Fahimeh Mirchooli; Seyed Hamidreza Sadeghi; Abdulvahed Khaledi Darvishan
Abstract
Soil erosion is an important subject in water and soil conservation researches which is influenced by natural and anthropogenic factors. Hence, knowledge on soil erosion amount enables the identification of critical areas and prioritization of measures. One of the effective factors in the evaluation ...
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Soil erosion is an important subject in water and soil conservation researches which is influenced by natural and anthropogenic factors. Hence, knowledge on soil erosion amount enables the identification of critical areas and prioritization of measures. One of the effective factors in the evaluation of soil erosion is slope and length (LS) which could be calculated using different methods and algorithms, so the selection of the best method to provide proper estimation is important. However, the comparison of the performance of the different estimation methods has not been sufficiently considered. Therefore, the present study was conducted to calculate the LS factor and evaluate its effect on estimations of soil erosion in the Shazand Watershed using four common algorithms viz. Renard et al. (1997); Desmet and Govers (1996); Moore et al., 1991, and Böhner and Selige (2006) in geographical information system. The results of this study while confirming the difference of about 15 times among performances of various algorithms, indicated that the mean soil erosion using the algorithm of Renard et al. (1997); Desmet and Govers (1996); Moore et al. (1991), and Böhner and Selige (2006) were 4.95, 19.47, 1.73, 1.34 t ha-1 yr-1 in case of the stability of other factors of RUSLE model. Considering the calculated amounts of slope length on the topographic map, the Desmet and Govers (1996) algorithm performed better than other algorithms in LS calculation for the study watershed. It clearly verified the necessity of selecting pertinent procedures for the calculation of input factors for the precise estimation of soil erosion.
Reza Izadpanah; Seyed Ali Asghar Hashemi; Alireza Farrokhi
Abstract
Estimation of sediment bed load is one of the most important issues in river engineering. Accordingly, several methods and relations have been proposed to estimate the bed load in streams for the past decades. The present research aimed to select the most accurate method to estimate bed load through ...
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Estimation of sediment bed load is one of the most important issues in river engineering. Accordingly, several methods and relations have been proposed to estimate the bed load in streams for the past decades. The present research aimed to select the most accurate method to estimate bed load through the testing of various relations to estimate the bed load of the Hablehroud River. The hydraulic and geometric specifications of the Hablehroud River at Bankouh hydrometry station were measured on specific dates by the expert team. The bed load rate was calculated by four different relations in Bankouh hydrometry station from 2011 to 2017. Resultant data showed that the Toffaletti method with RMSE, MAE, and R2 of 20.07, 10.86, and 83 estimates more accurate in comparison with other methods. The sensitivity analysis of the Toffaletti equation revealed that the bed load depends greatly on the velocity of the river flow. Such a method is firmly recommended to use in the mountainous region.
Elham Mahmodzadeh; Sedigheh Anvari
Abstract
The accurate estimation of daily Evapotranspiration (ET) improves the efficiency of water resources management especially in areas where suffers from water scarcity. In the present study, ET was estimated using surface energy balance algorithm for land (SEBAL) and the experimental model of FAO-Penman-Monteith ...
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The accurate estimation of daily Evapotranspiration (ET) improves the efficiency of water resources management especially in areas where suffers from water scarcity. In the present study, ET was estimated using surface energy balance algorithm for land (SEBAL) and the experimental model of FAO-Penman-Monteith (FPM) and finally compared and verified with those calculated from pan evaporation method. Since many climatic factors affect the ET values, the sensitivity analysis of SEBAL inputs variables was finally cerried out to determine the key affecting parameters. In this regard, by SEBAL model and emplying the satellite data of Landsat 8 (OLI and TIRS sensors), the ET values were estimated on a daily scale for the time period 2018/07/25 to 2018/09/11. Results of SEBAL model showed that the values of SEE, RMSE and R2 indices were equal to 1.27, 0.76 and 0.77 mm /day and 0.91, 0.6 and 0.92 mm /day, while compared with those of FPM and pan evaporation methods, respectively.
Behnam Farid Gigloo; Ebrahim Omidvar
Abstract
Ephemeral Gully (EG) erosion is one of the most destructive types of water erosion, which contributes significantly to land degradation. EG erosion prediction is necessary to assess the magnitude of soil loss and to implement the appropriate conservation measures. The aim of current study was to ...
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Ephemeral Gully (EG) erosion is one of the most destructive types of water erosion, which contributes significantly to land degradation. EG erosion prediction is necessary to assess the magnitude of soil loss and to implement the appropriate conservation measures. The aim of current study was to evaluate the efficiency of EGEM model for EG erosion prediction in Ghoorichay Watershed, Ardabil Province, Iran. For this purpose, a number of 17 EG erosion was identified and monitored between the years 2014 to 2016. The morphological characteristics and erosion rate of EGs were measured and recorded after seven effective rainfall events. In order to calculate the EG erosion, EGEM model requires four major categories of input data, including identification information, watershed data, soil data, and rainfall data. The model has two major components: hydrology and erosion. The runoff induced by a rainfall event in each gully catchment was determined by the Natural Recourses Conservation service (NRCS) Curve Number (CN). The result of EGEM model performance evaluation showed that the eroded soil volume and cross-section were predicted with a determination coefficient of 0.96 and 0.89, respectively. Sensitivity analysis revealed that the curve number was the most sensitive parameter, so that, with a 10% increasing and decreasing in CN, the volume of soil loss varied 22.98 and -18.92%, respectively. It can be concluded that EGEM model was suitable for event-based EG erosion prediction in Ghoorichay Watershed and it can be recommended for studying and planning on EGs in similar watersheds.
Jaber Salehpoor; Afshin Ashrafzadeh; Seyed Ali Moussavi
Abstract
In the present study, the effect of climate change on the flow of the Hablehroud River was assessed, using the HadCM3 general circulation model, the LRAS-WG downscaling model, and the SWAT hydrologic model. First, using the LARS-WG model, the output of HadCM3 model in the period of 2011-2040 was downscaled ...
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In the present study, the effect of climate change on the flow of the Hablehroud River was assessed, using the HadCM3 general circulation model, the LRAS-WG downscaling model, and the SWAT hydrologic model. First, using the LARS-WG model, the output of HadCM3 model in the period of 2011-2040 was downscaled and the necessary data for the SWAT model were obtained. The downscaling results showed that there is no meaningful difference between the future precipitation and the precipitation observed in the base period of 1995-2010. It was also observed that in the A2, B1, and A1B emission scenarios, the mean of minimum temperature will increase by 0.59, 0.47, and 0.43 0C, respectively, and the mean of maximum temperature will increase by 0.51, 0.39, and 0.35 0C. In the next stage, the SWAT model was calibrated and validated using the monthly flow data recorded at Bonkouh gaging station located at the outlet of the basin. The values of the coefficient of determination and Nash-Sutcliffe in validation phase were 0.8 and 0.72, respectively. Introducing the downscaled rainfall and temperature data to the SWAT model, the variation of the basin outflow was simulated in the period of 2011-2040. Results showed that in the three scenarios under study, the annual flow will increase 10.66, 17.72, and 17.52% in comparison to the base period.
Milad Baghalani; Noredin Rostami; Mohsen Tavakoli
Abstract
Urban flood is the volume of water that is out of the capacity of the drainage network of the city and results in many problems and damages. Most researches around the world shows an increase in urban floods, especially metropolitan areas. The concentration of human population in urban areas with urbanization ...
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Urban flood is the volume of water that is out of the capacity of the drainage network of the city and results in many problems and damages. Most researches around the world shows an increase in urban floods, especially metropolitan areas. The concentration of human population in urban areas with urbanization and changing the face of the earth's nature has caused an increase in impervious surfaces and change in hydrological cycle. This study was done to simulate runoff of Ilam City Catchment using of the SWMM hydrologic-hydraulic model. The model validation results showed that the simulated peak discharge and flow volume are in good correspondence with the observed value (BIAS= 3.25, RE= 0.065). According to the results obtained from the analysis of the sensitivity of the important parameters of the model, the factors affecting the flood occurrence in the study area include the inadequate size of urban channels, increase of impervious areas, coefficient of roughness of permeable areas, slope, area, equivalent width and roughness coefficient of impermeable areas. The results of the study show that sub-area 2 has the highest risk of flood due to land use changes, non-standard construction and inappropriate drainage network, which results in an increase in impervious surfaces, and in the absence of attention, the city of Ilam face severe flood risks due to the drainage network infrastructure and the lack of observance of the urbanization developments criteria. Also, the SWMM model has the accuracy required for urban flood simulation and it can be used for urban runoff management plans and designing superficial water collection and disposal networks.
arezoo kheyrkhah
Abstract
Correct and consistent uses of natural resources preserve this valuable wealth. Using optimization knowledge can assist us to achieve this object. Thus, this study aims to compare linear programming as a classical method of optimization with genetic evolutionary algorithm for land use optimization of ...
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Correct and consistent uses of natural resources preserve this valuable wealth. Using optimization knowledge can assist us to achieve this object. Thus, this study aims to compare linear programming as a classical method of optimization with genetic evolutionary algorithm for land use optimization of the Bayg watershed. Results showed that linear programming reduced dry farming acreage and increased the acreage of irrigated agriculture. After minimization, surface runoff and sediment yield declined by 1.16, 12.91 percent, respectively. Genetic algorithm led to an increase in rangeland, irrigated agriculture and horticulture acreages, while almond orchard and dry farming acreages were reduced. Furthermore, surface runoff and sediment yield declined by 13.95 and 31.99 percent, respectively. Linear programming acted stronger in satisfying the constraints, as compared with genetic algorithm. The constraint “total acreage” was satisfied by linear programming, while genetic algorithm could not meet this constraint. Sensitivity analysis of linear programming showed that the most critical factor in minimizing runoff and sediment yield function was the coefficient of dry farming with a reduced cost of 67.52. Results also established that the constraints “total acreage and minimum acreage of rangeland” with the shadow prices of 397.40 and 233.28, respectively had the highest negative impact on the optimal solution. Meanwhile, the constraints “maximum acreages of irrigated horticulture and almonds garden” with the shadow prices of -134.97 and -118.44, respectively had the highest positive impact on the optimal solution. As a general conclusion it can be stated that in land use optimization problems with a large number of constraints, genetic algorithm show poorer performance in satisfying constraints, as compared with linear programming.
Nafiseh Moghaddasi; Vahedberdi Sheikh; Ali Najafinejad; Iman Karimirad
Abstract
The aim of this study was to evaluate the effects of mechanical watershed management measures implemented across the Boostan Dam Watershed on reduction of flood peak. To this end, the Watershed Modeling System (WMS) was used to compare peak flow before and after of implementation of the ...
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The aim of this study was to evaluate the effects of mechanical watershed management measures implemented across the Boostan Dam Watershed on reduction of flood peak. To this end, the Watershed Modeling System (WMS) was used to compare peak flow before and after of implementation of the measures. The mechanical measures have been implemented during 2000–2007. The major soil and water conservation measures in the Boostan Dam Watershed were mechanical and biological measures implemented in a limited area. To determine the effect of these measures, the watershed has been modeled in WMS environment. Five flood events occurred before implementation of the measures were used for calibration and validation of the model. Three other flood events occurred after completion of the measures were then used for the evaluation. The results showed that the mechanical measures, despite the fact that their reservoirs are full of sediment, decrease the average peak flow 1.79 % compared to the absence of these measures and if some structures would not be destructed, the reduction would reach 5.95 percent. It should be noted that if the structures were out of sediment, the average peak flow rate would decrease 3.25 % in comparison with current situation and 7.64 % when compared to absence of structures.
Majid Hosseini
Abstract
In this study, a simulation has been performed using the Soil and Water Assessment Tool (SWAT) model with the data of the Ghare-sou watershed. The main objective of the study was testing the performance of SWAT and its feasibility to simulate the water balance in this watershed. Required data such as ...
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In this study, a simulation has been performed using the Soil and Water Assessment Tool (SWAT) model with the data of the Ghare-sou watershed. The main objective of the study was testing the performance of SWAT and its feasibility to simulate the water balance in this watershed. Required data such as soil properties, land use and topographic maps were collected from the Natural Resource Office of Kermanshah province, and the weather data, including daily rainfall, temperature, relative humidity and discharge were collected from Meteorology Agency and regional water company of the province. Before calibration, a sensitivity analysis has been performed for all parameters, using OAT (One parameter At a Time) method to evaluate and demonstrate the influences of the model parameters on four major components of water budget including surface runoff, lateral flow, groundwater and evapotranspiration. Calibration and validation of the model were performed using the SUFI2 algorithm. River discharge data from 1982 to 2000 were used for the calibration and those of 2001 to 2005 for the validation. Different criteria were used to evaluate the performance of the simulation. During calibration, the simulated flow matched the observed values with a Nash-Sutcliffe coefficient of 0.56 and a coefficient of determination (R2) of 0.6. These values were 0.6 and 0.65 during the validation. The calibrated SWAT model is suggested to be used in simulation of the monthly flow of the Ghare-Sou watershed, in order to assess the impacts of different management practices and environment changes on the flow.
Azade Jabary; Majid Hosseini; Amir Khosrojerdi
Abstract
The present research is looking for determining and evaluation of water balance in Sanjabi Watershed located in Kermanshah Province due to a variety of problems raised by the population increase. For this purpose, the SWAT model parameters have been calibrated by applying required information layers ...
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The present research is looking for determining and evaluation of water balance in Sanjabi Watershed located in Kermanshah Province due to a variety of problems raised by the population increase. For this purpose, the SWAT model parameters have been calibrated by applying required information layers in a period extending from 1995 to 2004 and their sensitivity were analyzed by SUFI2 program. The flow parameters’ sensitivity was computed by P-Value and t-State in SUFI2. The most sensitive parameters were calibrated and thereafter model was validated for a period extending from 2005 to 2007. The model evaluation results showed that the value of NS (Nash Sutcliff), R2 (Coefficient of determination), Mean Absolute Relative Error (MARE) and Percent Difference (D) for calibration period were 0.78, 0.78, 0.2 and -0.2, respectively and for validation period were 0.74, 0.86, 0.3 and 0.01, respectively. Results showed the desired accuracy of SWAT for runoff simulation. Discharges for calibration and validation periods were generally under and overestimated, respectively. The water balance values are calculated as the amount of water available in the soil. So that the water balance resulted as negative in years 2005 (normal year), 2006 (wet year) and 2007 (dry year). Nevertheless, in these three years, autumn and winter monthly water balances were positive while in spring and summer were negative. The results also showed that most water losses were due to evapotranspiration in this watershed.
Davood Nikkami; Hadi Chamheydar; Mohammad Hossein Mahdian; Ebrahim Pazira
Abstract
Environmental and economic impacts of soil erosion are due to improper land management in a watershed. Although it is impossible to stop soil erosion completely under natural conditions, there is a great need to control erosion for proper land use planning. According to the scarcity of literature in ...
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Environmental and economic impacts of soil erosion are due to improper land management in a watershed. Although it is impossible to stop soil erosion completely under natural conditions, there is a great need to control erosion for proper land use planning. According to the scarcity of literature in the area of soil nutrient evaluation with optimization models, the main objective of this research is determining the optimum level of land uses to minimize soil erosion and nutrients losses and maximize people incomes that live in a watershed. For this purpose, Abolabbas Watershed in the north-eastern part of Khouzestan Province was chosen for this research. A linear programming model was used in three different scenarios including current land use condition without land management, current land use condition with land management and standardized land use condition. Results demonstrated that the current land uses are not optimized for the least soil erosion and nutrient losses and high income. At optimized conditions, the area of forests and orchards increased by 1.81 and 55.7% respectively, rangelands with no changes, and irrigated and drylands decreased by 67.5 and 31.4% respectively. Also, results showed that land use optimization, in current land uses with no land management, decreases total soil erosion by 3.2% and total nutrient soil losses by 2.5 and increases total income by 29.7%, in current land uses with land management, decreases total soil erosion by 35.3% and total nutrient soil losses by 70.2 and increases total income by 37.2%, and in standardized land uses, total soil erosion by 47.2% and total nutrient soil losses by 70.4 and increases total income by 41.8%. Sensitivity analysis, also, showed that the change in the area of orchards and Irrigated lands has the most effects on increasing income and decreasing soil erosion and nutrients losses in Abolabbas watershed.
