Lake Urmia,Northwest Iran,has confronted a drying procedure in recent years with losing 90%of its water body.The authorities concerned about desertification processes and possible dust events throughout the region.In ...Lake Urmia,Northwest Iran,has confronted a drying procedure in recent years with losing 90%of its water body.The authorities concerned about desertification processes and possible dust events throughout the region.In this regard,the Iranian Natural Resources and Watershed Management Organization has taken ecological measures to plant vegetation using salt cedar(Tamarix ramosissima Ledeb.)shrubs to combat desertification.This study aimed to investigate the vegetation and soil characteristics of natural and plantation stands of salt cedar on the western shores of Lake Urmia.To this end,7 transects were randomly selected with 15 shrubs in natural stands,and 7 transects were randomly selected with 15 shrubs in the plantation parts along the planting rows.Then,vegetative characteristics were examined.Also,soil samples were taken from the vicinity of the shrubs.The results indicated that there was no significant difference between the mean diameter at breast height(DBH)of salt cedar in natural sites.There was a significant difference between the mean number of sprouts per sprout-clumps,mean crown diameter,collar diameter,total height,and also between mean crown diameter and freshness of shrubs among different sites(P<0.05).It was also found that soil variables,such as clay content,organic matter,electrical conductivity(EC),Na^(+),specific absorption rate(SAR),Cl^(-),SO_(4)^(2-),Na^(+),K^(+),and PO_(4)^(2-) are the most significant variable parameters between studied sites.As the results shown,the values of EC,SAR,Na^(+),and Cl^(-)are 6 times higher in the planted stands than in the natural stands of T.ramosissima.Also,the colonization of T.ramosissima in the planted stands is unsuccessful by dramatic drop in the total height and average diameter.Considering the role of soil characteristics in explaining the variance of data and site separation,it seems that these indicators can be applied in executive plans as important indicators to identify suitable planting sites for combating desertification.展开更多
In the current scenario,Lake Urmia,one of the vastest hyper saline lakes on the Earth,has been affected by serious environmental degradation.Using different satellite images and observational data,this study investiga...In the current scenario,Lake Urmia,one of the vastest hyper saline lakes on the Earth,has been affected by serious environmental degradation.Using different satellite images and observational data,this study investigated the changes in the lake for the period 1970–2020 based on the effects of climate change and several human-induced processes on Lake Urmia,such as population growth,excessive dam construction,low irrigation water use efficiency,poor water resources management,increased sediment flow into the lake,and lack of political and legal frameworks.The results indicated that between 1970 and 1997,the process of change in Lake Urmia was slow;however;the shrinkage was faster between 1998 and 2018,with about 30.00%of the lake area disappearing.As per the findings,anthropogenic factors had a much greater impact on Lake Urmia than climate change and prolonged drought;the mismanagement of water consumption in the agricultural sector and surface and underground water withdrawals in the basin have resulted in a sharp decrease in the lake's surface.These challenges have serious implications for water resources management in Lake Urmia Basin.Therefore,we provided a comprehensive overview of anthropogenic factors on the changes in Lake Urmia along with existing opportunities for better water resources management in Lake Urmia Basin.This study serves as a guideline framework for climate scientists and hydrologists in order to assess the effects of different factors on lake water resources and for decision-makers to formulate strategies and plans according to the management task.展开更多
1 Introduction Lake Urmia in the northwestern corner of Iran is one of the largest permanent hypersaline lakes in the world and the largest lake in the Middle East(1,2,3).The lake
Urmia Lake in northwest of Iran, through the recent years has been extremely faced with the water crisis. Climate variations and anthropogenic impacts could be two main affiliated factors in this regard. We considered...Urmia Lake in northwest of Iran, through the recent years has been extremely faced with the water crisis. Climate variations and anthropogenic impacts could be two main affiliated factors in this regard. We considered the long term data series of precipitation, temperature and evaporation in monthly and yearly scales in order to compare to water-level values of Urmia Lake. The statistics approaches such as: standard deviation, trend analysis, T test, Pearson and Spearman correlations, liner regression are used to analyze all variables. The results released that the water-level of Urmia Lake along with the precipitation and temperature of the lake’s basin have experienced the periodic changes through 1961 to 2010, as there are some gradual dryness trends on the study area according to precipitation and temperature variations. Urmia Lake periodic water-level fluctuations show more significant correlation to temperature than the precipitation. Whiles, the water-level’s decreasing behavior especially through 1998 to 2010 is more harsh and different than the rate that is considered for precipitation’s decrease and temperature’s increase. Thus, there could be some anthropogenic factors in the basin which produced some supplementary causes to shrink Urmia Lake. Extracting the double precipitation over the basin through introducing and categorizing of atmospheric synoptic systems in order to cloud seeding operation could be one of urgent and innovative solutions to mitigate water crisis in the basin.展开更多
Urmia Salt Lake(USL) is a hypersaline lake located at the NW corner of the Iran platform. The lake area is estimated to have been over 5000 km^2 at one point, but has now decreased to <1000 km^2 in the last two dec...Urmia Salt Lake(USL) is a hypersaline lake located at the NW corner of the Iran platform. The lake area is estimated to have been over 5000 km^2 at one point, but has now decreased to <1000 km^2 in the last two decades. It contains 4.6×10~9 tons of halite and other detrital and evaporative minerals such as calcite, aragonite, dolomite, quartz, feldspars, augite and sylvite. This study examined the mineralogy and geochemistry of bed sediments along the mid-east toward NE bank sediments collected from 1.5 meters depth and nearby augite placer. Due to the diverse lithology of the surrounding geology, bed sediments vary from felsic in the mid-east to mafic in the northeast. Weathering of tephrite and adakite rocks of the Islamic Island at the immediate boundary has produced a large volume of augite placer over a 40 km length, parallel to the shoreline. Based on the study result, weathering increases from south to north and the geochemistry of the sediments shows enrichment of Mg O, Ca O, Sr and Ba associated with Sr deployment in all samples. Rare earth elements(REE) patterns normalized to the upper continental crust(UCC) indicated LREEs enrichment compared to HREEs with an elevated anomaly of Eu, possibly due to surface absorbance of Mn and Fe minerals, associated with Sr elevation originating from adakites in the lake basin vicinity.展开更多
Ancient subduction zones are characterized by mctamorphic and orogenic belts.The Zagros Orogenic Belt comprises almost all sections of an ancient subduction zone along which Neo-Tethyan oceanic crust was subducted ben...Ancient subduction zones are characterized by mctamorphic and orogenic belts.The Zagros Orogenic Belt comprises almost all sections of an ancient subduction zone along which Neo-Tethyan oceanic crust was subducted beneath central Iran.The Eslami Peninsula,as a part of the Zagros Orogenic Belt in Azerbaijan province,northwestern Iran,is situated between the Lake Urmia fore-arc basin and the Sahand Magmatic Arc.This region contains Eocene leucite dikes,trachyte,tephrite,phenolite,basanite and syenite.Volcanic features related to the Sahand are located in the eastern part of the Eslami Peninsula.In view of its relative age and composition,the Eslami Peninsula proposed as an outer arc of the Sahand Magmatic Arc that formed within the post-collisional setting of the central Iranian and Arabian plates.After subduction and contact of the two plates,a symmetric pop-up structure has been created by thrusting in the Zagros belt as a result of the collision processes.The injesction of dikes in the Eslami Peninsula is also a result of the continent continent collision.展开更多
In this paper,GIS-based ordered weighted averaging(OWA)is applied to landslide susceptibility mapping(LSM)for the Urmia Lake Basin in northwest Iran.Nine landslide causal factors were used,whereby the respective param...In this paper,GIS-based ordered weighted averaging(OWA)is applied to landslide susceptibility mapping(LSM)for the Urmia Lake Basin in northwest Iran.Nine landslide causal factors were used,whereby the respective parameters were extracted from an associated spatial database.These factors were evaluated,and then the respective factor weight and class weight were assigned to each of the associated factors using analytic hierarchy process(AHP).A landslide suscept-ibility map was produced based on OWA multicriteria decision analysis.In order to validate the result,the outcome of the OWA method was qualitatively evaluated based on an existing inventory of known landslides.Correspondingly,an uncertainty analysis was carried out using the Dempster-Shafer theory.Based on the results,very strong support was determined for the high susceptibility category of the landslide susceptibility map,while strong support was received for the areas with moderate susceptibility.In this paper,we discuss in which respect these results are useful for an improved understanding of the effectiveness of OWA in LSM,and how the landslide prediction map can be used for spatial planning tasks and for the mitigation of future hazards in the study area.展开更多
The reason of this research is to identify the favorable areas for copper, zinc, and lead mineralization in the western part of the 1:100,000 Tafresh geological Sheet in the Urmia-Dokhtar structural zone of Iran. Effe...The reason of this research is to identify the favorable areas for copper, zinc, and lead mineralization in the western part of the 1:100,000 Tafresh geological Sheet in the Urmia-Dokhtar structural zone of Iran. Effective data layers for mineralization, such as geology, geochemistry, structures, and satellite images, were analyzed and then integrated using the AHP-OWA method to identify favorable areas. Geochemical stream samples were analyzed by univariate, multivariate, and classical statistical methods and revealed the first, second, and third class anomalies for copper, zinc, and lead in the study region. Detection of hydrothermal alteration zones by Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite imagery in various algorithms, such as Relative absorption Band Depth (RBD), Minimum Noise Fraction (MNF), and Least Square Fit (LS-Fit), shows that argillic, phyllic, propylitic, and iron oxide alterations develop around the faults in the area under study. The favorable areas for copper, zinc, and lead mineralization have been identified by a combination of evidence maps of lithology, faults, dikes, geochemistry, and alteration data layers. Field observations in the area under study have confirmed the results.展开更多
Homogeneity analysis of the streamflow time series is essential to hydrological modeling, water resources management and climate change studies. In this study, five absolute homogeneity tests and one clustering approa...Homogeneity analysis of the streamflow time series is essential to hydrological modeling, water resources management and climate change studies. In this study, five absolute homogeneity tests and one clustering approach were used to determine the homogeneity status of the streamflow time series(over the period 1960–2010) in 14 hydrometric stations of three important basins(i.e., Aras River Basin, Urmia Lake Basin and Sefid-Roud Basin) in northwestern Iran. Results of the Buishand range test, von Neumann ratio test, cumulative deviation test, standard normal homogeneity test and Pettitt test for monthly streamflow time series detected that about 42.26%, 38.09%, 33.33%, 39.28% and 68.45% of the streamflow time series were inhomogeneous at the 0.01 significance level, respectively. Streamflow time series of the stations located in the eastern parts of the study area or within the Urmia Lake Basin were mostly homogeneous. In contrast, streamflow time series in the stations of the Aras River Basin and Sefied-Roud Basin showed inhomogeneity at annual scales. Based on the overall classification for the monthly and annual streamflow series, we determined that about 45.60%, 11.53% and 42.85% of the time series were categorized into the 'useful', 'doubtful' and 'suspect' classes according to the five absolute homogeneity tests. We also found the homogeneity patterns of the streamflow time series by using the clustering approach. The results suggested the effectiveness of the clustering approach for homogeneity analysis of the streamflow time series in addition to the absolute homogeneity tests. Moreover, results of the absolute homogeneity tests and clustering approach indicated obvious decreasing change points of the streamflow time series in the 1990 s over the three basins, which were mostly related to the hydrological droughts.展开更多
基金financially supported by the Urmia University,Iran.
文摘Lake Urmia,Northwest Iran,has confronted a drying procedure in recent years with losing 90%of its water body.The authorities concerned about desertification processes and possible dust events throughout the region.In this regard,the Iranian Natural Resources and Watershed Management Organization has taken ecological measures to plant vegetation using salt cedar(Tamarix ramosissima Ledeb.)shrubs to combat desertification.This study aimed to investigate the vegetation and soil characteristics of natural and plantation stands of salt cedar on the western shores of Lake Urmia.To this end,7 transects were randomly selected with 15 shrubs in natural stands,and 7 transects were randomly selected with 15 shrubs in the plantation parts along the planting rows.Then,vegetative characteristics were examined.Also,soil samples were taken from the vicinity of the shrubs.The results indicated that there was no significant difference between the mean diameter at breast height(DBH)of salt cedar in natural sites.There was a significant difference between the mean number of sprouts per sprout-clumps,mean crown diameter,collar diameter,total height,and also between mean crown diameter and freshness of shrubs among different sites(P<0.05).It was also found that soil variables,such as clay content,organic matter,electrical conductivity(EC),Na^(+),specific absorption rate(SAR),Cl^(-),SO_(4)^(2-),Na^(+),K^(+),and PO_(4)^(2-) are the most significant variable parameters between studied sites.As the results shown,the values of EC,SAR,Na^(+),and Cl^(-)are 6 times higher in the planted stands than in the natural stands of T.ramosissima.Also,the colonization of T.ramosissima in the planted stands is unsuccessful by dramatic drop in the total height and average diameter.Considering the role of soil characteristics in explaining the variance of data and site separation,it seems that these indicators can be applied in executive plans as important indicators to identify suitable planting sites for combating desertification.
文摘In the current scenario,Lake Urmia,one of the vastest hyper saline lakes on the Earth,has been affected by serious environmental degradation.Using different satellite images and observational data,this study investigated the changes in the lake for the period 1970–2020 based on the effects of climate change and several human-induced processes on Lake Urmia,such as population growth,excessive dam construction,low irrigation water use efficiency,poor water resources management,increased sediment flow into the lake,and lack of political and legal frameworks.The results indicated that between 1970 and 1997,the process of change in Lake Urmia was slow;however;the shrinkage was faster between 1998 and 2018,with about 30.00%of the lake area disappearing.As per the findings,anthropogenic factors had a much greater impact on Lake Urmia than climate change and prolonged drought;the mismanagement of water consumption in the agricultural sector and surface and underground water withdrawals in the basin have resulted in a sharp decrease in the lake's surface.These challenges have serious implications for water resources management in Lake Urmia Basin.Therefore,we provided a comprehensive overview of anthropogenic factors on the changes in Lake Urmia along with existing opportunities for better water resources management in Lake Urmia Basin.This study serves as a guideline framework for climate scientists and hydrologists in order to assess the effects of different factors on lake water resources and for decision-makers to formulate strategies and plans according to the management task.
文摘1 Introduction Lake Urmia in the northwestern corner of Iran is one of the largest permanent hypersaline lakes in the world and the largest lake in the Middle East(1,2,3).The lake
文摘Urmia Lake in northwest of Iran, through the recent years has been extremely faced with the water crisis. Climate variations and anthropogenic impacts could be two main affiliated factors in this regard. We considered the long term data series of precipitation, temperature and evaporation in monthly and yearly scales in order to compare to water-level values of Urmia Lake. The statistics approaches such as: standard deviation, trend analysis, T test, Pearson and Spearman correlations, liner regression are used to analyze all variables. The results released that the water-level of Urmia Lake along with the precipitation and temperature of the lake’s basin have experienced the periodic changes through 1961 to 2010, as there are some gradual dryness trends on the study area according to precipitation and temperature variations. Urmia Lake periodic water-level fluctuations show more significant correlation to temperature than the precipitation. Whiles, the water-level’s decreasing behavior especially through 1998 to 2010 is more harsh and different than the rate that is considered for precipitation’s decrease and temperature’s increase. Thus, there could be some anthropogenic factors in the basin which produced some supplementary causes to shrink Urmia Lake. Extracting the double precipitation over the basin through introducing and categorizing of atmospheric synoptic systems in order to cloud seeding operation could be one of urgent and innovative solutions to mitigate water crisis in the basin.
基金the financial support provided from Urmia University by the vice chancellor for research
文摘Urmia Salt Lake(USL) is a hypersaline lake located at the NW corner of the Iran platform. The lake area is estimated to have been over 5000 km^2 at one point, but has now decreased to <1000 km^2 in the last two decades. It contains 4.6×10~9 tons of halite and other detrital and evaporative minerals such as calcite, aragonite, dolomite, quartz, feldspars, augite and sylvite. This study examined the mineralogy and geochemistry of bed sediments along the mid-east toward NE bank sediments collected from 1.5 meters depth and nearby augite placer. Due to the diverse lithology of the surrounding geology, bed sediments vary from felsic in the mid-east to mafic in the northeast. Weathering of tephrite and adakite rocks of the Islamic Island at the immediate boundary has produced a large volume of augite placer over a 40 km length, parallel to the shoreline. Based on the study result, weathering increases from south to north and the geochemistry of the sediments shows enrichment of Mg O, Ca O, Sr and Ba associated with Sr deployment in all samples. Rare earth elements(REE) patterns normalized to the upper continental crust(UCC) indicated LREEs enrichment compared to HREEs with an elevated anomaly of Eu, possibly due to surface absorbance of Mn and Fe minerals, associated with Sr elevation originating from adakites in the lake basin vicinity.
基金The support of Urmia University and facilities provided by the Geology Department
文摘Ancient subduction zones are characterized by mctamorphic and orogenic belts.The Zagros Orogenic Belt comprises almost all sections of an ancient subduction zone along which Neo-Tethyan oceanic crust was subducted beneath central Iran.The Eslami Peninsula,as a part of the Zagros Orogenic Belt in Azerbaijan province,northwestern Iran,is situated between the Lake Urmia fore-arc basin and the Sahand Magmatic Arc.This region contains Eocene leucite dikes,trachyte,tephrite,phenolite,basanite and syenite.Volcanic features related to the Sahand are located in the eastern part of the Eslami Peninsula.In view of its relative age and composition,the Eslami Peninsula proposed as an outer arc of the Sahand Magmatic Arc that formed within the post-collisional setting of the central Iranian and Arabian plates.After subduction and contact of the two plates,a symmetric pop-up structure has been created by thrusting in the Zagros belt as a result of the collision processes.The injesction of dikes in the Eslami Peninsula is also a result of the continent continent collision.
文摘In this paper,GIS-based ordered weighted averaging(OWA)is applied to landslide susceptibility mapping(LSM)for the Urmia Lake Basin in northwest Iran.Nine landslide causal factors were used,whereby the respective parameters were extracted from an associated spatial database.These factors were evaluated,and then the respective factor weight and class weight were assigned to each of the associated factors using analytic hierarchy process(AHP).A landslide suscept-ibility map was produced based on OWA multicriteria decision analysis.In order to validate the result,the outcome of the OWA method was qualitatively evaluated based on an existing inventory of known landslides.Correspondingly,an uncertainty analysis was carried out using the Dempster-Shafer theory.Based on the results,very strong support was determined for the high susceptibility category of the landslide susceptibility map,while strong support was received for the areas with moderate susceptibility.In this paper,we discuss in which respect these results are useful for an improved understanding of the effectiveness of OWA in LSM,and how the landslide prediction map can be used for spatial planning tasks and for the mitigation of future hazards in the study area.
文摘The reason of this research is to identify the favorable areas for copper, zinc, and lead mineralization in the western part of the 1:100,000 Tafresh geological Sheet in the Urmia-Dokhtar structural zone of Iran. Effective data layers for mineralization, such as geology, geochemistry, structures, and satellite images, were analyzed and then integrated using the AHP-OWA method to identify favorable areas. Geochemical stream samples were analyzed by univariate, multivariate, and classical statistical methods and revealed the first, second, and third class anomalies for copper, zinc, and lead in the study region. Detection of hydrothermal alteration zones by Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite imagery in various algorithms, such as Relative absorption Band Depth (RBD), Minimum Noise Fraction (MNF), and Least Square Fit (LS-Fit), shows that argillic, phyllic, propylitic, and iron oxide alterations develop around the faults in the area under study. The favorable areas for copper, zinc, and lead mineralization have been identified by a combination of evidence maps of lithology, faults, dikes, geochemistry, and alteration data layers. Field observations in the area under study have confirmed the results.
文摘Homogeneity analysis of the streamflow time series is essential to hydrological modeling, water resources management and climate change studies. In this study, five absolute homogeneity tests and one clustering approach were used to determine the homogeneity status of the streamflow time series(over the period 1960–2010) in 14 hydrometric stations of three important basins(i.e., Aras River Basin, Urmia Lake Basin and Sefid-Roud Basin) in northwestern Iran. Results of the Buishand range test, von Neumann ratio test, cumulative deviation test, standard normal homogeneity test and Pettitt test for monthly streamflow time series detected that about 42.26%, 38.09%, 33.33%, 39.28% and 68.45% of the streamflow time series were inhomogeneous at the 0.01 significance level, respectively. Streamflow time series of the stations located in the eastern parts of the study area or within the Urmia Lake Basin were mostly homogeneous. In contrast, streamflow time series in the stations of the Aras River Basin and Sefied-Roud Basin showed inhomogeneity at annual scales. Based on the overall classification for the monthly and annual streamflow series, we determined that about 45.60%, 11.53% and 42.85% of the time series were categorized into the 'useful', 'doubtful' and 'suspect' classes according to the five absolute homogeneity tests. We also found the homogeneity patterns of the streamflow time series by using the clustering approach. The results suggested the effectiveness of the clustering approach for homogeneity analysis of the streamflow time series in addition to the absolute homogeneity tests. Moreover, results of the absolute homogeneity tests and clustering approach indicated obvious decreasing change points of the streamflow time series in the 1990 s over the three basins, which were mostly related to the hydrological droughts.
