventory map. The study results show that the weighted overlay analysis method using the FAHP and eigenvector method is a reliable technique to map landslide susceptibility areas. The landslide susceptibility areas were classified into five categories, viz. very low susceptibility, low susceptibility, moderate susceptibility, high susceptibility, and very high susceptibility. The very high and high susceptibility zones account for 15.11% area coverage. The results are useful to get an impression of the sustainability of the watershed in terms of landsliding and therefore may help decision makers in future planning and mitigation of landslide impacts.  相似文献   

Uncertainty analysis in bed load transport prediction of gravel bed rivers by ANN and ANFIS     

Hossien Riahi-Madvar  Akram Seifi 《Arabian Journal of Geosciences》2018,11(21):688

River flow is a complex dynamic system of hydraulic and sediment transport. Bed load transport have a dynamic nature in gravel bed rivers and because of the complexity of the phenomenon include uncertainties in predictions. In the present paper, two methods based on the Artificial neural networks (ANN) and adaptive neuro-fuzzy inference system (ANFIS) are developed by using 360 data points. Totally, 21 different combination of input parameters are used for predicting bed load transport in gravel bed rivers. In order to acquire reliable data subsets of training and testing, subset selection of maximum dissimilarity (SSMD) method, rather than classical trial and error method, is used in finding randomly manipulation of these subsets. Furthermore, uncertainty analysis of ANN and ANFIS models are determined using Monte Carlo simulation. Two uncertainty indices of d factor and 95% prediction uncertainty and uncertainty bounds in comparison with observed values show that these models have relatively large uncertainties in bed load predictions and using of them in practical problems requires considerable effort on training and developing processes. Results indicated that ANFIS and ANN are suitable models for predicting bed load transport; but there are many uncertainties in determination of bed load transport by ANFIS and ANN, especially for high sediment loads. Based on the predictions and confidence intervals, the superiority of ANFIS to those of ANN is proved.  相似文献   

Erosion potential assessment of watersheds through GIS<Emphasis Type="Bold">-</Emphasis>based hypsometric analysis: a case study of Kurram Tangi Dam     

Wasif Yousaf  Syed Ghulam Mohayud-Din-Hashmi  Usman Akram  Urooj Saeed  Sajid Rashid Ahmad  Muhammad Umar  Ambreena Mubashir 《Arabian Journal of Geosciences》2018,11(22):711

Sediment discharge due to soil and rock erosion within the watersheds is the major cause of siltation in water reservoirs. Siltation in reservoirs reduces the capacity for power production, irrigation water supply, and other domestic purposes. Hypsometric analysis has widely been used to identifying the geomorphic development stages (stabilized, equilibrium, and un-stable) to assess the erosion proneness of watersheds. In this study, watershed of Kurram Tangi Dam and its four sub-watersheds (SWs) were considered to determine their sediment discharge capacity through hypsometric analysis. The boundaries of watershed and sub-watersheds were delineated from Digital Elevation Model (DEM). The hypsometric parameters i.e., hypsometric integral (HI) and curves were generated using Geographic Information System (GIS) techniques. The HI values of SW-1 (0.41) and SW-2 (0.36) indicated that these two SWs were relatively more prone to erosion and contributed higher sediment discharge in Dam siltation. The results were validated through sampling the main drainage channel (Kurram River) to determine the sediment concentration at 12 sites during summer, winter, and spring seasons. Comparison of HI and sediment concentration of SWs presented high correlation (R²?=?0.87). The results emphasized the effective watershed management, extensive afforestation, and construction of silt-control structures at appropriate locations in sub-watersheds. This will ultimately maintain the water and power generation capacity as well as extending the life span of the Dam.  相似文献