Geospatial modeling for assessing the nutrient load of a Himalayan lake   总被引：1，自引：0，他引：1  

Shakil Ahmad Romshoo  Mohammad Muslim 《Environmental Earth Sciences》2011,64(5):1269-1282

This research makes use of the remote sensing, simulation modeling and field observations to assess the non-point source pollution load of a Himalayan lake from its catchment. The lake catchment, spread over an area of about 11 km², is covered by different land cover types including wasteland (36%), rocky outcrops (30%), agriculture (12%), plantation (12.2%), horticulture (6.2%) and built-up (3.1%) The GIS-based distributed modeling approach employed relied on the use of geospatial data sets for simulating runoff, sediment, and nutrient (N and P) loadings from a watershed, given variable-size source areas, on a continuous basis using daily time steps for weather data and water balance calculations. The model simulations showed that the highest amount of nutrient loadings are observed during wet season in the month of March (905.65 kg of dissolved N, 10 kg of dissolved P, 10,386.81 kg of total N and 2,381.89 kg of total P). During the wet season, the runoff being the highest, almost all the excess soil nutrients that are trapped in the soil are easily flushed out and thus contribute to higher nutrient loading into the lake during this time period. The 11-year simulations (1994–2004) showed that the main source areas of nutrient pollution are agriculture lands and wastelands. On an average basis, the source areas generated about 3,969.66 kg/year of total nitrogen and 817.25 kg/year of total phosphorous. Nash–Sutcliffe coefficients of correlation between the daily observed and predicted nutrient load ranged in value from 0.80 to 0.91 for both nitrogen and phosphorus.  相似文献   

Assessing morphological changes in a human-impacted alluvial system using hydro-sediment modeling and remote sensing     

Mohammad Reza Shojaeian  Zahra Karimidastenaei  Omid Rahmati  Ali Torabi Haghighi 《国际泥沙研究》2021,36(3):439-448

Construction of managed aquifer recharge structures(MARS)to store floodwater is a common strategy for storing depleted groundwater resources in arid and semi-arid regions,as part of integrated water resources management(IWRM).MARS divert surface water to groundwater,but this can affect downstream fluvial processes.The impact of MARS on fluvial processes was investigated in this study by combining remote sensing techniques with hydro-sediment modeling for the case of the Kaboutar-Ali-Chay aquifer,northwestern Iran.The impact of MARS on groundwater dynamics was assessed,sedimentation across the MARS was modeled using a 2D hydrodynamic model,and morphological changes were quantified in the human-impacted alluvial fan using Landsat time series data and statistical methods.Changes were detected by comparing data for the periods before(1985e1996)and after(1997 e2018)MARS construction.The results showed that the rate of groundwater depletion decreased from 2.14 m/yr before to 0.86 m/yr after MARS construction.Hydro-sediment modeling revealed that MARS ponds slowed water outflow,resulting in a severe decrease in sediment load which lead to a change from sediment deposition to sediment erosion in the alluvial fan.Morphometric analyses revealed decreasing alluvial fan area and indicated significant differences(p<0.01)between pre-and post-impact periods for different morphometric parameters analyzed.The rate of change in area of the Kaboutar-Ali-Chay alluvial fan changed from
0.228 to
0.115 km2/year between pre-and post-impact periods.  相似文献   

Assessment of heavy metal contamination in the surficial sediments from the lower Meghna River estuary,Noakhali coast,Bangladesh   总被引：1，自引：0，他引：1  

Mohammad Abdul Momin Siddique  Mahfuzur Rahman  Shahriar MdArifur Rahman  MdRubel Hassan  Zeenath Fardous  Muhammed Alamgir Zaman Chowdhury  Mohammad Belal Hossain 《国际泥沙研究》2021,36(3):384-391

Sediment samples were collected from ten selected sites of the lower Meghna River estuary,and six heavy metals were analyzed with Atomic Absorption Spectrophotometry(AAS)to assess the contamination level and the metals’association with sediment grain size.The current results revealed that the mean concentrations of the studied metals were ranked in descending order of iron(Fe)(1.29×103 mg/kg)>zinc(Zn)(42.41 mg/kg)>lead(Pb)(12.48 mg/kg)>chromium(Cr)(10.59 mg/kg)>copper(Cu)(6.22 mg/kg)>cadmium(Cd)(0.28 mg/kg).The geo-accumulation,contamination,and pollution load indexes suggested that the lower Meghna river estuary was not contaminated by Fe,Zn,Pb,Cr,and Cu.The mean size of the sediment ranged from 28.92 to 126.2 mm,and the Pearson correlation coefficient showed a significant association between Fe and Pb(coefficient of determination,r2=0.836;p<0.05),and no significant correlation was found between individual metals and grain size,indicating no or low influence on the metals distribution.  相似文献   

An assessment of metal contamination in coastal sediments of the Caspian Sea   总被引：11，自引：0，他引：11  

de Mora S  Sheikholeslami MR  Wyse E  Azemard S  Cassi R 《Marine pollution bulletin》2004,48(1-2):61-77

An assessment of marine pollution due to metals was made in the Caspian Sea based on coastal sediment collected in Azerbaijan, Iran, Kazakhstan, Russia and Turkmenistan. Despite the high carbonate content, the distribution of most metals was largely controlled by terrigenous inputs. Several metals (As, Cr, Ni) exhibited concentrations that exceed sediment quality guidelines. Such metals have a high natural background but anthropogenic activities, notably mining, may further enhance concentrations. This would explain hot spots for Cu and Zn in Azerbaijan and Iran, and Cr at the mouth of the Ural River in Kazakhstan. Contamination by Hg was observed to the south of Baku Bay, Azerbaijan. Some anomalously high concentrations of Ba in the central Caspian are probably from offshore drilling operations, but the elevated U concentrations (up to 11.1 microg g(-1)) may be natural in origin. Several metals (Ag, Cd, Pb) have relatively low levels that pose no environmental concerns.  相似文献   

Mineralogy and distribution of Platinum-Group Minerals (PGM) and other solid inclusions in the Faryab ophiolitic chromitites, Southern Iran     

Mohammad Ali Rajabzadeh  Zohreh Moosavinasab 《Mineralogy and Petrology》2013,107(6):943-962

High-Cr podiform chromitites hosted by upper mantle depleted harzburgite were investigated for PGM and other solid inclusions from Faryab ophiolitic complex, southern Iran. Chemical composition of the chromian spinels, Cr#[100*Cr/(Cr+Al) = 77–85], Mg# [100*Mg/(Mg+Fe²⁺) = 56–73], TiO₂≤0.25wt%, and the presence of abundant primary hydrosilicates included in the chromian spinels indicate that the deposits were formed from aqueous melt generated by high degree of partial melting in a suprasubduction zone setting. Solid phases hosted by chromian spinel grains from the Faryab ophiolitic chromitites can be divided into three categories: PGM, base-metal minerals and silicates. Most of the studied PGM occurred as very small (generally less than 20 μm in size) primary single or composite inclusions of IPGE-bearing phases with or without silicates and base metal minerals. The PGM were divided into the three subgroups: sulfides, alloys and sulfarsenides. Spinel-olivine geothermometry gives the temperatures 1,131–1,177 °C for the formation of the studied chromitites. At those temperatures, fS₂ values ranged from 10^?3 to 10^?1 and provided a suitable condition for Ru-rich laurite formation in equilibrium with Os-Ir alloys. Progressive crystallization of chromian spinel was accompanied by increase of fS₂ in the melt. The formation of Os-rich laurite, erlichmanite and then sulfarsenides occurred by increase of fS₂ and slight decrease in temperature of the milieu. The compositional and mineralogical determinations of PGM inclusions respect to their spatial distribution in chromian spinels show that the minerals regularly distributed within the chromitites, reflecting cryptic variation consistent with magmatic evolution during host chromian spinel crystallization.  相似文献   

Asian Continental Growth in the Phanerozoic: Zircon Hf Isotopic Constraints from the Central Asian to Eastern Tethyan Orogenic Belts     

CHUNG Sun-Lin  CHIU Han-Yi  LEE Hao-Yang  SHAO Wen-Yu  Mohammad H. ZARRINKOUB  WU Fu-Yuan 《《地质学报》英文版》2013,87(Z1):298-298

  相似文献   

The Aghajari (Upper Fars) Formation in the Folded Zagros Zone, Iran:Insights to Identify Facies, Architectural Elements, Fluvial Systems,Petrography and Provenance     

Mohammad SAHRAEYAN  Mohammad BAHRAMI  Sayed Hassan HEJAZI 《《地质学报》英文版》2013,87(4):1019-1031

The Aghajari Formation, called also the Upper Fars, develops throughout the Folded Zagros Zone and its thickness in the type section in southwest of Iran is 2966 meters. To analyze the sedimentary basin of this Formation, lithofacies, architectural elements and petrofacies of the related deposits in a section in southeast of Sarvestan in Fars Province of Iran with a thickness of 2221.45 meters were examined. Microscopically studying thin sections, the petrography and the occurrence of the deposits were determined. In this section, 16 lithofacies, 10 architectural elements and 2 sandstone petrofacies were identified. The lithofacies were divided into two major and minor groups, in which the major lithofacies consist of coarse-grained (Gh, Gp, Gt and Gm), medium-grained (Sh, Sp, St, Sl, Sm, Sr and Ss and fine-grained ones (Fm, Fl and Fsm), and the minor lithofacies were evaporative and mixed silisiclastic-carbonate. The identified architectural elements are CH, SB, GB, LA, DA, CR, CS, LV, LS, CH (FF) and FF. By combining evidences from facies analysis and architectural elements together, the Aghajari Formation was divided into three parts in which the related sedimentation environments, from top to bottom, are gravel, gravel-sand and fine-grained meandering river respectively. There have also been playas and shoreface in the lower part. Based on petrography, the sandstones of this formation were classified into two groups: litharenite and sublitharenite. The origin of these deposits (sandstones) was appointed to the recycled orogeny and the source of quartz is low and medium to high metamorphic rank. Using the field evidences, the paleocurrent direction was achieved indicating the direction of the paleocurrent from northwest to southeast at the time of deposition. It is hoped that these data can be used in the interpretation of the basin and reconstruction of the paleogeography in the local and regional scales.  相似文献   

Prediction of drought in dry lands through feedforward artificial neural network abilities     

Hossein Bari Abarghouei  Mohammad Reza Kousari  Mohammad Amin Asadi Zarch 《Arabian Journal of Geosciences》2013,6(5):1417-1433

Drought is one of the most important natural hazards in Iran. It is especially more prevalent in arid and hyper arid regions where there are serious limitations in regard to providing sufficient water resources. On the other hand, drought modeling and particularly its prediction can play important role in water resources management under conditions of lack of sufficient water resources. Therefore, in this study, drought prediction in a hyper arid location of Iran (Ardakan region) has been surveyed based on the abilities of artificial neural. Standardized Precipitation Index (SPI) in different time scales (3, 6, 9, 12, and 24 monthly time series) computed based on the data gathered from four rain gauge stations. After evaluation and testing of different artificial neural networks (ANN) structures, gradient descent back propagation (traingd) network showed higher abilities than others. Then, the predictions of SPI time series with different monthly lag times (1:12 months) were tested. Generally, drought prediction by ANNs in the Ardakan region has shown considerable results with the correlation coefficient (R) more than 0.79 and in the most cases and it rises more than 0.90, which indicates the ANN’s ability of drought prediction.  相似文献   

Groundwater arsenic contamination in Ganga–Meghna–Brahmaputra plain, its health effects and an approach for mitigation     

Dipankar Chakraborti  Mohammad Mahmudur Rahman  Bhaskar Das  Bishwajit Nayak  Arup Pal  Mrinal Kumar Sengupta  Md. Amir Hossain  Sad Ahamed  Manabendranath Sahu  Kshitish Chandra Saha  Subhash Chandra Mukherjee  Shyamapada Pati  Rathindra Nath Dutta  Quazi Quamruzzaman 《Environmental Earth Sciences》2013,70(5):1993-2008

The authors’ survey of the Ganga–Meghna–Brahmaputra (GMB) plain (area 569,749 km²; population >500 million) over the past 20 years and analysis of more than 220,000 hand tube-well water samples revealed groundwater arsenic contamination in the floodplains of the Ganga–Brahmaputra river (Uttar Pradesh, Bihar, Jharkhand, West Bengal, and Assam) in India and the Padma–Meghna–Brahmaputra river in Bangladesh. On average, 50 % of the water samples contain arsenic above the World Health Organization guideline value of 10 μg/L in India and Bangladesh. More than 100 million people in the GMB plain are potentially at risk. The authors’ medical team screened around 155,000 people from the affected villages and registered 16,000 patients with different types of arsenical skin lesions. Arsenic neuropathy and adverse pregnancy outcomes have been recorded. Infants and children drinking arsenic-contaminated water are believed to be at high risk. About 45,000 biological samples analyzed from arsenic-affected villages of the GMB plain revealed an elevated level of arsenic present in patients as well as non-patients, indicating that many are sub-clinically affected. In West Bengal and Bangladesh, there are huge surface water in rivers, wetlands, and flooded river basins. In the arsenic-affected GMB plain, the crisis is not over water scarcity but about managing the available water resources.  相似文献   

Assessment of bioclimatic comfort conditions based on Physiologically Equivalent Temperature (PET) using the RayMan Model in Iran   总被引：3，自引：0，他引：3  

Mohammad Reza Mansouri Daneshvar  Ali Bagherzadeh  Taghi Tavousi 《Central European Journal of Geosciences》2013,5(1):53-60

In this study thermal comfort conditions are analyzed to determine possible thermal perceptions during different months in Iran through the Physiologically Equivalent Temperature (PET). The monthly PET values produced using the RayMan Model ranged from ?7.6°C to 46.8°C. Over the winter months the thermal comfort condition (18–23°C) were concentrated in southern coastal areas along the Persian Gulf and Oman Sea. Most of the country experienced comfort conditions during the spring months, in particular in April, while during the summer months of July and August no thermal comfort conditions were observed. In November coastal areas of the Caspian Sea had the same physiological stress level of thermal comfort as April. The map produced showing mean annual PET conditions demonstrated the greatest spatial distribution of comfortable levels in the elevation range from 1000 to 2000 meter a.s.l., with annual temperatures of 12–20°C and annual precipitation of under 200 mm. The statistical relationship between PET conditions and each controlling parameter revealed a significant correlation in areas above 2000 meter, annual temperature over 20°C and annual precipitation of 200–400 mm with a correlation coefficient (R ²) of 0.91, 0.97 and 0.96, respectively.  相似文献