Mohammad Reza Daneshvar; Mohammad Reza Danaeian
Abstract
In recent years, several flood-spreading projects are constructed in different provinces. Lack of information about planning criteria caused unsuitable ratio between flood spreading area and selected design flood discharge. To find a relation between two above-mentioned parameters this investigation ...
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In recent years, several flood-spreading projects are constructed in different provinces. Lack of information about planning criteria caused unsuitable ratio between flood spreading area and selected design flood discharge. To find a relation between two above-mentioned parameters this investigation was performed in 70-hec area of Miankooh flood spreading station. Soil infiltration tests were carried out before and after every flood spreading event. During the research period six flood events were harvested and several parameters were measured including; discharge, volume of flood, time of flood, volume of tail runoff, time of infiltration, area of flooded sections. In total, 2767288 m3 of flood volume was harvested and 2732361 m3 of water was infiltrated. Considering above-mentioned parameters, relation between maximum input discharge and flooded area, slope of the site, length of the embankment, height of weir and flood time were estimated and the final function was offered. As a result, height of weir and length of embankment have significant coordination (99%) with maximum input discharge.
Raoof Mostafazadeh; Mohsen Zabihi; Maryam Adhami
Abstract
Self-similarity characteristic of climate variables provides the spatial and temporal analysis, using fractal dimension. Therefore, the application of fractal geometry in predicting the nature of many natural processes (e.g. rainfall) in several areas is of great importance. The purpose of this study ...
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Self-similarity characteristic of climate variables provides the spatial and temporal analysis, using fractal dimension. Therefore, the application of fractal geometry in predicting the nature of many natural processes (e.g. rainfall) in several areas is of great importance. The purpose of this study is to determine and calculate the fractal dimension of wet and dry periods, interpret and evaluate the spatial characteristics of dry and wet periods over 40 rain gauge stations in Golestan Province. Toward this attempt, the box-counting method has been employed to determine the number of wet-dry months at one to nine months temporal scales and the calculation of fractal dimension. Then, the regression lines are used to estimate the corresponding fractal dimensions over rainy and non-rainy periods. As well as the severity and duration of wet-dry durations were presented over the study area. The results indicated that variations of rainy/non-rainy durations vary in a range of 11 percent. According to the results, the number of consecutive wet-dry months decreased in coarser time scales (months). The analysis of fractal dimension showed that the dry periods have a lower frequency. The fractal dimension values were considered to determine the variations of precipitation regime over studied stations. Also, the intensity of wet durations is higher in central and eastern parts of the study area, while the western part of the Golestan Province had experienced more persistent wet periods.
Ali Khodaie; Abbas Pahlavani; Zahra Ghelichipour; rahman zandi
Abstract
The protection and management of each user in different areas should be based on ecological conditions, which can be achieved by assessing the ecological potential in each area. Assessing ecological potential means examining the potential power of the land and determining its natural use by humans. The ...
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The protection and management of each user in different areas should be based on ecological conditions, which can be achieved by assessing the ecological potential in each area. Assessing ecological potential means examining the potential power of the land and determining its natural use by humans. The main purpose of this study is to identify the ecological potential in Khodaafarin City with an area of 161,607 ha, using the multi-criteria assessment method, the common land management model of Dr. Makhdoom and using GIS. In this study, after identifying ecological resources (sustainable and unstable), the resources were analyzed and summarized. Then, in the software environment (ArcGIS 10.6), the information layers were combined and then the maps were evaluated. Finally, according to the existing values, the potential strengths and bottlenecks of the region were estimated and the permitted uses were prioritized in the region. As a result, after combining the necessary maps and correcting them, the environmental capacities and ecological potential of the region were estimated as area (percentage) in Khodaafarin City. According to the objectives of the research, areas prone to segregation of aquaculture-agriculture (2.65), aquaculture-rangeland management (0.14), aquaculture-urban and rural development (0.2), aquaculture-extensive tourism (0.049), conservation-extensive tourism (0.45), conservation-forestry (0.12), centralized tourism-forestry (0.021), aquaculture (6.34), extensive tourism (12.61), centralized tourism (2.64), rangeland management (33.1), agriculture (7.51), conservation (13.57), urban, rural and industrial development (1.8), forestry (18.8) were zoned and identified. The results also showed that the highest potential is related to the rangeland management with an area of 61567.55 ha of which less than 50% (30457 ha) is consistent with the current conditions.
Seyede Maryam Bagheri; Mohammadhossein Mahdian
Abstract
Due to the complexity and wide changes in wetlands' environmental factors, pollution monitoring, protection and control of soil quality is deemed to be necessary. Therefore, understanding the spatial distribution of characteristics including the concentration of heavy metals is of great importance. In ...
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Due to the complexity and wide changes in wetlands' environmental factors, pollution monitoring, protection and control of soil quality is deemed to be necessary. Therefore, understanding the spatial distribution of characteristics including the concentration of heavy metals is of great importance. In this context, this study aimed to investigate the spatial variations of copper element as for some chemical properties of Anzali wetland's soil. In this regard, sampling was conducted at 48 sites of the wetland topsoil and copper concentration, pH and cation exchange capacity of their soil was determined. Inverse distance estimators, polynomials, five spline functions including regularized spline, tension spline, multi quadratic function spline, inverse multi quadratic function, thin plates spline and universal kriging and combination of above mentioned and fuzzy methods using cross-evaluation method have been examined in this research. Also, assessment criteria of Mean Absolute Error (MAE), Mean Bias Error (MBE) and Model Efficiency (EF) were used to compare the differences between observed and estimated values and determine the appropriate method. Based on the results, fuzzy tension spline method using the auxiliary variable of cation exchange capacity (least MAE=5.64, percent error=90/11 and EF=0.3) was chosen as the preferred method in copper's distribution mapping. This method decreased the mean absolute error of 50, 56, 56, 53, 53 and 50 percent compared with techniques such as inverse distance estimators, local polynomials, universal polynomials, spline, universal kriging and fuzzy ordinary kriging, respectively. Furthermore, comparing maximum and average values of copper's allowable concentration in this study with the same values in Poland and Australia's soil standards showed that nowadays given to the data obtained from samples, the level of copper element in Anzali wetland's soil is less than the critical level.
Aliakbar Sabziparvar; Behnaz Khataar; Majid Sadeghifar; Saba Saghaei; Farnaz Ershadfath; Reza Norooz Valashedi
Abstract
Nowadays, wise scheduling of water resources is an important task for sustainable development. In this scope, accurate knowledge about daily evaporation from surface water is important for optimum agricultural products. Shortage or lack of evaporation sites, quality of the data and gaps in pan observations ...
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Nowadays, wise scheduling of water resources is an important task for sustainable development. In this scope, accurate knowledge about daily evaporation from surface water is important for optimum agricultural products. Shortage or lack of evaporation sites, quality of the data and gaps in pan observations force the researchers to use prediction models. In this work, three different time series were applied for estimating daily pan evaporation in Hamedan province (Ekbatan dam, Kooshk-Abad and Agh-Kahriz). Evaluations of time series data indicated that pan evaporation of all stations, contains no seasonal trend. Based on the results, the ARIMA showed the highest performance in estimating the daily pan evaporation for the selected sites. With respect to the obtained errors, the best time-series structure were ARIMA(1,1,1) for Agh-Kahriz and ARIMA(2,0,1) for Ekbatan dam and Kooshk-Abad, respectively. The calculated R2 and RMSE for selected sites were 0.93 and 2.44 mm/day for Agh-Kahriz, 0.93 and 1.23 mm/day for Ekbatan dam and 0.92 and 1.03 mm/day for Kooshk-Abad. For the selected model, the Mean Percentage Errors (MPE) varied between 5.85 to 6.92 percent, which denotes models overestimation versus the measurements. The standard deviations of the best performance model are: 0.15, 0.14 and 0.13 mm for Agh-Kahriz, Ekbatan dam and Kooshk-Abad, respectively.
Salman Mirzaee; Shoja Ghorbani Dashtaki; Jahangard Mohammadi; Hossein Asadi; Farokh Asadzadeh
Abstract
Understanding the spatial distribution and variability of erodibility and soil properties is essential for planning of water conservation methods, controlling of flood and runoff and managing of soil erosion or watershed. Selecting and using appropriate interpolation techniques for soil properties and ...
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Understanding the spatial distribution and variability of erodibility and soil properties is essential for planning of water conservation methods, controlling of flood and runoff and managing of soil erosion or watershed. Selecting and using appropriate interpolation techniques for soil properties and erodibility mapping by erosion models such as WEPP is essential. The objective of this study was regionalization of interrill erodibility and effective factors like clay, organic matter and lime using kriging and cokriging and remote sensing data (Landsat 7). For this purpose, 100 soil samples were selected randomly from 0-15 cm depth of Selin watershed in Kaleibar region of East Azerbaijan. Interrill erodibility of WEPP model and some soil properties as clay, organic matter and lime were measured. Correlation analysis between soil properties and digital number (DN) ETM+ image showed that clay, organic matter, lime and interrill erodibility had the highest correlation with DN of Band 7, 1, 1 and 3 ETM+ image (−0.406, -0.431, 0.291 and 0.299), respectively. Therefore, the DN of these bands used as auxiliary data for cokriging estimator. The spherical model was fitted the best model to calculate variogram of interrill erodibility, clay, organic matter and lime. No significant difference were noted between kriging and cokriging despite using remote sensing data as auxiliary data. This can be attributed no strong correlation between interrill erodibility, clay, organic matter and lime and remote sensing data.
Mahtab Safari Shad; Mahmoud Habibnejad Roshan; Karim Solaimani; Alireza Ildoromi; Hossein Zeinivand
Abstract
Many of the environmental problems are caused by the changes in the main components of the hydrological cycle. However, water balance modeling can help to better understanding the components of the hydrological cycle in order to develop appropriate management options. The purpose of this study is to ...
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Many of the environmental problems are caused by the changes in the main components of the hydrological cycle. However, water balance modeling can help to better understanding the components of the hydrological cycle in order to develop appropriate management options. The purpose of this study is to calculate three important components of surface water balance using the WetSpass model and evaluate the model in Hamadan-Bahar Watershed located in Hamadan Province on a monthly time scale. The results of the model evaluation in the study showed that the coefficient of determination between the observed and simulated runoff in the calibration and validation period is equal to 0.79 and 0.83, respectively. Groundwater nutrition assessment was also performed according to manual calculations of the variable for 2012-2013. Then, the results of Kramer correlation coefficient between spatial distribution maps of runoff, actual evapotranspiration and groundwater recharge were investigated with input maps of the model. In general, due to the importance of evapotranspiration in water balance calculations, the evaporation and transpiration maps of the model were evaluated separately for different uses. The evaluation results confirmed the capability of the WetSpass model in simulating runoff, evapotranspiration and groundwater feeding with an acceptable accuracy. The results of spatial distribution maps of runoff, actual evapotranspiration and groundwater recharge indicate a high correlation between evapotranspiration component with land use (0.54), soil texture (0.45), evapotranspiration potential (0.42) and temperature (0.31). Also, these results indicate a high correlation between runoff components with land use (0.62) and soil texture (0.58), and average correlations between groundwater recharge component with land use (0.32) and soil texture (0.34). Therefore, land use and soil texture were the first and second factors affecting the distribution of surface balance components, respectively.
Forood Sharifi; Samane Arvandi
Abstract
This research was carried out to; evaluate the hydrological processes (rainfall, runoff, evaporation, infiltration, etc.), study the water capacity, to simulate the behavior of watersheds. After examining a number of simulation models, the SFBM, AWBM2002, SCS and ISDI were selected and adjusted. Data ...
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This research was carried out to; evaluate the hydrological processes (rainfall, runoff, evaporation, infiltration, etc.), study the water capacity, to simulate the behavior of watersheds. After examining a number of simulation models, the SFBM, AWBM2002, SCS and ISDI were selected and adjusted. Data from 15 catchments and a representative watershed were used. The results such as, simulation parameters, runoff threshold, flow duration curve, snow line, flow recession curve, and base flow index are analysed. The results showed that the models, can well simulate the runoff, and are able to estimate response of ungauged catchments, and form a good capability for design and research. In more than 61.5% of the area, after a rainfall of 5 to 10 mm, runoff generates, hence it was concluded that most of the basins are susceptible to flooding. Also, the highest threshold value in the Bandar Gaz basin is 20 mm, with a maximum specific discharge of 0.27 m3/km2. The lowest value was obtained in Azadshahr and Gonbad-Kavoos basins, respectively, equal to 2 and 4 mm, with a specific instantaneous flow rate of 0.16 in the Gonbad-Kavo basin to 0.26 m3/km2 in the basin no. 171. Also, the highest threshold value in the Bandar Gaz basin is 20 mm, with a specific maximum discharge of 0.27 m3/km2. Among the basins of the similar areas, the Delour Qotorchai Basin with an area of 45.2 km2 with a maximum specific discharge of 0.49 m3/km2, the highest and middle Shor basins, with an area of 37.22 km2and Gorgan Bay with an area of 299.26 km2 with a discharge of 0.04 m3/sec/km2.The results indicated that the runoff threshold has a good correlation with precipitation. The results of the dryness model showed that the model with a high correlation coefficient (83%) simulated the discharge.
Somayeh Emami; Javad Parsa
Abstract
Due to the flow regime and consequently the sediment regime are not constantly in the watersheds, the prediction of sediment discharge is a great help in estimating and managing the sediment input to hydraulic structures. Measurement of sediment in the usual way is not justified in nowadays and may also ...
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Due to the flow regime and consequently the sediment regime are not constantly in the watersheds, the prediction of sediment discharge is a great help in estimating and managing the sediment input to hydraulic structures. Measurement of sediment in the usual way is not justified in nowadays and may also lead to human error. Therefore, in this study, three meta-heuristic optimization algorithms, including imperialist competitive algorithm (ICA), grey wolf optimizer algorithm (GWO) and election algorithm (EA), were used to predict the suspended sediment load of the Zarrineh river. In order to calculate the sediment discharge by the models, firstly, the necessary statistics and data were collected from the studied station in the period 1993-2015. After processing the data, 210 corresponding discharge and sediment data were selected. The corresponding discharge-sediment data from the study station were randomly separated into two parts, 70% for training and 30% for testing. In order to evaluate the performance of the algorithms, four statistics consist of R2, RMSE, MAE and the NSE were used. The results showed that GWO algorithm with values of statistical criteria R2=0.96, RMSE=228.86 ton/day, NSE=0.74 and MAE=67.32 ton/day, has a very high accuracy compared to other algorithms used which this would lead to comprehensive planning for the design and construction of hydraulic structures.
Mokhtar Karami; Rasol Sarvestan; Reza Sabouri
Abstract
The purpose of this study was to investigate the effect of climate change on the monthly discharge of Karoon Catchment as the largest basin in the country. In this study, five hydrometric stations (Bamdgeh, Telezang, Gharmaleh, Gotvand and Dezful) and three synoptic stations (Ahwaz, Dezful and Masjed ...
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The purpose of this study was to investigate the effect of climate change on the monthly discharge of Karoon Catchment as the largest basin in the country. In this study, five hydrometric stations (Bamdgeh, Telezang, Gharmaleh, Gotvand and Dezful) and three synoptic stations (Ahwaz, Dezful and Masjed Soleiman) were considered. Using the SDSM software, NCEP data and large-scale data from the general circulation model (HadCM3 for temperature and CgCM3 for water discharge) were scaled parameters under two climate scenarios A1B and A2 in the Karun Basin. Then, the climate change data and the output of the microscale model were applied to the SPSS 19 and Minitab 17 to predict the significance of water discharge for future climate courses (2020-2070) be simulated. Results of climate change analysis showed that under different scenarios, monthly air temperature in the scenario A1B increases by 1.60°C and in the scenario A2 1.58°C, but the average annual rate of stations in the scenario A1B is 19.82 m S-1 in size and 16.27 m S-1 in the A2 scenario. The modified Kendall and age tests were used to identify seasonal and semi-annual seasonal time series trends. Results also showed that under climate scenarios of discharge in spring and first half of the year, there was no significant trend at 95% of confidence, but in other seasons of the second half of the year, there was a significant decrease.
Fatemeh Vatanparast Ghaleh Juq; Bromand Salahi
Abstract
Introduction
Human life is constantly affected by various natural hazards, some of which result from climate events and global warming. This issue is so significant that the Intergovernmental Panel on Climate Change (IPCC) was established to study climate change on a global scale and assess the role ...
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Introduction
Human life is constantly affected by various natural hazards, some of which result from climate events and global warming. This issue is so significant that the Intergovernmental Panel on Climate Change (IPCC) was established to study climate change on a global scale and assess the role of human activity in this matter. One of the consequences of climate change is the occurrence of extreme events such as drought. In fact, with climate change, the intensity and frequency of droughts are becoming more complex. Given the vital role of water in human life, agricultural production, and the environment, it is crucial to assess its adverse effects on the occurrence and severity of droughts. The primary cause of droughts is fluctuations in climatic components, such as decreased precipitation and increased temperature.
Materials and methods
This study aimed to predict drought conditions in Ardabil, Ahar, Parsabad, Jolfa, Khoi, and Maku stations, located within the Aras River watershed. To achieve this, the accuracy of the General Circulation Models (GCMs) from the IPCC’s CMIP6 dataset was evaluated. The climate models used for forecasting precipitation in the future period (2024–2043) include CanESM5, NorESM2-MM, and MPI-ESM1-2-HR under both optimistic (SSP1-2.6) and pessimistic (SSP5-8.5) emission scenarios. Then, using the Standardized Precipitation Index (SPI), drought characteristics on an annual scale during the historical period (1985–2014) were compared with those in the future period. Model validation was performed using R², RMSE, and NSE parameters. Finally, the SPI drought index was analyzed in terms of intensity and frequency based on the generated precipitation data.
Results and discussion
Model evaluation using different error metrics indicated that the CanESM5 model outperformed the others in simulating precipitation for the studied stations. A comparison of the models and scenarios revealed that, according to the MPI-ESM1-2-HR model, drought severity is projected to increase, while the CanESM5 model suggests a rise in drought frequency. The results also indicate that under the most pessimistic scenario, both the number and intensity of dry periods will increase compared to the optimistic scenario. Furthermore, normal conditions are expected to decrease, while the number and frequency of dry periods will rise due to the consequences of climate change in the study area. Additionally, the frequency and intensity of wet years have shown a slight increase compared to the historical period. Overall, climate change is expected to have a significant impact on the future drought conditions in the Aras River watershed.
Conclusion
In summary, understanding changes in precipitation and water resources is crucial due to their various applications in agriculture, drinking water supply, and industry. The accuracy of future climate models varies depending on the climate of each region, the month, and the predicted climate variable. The Aras River Basin is facing a decline in water resources due to agricultural activities exceeding capacity and high water consumption in different agricultural sectors. This study aimed to assess the impact of climate change on drought severity and frequency in the Aras River Basin, providing insights for developing intelligent policies for sustainable water and land resource management. The findings confirm the occurrence of climate change and, in particular, the recurrence of droughts in the studied stations. Using multiple climate models, as the most reliable tool for generating climate scenarios, not only allows for more accurate forecasts but also helps evaluate uncertainties in future climate conditions. These insights assist planners and decision-makers in better monitoring the adverse effects of drought on water resources and agriculture, enabling proactive planning to mitigate regional losses before a crisis occurs.
Kianush Behrahi; Gholamabbas Sayyad; Ahmad Landi; Hamidreza Peyrowan
Abstract
Study of effective factors on runoff quantity to achieve optimum measures for runoff controlling is an essential subject in watershed management. This study aimed to investigate the effects of land use type and land slope degree on runoff quantity using an artificial rainfall simulator in Kakasharaf ...
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Study of effective factors on runoff quantity to achieve optimum measures for runoff controlling is an essential subject in watershed management. This study aimed to investigate the effects of land use type and land slope degree on runoff quantity using an artificial rainfall simulator in Kakasharaf watershed from branches karkhe watershed (Lorestan Province). Based on the land use map, at 6 work units (sub basins), three land use types of pasture, forest and agriculture; and three land slope degrees of 10, 20 and 30 percent was chosen. In total 93 tests were run using an artificial rainfall simulator and the runoff quantities were collected and measured. Artificial rainfall simulator was a plexiglass non-pressure rainfall simulator with a plot size of 83.5 × 119 cm2 and height 160 cm. Statistical analysis was done using SAS software. Results showed that the average, minimum and maximum runoff quantity were 1499, 0, and 9100 cm3, respectively. Analysis of variance showed a significant difference (p<0.01) between sub basins and runoff quantity. Also, the interaction of sub-basins and land use showed a significant difference (p<0.01) on runoff quantity. There was a significant difference (at 1% level) between runoff quantity and the land slope so that by increasing the slope from 10 to 30 percent, the produced runoff volume increased. Besides, there was a significant difference (1% level) among runoff quantity of pasture, forest and agriculture. The volume of runoff in the forest regions was more than pasture and agriculture land use types.
Zahra Jaberalansar; Morteza Khodagholi; Masoud Borhany; Hossein Arzani
Abstract
Rangeland ecosystems in semi-arid regions are vulnerable systems to climatic changes specially precipitation. In such conditions droughts are predictable. In this study the relationship between rangeland production and spatial and temporal changes of precipitation was investigated. Therefore, rangeland ...
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Rangeland ecosystems in semi-arid regions are vulnerable systems to climatic changes specially precipitation. In such conditions droughts are predictable. In this study the relationship between rangeland production and spatial and temporal changes of precipitation was investigated. Therefore, rangeland production through 10 years data set (1377-1387) in steppic bioclimatic of Esfahan province (Alavije, Muteh, Kalahrood and Gardaneshadian) using Standard Precipitation Index (SPI), the relationship between SPI series of 3, 5 and 8 month time scales, and rangeland production of 10 years. Thus Anova and correlation matrix between production and SPI factors were formed. Results indicated that the most severe drought has occurred in 1387 simultaneously, with the least production. A harmony between change trend of production and SPI in the sites showed that in most cases maximum and minimum production have occurred simultaneously with maximum and minimum of SPI series. Also, the production correlated with SPI series of three, five and eight months' time scales with correlation coefficients more than 63 percent which were significant in 1% and 5% level. Due to efficacy of production from spring precipitation and soil depth less than 30 cm in the sites, it is proposed to use SPI series of three months scale to evaluate drought in similar rangelands.
Vahid Chitsaz; Seyed Bagher Fatemi; Zabihollah Eskandari
Abstract
Nowadays, application of remote sensing is common in soil conservation and erosion projects and most of them are used aerial photogarphs and desipte of the numerous advantages, there are some limitations. In this study, replacemen of moderate-resolution satellite data instead of aerial photographs has ...
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Nowadays, application of remote sensing is common in soil conservation and erosion projects and most of them are used aerial photogarphs and desipte of the numerous advantages, there are some limitations. In this study, replacemen of moderate-resolution satellite data instead of aerial photographs has been investigated with emphasis on processing of satellite images and using image filters and the purpose of soil erosion figures detection. Finaly, image processing of area are prepared with maximum capability vitual interpretation of effects associated with erosion, after the study design, atmospheric and geometric corrections and perform pre-processing and initial processing on ETM+ and ASTER images. In order to evaluate the efficiency of filters for detection and identification of soil erosion were used low-pass and high-pass filters such as filters, median, mean, High Pass, Gaussian, Laplacian, Sobel and linear filters on ASTER and ETM images in the part of the Esfahan Dastkan basin. According to the results, using of low pass filters are not recommended because of the resolution reduction of soil erosion. High-Pass filters can be partialy appeard the edages of image and can be help to visual interpretation (especially in combination with the original image). Use of filters is recommended in combination with the image and as an aid to vitual interpretation, due to problems of application the fiters for separate soil erosion units. Regard to the dimension of soil erosion (rill and gully) and compared to the spatial resolution of the used sensor in this study, the erosions are not clearly appeared in the picture and application various image filters to automatically discover and exploit of these effects can not be efficiently. Resolution images of ASTER and ETM+ are not responsive for mapping erosion by using automated method and should be looked for a solution of semi-automated and visual interpretation. Also, because of the similarity between the spectral and geometrical picture was not found a major difference in the results. Therefore, it is recommended to produce a susceptibility map of erosion or erosion risk map instead the variouse types of regional soil erosion.
Tooraj Asadi; Seyed Saber Shahooei; Mohammad Asadi; Amir Mansour Shahsavar
Abstract
Due to the importance of water erosion in reducing soil fertility many studies have been done on the quantity of this destructive phenomenon. Tamura and Rogowosky found a meaningful relation between water erosion and Cs-137 loss in soil matrix. This report was the first of application of Cs-137 method ...
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Due to the importance of water erosion in reducing soil fertility many studies have been done on the quantity of this destructive phenomenon. Tamura and Rogowosky found a meaningful relation between water erosion and Cs-137 loss in soil matrix. This report was the first of application of Cs-137 method to estimate soil erosion since 1974. From 1974, the method has changed gradually and now is used in many studies. In this study,aerial photographs with scale of 1:20000 and topographic maps with scale of 1:50000 were used. 12 transects on the hilly lands (compound and uniform slopes) and 3 transects on the piedmont plain were studied. Surface samples were collected from different slope situations. The situations were collected from different slope situations.The situations were summits, shoulders, back slopes, foot slopes and toe slopes; gamma spectrometer was used to determine the Cs-137 of the samples. Soil erosion and sediment were calculated by Cochanouski (1993) Equation. Results showed that in summit, shoulder and back slope of the compound slopes, erosion is 68.42, 45.46 and51.16 Ton/ha/yr respectively. On the same situations of uniform slopes 79.6, 65.3 and 84.23 ton /ha/yr of soil losses were expected. In non-erosional situations (toe slopes), soil loss has been deposited. In foot slopes, i.e. dynamic sites, sedimentation process is more dominant than destructive ones. The correlation between USLE and Cs-137 models were statistically signification with % 95 probability.
Abbas Pourmeydani; Abolfazl Khalilpour; Hossein Tavakoli Neku; Mohammad Hassan Marefat
Volume 2, Issue 2 , July 2010, , Pages 95-101
Abstract
One of the important problems is erosion and soil degradation in watershed areas. Polymer usage is a way for both erosion control and soil and water conservation. In this research the effects of the BT53 polymer application for moisture storage in soil, reduction of runoff and erosion and prevention ...
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One of the important problems is erosion and soil degradation in watershed areas. Polymer usage is a way for both erosion control and soil and water conservation. In this research the effects of the BT53 polymer application for moisture storage in soil, reduction of runoff and erosion and prevention of loss soil are studied for 1998-2001. The research plan was CRBD and factorial method. First factor included polymer levels of 0, 2 and 4 gr/m2. Second factor included Secale montanum species planted and not-planted. After every rainfall event both runoff volume and sediment amount were measured. Analysis of variance showed there was significant difference between polymer levels and sediments amount (P<0.01). Compression of averages by Duncan's method in first factor showed all polymer levels fall in one group from runoff volume point of view, and in three groups based on sediment amounts. The most effect of polymer usage was on sediment amounts reduction rather than runoff. This means that polymer BT53 is suitable more for soil protection besides runoff reduction. Polymer level 1 had most amounts and polymer level 2 had least amounts of sediment. So application of polymer BT53 in level 2 (4 gr/m2) was suggested for sediment control. Polymer level 2 with non-planted treatment had least effects on runoff volume and sediment amounts among six treatments of polymer levels and planted or non-planted.
Maral Khodadadi; Mohammad Sadegh Askari; Fereydoon Sarmadian; Hossein Gholi Refahi; Ali Akbar Norouzi; Ahmad Heidari; Hamid Reza Matinfar
Volume 1, Issue 2 , July 2009, , Pages 99-110
Abstract
Salinity is the major factors of soil degradation in semi arid and arid regions. The main aim of this study was to evaluate the capability of Landsat ETM+ data for soil Salinity mapping in the selected part of the Qazvin plain, an area of arid environment. In this study spectral classes carried out on ...
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Salinity is the major factors of soil degradation in semi arid and arid regions. The main aim of this study was to evaluate the capability of Landsat ETM+ data for soil Salinity mapping in the selected part of the Qazvin plain, an area of arid environment. In this study spectral classes carried out on remotely sensed data and with the help of field observation and soil analysis were regrouped to soil salinity classes to prepare soil salinity map.. Soil sampling was implemented using stratified random sampling method, depending on landscape complexity and homogeneity as well as on the representativeness of Landsat ETM+ data. Also in each soil map unit at least one profile was studied for subsoil salinity variations. Field samples taken by using augur and profiles were analyzed in laboratory for Na+ , Ca2+ , Mg2+ cations, as well as soil texture, ECe and pH. We have analyzed the effectiveness of additional data such as digital elevation model to improve the accuracy of classification. Also NDVI, SRVI, PVI, SAVI, SI, BI and NDSI indices, PCA and Tasseled cap were analyzed. Soil salinity map of each selected bands produced and with ground truth map crossed. The results indicated that combination of DEM with ETM+ bands has highest accuracy. This study addressed that thermal band of ETM+ can increase the classification accuracy which illustrated its effective role to classify the soil salinity. Tasseled cap and other indices had almost high accuracy among studied image processing techniques. The SI and BI indices had the highest correlation with EC and could distinguish the saline and non saline soils while the optimum index factor had overall low accuracy.
Akbar Hassani; Hosseinali Bahrami; Aliakbar Noroozi; Shahin Oustan
Abstract
Reflectance spectroscopy can be used to study agricultural and environmental aspect of soil that are sensitive to soil organic and inorganic compounds. Despite the extensive studies in the field of visible-near infrared reflectance spectroscopy, there are rare researches in gypseous and calcareous soils. ...
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Reflectance spectroscopy can be used to study agricultural and environmental aspect of soil that are sensitive to soil organic and inorganic compounds. Despite the extensive studies in the field of visible-near infrared reflectance spectroscopy, there are rare researches in gypseous and calcareous soils. The objective of this study was to obtain a model that can predict chemical properties of gypseous soils via reflectance spectroscopy methods. Soil samples were collected from 102 locations in five different provinces in 0-30 cm of depth. Some chemical properties of soils, such amount of gypsum, equivalent calcite, cation exchange capacity, pH, EC, exchangeable calcium, magnesium, sodium and potassium and amount of silt, clay and sand were measured by standard methods in the laboratory. Air-dried soil samples were scanned at one nm resolution from 350 to 2500 nm, and calibrations between properties and reflectance spectra were developed using cross-validation under Partial Least Squares Regression (PLSR) and Boosted Regression Trees (BRT). Raw reflectance and first derivative reflectance data were used separately and combined for all samples in the data set. Data were additionally divided into two random subsets of 70 and 30 percent of the full data, which were each used for calibration and validation. Strongest correlations were obtained with gypsum, equivalent calcium carbonate, cation exchange capacity, exchangeable Ca and Mg, organic matter, sand and clay contents. Overall, BRT provided better predictions when under cross-validation. However, PLSR and BRT results were comparable in terms of prediction accuracy when using separate data sets for calibration and validation. In conclusion, VNIR spectroscopy was variably successful in estimating soil properties and showed its potential for substituting laboratory analyses or providing inexpensive co-variable data in environmental studies.
Majid Mahmoudabadi; Samira Zamani
Abstract
Wind erosion is one of the aspects of land degradation resulting in some problems especially for arid and semi-arid regions. Recognition of Sediment size Distribution (PSD) as well as transport mechanisms is important in modelling of wind erosion. In the present study, this topic was investigated on ...
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Wind erosion is one of the aspects of land degradation resulting in some problems especially for arid and semi-arid regions. Recognition of Sediment size Distribution (PSD) as well as transport mechanisms is important in modelling of wind erosion. In the present study, this topic was investigated on two soils taken from cropland and sand dune with different PSD, using wind tunnel. Results showed that compared to the original soil, the collected sediment had finer sizes, indicating a selective mechanism in transporting detachable particles. It was found that for cropland soil, increasing wind speed from 2 to 18 m/s at the height of 20 cm, the PSD of sediment approached to the original soil. This trend was reverse for sandy soil so that, for higher wind velocities, the frequency of fine particles was more than the original soil. The result of transport mechanisms indicated that compared to saltation as well as suspension, creeping was the least important mechanism. The contributing percentage of creeping for cropland and sandy soils was determined less than 10 and 1 %, respectively. For the cropland soil at wind speed of 2 m/s, suspension was the most important mechanism of transport and depends on soil's PSD, 61.1- 68.5 % of particles were transported. Increasing wind speed up to 18 m/s, saltation with 50.4- 53.8 % was found as the main transport mechanism. Reversely, in the sandy soil at low wind speed, most of sediment (59.3 %) was transported through saltation, whereas increasing the speed, suspension with 55.3 % became the dominant mechanism. The finding of this study brings up the important of soil PSD on the PSD of sediment as well as transport mechanisms.
Siavash Taei Semiromi; Hamidreza Moradi; Morteza Khodagholi
Abstract
Now a day, long-term prediction of climate variables is necessary for climate change impact studies. Currently Global Circulation Models (GCM) are powerful tools to generate climate scenarios. These models are limited to capture the local climate due to their low spatial resolution. So, they cannot be ...
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Now a day, long-term prediction of climate variables is necessary for climate change impact studies. Currently Global Circulation Models (GCM) are powerful tools to generate climate scenarios. These models are limited to capture the local climate due to their low spatial resolution. So, they cannot be directly applied for hydrological modeling in a catchment scale. In this research, first the trend of variables such as rainfall, radiation, maximum and minimum temperature were assessed for the base period with nonparametric Man-Kendall test. Second, these variables were downscaled by using the outputs of HADCM model and under three scenarios of A1, A2 and B1 which are accepted by IPCC(1971-2010) under three scenarios and their monthly changes were investigated for three periods of 2011-2030, 2046-2065 and 2080-2099 compared to the base predicted period of (1971-2010). All these scenarios showed almost similar results on precipitation shortage and increasing of solar radiation, minimum and maximum temperature over the future periods. As an example, the results of A2 scenario showed increasing of the annual mean, minimum and maximum temperature by 1.1, 3.2, and 4.6 °C, increasing of solar radiation by 0.07, 0.30 and 0.33 mJ m-2d-1 and decreasing precipitation by 16.4, 17.6 and 31.9 percent for these periods compared to the base period.
Ali Mohammadi Torkashvand; Davood Nikkami; Mehrdad Esfandiari; Seyed Kazem Alavipanah
Volume 2, Issue 3 , October 2010, , Pages 150-160
Abstract
Rill erosion map is one of the basic maps in erosion and sediment studies and also watershed management programs. Some methodologies for preparing rill erosion map (1:250000) by using RS and GIS were compared in a research carried out in Kan-Sologhan and Jajrood sub-basins in North-west and North-east ...
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Rill erosion map is one of the basic maps in erosion and sediment studies and also watershed management programs. Some methodologies for preparing rill erosion map (1:250000) by using RS and GIS were compared in a research carried out in Kan-Sologhan and Jajrood sub-basins in North-west and North-east Tehran, Iran. At the first phase, four working units' maps were prepared by integration of a) plant cover, geology and slope b) land use, geology and slope c) land use, rocks sensitivity to erosion and slope and d) land use, rocks sensitivity to erosion and land units’ layers in Kan-Sologhan basin. For comparing the efficiency of four working units’ maps, 53 ground control points were investigated. Results showed that map "d" was better than "a", "b" and "c" in providing rill erosion regarding economic and executive considerations. At the second stage, map "d" was compared with three maps of e) land units f) rocks sensitivity to erosion and g) satellite image photomorphic units (ETM+ images) in a broader basin of Jajroud. Rill erosion intensities in 314 ground control points were controlled and ground truth rill erosion map was prepared. Rill erosion map was crossed with different working unit maps where results showed that the highest accuracy is related to the images interpretation (81.0% accuracy). Accuracy was 78.4, 66.8 and 59.9 percent for methods of "d", "e" and "f", respectively. Root Mean Squared Error was the highest for map "f" and the least for integrated layers method (map "d"). The greatest precision is related to image interpretation and the images interpretation method is better than other methods in preparation of rill erosion map.
Ahmad Fatehi marj; Farzad Hosseini Hosseinabadi
Abstract
Drought is a phenomenon which is not preventable, but its outcomes could be mitigated by a holistic and scientific managerial vision. In order to approach to this goal, some practical frameworks is needed for different parts of the country, in respect to their climates. This paper is introducing development ...
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Drought is a phenomenon which is not preventable, but its outcomes could be mitigated by a holistic and scientific managerial vision. In order to approach to this goal, some practical frameworks is needed for different parts of the country, in respect to their climates. This paper is introducing development of the first agricultural drought risk management plan by experts of Agricultural Drought Management (ADM) for a pilot area. This project lasted for three years from 2009 to 2011. In this project some educational workshops and specialized meetings were held and have helped the plan to be more succeeded. At first, all needed climatic and agricultural information were collected and then a program for agricultural risk assessment in the region were selected. The drought plan was developed with a nine steps proposed method, in respect to advice of experts. Considering the average income of 41 billion Riyals from agricultural and animal husbandry activities, damages costs of poor to very severe drought varied from 3.450 to 10.350 billion Rials. Agricultural drought risk management plan can reduce drought damages from 30 to 47 percent, depended on drought intensity.
Morteza Dehghani; Ali Karami Khaniki; Seyed Hamid Reza Sadeghi
Abstract
One of the main objectives of hydrology is rainfall–runoff forecasting process for determination of flood hydrograph at the outlet of a watershed. The aim of this study was to investigate the consistency, accuracy and reliability of time–area and Clark instantaneous unit hydrograph models ...
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One of the main objectives of hydrology is rainfall–runoff forecasting process for determination of flood hydrograph at the outlet of a watershed. The aim of this study was to investigate the consistency, accuracy and reliability of time–area and Clark instantaneous unit hydrograph models for estimating the shape, peak discharge, time to peak, base time and volume of flood resulting from a rainfall with certain intensity and duration. For this purpose, the topographic map of Bazoft watershed was digitized by using R2V package, the digital elevation model (DEM) and isochronal prepared with the ILWIS software. Finally, the flood hydrographs were estimated by Clark and time-area models for six selected storm events. The computed hydrographs then compared with those obtained by measured data an outlet of the basin. The results showed that while both methods have some errors, the Clark model gives a better estimation of outlet hydrograph in comparison with time-area model. The amount of relative error for peak discharge for Clark and Time- Area methods were 23.3% and 32.8%, respectively.
Mahnaz Babaei; Seyed Zeynalabedin Hosseini; Aliakbar Nazari Samani; Seyed Ali Almodaresi
Abstract
Recently soil erosion and sediment yield has become one of the most important problems of the environment. Soil erosion risk assessment and sediment yield are first steps to confront with this problem. In this regard, various models and methods proposed. What is certain, first of all must be verified ...
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Recently soil erosion and sediment yield has become one of the most important problems of the environment. Soil erosion risk assessment and sediment yield are first steps to confront with this problem. In this regard, various models and methods proposed. What is certain, first of all must be verified the functionality of these models. The present study is carried out to KanSoleghan watershed in order to estimate the soil erosion risk and sediment yield. RUSLE 3D was used in geographical information system platform. Rainfall Erosivity (R), were obtained from monthly and annual data and IDW techniques, Soil Erodibility (K) were obtained from soil data and regin map, Land cover Management (C) using remote sensing techniques (with use of NDVI), LS using digital elevation model, Soil Conservation Practice with using slope percent map. Eventually based on RUSLE 3D model combining these factors together, annual average risk of soil erosion was obtained 22.20 t.ha-1.y to estimate the sediment delivery ratio was used several models, accordingly, the estimated annual sediment yield was overestimated in all models. Sedimentation basin was calculated using statistics gauging stations sooleghan (1.82 tons per hectare per year). Our study indicated that LS factors of the RUSLE 3D model (r2=0.68) were the most effective factors controlling soil erosion in the region. In general, it can be said that the reliability of the used data and used methods is too low and too many uncertainses exist for areliable calculation of soil loss amounts in kan soleghan watershed using the RUSLE 3D Model.
Mohammad Reza Yazdani; Sattar Chavoshi; Morteza Khodagholi; Bahram Saghafian
Volume 1, Issue 3 , October 2009, , Pages 167-178
Abstract
Most parts of the Isfahan province are located in central arid land of Iran and are sensitive to drought occurrences. So it is required to study drought for prediction. There are many ways to define drought using different indicators. Climatology drought was evaluated using annual precipitation time ...
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Most parts of the Isfahan province are located in central arid land of Iran and are sensitive to drought occurrences. So it is required to study drought for prediction. There are many ways to define drought using different indicators. Climatology drought was evaluated using annual precipitation time series and different truncation levels including 30% 40, 50, 60, 70, 80, 90 and 95%. In this study 85 precipitation stations were selected in Isfahan province and around of it, in period of 1966-1998.Interpolation methods such as, kriging, Co-kriging, inverse distance weighted and TPSS were evaluated for interpolation of truncation levels and the error of each method was calculated. In the selected methods, Co-kriging method had minimum error and TPSS method had maximum error. Drought extension maps were drawn for each truncation levels using ILWIS software. Also water volume of probable precipitation is calculated for each truncation levels. Results showed about half of rainfall events occurred in 30 percent truncation level, whereas about 80 percent of the events are in 30 percent truncation level. Thus intense droughts occurred in the study area. Maximum frequency of drought occurrences in basis of truncation levels in study area are 30, 80, 60, 50, 40, 90, 70, 95%, respectively. Results indicated that truncation levels are suitable method for climatological drought evaluation in the studied area.
