Direct measurement of snow water equivalent(SWE)in snow-dominated mountainous areas is difficult,thus its prediction is essential for water resources management in such areas.In addition,because of nonlinear trend of ...Direct measurement of snow water equivalent(SWE)in snow-dominated mountainous areas is difficult,thus its prediction is essential for water resources management in such areas.In addition,because of nonlinear trend of snow spatial distribution and the multiple influencing factors concerning the SWE spatial distribution,statistical models are not usually able to present acceptable results.Therefore,applicable methods that are able to predict nonlinear trends are necessary.In this research,to predict SWE,the Sohrevard Watershed located in northwest of Iran was selected as the case study.Database was collected,and the required maps were derived.Snow depth(SD)at 150 points with two sampling patterns including systematic random sampling and Latin hypercube sampling(LHS),and snow density at 18 points were randomly measured,and then SWE was calculated.SWE was predicted using artificial neural network(ANN),adaptive neuro-fuzzy inference system(ANFIS)and regression methods.The results showed that the performance of ANN and ANFIS models with two sampling patterns were observed better than the regression method.Moreover,based on most of the efficiency criteria,the efficiency of ANN,ANFIS and regression methods under LHS pattern were observed higher than the systematic random sampling pattern.However,there were no significant differences between the two methods of ANN and ANFIS in SWE prediction.Data of both two sampling patterns had the highest sensitivity to the elevation.In addition,the LHS and the systematic random sampling patterns had the least sensitivity to the profile curvature and plan curvature,respectively.展开更多
Raindrop size,rainfall intensity and runoff discharge affect the detachment and transportation of soil particles.Among these three factors,the rainfall intensity seems to be more important because it can change other ...Raindrop size,rainfall intensity and runoff discharge affect the detachment and transportation of soil particles.Among these three factors,the rainfall intensity seems to be more important because it can change other two factors.Storm patterns can be determined by changing the rainfall intensity during the storm.Therefore,the objective of this research is to test the influence of storm pattern on runoff,soil erosion and sediment concentration on a rangeland soil slope under field rainfall simulation.Four storm rainfall intensity patterns were selected for examining the effects of variations in storm event characteristics on soil erosion processes.The selected storm patterns were:I(45,55 and 70 mm h-1);II(45,70 and 55 mm h-1);III:(70,55 and 45 mm h-1);and IV(55,45 and 70 mm h1).The last pattern is a new one instead of the uniform pattern which has been sufficiently studied in previous researches.The experiments were conducted in field plots(in Kojour watershed,Mazandaran Province,Iran)with an area of one square meter and an constant slope gradient of 18%,surrounded by galvanised sheets.Following the nonuniform prioritization of the storm patterns for the studied variables,time to runoff(I>II>IV>III),runoff volume(III>IV>II>I),sediment concentration(IV>III>I>II)and soil erosion(III>IV>II>I)),it can be generally inferred that each pattern has specific effect on soil erosion processes during a storm.The results of the general linear model(GLM)test indicated that the effects of storm pattern on time to runoff,total runoff volume,runoff coefficient and soil erosion were significant at a level of 99%.The Duncan test showed that the storm patterns can be divided into three groups of III,IV;II;I(for time to runoff),I,II;IV,III(for runoff coefficient),and I;II;IV,III(for runoff volume and soil erosion).展开更多
The growing demand for current and precise geographic information that pertains to urban areas has given rise to a significant interest in digital surface models that exhibit a high level of detail. Traditional method...The growing demand for current and precise geographic information that pertains to urban areas has given rise to a significant interest in digital surface models that exhibit a high level of detail. Traditional methods for creating digital surface models are insufficient to reflect the details of earth’s features. These models only represent three-dimensional objects in a single texture and fail to offer a realistic depiction of the real world. Furthermore, the need for current and precise geographic information regarding urban areas has been increasing significantly. This study proposes a new technique to address this problem, which involves integrating remote sensing, Geographic Information Systems (GIS), and Architecture Environment software environments to generate a detailed three-dimensional model. The processing of this study starts with: 1) Downloading high-resolution satellite imagery; 2) Collecting ground truth datasets from fieldwork; 3) Imaging nose removing; 4) Generating a Two-dimensional Model to create a digital surface model in GIS using the extracted building outlines; 5) Converting the model into multi-patch layers to construct a 3D model for each object separately. The results show that the 3D model obtained through this method is highly detailed and effective for various applications, including environmental studies, urban development, expansion planning, and shape understanding tasks.展开更多
Determination of the infiltration rate in a watershed is not easy and in empirical and theoretical point of view, it is important to access average value of infiltration. Infiltration models has main role in managing ...Determination of the infiltration rate in a watershed is not easy and in empirical and theoretical point of view, it is important to access average value of infiltration. Infiltration models has main role in managing water sources. Therefore different types of models with various degrees of complexity were developed to reach this aim. Most of the estimating methods of soil infiltration are expensive and time consuming and these methods estimate infiltration with hypothesis of zero slope. One of the conceptual and physical models for estimating soil infiltration is Green-Ampt model which is similar to Richard model. This model uses slope factor in estimating infiltration and this is the power point of Green-Ampt model. In this research the empirical model of Green-Ampt was optimized with integrating artificial neural network model (ANN) and a model of geographical information system WMS to estimate the infiltration in Kakasharaf watershed. Results of the comparison between the output of this method and real value of infiltration in region (through multiple cylinders) showed that this method can estimate the infiltration rate of Kakasharaf watershed with low error and acceptable accuracy (Nash-Sutcliff performance coefficient 0.821, square error 0.216, correlation coefficient 0.905 and model error 0.024).展开更多
Complete and comprehensive information about sediment dynamic and identification of hotspots of sediment production and transport are necessary for understanding the erosion processes and increasing the efficiency of ...Complete and comprehensive information about sediment dynamic and identification of hotspots of sediment production and transport are necessary for understanding the erosion processes and increasing the efficiency of soil and water conservation practices.Numerous studies used the sediment fingerprint techniques to investigate the contribution of different sources in suspended and bed sediment yield of the watersheds.However,the contribution of various land use/land covers in suspended and bed sediment yield for the great Caspian Sea basin is in an aura of ambiguity and the present study was conducted to gather information about an important part of this area in northern Iran,where rangelands are located upstream of Hyrcanian forests and dense agricultural lands are located downstream.The surface soil of different land use/land covers including forest,rangeland,agriculture and streambank lands were sampled in 30 points.Suspended and bed sediments were sampled in the watershed outlet in two high and low water periods.Geochemical characteristics of soil and sediment samples containing 59 elements were measured using ICP-OES GBC Integra.The reliable and suitable tracers from 59 elements were then selected using Range test,Kruskal-Wallis and Discriminant Function Analysis,respectively,in FingerPro package of R software.The results showed that for suspended sediment,streambank and rangeland had the highest contributions of 86.2%and 47.5%,respectively,in two high and low water periods.For bed sediment,in two high and low water periods,rangeland and streambank had the highest contributions of 73.8%and 84.4%,respectively.Land use change and especially human activities such as agriculture,road construction and development of residential areas along the main river riparian zone has led to a significant increase in suspended and bed sediments.展开更多
A ship＇s crew plays an important role in the maritime transportation sector and their performance is paramont in the shipping industry. On this account, an impartial evaluation of the crew＇s performance is an import...A ship＇s crew plays an important role in the maritime transportation sector and their performance is paramont in the shipping industry. On this account, an impartial evaluation of the crew＇s performance is an important issue. In this paper, the ship officer＇s performance evaluation problem is studied. The performance evaluation criteria that shipping companies take into account are determined and a performance evaluation process is modelled by using the FAHP （Fuzzy Analytic Hierarchy Process） based on Chang＇s Algorithm. Linguistic variables and fuzzy numbers are used in the assessment process. The results of the proposed model demonstrate that the FAHP method is effective and helps managers make better and more reliable decisions under fuzzy circumstances.展开更多
Scientists have long sought frameworks to understand the complex systems that shape our world,from ecological dynamics to socio-technical networks.The concept of simplexity,intermittently explored for over 70 years,ha...Scientists have long sought frameworks to understand the complex systems that shape our world,from ecological dynamics to socio-technical networks.The concept of simplexity,intermittently explored for over 70 years,has now been redefined,offering a revolutionary perspective on complexity and simplicity across natural,social,and technological domains.1 This breakthrough provides insights into the interplay between simplicity and complexity,unifying disciplines and driving scientific and technological progress.In this context,information management shifts from mere storage and dissemination to dynamic strategies that shape behaviors and interactions,fostering knowledge-driven activities.展开更多
The objective of this study is to investigate the utilization of tungsten oxide(WO_(3))supported on natural materials,including activated carbon(AC)and montmorillonite clay(MMT),for the catalytic dehydration of ethano...The objective of this study is to investigate the utilization of tungsten oxide(WO_(3))supported on natural materials,including activated carbon(AC)and montmorillonite clay(MMT),for the catalytic dehydration of ethanol.This study addresses the growing demand for sustainable chemical processes that produce key intermediates,such as ethylene and diethyl ether,from renewable resources.The research examined the effect of varying WO_(3) loadings on catalyst performance using the incipient wetness impregnation method.The physicochemical properties of catalysts were elucidated through a variety of characterization techniques.The results revealed that MMT supports exhibited a more significant enhancement in catalytic efficiency compared to AC when loaded with W.This superior performance is attributed to MMT’s unique layered structure,enabling efficient dispersion of tungsten species and optimized acid site distribution.The structural properties of the support and the higher density of weak acid sites were found to significantly influence catalytic activity.The 13.5WMMT catalyst demonstrated remarkable dual functionality,achieving 42.63%diethyl ether yield at 250℃ and 96.73%ethylene yield at 400℃.In contrast,the 13.5WAC catalyst produced only 22.30%diethyl ether yield at 300℃ and 77.02%ethylene yield at 400℃.The study not only underscores the significance of metal loading and support type in achieving superior catalytic performance,but also highlights the exceptional potential of MMT as a promising candidate for sustainable and efficient ethanol dehydration processes.展开更多
In this paper we introduce HOTSED,a novel,innovative GIS-based model designed for assessing potential hotspots of sediment dynamics at watershed scale.HOTSED integrates geomorphic spatial information with both structu...In this paper we introduce HOTSED,a novel,innovative GIS-based model designed for assessing potential hotspots of sediment dynamics at watershed scale.HOTSED integrates geomorphic spatial information with both structural and functional properties of connectivity.HOTSED provides a single and intuitive output that depicts the location of sediment source hotspots.Moreover,it enables the identification of“relative hazard”classes for sediment production and related effects.The general methodological framework is based on the initial elaboration of an Inventory Map(IM)of sediment-related landforms and processes,along with the implementation of a corresponding database.Subsequently,we used data stored in the IM to estimate the geomorphic Potential of Sediment Sources(PSS)through a relative scoring system.Furthermore,we computed Structural Sediment Connectivity(STC)and the Potential for Sediment Transport(PST)by combining terrain and hydrological parameters,vegetation roughness,and rainfall erosivity.Afterwards,PSS,STC,and PST components are integrated through a raster-based calculation method yielding the HOTSED model.We tested the HOTSED procedure in the upper Val d’Arda-Mignano watershed,which is a representative geomorphologically highly active Mediterranean area of the Northern Apennines(Italy).Through photointerpretation,terrain analysis,and fieldwork,we mapped sedimentrelated geomorphic features for a total of 4640 ha including:badlands and gullies(0.26%),rill-interrill erosion(15.03%),fluvial erosion(0.03%),landslides(70.06%),litho-structural erosional systems(0.87%),slope deposits(12.56%),and alluvial deposits(1.19%).HOTSED revealed hotspots with a very high hazard potential located near main channels or upstream of the reservoir.These areas are often linked with active landslides highly connected to the drainage system and frequently associated with other processes like bank erosion or surficial soil erosion.The model also highlighted linear hotspots corresponding to drainages flowing alongside or intersecting complex geomorphic systems such as landslides.Furthermore,HOTSED identified areas where sediments are stored in depositional landforms,exhibiting a low hazard potential,considering both low geomorphic potential and sediment connectivity.Our conceptual model is generally applicable but proves to be particularly effective in areas characterized by complex and polygenetic geomorphic systems,such as the Northern Apennines.HOTSED offers a valuable tool for watershed authorities to support sustainable watershed and reservoir management.展开更多
Translocation of absorbed phosphorus （P） from metabolically inactive sites to active sites in plants growing under P deprivation may increase its P utilization efficiency （PUE）. Acclimation to phosphate （Pi） sta...Translocation of absorbed phosphorus （P） from metabolically inactive sites to active sites in plants growing under P deprivation may increase its P utilization efficiency （PUE）. Acclimation to phosphate （Pi） starvation may be caused by a differential storage pool of vacuolar P, its release, and the intensity of re-translocation of absorbed P as P starvation inducible environmental cues （PSlEC） from ambient environment. Biomass assay and three P forms, namely inorganic （Pi）, organic （Po）, and acid-soluble total （Ptas） were estimated in Brassica cultivars exposed to 10 d P deprivation in the culture media. Considering that -aPi/at denotes the rate of Pi release, Pi release velocity （RSPi） was determined as the tangent to the equations obtained for Pi f（t） at the mean point in the period of greatest Pi decrease, whereas the inverse of the RSPi was an estimate of the internal Pi buffering capacity （IBCPi）. Inter cultivar variations in size of the non-metabolic Pi pool, RSPi, re-translocation of Pi from less to more active metabolic sites, and preferential Pi source and sink compartments were evaluated under P starvation. The cultivar ＇Brown Raya＇ showed the highest Pi storage ability under adequate external P supply, and a more intensive release than ＇Rain Bow＇ and ＇Dunkled＇ under P stress. Cultivar ＇B.S.A＇ was inferior to ＇Con-l＇ in its ability to store and use Pi. Roots and upper leaves were the main sink of Pi stored in the lower and middle leaves of all cultivars and showed lower IBCPi and larger RSPi values than lower and middle leaves. In another trial, six cultivars were exposed to P-free nutrition for 29 d after initial feeding on optimum nutrition for 15 d. With variable magnitude, all of the cultivars re-translocatad P from the above ground parts to their roots under P starvation, and [P] at 44 d after transplanting was higher in developing leaves compared with developed leaves. Under P deprivation, translocation of absorbed P from metabolically inactive to active sites may have helped the tolerant cultivars to establish a better rooting system, which provided a basis for tolerance against P starvation and increased PUE. A better understanding of the extent to which changes in the flux of P absorption and re-translocation under PSIEC will help to scavenge Pi from bound P reserves and will bring more sparingly soluble P into cropping systems and obtain capitalization of P reserves.展开更多
Phosphorus （P） starvation is highly notorious for limiting plant growth around the globe. To combat P-starvation, plants constantly sense the changes in their environment, and elicit an elegant myriad of plastic res...Phosphorus （P） starvation is highly notorious for limiting plant growth around the globe. To combat P-starvation, plants constantly sense the changes in their environment, and elicit an elegant myriad of plastic responses and rescue strategies to enhance P-solublization and acquisition from bound soil P-forms. Relative growth responses, P-solublization and P- acquisition ability of 14 diverse Brassica cultivars grown with sparingly soluble P-sources （Rock-P （RP） and Ca3（PO4）2 （TCP）） were evaluated in a solution culture experiment. Cultivars showed considerable genetic diversity in terms of biomass accumulation, concentration and contents of P and Ca in shoots and roots, P-stress factor （PSF） and P use efficiency. Cultivars showed variable P-stress tolerance, and cultivars depicting low PSF and high P-efficiency values were better adaptable to P-starvation. In experiment 2, after initial feeding on optimum nutrition for 12 d after transplanting （DAT）, class-I （low P-tolerant （Oscar and Con-II）） and class-II （low P-sensitive （Gold Rush and RL-18）） cultivars were exposed to P-free environment for 25 d. All of the cultivars remobilized P from above ground parts to their roots during growth in P-free environment, the magnitude of which was variable in tested cultivars. P-concentrations （[P]s） at 37 DAT were higher in developing compared with developed leaves. Translocation of absorbed P from metabolically inactive to active sites in P- stressed plants may have helped class-I cultivars to establish a better rooting system, which provided a basis for enhanced P-utilization efficiency （PUE） and tolerance against P-stress. By supplying TCP and RP spatially separated from other nutrients in split root study, class-I cultivars were still able to mobilize RP and TCP more efficiently compared with class-II cultivars. To compare the growth behavior under P-stress, cultivars were grown in pots for 41 d after sowing, using a soil low in P （NaHCO3-extractable P = 3.97 mg/kg, Mehlich-III-extractable P = 6.13 mg/kg） with （＋P=60 mg P/kg soil） or without P addition （0P） in study 4. Tested cultivars showed genetic diversity in PUE, P-efficiency （PE）, P-efficiency ratio （PER） and PSF. P-stress markedly reduced biomass and plant P contents. Cultivars that produced higher root biomass accumulated higher total P-contents （r = 0.98＊＊）, which in turn was related negatively to PSF （r = -0.95＊＊） and positively to shoot and total biomass. PER and PE showed significant correlations with shoot P-contents and biomass. Cultivars depicting high PUE and PE, and low PSF values showed better growth behavior under low soil P-environment. Systematic analysis and deployment of the plant rescue traits underlying the nutrient acquisition, assimilation, utilization and remobilization under P-starvation will bring more sparingly soluble P into cropping systems and will help to scavenge more P from plant unavailable bound P reserves.展开更多
Non-mycorrhizal Brassica does not produce specialized root structures such as cluster or dauciform roots but is an effective user of P compared with other crops. In addition to P-uptake, utilization and remobilization...Non-mycorrhizal Brassica does not produce specialized root structures such as cluster or dauciform roots but is an effective user of P compared with other crops. In addition to P-uptake, utilization and remobilization activity, acquisition of orthophosphate （Pi） from extracellular sparingly P-sources or unavailable bound P-forms can be enhanced by biochemical rescue mechanisms such copious H＋-efflux and/or carboxylates exudation into rhizosphere by roots via plasmalemma H＋ ATPase and anion channels triggered by P-starvation. To visualize the dissolution of sparingly soluble Ca-phosphate （Ca-P）, newly formed Ca-P was suspended in agar containing other essential nutrients. With NH4＋ applied as the N source, the precipitate dissolved in the root vicinity can be ascribed to rhizosphere acidification, whereas no dissolution occurred with nitrate nutrition. To observe in situ rhizospheric pH changes, images were recorded after embedding the roots in agar containing bromocresol purple as a pH indicator. P-tolerant cultivar showed a greater decrease in pH than the sensitive cultivar in the culture media （the appearance of typical patterns of various colors of pH indicator in the root vicinity）, and at stress P-level this acidification was more prominent. In experiment 2, low P-tolerant class-I cultivars （Oscar and Con-II） showed a greater decrease in solution media pH than low P-sensitive class-II （Gold Rush and RL-18） cultivars, and P-contents of the cultivars was inversely related to decrease in culture media pH. To elucidate P-stress- induced remodeling and redesigning in a root architectural system, cultivars were grown in rhizoboxes in experiment 3. The elongation rates of primary roots increased as P-supply increased, but the elongation rates of the branched zones of primary roots decreased. The length of the lateral roots and topological index values increased when cultivars were exposed to a P-stress environment. To elucidate Pi-uptake kinetics, parameters related to P influx： maximal transport rate （Vmax）, the Michaelis-Menten constant （Km）, and the external concentration when net uptake is zero （Cmin） were tested in experiment 4. Lower Km and Cmin values were better indicative of the P-uptake ability of the class-I cultivars, evidencing their adaptability to P.starved environmental cues. In experiment 5, class-I cultivars exuded two- to threefold more carboxylates than class-II cultivars under the P-stress environment. The amount and types of carboxylates exuded from the roots of P-starved plants differed from those of plants grown under P-sufficient conditions. Nevertheless, the exudation rate of both class-I and class-II cultivars decreased with time, and the highest exudation rate was found after the first 4 h of carboxylates collection. Higher P uptake by class-I cultivars was significantly related to the drop in root medium pH, which can be ascribed to H＋-efflux from the roots supplied with sparingly soluble rock-P and Ca3（PO4）2. These classical rescue strategies provided the basis of P-solubilization and acquisition from sparingly soluble P-sources by Brassica cultivars to thrive in a typically stressful environment.展开更多
Soil erosion is recognized as one of the most important types of land degradation in the world particularly in many developing countries like Iran. Water erosion is initiated by splash erosion triggered by raindrop im...Soil erosion is recognized as one of the most important types of land degradation in the world particularly in many developing countries like Iran. Water erosion is initiated by splash erosion triggered by raindrop impact. Understanding the process of splash erosion under freezing and thawing conditions is essential to unravel soil erosion mechanisms under temperate conditions leading to appropriate planning of soil and water conservation projects. The present study aimed to study the individual effects of freeze-only as well as freezing-thawing cycle on splash erosion in a loess soil from an erosion prone area in mountainous northern regions of Iran. The study was conducted under laboratory conditions using erosion plots. The erosion plots were subjected to freeze only and freeze-thawing treatments by simulating cold conditions using a large cooling compartment system specifically manufactured for this purpose. The splash erosion under a designed simulated rainfall (1.2mmmin-1 for 30 min) was then measured as upward, downward and net splash erosion in splash cups. The results showed that freeze only decreased the upward, downward and net splash erosion by 0.81 ± 0.43, 0.82 ± 0.29 and 0.85 ± 0.23% while freezing-thawing cycle decreased splash erosion to 0.93 ± 0.83, 0.61 ± 0.43 and 0.57 ± 0.36%. This may be attributed to temporary increase in soil strength and stability or surface sealing during freezing process leading to reduced splash erosion.展开更多
This study investigated the role of three rangeland species viz.Agropyron trichophorum,Medicago sativa,and Lolium prenne on mitigating of effects of a freeze-thaw(FT)cycle on runoff generation and soil loss from small...This study investigated the role of three rangeland species viz.Agropyron trichophorum,Medicago sativa,and Lolium prenne on mitigating of effects of a freeze-thaw(FT)cycle on runoff generation and soil loss from small experimental plots.Small plots(0.5×0.5m)were prepared in three replicates for control(i.e.,under a FT cycle only)and treatments(i.e.,individually planted with the study species and subject to a FT cycle).The treated plots were then placed at a slope of 20%and subjected to simulated rainfall with intensity of 70 mm h-1 and 30 min duration.The results of the study showed a significant effect(P<0.05)of the plants on controlling runoff and soil loss after a FT cycle.Also,the detrimental effects of the FT cycle due to performance of ice lenses and formation of an active melting layer in the soil surface were ameliorated by the presence of litter on the soil and root-binding effect of the plants.Time to runoff increased by 54,111 and 10%,runoff volume decreased by 27,68 and 0.4%and soil loss changed by-34,-62,and+6.5%in the plots planted with A.trichophorum,L.prenne and M.sativa,respectively.The results of the current study indicated that L.prenne had the maximum benefit on reducing runoff and soil loss from the plots undergoing a FT cycle.展开更多
Gully erosion is one of the most important forms of land degradation in many regions of the world.Understanding the process of gully erosion therefore is important for better management of the wa-tersheds prone to gul...Gully erosion is one of the most important forms of land degradation in many regions of the world.Understanding the process of gully erosion therefore is important for better management of the wa-tersheds prone to gully erosion.However,many different aspects of gully erosion,like hydrological behavior,are still not fully understood.The present study investigates the spatial distribution of soil moisture content(SMC),as one of the hydrological factors,at different depths and points across the cross section in the vicinity of the headcut of three gullies located in the Kalat County,Khorasan Razavi Province,Iran.SMCs were measured at depths of 10,20,30,50,70 and 100 cm at each seven points across the study cross sections one to three days after occurrence of three rain events.Two sampling points were symmetrically located at a distance of 50 cm outside the gully banks,two at the vertex of the sidewalls,two in the middle of the sidewalls and one at the center of gully cross section.SMCs were measured using a weighted method.Results of the study revealed a broad range of changes in SMCs at various depths and points.The minimum and maximum SMCs were found to be about 2%and 38%,respectively,for the study period and gullies under consideration.The coefficient of variation(CV)had drastic changes for various gullies and storm events from 2 to 107%.Results further indicated that SMC moved from the sidewalls towards the floor of the cross section.Accordingly,the maximum SMC for storm events was associated with the point located in the center of gullies,which indicated the role of gully system in draining soil moisture.The findings of this study will help watershed managers un-derstand the important role of gully facies in changing water content of the soil that affects other eco-hydrological processes.展开更多
The evaluation of scale effects on modeling performance of sedimentgraphs as the ultimate outputs of the hydrological simulation is vital for adaptive watershed management.The present study therefore analyzed effectab...The evaluation of scale effects on modeling performance of sedimentgraphs as the ultimate outputs of the hydrological simulation is vital for adaptive watershed management.The present study therefore analyzed effectability of simulated sedimentgraphs components in association with different topographic maps with various vector scales.The whole procedure was materialized to select the critical scale and cell size for the Galazchai Watershed,Iran.To this end,the stormwise sedimentgraphs were modeled for 23 recorded events using the Clark's Instantaneous Unit Hydrograph (IUH) model stemmed for developing Instantaneous Unit Sedimentgraphs (IUSGs) incorporated with dimensionless sediment concentTation distribution (DSCD) based on the vector scales of 1∶25000,1∶50000,1∶100000 and 1∶250000 and cell sizes of 5,10,20 30,50,100 and 200 m.Some 644 direct sedimentgraphs (DSGs) were then evaluated based on Relative Errors (REs) for sediment volume,peak sediment,time to peak,base time and the Coefficient of Efficiency (CE).The results confirmed that REs for peak sediment,time to peak and CE were sensitive to cell size.The results further verified that the cell sizes of 5,20,30,50 and 100 m were critical cell sizes in viewpoint of time to peak.In addition,the vector scales of 1∶50000 with cell size of 50 m,and 1∶100000 with cell sizes of 5 and 10 m were critical vector scales and cell sizes based on RMSE evaluation criterion.It is concluded from the current research that the accuracy of simulation of sedimentgraph was influenced by map scales and mesh sizes.展开更多
The aim of this study was the spatial and temporal monitoring of soil erosion patterns in Iran.The G2 model was used,as an appropriate tool to provide the required month-time step country-wide soil loss maps and stati...The aim of this study was the spatial and temporal monitoring of soil erosion patterns in Iran.The G2 model was used,as an appropriate tool to provide the required month-time step country-wide soil loss maps and statistical outputs.The input parameters were derived with field surveys and remote sensing imagery(MODIS,SRTM,SPOT,and Sentinel-2 scenes).An innovation for G2 was the consideration of the snow cover effect on the rainfall erosivity.It was also the first time G2 was used to map such a big country like Iran on a country scale.The mean annual soil erosion in Iran was found to be 16.5 t ha−1,which is equal to about 2.7 billion tons of soil loss.In spatial terms,the highest soil loss values were found in the north,west and southwest part of Iran,in the steep slopes in Alborz and Zagros mountains.In temporal terms,the highest and lowest monthly erosion values of 3.2 and 0.09 t ha−1 correspond to January and July,respectively.展开更多
Shear stress distribution prediction in open channels is of utmost importance in hydraulic structural engineering as it directly affects the design of stable channels.In this study,at first,a series of experimental te...Shear stress distribution prediction in open channels is of utmost importance in hydraulic structural engineering as it directly affects the design of stable channels.In this study,at first,a series of experimental tests were conducted to assess the shear stress distribution in prismatic compound channels.The shear stress values around the whole wetted perimeter were measured in the compound channel with different floodplain widths also in different flow depths in subcritical and supercritical conditions.A set of,data mining and machine learning algorithms including Random Forest(RF),M5P,Random Committee,KStar and Additive Regression implemented on attained data to predict the shear stress distribution in the compound channel.Results indicated among these five models;RF method indicated the most precise results with the highest R2 value of 0.9.Finally,the most powerful data mining method which studied in this research compared with two well-known analytical models of Shiono and Knight method(SKM)and Shannon method to acquire the proposed model functioning in predicting the shear stress distribution.The results showed that the RF model has the best prediction performance compared to SKM and Shannon models.展开更多
Exploring spatial and temporal land-use changes is valuable for local governments to address issues of sustainability and planning policy where urbanization and industrialization are taking place.Besides anthropogenic...Exploring spatial and temporal land-use changes is valuable for local governments to address issues of sustainability and planning policy where urbanization and industrialization are taking place.Besides anthropogenic effects,natural driving forces like climate change may also affect sustainability.However,such relationships have not been studied minutely.Hence,this study first investigates the land-use changes and their relationship with land surface temperature(LST)for the Shazand Watershed,Iran,in 1986,1998,2008,and 2016 coincided with supplementary industrialization stages.Furthermore,the relations among LST and other biophysical parameters,including Normalized Difference Vegetation Index(NDVI),Normalized Difference Buildup Index(NDBI),and Normalized Difference Water Index(NDWI),were analyzed,and corresponding variations were explored.The results indicated that the mean LST of the study watershed has an increasing trend from 1986 to 2008 due to land-use change and drought intensification.Later,LST decreased in 2016.Lower LST was associated with irrigation farming and orchard,and higher LST was related to sparse oak forest areas.There was also a negative correlation between LST and NDVI.As a result,it was inferred that greenery declined LST.Conversely,a positive correlation was found between LST and NDBI resulting from the built-up areas.Since LST could influence biological,physical,chemical processes,it can therefore be supported as an effective index for environmental sustainability assessment.展开更多
Monitoring the sediment transport behavior induced by different interventions, particularly sand mining from rivers, is needed to adaptively manage the watersheds. The particle size distribution of the sus-pended sedi...Monitoring the sediment transport behavior induced by different interventions, particularly sand mining from rivers, is needed to adaptively manage the watersheds. The particle size distribution of the sus-pended sediment in up and downstream of rivers is one of the main indicators to know about fate of sediments, which may be varied in different conditions. We investigated the effect of some types of sand and gravel (i.e., manual and low, semi-heavy, and heavy machinery) mining on particle size distribution of suspended sediment in the Vaz-e-Owlya, Vaz-e-Sofla and Alesh-Roud riverine mines located in Ma-zandaran Province, northern Iran. The study was conducted on a monthly basis from February, 2012 to January, 2013. Laser granulometry was used to analyze the particle size distribution of suspended se-diment samples taken from up and downstream sections of the study mines. The results revealed that the level and intensity of mining activity affected particle size distribution of suspended sediments. Further statistical assessments in up and downstream sections of the mines proved that sorting, D50, mean, D90, kurtosis, skewness and D10 of the suspended sediment were not significantly influenced by mining activities at levels of 0.09, 0.11, 0.12, 0.15 to 0.69, 0.15–0.69, 0.77, 0.87, 0.97, respectively. While it was not statistically significant, we found that the type of mine and the level of the exploitation changed the particle size distribution of the suspended sediment.展开更多
文摘Direct measurement of snow water equivalent(SWE)in snow-dominated mountainous areas is difficult,thus its prediction is essential for water resources management in such areas.In addition,because of nonlinear trend of snow spatial distribution and the multiple influencing factors concerning the SWE spatial distribution,statistical models are not usually able to present acceptable results.Therefore,applicable methods that are able to predict nonlinear trends are necessary.In this research,to predict SWE,the Sohrevard Watershed located in northwest of Iran was selected as the case study.Database was collected,and the required maps were derived.Snow depth(SD)at 150 points with two sampling patterns including systematic random sampling and Latin hypercube sampling(LHS),and snow density at 18 points were randomly measured,and then SWE was calculated.SWE was predicted using artificial neural network(ANN),adaptive neuro-fuzzy inference system(ANFIS)and regression methods.The results showed that the performance of ANN and ANFIS models with two sampling patterns were observed better than the regression method.Moreover,based on most of the efficiency criteria,the efficiency of ANN,ANFIS and regression methods under LHS pattern were observed higher than the systematic random sampling pattern.However,there were no significant differences between the two methods of ANN and ANFIS in SWE prediction.Data of both two sampling patterns had the highest sensitivity to the elevation.In addition,the LHS and the systematic random sampling patterns had the least sensitivity to the profile curvature and plan curvature,respectively.
文摘Raindrop size,rainfall intensity and runoff discharge affect the detachment and transportation of soil particles.Among these three factors,the rainfall intensity seems to be more important because it can change other two factors.Storm patterns can be determined by changing the rainfall intensity during the storm.Therefore,the objective of this research is to test the influence of storm pattern on runoff,soil erosion and sediment concentration on a rangeland soil slope under field rainfall simulation.Four storm rainfall intensity patterns were selected for examining the effects of variations in storm event characteristics on soil erosion processes.The selected storm patterns were:I(45,55 and 70 mm h-1);II(45,70 and 55 mm h-1);III:(70,55 and 45 mm h-1);and IV(55,45 and 70 mm h1).The last pattern is a new one instead of the uniform pattern which has been sufficiently studied in previous researches.The experiments were conducted in field plots(in Kojour watershed,Mazandaran Province,Iran)with an area of one square meter and an constant slope gradient of 18%,surrounded by galvanised sheets.Following the nonuniform prioritization of the storm patterns for the studied variables,time to runoff(I>II>IV>III),runoff volume(III>IV>II>I),sediment concentration(IV>III>I>II)and soil erosion(III>IV>II>I)),it can be generally inferred that each pattern has specific effect on soil erosion processes during a storm.The results of the general linear model(GLM)test indicated that the effects of storm pattern on time to runoff,total runoff volume,runoff coefficient and soil erosion were significant at a level of 99%.The Duncan test showed that the storm patterns can be divided into three groups of III,IV;II;I(for time to runoff),I,II;IV,III(for runoff coefficient),and I;II;IV,III(for runoff volume and soil erosion).
文摘The growing demand for current and precise geographic information that pertains to urban areas has given rise to a significant interest in digital surface models that exhibit a high level of detail. Traditional methods for creating digital surface models are insufficient to reflect the details of earth’s features. These models only represent three-dimensional objects in a single texture and fail to offer a realistic depiction of the real world. Furthermore, the need for current and precise geographic information regarding urban areas has been increasing significantly. This study proposes a new technique to address this problem, which involves integrating remote sensing, Geographic Information Systems (GIS), and Architecture Environment software environments to generate a detailed three-dimensional model. The processing of this study starts with: 1) Downloading high-resolution satellite imagery; 2) Collecting ground truth datasets from fieldwork; 3) Imaging nose removing; 4) Generating a Two-dimensional Model to create a digital surface model in GIS using the extracted building outlines; 5) Converting the model into multi-patch layers to construct a 3D model for each object separately. The results show that the 3D model obtained through this method is highly detailed and effective for various applications, including environmental studies, urban development, expansion planning, and shape understanding tasks.
文摘Determination of the infiltration rate in a watershed is not easy and in empirical and theoretical point of view, it is important to access average value of infiltration. Infiltration models has main role in managing water sources. Therefore different types of models with various degrees of complexity were developed to reach this aim. Most of the estimating methods of soil infiltration are expensive and time consuming and these methods estimate infiltration with hypothesis of zero slope. One of the conceptual and physical models for estimating soil infiltration is Green-Ampt model which is similar to Richard model. This model uses slope factor in estimating infiltration and this is the power point of Green-Ampt model. In this research the empirical model of Green-Ampt was optimized with integrating artificial neural network model (ANN) and a model of geographical information system WMS to estimate the infiltration in Kakasharaf watershed. Results of the comparison between the output of this method and real value of infiltration in region (through multiple cylinders) showed that this method can estimate the infiltration rate of Kakasharaf watershed with low error and acceptable accuracy (Nash-Sutcliff performance coefficient 0.821, square error 0.216, correlation coefficient 0.905 and model error 0.024).
基金the doctoral dissertation of Nabiyeh Karimi with the financial support of Sari University of Agricultural Sciences and Natural Resources, Iran
文摘Complete and comprehensive information about sediment dynamic and identification of hotspots of sediment production and transport are necessary for understanding the erosion processes and increasing the efficiency of soil and water conservation practices.Numerous studies used the sediment fingerprint techniques to investigate the contribution of different sources in suspended and bed sediment yield of the watersheds.However,the contribution of various land use/land covers in suspended and bed sediment yield for the great Caspian Sea basin is in an aura of ambiguity and the present study was conducted to gather information about an important part of this area in northern Iran,where rangelands are located upstream of Hyrcanian forests and dense agricultural lands are located downstream.The surface soil of different land use/land covers including forest,rangeland,agriculture and streambank lands were sampled in 30 points.Suspended and bed sediments were sampled in the watershed outlet in two high and low water periods.Geochemical characteristics of soil and sediment samples containing 59 elements were measured using ICP-OES GBC Integra.The reliable and suitable tracers from 59 elements were then selected using Range test,Kruskal-Wallis and Discriminant Function Analysis,respectively,in FingerPro package of R software.The results showed that for suspended sediment,streambank and rangeland had the highest contributions of 86.2%and 47.5%,respectively,in two high and low water periods.For bed sediment,in two high and low water periods,rangeland and streambank had the highest contributions of 73.8%and 84.4%,respectively.Land use change and especially human activities such as agriculture,road construction and development of residential areas along the main river riparian zone has led to a significant increase in suspended and bed sediments.
文摘A ship＇s crew plays an important role in the maritime transportation sector and their performance is paramont in the shipping industry. On this account, an impartial evaluation of the crew＇s performance is an important issue. In this paper, the ship officer＇s performance evaluation problem is studied. The performance evaluation criteria that shipping companies take into account are determined and a performance evaluation process is modelled by using the FAHP （Fuzzy Analytic Hierarchy Process） based on Chang＇s Algorithm. Linguistic variables and fuzzy numbers are used in the assessment process. The results of the proposed model demonstrate that the FAHP method is effective and helps managers make better and more reliable decisions under fuzzy circumstances.
基金funding under the program Horizon Europe:Digital,Industry and Space grant agreement ID 101070658.
文摘Scientists have long sought frameworks to understand the complex systems that shape our world,from ecological dynamics to socio-technical networks.The concept of simplexity,intermittently explored for over 70 years,has now been redefined,offering a revolutionary perspective on complexity and simplicity across natural,social,and technological domains.1 This breakthrough provides insights into the interplay between simplicity and complexity,unifying disciplines and driving scientific and technological progress.In this context,information management shifts from mere storage and dissemination to dynamic strategies that shape behaviors and interactions,fostering knowledge-driven activities.
基金Fund Chulalongkorn University(BCG_FF_68_074_2100_011)for supporting this research.
文摘The objective of this study is to investigate the utilization of tungsten oxide(WO_(3))supported on natural materials,including activated carbon(AC)and montmorillonite clay(MMT),for the catalytic dehydration of ethanol.This study addresses the growing demand for sustainable chemical processes that produce key intermediates,such as ethylene and diethyl ether,from renewable resources.The research examined the effect of varying WO_(3) loadings on catalyst performance using the incipient wetness impregnation method.The physicochemical properties of catalysts were elucidated through a variety of characterization techniques.The results revealed that MMT supports exhibited a more significant enhancement in catalytic efficiency compared to AC when loaded with W.This superior performance is attributed to MMT’s unique layered structure,enabling efficient dispersion of tungsten species and optimized acid site distribution.The structural properties of the support and the higher density of weak acid sites were found to significantly influence catalytic activity.The 13.5WMMT catalyst demonstrated remarkable dual functionality,achieving 42.63%diethyl ether yield at 250℃ and 96.73%ethylene yield at 400℃.In contrast,the 13.5WAC catalyst produced only 22.30%diethyl ether yield at 300℃ and 77.02%ethylene yield at 400℃.The study not only underscores the significance of metal loading and support type in achieving superior catalytic performance,but also highlights the exceptional potential of MMT as a promising candidate for sustainable and efficient ethanol dehydration processes.
基金the financial support of the Earth and Environmental Sciences PhD-PON program(Research&Innovation,2014-2020,Education and research for recovery-REACT-EU,DOT1322534-4)of University of Pavia,Department of Earth and Environmental Sciencesthe financial support of the RTDA-PON program(Research&Innovation 2014-2020,Education and research for recovery-REACT-EU,C6-G-32370-3),University of Milano-Bicocca,Department of Earth and Environmental Sciencessupported by the Belmont ABRESO project(https://www.belmontforum.org).
文摘In this paper we introduce HOTSED,a novel,innovative GIS-based model designed for assessing potential hotspots of sediment dynamics at watershed scale.HOTSED integrates geomorphic spatial information with both structural and functional properties of connectivity.HOTSED provides a single and intuitive output that depicts the location of sediment source hotspots.Moreover,it enables the identification of“relative hazard”classes for sediment production and related effects.The general methodological framework is based on the initial elaboration of an Inventory Map(IM)of sediment-related landforms and processes,along with the implementation of a corresponding database.Subsequently,we used data stored in the IM to estimate the geomorphic Potential of Sediment Sources(PSS)through a relative scoring system.Furthermore,we computed Structural Sediment Connectivity(STC)and the Potential for Sediment Transport(PST)by combining terrain and hydrological parameters,vegetation roughness,and rainfall erosivity.Afterwards,PSS,STC,and PST components are integrated through a raster-based calculation method yielding the HOTSED model.We tested the HOTSED procedure in the upper Val d’Arda-Mignano watershed,which is a representative geomorphologically highly active Mediterranean area of the Northern Apennines(Italy).Through photointerpretation,terrain analysis,and fieldwork,we mapped sedimentrelated geomorphic features for a total of 4640 ha including:badlands and gullies(0.26%),rill-interrill erosion(15.03%),fluvial erosion(0.03%),landslides(70.06%),litho-structural erosional systems(0.87%),slope deposits(12.56%),and alluvial deposits(1.19%).HOTSED revealed hotspots with a very high hazard potential located near main channels or upstream of the reservoir.These areas are often linked with active landslides highly connected to the drainage system and frequently associated with other processes like bank erosion or surficial soil erosion.The model also highlighted linear hotspots corresponding to drainages flowing alongside or intersecting complex geomorphic systems such as landslides.Furthermore,HOTSED identified areas where sediments are stored in depositional landforms,exhibiting a low hazard potential,considering both low geomorphic potential and sediment connectivity.Our conceptual model is generally applicable but proves to be particularly effective in areas characterized by complex and polygenetic geomorphic systems,such as the Northern Apennines.HOTSED offers a valuable tool for watershed authorities to support sustainable watershed and reservoir management.
基金the Ministry of Education, Science, Sports and Culture (MEXT),Japan.
文摘Translocation of absorbed phosphorus （P） from metabolically inactive sites to active sites in plants growing under P deprivation may increase its P utilization efficiency （PUE）. Acclimation to phosphate （Pi） starvation may be caused by a differential storage pool of vacuolar P, its release, and the intensity of re-translocation of absorbed P as P starvation inducible environmental cues （PSlEC） from ambient environment. Biomass assay and three P forms, namely inorganic （Pi）, organic （Po）, and acid-soluble total （Ptas） were estimated in Brassica cultivars exposed to 10 d P deprivation in the culture media. Considering that -aPi/at denotes the rate of Pi release, Pi release velocity （RSPi） was determined as the tangent to the equations obtained for Pi f（t） at the mean point in the period of greatest Pi decrease, whereas the inverse of the RSPi was an estimate of the internal Pi buffering capacity （IBCPi）. Inter cultivar variations in size of the non-metabolic Pi pool, RSPi, re-translocation of Pi from less to more active metabolic sites, and preferential Pi source and sink compartments were evaluated under P starvation. The cultivar ＇Brown Raya＇ showed the highest Pi storage ability under adequate external P supply, and a more intensive release than ＇Rain Bow＇ and ＇Dunkled＇ under P stress. Cultivar ＇B.S.A＇ was inferior to ＇Con-l＇ in its ability to store and use Pi. Roots and upper leaves were the main sink of Pi stored in the lower and middle leaves of all cultivars and showed lower IBCPi and larger RSPi values than lower and middle leaves. In another trial, six cultivars were exposed to P-free nutrition for 29 d after initial feeding on optimum nutrition for 15 d. With variable magnitude, all of the cultivars re-translocatad P from the above ground parts to their roots under P starvation, and [P] at 44 d after transplanting was higher in developing leaves compared with developed leaves. Under P deprivation, translocation of absorbed P from metabolically inactive to active sites may have helped the tolerant cultivars to establish a better rooting system, which provided a basis for tolerance against P starvation and increased PUE. A better understanding of the extent to which changes in the flux of P absorption and re-translocation under PSIEC will help to scavenge Pi from bound P reserves and will bring more sparingly soluble P into cropping systems and obtain capitalization of P reserves.
基金the Japan Society for the Promotion of Science (JSPS) for financial support, which enabled him to pursue this research work
文摘Phosphorus （P） starvation is highly notorious for limiting plant growth around the globe. To combat P-starvation, plants constantly sense the changes in their environment, and elicit an elegant myriad of plastic responses and rescue strategies to enhance P-solublization and acquisition from bound soil P-forms. Relative growth responses, P-solublization and P- acquisition ability of 14 diverse Brassica cultivars grown with sparingly soluble P-sources （Rock-P （RP） and Ca3（PO4）2 （TCP）） were evaluated in a solution culture experiment. Cultivars showed considerable genetic diversity in terms of biomass accumulation, concentration and contents of P and Ca in shoots and roots, P-stress factor （PSF） and P use efficiency. Cultivars showed variable P-stress tolerance, and cultivars depicting low PSF and high P-efficiency values were better adaptable to P-starvation. In experiment 2, after initial feeding on optimum nutrition for 12 d after transplanting （DAT）, class-I （low P-tolerant （Oscar and Con-II）） and class-II （low P-sensitive （Gold Rush and RL-18）） cultivars were exposed to P-free environment for 25 d. All of the cultivars remobilized P from above ground parts to their roots during growth in P-free environment, the magnitude of which was variable in tested cultivars. P-concentrations （[P]s） at 37 DAT were higher in developing compared with developed leaves. Translocation of absorbed P from metabolically inactive to active sites in P- stressed plants may have helped class-I cultivars to establish a better rooting system, which provided a basis for enhanced P-utilization efficiency （PUE） and tolerance against P-stress. By supplying TCP and RP spatially separated from other nutrients in split root study, class-I cultivars were still able to mobilize RP and TCP more efficiently compared with class-II cultivars. To compare the growth behavior under P-stress, cultivars were grown in pots for 41 d after sowing, using a soil low in P （NaHCO3-extractable P = 3.97 mg/kg, Mehlich-III-extractable P = 6.13 mg/kg） with （＋P=60 mg P/kg soil） or without P addition （0P） in study 4. Tested cultivars showed genetic diversity in PUE, P-efficiency （PE）, P-efficiency ratio （PER） and PSF. P-stress markedly reduced biomass and plant P contents. Cultivars that produced higher root biomass accumulated higher total P-contents （r = 0.98＊＊）, which in turn was related negatively to PSF （r = -0.95＊＊） and positively to shoot and total biomass. PER and PE showed significant correlations with shoot P-contents and biomass. Cultivars depicting high PUE and PE, and low PSF values showed better growth behavior under low soil P-environment. Systematic analysis and deployment of the plant rescue traits underlying the nutrient acquisition, assimilation, utilization and remobilization under P-starvation will bring more sparingly soluble P into cropping systems and will help to scavenge more P from plant unavailable bound P reserves.
基金Japan Society for the Promotion of Science (JSPS)for financial support, which enabled him to pursue this researchwork
文摘Non-mycorrhizal Brassica does not produce specialized root structures such as cluster or dauciform roots but is an effective user of P compared with other crops. In addition to P-uptake, utilization and remobilization activity, acquisition of orthophosphate （Pi） from extracellular sparingly P-sources or unavailable bound P-forms can be enhanced by biochemical rescue mechanisms such copious H＋-efflux and/or carboxylates exudation into rhizosphere by roots via plasmalemma H＋ ATPase and anion channels triggered by P-starvation. To visualize the dissolution of sparingly soluble Ca-phosphate （Ca-P）, newly formed Ca-P was suspended in agar containing other essential nutrients. With NH4＋ applied as the N source, the precipitate dissolved in the root vicinity can be ascribed to rhizosphere acidification, whereas no dissolution occurred with nitrate nutrition. To observe in situ rhizospheric pH changes, images were recorded after embedding the roots in agar containing bromocresol purple as a pH indicator. P-tolerant cultivar showed a greater decrease in pH than the sensitive cultivar in the culture media （the appearance of typical patterns of various colors of pH indicator in the root vicinity）, and at stress P-level this acidification was more prominent. In experiment 2, low P-tolerant class-I cultivars （Oscar and Con-II） showed a greater decrease in solution media pH than low P-sensitive class-II （Gold Rush and RL-18） cultivars, and P-contents of the cultivars was inversely related to decrease in culture media pH. To elucidate P-stress- induced remodeling and redesigning in a root architectural system, cultivars were grown in rhizoboxes in experiment 3. The elongation rates of primary roots increased as P-supply increased, but the elongation rates of the branched zones of primary roots decreased. The length of the lateral roots and topological index values increased when cultivars were exposed to a P-stress environment. To elucidate Pi-uptake kinetics, parameters related to P influx： maximal transport rate （Vmax）, the Michaelis-Menten constant （Km）, and the external concentration when net uptake is zero （Cmin） were tested in experiment 4. Lower Km and Cmin values were better indicative of the P-uptake ability of the class-I cultivars, evidencing their adaptability to P.starved environmental cues. In experiment 5, class-I cultivars exuded two- to threefold more carboxylates than class-II cultivars under the P-stress environment. The amount and types of carboxylates exuded from the roots of P-starved plants differed from those of plants grown under P-sufficient conditions. Nevertheless, the exudation rate of both class-I and class-II cultivars decreased with time, and the highest exudation rate was found after the first 4 h of carboxylates collection. Higher P uptake by class-I cultivars was significantly related to the drop in root medium pH, which can be ascribed to H＋-efflux from the roots supplied with sparingly soluble rock-P and Ca3（PO4）2. These classical rescue strategies provided the basis of P-solubilization and acquisition from sparingly soluble P-sources by Brassica cultivars to thrive in a typically stressful environment.
文摘Soil erosion is recognized as one of the most important types of land degradation in the world particularly in many developing countries like Iran. Water erosion is initiated by splash erosion triggered by raindrop impact. Understanding the process of splash erosion under freezing and thawing conditions is essential to unravel soil erosion mechanisms under temperate conditions leading to appropriate planning of soil and water conservation projects. The present study aimed to study the individual effects of freeze-only as well as freezing-thawing cycle on splash erosion in a loess soil from an erosion prone area in mountainous northern regions of Iran. The study was conducted under laboratory conditions using erosion plots. The erosion plots were subjected to freeze only and freeze-thawing treatments by simulating cold conditions using a large cooling compartment system specifically manufactured for this purpose. The splash erosion under a designed simulated rainfall (1.2mmmin-1 for 30 min) was then measured as upward, downward and net splash erosion in splash cups. The results showed that freeze only decreased the upward, downward and net splash erosion by 0.81 ± 0.43, 0.82 ± 0.29 and 0.85 ± 0.23% while freezing-thawing cycle decreased splash erosion to 0.93 ± 0.83, 0.61 ± 0.43 and 0.57 ± 0.36%. This may be attributed to temporary increase in soil strength and stability or surface sealing during freezing process leading to reduced splash erosion.
基金The present research has been prepared based on the facilities provided by Tarbiat Modares University,IranThe partial support of the Agrohydrology Research Group of Tarbiat Modares University(grant No.IG-39713)
文摘This study investigated the role of three rangeland species viz.Agropyron trichophorum,Medicago sativa,and Lolium prenne on mitigating of effects of a freeze-thaw(FT)cycle on runoff generation and soil loss from small experimental plots.Small plots(0.5×0.5m)were prepared in three replicates for control(i.e.,under a FT cycle only)and treatments(i.e.,individually planted with the study species and subject to a FT cycle).The treated plots were then placed at a slope of 20%and subjected to simulated rainfall with intensity of 70 mm h-1 and 30 min duration.The results of the study showed a significant effect(P<0.05)of the plants on controlling runoff and soil loss after a FT cycle.Also,the detrimental effects of the FT cycle due to performance of ice lenses and formation of an active melting layer in the soil surface were ameliorated by the presence of litter on the soil and root-binding effect of the plants.Time to runoff increased by 54,111 and 10%,runoff volume decreased by 27,68 and 0.4%and soil loss changed by-34,-62,and+6.5%in the plots planted with A.trichophorum,L.prenne and M.sativa,respectively.The results of the current study indicated that L.prenne had the maximum benefit on reducing runoff and soil loss from the plots undergoing a FT cycle.
基金The present manuscript has been partially supported by the Agrohydrology Research Group of Tarbiat Modares University(grant IG-39713),Iran,concerning the corresponding author
文摘Gully erosion is one of the most important forms of land degradation in many regions of the world.Understanding the process of gully erosion therefore is important for better management of the wa-tersheds prone to gully erosion.However,many different aspects of gully erosion,like hydrological behavior,are still not fully understood.The present study investigates the spatial distribution of soil moisture content(SMC),as one of the hydrological factors,at different depths and points across the cross section in the vicinity of the headcut of three gullies located in the Kalat County,Khorasan Razavi Province,Iran.SMCs were measured at depths of 10,20,30,50,70 and 100 cm at each seven points across the study cross sections one to three days after occurrence of three rain events.Two sampling points were symmetrically located at a distance of 50 cm outside the gully banks,two at the vertex of the sidewalls,two in the middle of the sidewalls and one at the center of gully cross section.SMCs were measured using a weighted method.Results of the study revealed a broad range of changes in SMCs at various depths and points.The minimum and maximum SMCs were found to be about 2%and 38%,respectively,for the study period and gullies under consideration.The coefficient of variation(CV)had drastic changes for various gullies and storm events from 2 to 107%.Results further indicated that SMC moved from the sidewalls towards the floor of the cross section.Accordingly,the maximum SMC for storm events was associated with the point located in the center of gullies,which indicated the role of gully system in draining soil moisture.The findings of this study will help watershed managers un-derstand the important role of gully facies in changing water content of the soil that affects other eco-hydrological processes.
文摘The evaluation of scale effects on modeling performance of sedimentgraphs as the ultimate outputs of the hydrological simulation is vital for adaptive watershed management.The present study therefore analyzed effectability of simulated sedimentgraphs components in association with different topographic maps with various vector scales.The whole procedure was materialized to select the critical scale and cell size for the Galazchai Watershed,Iran.To this end,the stormwise sedimentgraphs were modeled for 23 recorded events using the Clark's Instantaneous Unit Hydrograph (IUH) model stemmed for developing Instantaneous Unit Sedimentgraphs (IUSGs) incorporated with dimensionless sediment concentTation distribution (DSCD) based on the vector scales of 1∶25000,1∶50000,1∶100000 and 1∶250000 and cell sizes of 5,10,20 30,50,100 and 200 m.Some 644 direct sedimentgraphs (DSGs) were then evaluated based on Relative Errors (REs) for sediment volume,peak sediment,time to peak,base time and the Coefficient of Efficiency (CE).The results confirmed that REs for peak sediment,time to peak and CE were sensitive to cell size.The results further verified that the cell sizes of 5,20,30,50 and 100 m were critical cell sizes in viewpoint of time to peak.In addition,the vector scales of 1∶50000 with cell size of 50 m,and 1∶100000 with cell sizes of 5 and 10 m were critical vector scales and cell sizes based on RMSE evaluation criterion.It is concluded from the current research that the accuracy of simulation of sedimentgraph was influenced by map scales and mesh sizes.
文摘The aim of this study was the spatial and temporal monitoring of soil erosion patterns in Iran.The G2 model was used,as an appropriate tool to provide the required month-time step country-wide soil loss maps and statistical outputs.The input parameters were derived with field surveys and remote sensing imagery(MODIS,SRTM,SPOT,and Sentinel-2 scenes).An innovation for G2 was the consideration of the snow cover effect on the rainfall erosivity.It was also the first time G2 was used to map such a big country like Iran on a country scale.The mean annual soil erosion in Iran was found to be 16.5 t ha−1,which is equal to about 2.7 billion tons of soil loss.In spatial terms,the highest soil loss values were found in the north,west and southwest part of Iran,in the steep slopes in Alborz and Zagros mountains.In temporal terms,the highest and lowest monthly erosion values of 3.2 and 0.09 t ha−1 correspond to January and July,respectively.
文摘Shear stress distribution prediction in open channels is of utmost importance in hydraulic structural engineering as it directly affects the design of stable channels.In this study,at first,a series of experimental tests were conducted to assess the shear stress distribution in prismatic compound channels.The shear stress values around the whole wetted perimeter were measured in the compound channel with different floodplain widths also in different flow depths in subcritical and supercritical conditions.A set of,data mining and machine learning algorithms including Random Forest(RF),M5P,Random Committee,KStar and Additive Regression implemented on attained data to predict the shear stress distribution in the compound channel.Results indicated among these five models;RF method indicated the most precise results with the highest R2 value of 0.9.Finally,the most powerful data mining method which studied in this research compared with two well-known analytical models of Shiono and Knight method(SKM)and Shannon method to acquire the proposed model functioning in predicting the shear stress distribution.The results showed that the RF model has the best prediction performance compared to SKM and Shannon models.
基金This work was partially supported by the Tarbiat Modares University Agrohydrology Research Group[Grant No.IG39713]。
文摘Exploring spatial and temporal land-use changes is valuable for local governments to address issues of sustainability and planning policy where urbanization and industrialization are taking place.Besides anthropogenic effects,natural driving forces like climate change may also affect sustainability.However,such relationships have not been studied minutely.Hence,this study first investigates the land-use changes and their relationship with land surface temperature(LST)for the Shazand Watershed,Iran,in 1986,1998,2008,and 2016 coincided with supplementary industrialization stages.Furthermore,the relations among LST and other biophysical parameters,including Normalized Difference Vegetation Index(NDVI),Normalized Difference Buildup Index(NDBI),and Normalized Difference Water Index(NDWI),were analyzed,and corresponding variations were explored.The results indicated that the mean LST of the study watershed has an increasing trend from 1986 to 2008 due to land-use change and drought intensification.Later,LST decreased in 2016.Lower LST was associated with irrigation farming and orchard,and higher LST was related to sparse oak forest areas.There was also a negative correlation between LST and NDVI.As a result,it was inferred that greenery declined LST.Conversely,a positive correlation was found between LST and NDBI resulting from the built-up areas.Since LST could influence biological,physical,chemical processes,it can therefore be supported as an effective index for environmental sustainability assessment.
基金The authors would like to thank Engs.S.Azizi and R.Alijani for their valuable accompany in field sampling and data collection.Additional thanks are extended to Eng.N.Ghasvari for his co-operation in laboratory services.This research has also been partly supported by the Iran National Science Foundation(Project no.10100012-12)whose valuable assistance is appreciated.
文摘Monitoring the sediment transport behavior induced by different interventions, particularly sand mining from rivers, is needed to adaptively manage the watersheds. The particle size distribution of the sus-pended sediment in up and downstream of rivers is one of the main indicators to know about fate of sediments, which may be varied in different conditions. We investigated the effect of some types of sand and gravel (i.e., manual and low, semi-heavy, and heavy machinery) mining on particle size distribution of suspended sediment in the Vaz-e-Owlya, Vaz-e-Sofla and Alesh-Roud riverine mines located in Ma-zandaran Province, northern Iran. The study was conducted on a monthly basis from February, 2012 to January, 2013. Laser granulometry was used to analyze the particle size distribution of suspended se-diment samples taken from up and downstream sections of the study mines. The results revealed that the level and intensity of mining activity affected particle size distribution of suspended sediments. Further statistical assessments in up and downstream sections of the mines proved that sorting, D50, mean, D90, kurtosis, skewness and D10 of the suspended sediment were not significantly influenced by mining activities at levels of 0.09, 0.11, 0.12, 0.15 to 0.69, 0.15–0.69, 0.77, 0.87, 0.97, respectively. While it was not statistically significant, we found that the type of mine and the level of the exploitation changed the particle size distribution of the suspended sediment.
