Mahmood Baghaei; Hamid Gholami; Aboalhasan fathabadi; Marzieh Rezai
Abstract
Introduction
Accelerated soil erosion by water is an environmental threat on different continents. Suspended sediment loads in riverine systems resulting from the accelerated erosion due to human activities are a serious threat to the sustainable management of watersheds and ecosystem services therein ...
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Introduction
Accelerated soil erosion by water is an environmental threat on different continents. Suspended sediment loads in riverine systems resulting from the accelerated erosion due to human activities are a serious threat to the sustainable management of watersheds and ecosystem services therein worldwide. Identifying sediment provenance in the catchments is essential to to mitigate its negative effects consisting of on-site (e.g., decreasing soil depth and depletion of soil organic, degradation of soil structure, and etc.) and off-site effects and to help remedy problems such as eutrophication, and siltation of reservoirs. Among direct and indirect methods used to study the sediment source, sediment fingerprinting is a useful technique for determining contribution of sediment sources within a catchment like agricultural lands, rangelands, barelands, and etc. The successful application of this method reported in fluvial and aeolian environments. In this study, sediment fingerprinting method used to identify sediment sources and quantifying contribution of its sources in the Farghan Catchment in Hormozgan Province.
Materials and methods
In this research, 38 surficial samples (0-5 cm) were collected randomly-systematic with a good distribution from the potential sources (consisting of eight samples in agricultural lands, 18 samples from gully erosion sites and 12 samples from barelands and rangelands) and six samples from sediment deposited in the bed of the river in vicinity of catchment outlet, respectively, and after samples preparation, the concentration of the geochemical elements (consisting of major elements, rare earth elements and trace elements) were measured by ICP-OES in the central laboratory of University of Hormozgan. Stepwise discriminant function (DFA) was applied to discriminate the sediment sources, and five tracers consisting of Te, Zr, Ta, Be and Na were selected as the final tracers. Finally, the relative contribution from each source was determined by mixing model.
Results and discussion
Based on the results, the mean contribution for the agricultural lands, barelands and rangelands, and gully erosion sited were estimated 16.7, 50.6, and 32.7 %, respectively. Based on the results, a combination of Te, Zr, Ta, Be and Na were able to correctly classify 89.3% of the source sediment samples consisting of agricultural lands, gully erosion sites, barelands and rangelands. Due to high sediment rate, gully erosion sites are one of the important forms of soil erosion by water. The central parts of catchment are the most susceptible region to gully erosion because these areas are covered by lithological formations such as Bangestan, Aghajari and Mishan. Mishan lithological formation is involving the marl, limestone, and the Aghajari outcrop consists of sandstone and marl. The lands of flat plains are covered by quaternary fluvial depositions resulting from the erosion of Aghajari, Mishan and older lithological formations. Due to low slop of central parts of study area, existing young soils and without developed horizons and mismanagement of land uses, the land susceptibility to gully erosion is high in central parts.
Conclusion
Sediment source fingerprinting is a useful technique to investigate the origin of sediment in both windy and fluvial sedimentary environments. The estimated source proportions can help watershed engineers plan the targeting of conservation programmes for soil and water resources and due to the variability of geological units from one region to another, the type of land use management, and the type of soil units of each region, the selected trackers for each region are different, and for this reason, until now researchers are able to provide a comprehensive guide for choosing a tracker. were not optimal in all regions, and this issue is one of the main challenges of sediment fingerprinting.
Ahmad MolaAhmadi; Marzieh Rezai; Mansoureh Shamili
Abstract
Extended abstractIntroductionProper watershed management is based on ecological principles, and understanding the ecological process is the main prerequisite for natural resource planning. The watersheds adjacent to the Oman Sea and the Persian Gulf have special conditions compared to other watersheds ...
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Extended abstractIntroductionProper watershed management is based on ecological principles, and understanding the ecological process is the main prerequisite for natural resource planning. The watersheds adjacent to the Oman Sea and the Persian Gulf have special conditions compared to other watersheds in the country, such that these watersheds have many salt domes. These geomorphological facies affect the quality of underground water in the areas and require special management techniques. Among the ecological factors, soil is one of the factors that play an important and influential role in the distribution and density of vegetation. The strong correlation and close relationship between vegetation and soil are such that a change in the status of each will have a very strong impact on other ecosystem functions. The present study was conducted to investigate the changes in plant communities and the role of soil factors on these communities in these Gulf and Omani vegetation areas in Bastak city of Hormozgan. Materials and methodsFor this purpose, after determining the desired area, using Google Earth satellite images and ground control, typing was performed and then sampling was done in each type on three transects of 1000 meters with a plot of 4 square meters with a suitable distance. In each plot, canopy percentage, density, height, and two diameters perpendicular to each other of dominant plants were measured. To study the soil, 9 profiles were dug in each type and sampled from two depths of 0 to 45 and 45 to 90 cm and transferred to the laboratory. Statistical analysis was performed by SPSS software and a comparison of means by Duncan method in a randomized complete block design. Results and discussionThe results show that during the 20 years of 1379-1399, all land uses have undergone drastic changes. In this period, pastures have decreased by 18.32%, of which 83.50% belong to pastures, 9.85% to saline and barren lands, 0.70% to urban-man-made areas, and 5.95% to agricultural lands. The results of the correlation coefficient analysis indicate that the vegetation parameter was electrically correlated with the amount of sodium at 95% statistical level. The height of plant species is related to the percentage of saturated moisture and the percentage of silt in the first and second depths. Showed a negative correlation with soil acidity at both depths with a negative approach at 95% level. ConclusionSoil salinization and its development in dry and semi-arid fragile watersheds is one of the environmental hazards that has received attention in recent years. Faramarzan city of Bastak is one of the areas that have arid and semi-arid environmental conditions and one of the environmental hazards of this watershed is salinization and salinization of lands. In summary, it can be stated that the trans-border area of Bastak is limited by the salt marshlands of Hormozgan in the high areas with salt domes and in the lower areas with the salty river. The type of plant species in the plant types in this salt marsh was different according to the salinity center, and this difference is the result of the soil charact.
mohammad ekrami; Rasool Mahdavi Najaf abadi; Marzieh Rezai; hassan vagharfard; Jalal Barkhordari
Abstract
In recent decades, among natural disasters, the frequency of agricultural drought has been higher than other natural disasters. The best way to management of agricultural drought was to management drought-stricken society. The purpose of this study was to assess the vulnerability and spatial analysis ...
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In recent decades, among natural disasters, the frequency of agricultural drought has been higher than other natural disasters. The best way to management of agricultural drought was to management drought-stricken society. The purpose of this study was to assess the vulnerability and spatial analysis of drought in Pishkuh watershed in Yazd province. the effective parameters in the vulnerability of agricultural drought in the region became information layers, and after weighting the layers in terms of the importance of agricultural drought vulnerability in the framework of multi-criteria decision making (MCDM) Agricultural drought in the study area was prepared. In order to control, monitoring and evaluation the final map, field studies of the study area were also used. The results showed that the highest weight of the effective parameters in drought vulnerability was related to the precipitation parameter, the value of which is equal to 0.31, and the lowest weight was related to the slope parameter with a value of 0.05. According to the obtained results, the most vulnerable agricultural droughts were related to Sanich, Darashir, Darasir, Eshkaft, Morok, etc. Geomorphologically, these areas were considered to be high and mountainous, more severe than plain areas due to the low depth of sediments, coarse-grained soil texture and aquatic resources (Qanats), mainly their vulnerability to drought, and In terms of time, they suffer more quickly, in other words, they suffer a lot of damage in the short term. While areas such as Islamia, Nasrabad, Mazrea Akhund, Hemmatabad , etc. were in a lower degree of agricultural drought damage. The results indicate that the degree of damage to agricultural drought estimated in the final map is in line with the findings of field studies. Therefore, the map of agricultural drought vulnerability has acceptable and desirable accuracy.
Malihe Sadat Zarif Moazem; Rasool Mahdavi; Soheila Javanmard; Marzieh Rezaei
Abstract
The rain process is affected by numerous environmental factors such as dust events and the interaction of these two events can influence the hydrological cycle. According to various reports on increasing of dust occurrences in different regions, this study aimed to investigate the potential impact of ...
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The rain process is affected by numerous environmental factors such as dust events and the interaction of these two events can influence the hydrological cycle. According to various reports on increasing of dust occurrences in different regions, this study aimed to investigate the potential impact of dust storms on rainfall in Khorasan Razavi during 2000-2013. The statistical method of "historical regression" was used to investigate dust effect on rainfall, which is based on comparison of observed rainfall with its prediction. Nine synoptic stations were selected as target stations. Regression equations were used to predict precipitation of target stations using the daily rainfall data of the hydrometric stations using the Least Squares Method. Then, the statistical ratio index for historical regression was calculated for each target station based on the observed and predicted rainfall values. The statistical ratio of each station was evaluated by Monte Carlo of permutation test using R-software. Since relative humidity variations play important role in the precipitation process, the correlation coefficient was calculated between the relative humidity and the statistical ratio index of each target station. The statistical test of correlation between relative humidity variables and the statistical ratio of historical regression were significant for all stations. The permutation tests for each station statistical ratio index showed a variable effect of dust on rainfall. The lowest statistical ratio index of 0.8 belonged to the Neyshabur Station with a relative humidity of 38%, whereas the highest statistical ratio index of 1.5 was found for Torbat Heydarieh Station with a relative humidity of 59.45%. In the present study, precipitation response to dust events was affected by relative humidity conditions. In a general conclusion, components of hydrological cycle does not have constant response to environmental variables and therefore, obtained comprehensive conclusions in atmospheric processes need more extensive studies.
