Parviz Garshasbi; Davood Ghorbanpour
Abstract
Soil erosion is one of the critical issues in Iranian watersheds. There are fewer quantitative economic analysis of soil conservation practices effects in Iran. Economic evaluation of soil conservation activities is difficult due to the effect of combined indices and lack of market economic value. In ...
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Soil erosion is one of the critical issues in Iranian watersheds. There are fewer quantitative economic analysis of soil conservation practices effects in Iran. Economic evaluation of soil conservation activities is difficult due to the effect of combined indices and lack of market economic value. In this research, the effects of soil conservation practices are analyzed using Net Present Value (NPV) method in Mian Bishe Sub-basin of Taleghan Watershed in Alborz Province, Iran. This sub-basin was selected due to acceptable period of soil conservation practices for analysis and its technical evaluation experiences. First, basic data were updated using GIS, field survey and identification and measurement of benefit and cost indices. Then, economic value of three main cost indices and six combined benefit indices were identified and computed. Economic indices, including NPV and benefit-cost ratio were estimated by integrating available data. Evaluations show that rehabilitation of Main Bishe Sub-basin in a 30 years period with a discount rate of 15 percent has economic justification in lands with comparative productivity, including mountainous rangelands and hilly badlands with high rate of soil erosion and positive NPV. Also, 25 percent of the total benefits comes through onsite, 55 percent through down streams and 20 percent through neighboring sub-basins and due to reduced flooding risk.
Farhad Shiva; Jalal Attari; Mojtaba Saneie
Abstract
Scour phenomena can impair infrastructures and result in non-reparable damages. Few researches conducted so far show that application of non-cohesive criteria for situations where the bed is formed of cohesive materials, overestimates dimensions of the scour hole and will impose large costs to the project. ...
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Scour phenomena can impair infrastructures and result in non-reparable damages. Few researches conducted so far show that application of non-cohesive criteria for situations where the bed is formed of cohesive materials, overestimates dimensions of the scour hole and will impose large costs to the project. According to the previous researches, type and content of clay also significantly affects scour in the cohesive materials. In this paper, the local scour in the cohesive bed due to a horizontal submerged jet issued from a vertical sluice gate is experimentally studied. Initially, the effective factors were identified and Bentonite clay was selected as cohesive material. A total of 48 tests, considering four different clay contents, three amounts of gate openings and four different tailwater depths, were conducted in a rectangular flume of Soil Conservation and Watershed Management Research Institute laboratory. The results show that by adding Bentonite clay to the erodible bed, effect of cohesion appears in the 10% ratio and with further increase of the clay content the scour depth decreases considerably. So that in a bed containing 20% Bentonite clay the maximum scour depth reduces by 76% on average in relation with a non-cohesive bed. Based on the experimental results, a general equation for predicting the maximum scour depth valid in both conditions of presence and absence of the cohesive materials is presented. A sensitivity analysis on the existing parameters that effect on scour depth was conducted and compared with the results of previous researches. Finally, two types of scour hole profiles were defined which showed a relatively good agreement with previous empirical relationships.
Hamidreza Gharechaei; Alireza Moghaddamnia; Arash Malekian; Azadeh Ahmadi
Abstract
Climate change and anthropogenic effects are two main drivers of stream flow changes. In this study, the trend and Fluctuations in hydro climatic data series of Kashkan River were evaluated during 1972-2011. Then, the climate elasticity method was used for quantitative assessment of stream flow response ...
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Climate change and anthropogenic effects are two main drivers of stream flow changes. In this study, the trend and Fluctuations in hydro climatic data series of Kashkan River were evaluated during 1972-2011. Then, the climate elasticity method was used for quantitative assessment of stream flow response to climate variability and human activity. Results revealed that if precipitation decreases by 10%, runoff will decrease by 25.7∼25.1 percent, and if potential evapotranspiration decreases by 10%, runoff will increasing by 15.7∼15.1 percent. In 1999-2011, human activity was the main factor that decreased the amount of runoff in Kashkan river basin. The contribution of human activities were 73.97∼74.22 percent, while the increasing percentage due to climate variability accounted for 25.77∼26.02 percent, showing that runoff in the Kashkan river basin is more sensitive to climate variability than human activities. The results of this study can provide a reference for the development, utilization and management of the regional water resources and ecological environment protection.
Ebrahim Borooshke; Mahmood Arabkhedri
Abstract
Soil erosion and sediment transport is an important issue in many Iranian watersheds. Watershed planning without accurate estimates of erosion and sediment yield with appropriate models is not possible. The objective of this study was evaluating of two common empirical models of MPSIAC and EPM. First, ...
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Soil erosion and sediment transport is an important issue in many Iranian watersheds. Watershed planning without accurate estimates of erosion and sediment yield with appropriate models is not possible. The objective of this study was evaluating of two common empirical models of MPSIAC and EPM. First, 10 small watersheds were selected in Western Azerbaijan Province, with several consecutive check dams on their streams implemented under watershed management projects. No flow over the last downstream check dam was considered as the main criterion in each selected basin. In addition to the direct measurement of sediment deposited behind the dams, sediment yield of watersheds were estimated using the models. Comparison of means using (Mann-Whithney) did not show any significant difference at 0.05 percent level between measured and estimated data. At final step, both models were tested by MAE and MBE statistics. The MPSIAC showed better performance than EPM with MAE=1.34 and MBE =-0.12.
Gholamreza Chamanpira; Gholamreza Zehtabian; Hassan Ahmadi; Arash Malekian
Abstract
Utilization of water resources, using a combination of simulation and optimization, are a useful and powerful set for specifying decision-making and management strategies. In this regard, MODFLOW mathematical model, as an efficient and cost-effective tool to evaluate different management options was ...
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Utilization of water resources, using a combination of simulation and optimization, are a useful and powerful set for specifying decision-making and management strategies. In this regard, MODFLOW mathematical model, as an efficient and cost-effective tool to evaluate different management options was used. After providing a conceptual model of the aquifer, requirement data were defined in different versions of the V. MODFLOW (V. 5.33) software. Then, the model was calibrated by the manual method that has higher accuracy than software techniques and validation operations were also carried out. In the simulation process, with the goal of water resource management, the results of modeling and calibration model were used to optimize the groundwater table level. In this study, a linear programming model was used for optimizing the management. Lingo software was used to implement this model and achieve the optimal management. The information needed to solve the problem, was based on the output of a simulation model and optimization options. Due to linearity of objective function, a multi-objective linear programming model was selected to solve the problem. General multi-objective optimization problem with n decision variables, m constraints and p objectives is presented in optimizing relationships. The objectives of the optimization problem were maximizing the profits of agricultural products and minimizing the use of aquifer water. Results indicated that the amount of yield and water use were different before and after optimization. . The amount of annual water consumption before optimization was 92.22 million m3 while after optimization was 75.51 million m3. In other words, the rate of water consumption was reduced by 18 prevent. Results also showed that annual water consumption in agriculture was 31.79 million m3 that shows 65.5 percent reduction compared to the present situation. The amount of benefits before optimization was 47, 798 million Rials, while after optimization it was 63,689 million Rials. In other words, the amount of total profit increased by 33.25 percent. Based on the scenario of a national document (pure water requirement), total profits increased by 15 percent.
Majid Hosseini
Abstract
At present due to lack of proper utilization and management in non-renewable natural resources, most of the watersheds are in critical conditions. Since about 80 percent of Iran watersheds located in arid and semi-arid climatic conditions, thus addressing the issue of optimal utilization of rainfall ...
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At present due to lack of proper utilization and management in non-renewable natural resources, most of the watersheds are in critical conditions. Since about 80 percent of Iran watersheds located in arid and semi-arid climatic conditions, thus addressing the issue of optimal utilization of rainfall is most important. In this research, the surface of micro catchment was isolated by plastic to increase runoff coefficient. Six treatments and three replications were considered in down part of the micro catchment. The surfaceswere prepared by available materials such as greenhouse plastic, gravel, fine and coarse sand, and for infiltration, a filter with 50 cm depth and 15 cm diameter was used. Soil moisture in 30 and 50 cm depths, was monitored by Time Domain Reflectometry (TDR). The first step eas started by cleaning grasses and compacting soil surface and monitoring 18 rainfall events. In the next step, soil surface was covered by plastic and 21 rainfall events were monitored. Results showed that the runoff coefficient increases by six to 47 percent or 7.8 times more than natural condition. The statistical analysis by T-test showed that all treatments and depths of isolated and natural conditions have significantly different results in 90 percent level of confidence. Finally, the average soil moisture content for isolated condition in comparison of natural condition is 6.4 and 9.4 percent in 50 and 30 cm of soil depth, respectively. In other hand, isolated surface increased soil moisture 3.8 and 2.8 times compared to treatments in 50 and 30 cm of soil depth, respectively.
Mansour Jahantigh
Abstract
Duststorms occur generally in Sistan region. So, it limits the development of the region. Many factors play especial role on duststorms such as removal of vegetation cover due to automobile transportation. The aim of this research was to identify car transportation role in producing dust storm. For this ...
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Duststorms occur generally in Sistan region. So, it limits the development of the region. Many factors play especial role on duststorms such as removal of vegetation cover due to automobile transportation. The aim of this research was to identify car transportation role in producing dust storm. For this reason, three sites with different characteristics were chosen and in each area, two sites of 600 and 300 m length and wide respectively were selected with and without car transportation. Three soil samples were taken randomly from the first, mid and the end of the sites of each location and they were analyzed for pH, EC, CaCO3, organic carbon, moisture, calcium and vegetation cover. The soil erosion measured according to the Universal Soil Loss Equation. The results showed that the car transportation areas have less amount of clay, vegetation cover, topography, soil surface roughness, organic carbon, but, they have an increase in soil small particles with less than 0.84 mm in diameter, pH, EC, CaCo3and land length which they have especial effect on wind erosion of the region. Results also show that the amount of soil erosion is 15.8-216.3 tonsperhectare in study area.
Bagher Ghermezcheshmeh; Aliakbar Rasuli; Majid Rezaei-Banafsheh; Alireza Massah; Alimohammad Khorshiddoost
Abstract
In the statistical downscaling methods which is based on the relationship between AOGCMs data and ground based climatic variables (such as rain and temperature), the future period of those variables are simulated. Since in the simulation, all effective parameters cannot be modeled, estimated values suffers ...
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In the statistical downscaling methods which is based on the relationship between AOGCMs data and ground based climatic variables (such as rain and temperature), the future period of those variables are simulated. Since in the simulation, all effective parameters cannot be modeled, estimated values suffers from be uncertainty. The outputs of downscaling models are used as inputs to agriculture and water resources models; therefore, identifying the models inputs’ error or uncertainty is essential to realize the reliability of obtained results. In this research, an attempt is made to investigate the uncertainty of Artificial Neural Network (ANN) as a downscaling model in a case study in the northwest of Iran. For this purpose, precipitation, minimum and maximum temperature variables were used in the designed ANN model, and the NCEP data was employed for its calibration and validation. The HadCM3 was the selected AOGCM in this study. Observed daily time series were gathered at all stations in the study period and on the basis of bootstrap method the 99% confidence interval was calculated for all the variables. In the next step, the simulated (downscaled) mean and variance of the variables by the ANN model, compared to the calculated confidence interval. To compare the results, the criterion of the number of station-month was used. The results showed that the average maximum temperature at 14 station-months were within the confidence interval. The results of monthly analysis showed that the accuracy of ANN model in summer was low and its uncertainty is more than the other seasons. In the simulation of minimum temperature based on this criterion, 18 station-months were within the confidence interval. The accuracy of ANN to estimate the minimum temperature in summer was low with high uncertainty in almost all the stations. Moreover, in June and August in any of the stations estimated values were not within the confidence interval. Due to the high variability of rainfall in relation to temperature, confidence range was very high, and in some stations was more than 50% of average monthly precipitation. Because of the high confidence rang of precipitation, in 53 Stations-month cases were within the confidence interval.
Bagher Heidarpour; Bahram Saghafian; Abolfazl Shamsai; Saeed Golian
Abstract
In present research, the exceptional floods of study area at Golestan Dam watershed were identified using one of the standard tests of identifying outlier values, e.g. Dixon, Grubbs and Grubbs and Beck.In order to determine the probability distribution function and the effect of direct application of ...
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In present research, the exceptional floods of study area at Golestan Dam watershed were identified using one of the standard tests of identifying outlier values, e.g. Dixon, Grubbs and Grubbs and Beck.In order to determine the probability distribution function and the effect of direct application of the floods in flood frequency analysis, two sets of analysis were performed one with the whole data series and the other with deleting the outliers. At this stage, 15 different probability distribution functions were applied with biased and unbiased estimates of the parameters using three estimation methods namely method of moments, maximum likelihood and Probability Weighted Moments methods. According to Kolmogorov-Smirnov and Chi-square goodness-of-fit tests and index error calculation, the log Pearson Type III distribution was determined as the best distribution for both complete data series and data without exceptional floods. Results of the Flood frequency analysis at this stage showed that the probability distribution did not change after removing the exceptional floods, but was highly influential in the magnitude of design flood.In the next step, the method of Water Resources Committee of the United States was used to combine the exceptional floods with other observational data. Using the sensitivity analysis, the historical period for exceptional floods at Tangrah, Tamer and Galikesh stations were calculated to be 300, 60 and 80 years, respectively. The derived historical period were considered in calculation of the flood values for different return periods. For example, 1000-year design flood for the complete data series were calculated to be 14946, 1639 and 2635 cms for the aformentioned stations respectively and reduced to 1434, 1423 and 1296 for the complete data series with modification of the parameters for the probability distribution functions. Therefore, the technique used in this study effectively reduced the cost of the designed hydraulic structures.
Aliakbar Jamali; Navab Raeesi
Abstract
By increasing in population, water resources become more important. Watershed Management today has an essential role in water supply in arid and semi-arid regions. Study area consists of a watershed with 6100 hectares areas situate in the northeastern of Nikshahr city named Matesang in the southeastern ...
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By increasing in population, water resources become more important. Watershed Management today has an essential role in water supply in arid and semi-arid regions. Study area consists of a watershed with 6100 hectares areas situate in the northeastern of Nikshahr city named Matesang in the southeastern of Iran. The survey data collected by a questionnaire, which its validity was examined by specialists such as professors, watershed and natural resource experts. Using SPSS, software reliability and Cronbach's alpha between 0.76 and 0.78 were obtained for different scales. In order to evaluate the economic impacts of watershed management projects based on benefit-cost ratio analysis and questionnaire method, the Chi-square test was used. The benefit cost ratio of 1.03 was obtained indicating the economic feasibility of the project. In order to assess the social-economic impacts of watershed management projects in the area questioners and Chi-square test was used. Chi-square test results showed, watershed projects had significant effect by reduction in immigration, flooding, unemployment, and success in flood and sediment control. Watershed management plans, were gained 100% participation satisfaction. The economic debate, results showed the significant reliability of soil and water conservation plans performance on increasing the amount of production, plant cover, the number of animals, water resources, the area of orchards and farmlands and reducing the area of uncultivated lands. In general, this research showed positive multipurpose aspects of mechanical soil and water conservation projects.
