Majid Kazemzadeh; Zahra Noori; Mohammad Jahantigh
Abstract
Occurrence of avalanches in mountainous areas is one of the most important natural hazards that cause a lot of human and financial losses. The study of affecting factors on avalanche occurrence and simulation is very important to manage this phenomenon. In this study, the affecting factors on the occurrence ...
Read More
Occurrence of avalanches in mountainous areas is one of the most important natural hazards that cause a lot of human and financial losses. The study of affecting factors on avalanche occurrence and simulation is very important to manage this phenomenon. In this study, the affecting factors on the occurrence of snow avalanche (terrestrial and meteorological factors) and its simulation have been studied using the RAMMS simulation model in the Central Alborz Velayat Rood (Dizin Road), Alborz Province. Topographic and geomorphological factors such as slope, aspect, curvature, topographic position index (TPI), terrain roughness index (TRI) and topographic wetness index (TWI) using 6 ×6 cm2 pixel size of digital elevation model (DEM) were prepared by using a drone. Meteorological factors such as rainfall, temperature and wind were also considered. Then, using RAMMS simulation model, avalanche components such as avalanche speed, pressure and height were estimated in the study area. The results showed that the amount of slope and aspect as a topographic indicator have a great impact on the formation and occurrence of the snow avalanche. The largest part of the region with an area of 5.7 hectares (54.6% of the study area) with a northeast aspect and slope of 60 to 120%, the accumulation and track areas, has the greatest potential for avalanche. Also, the results of RAMMS simulation model showed that the average speed and maximum avalanche speed in the region were 5.3 m/s and 16 m/s. The average effective avalanche pressure was 7 and the maximum avalanche pressure in the region was 45 KPa. Estimation of avalanche height in the region also showed that the average avalanche height in the runout area (residential areas) was 4.5 meters and the maximum avalanche height in the region was 10 meters, which is classified as a large avalanche.
Hossain shirani; Anis Asadi; ُSomayeh Sadr; Ali Asghar besalatpour; Isa esfandiarpoor
Abstract
Introduction
SWAT model is a suitable tool for simulating hydrological processes. This model requires many inputs that often cannot be measured directly and is considered one of the main sources of uncertainty in these models. The recalibration process can reduce the uncertainty in the model results ...
Read More
Introduction
SWAT model is a suitable tool for simulating hydrological processes. This model requires many inputs that often cannot be measured directly and is considered one of the main sources of uncertainty in these models. The recalibration process can reduce the uncertainty in the model results by adjusting and adapting these inputs. The researches showed that calibrating a hydrological model by using the common automatic CV calibrating algorithms will not provide proper accuracy in the prediction of hydrological variables during the validation period, so PSO algorithm was used to calibrate the SWAT model. Since there is no mathematical and logical rule to determine the best combination of PSO algorithm parameters and these combinations are selected based on trial and error and among many different combinations, therefore trial and error based methods are very time-consuming and sometimes impossible. In this research, Taguchi method was used to determine the best combination of PSO algorithm parameters.
Materials and methods
In this research, the ability to use the SWAT model to simulate monthly runoff in the Javanmardi Watershed, one of the main sub-basins of the Lordegan Watershed with an area of 380 square kilometers, was investigated. In this study, the PSO algorithm parameters, including the number of simulations (A), the number of repetitions (B), the speed calculation weight (C) and the movement parameter (D), were defined in four levels. Then, these parameters were designed and implemented according to the experiments in the L16 orthogonal array (using the Taguchi experiments design method). The performance scale used to evaluate the algorithms was RPD (Relative Percentage Deviation). Considering the variable nature of the response in this study, the S/N index "the lower the better" was used to analyze the Taguchi test results. The selection of arrays and calculations were done in Minitab 16 software.
Results and discussion
In the sensitivity analysis stage, which was performed before the model recalibration, among the 28 parameters studied in this research, the model showed sensitivity to the changes of 22 parameters, and they were identified as variables influencing the simulation of runoff in Javanmardi Watershed. The results showed that the parameter of the runoff curve number (CN) is the most important factor and the parameters of soil apparent density in the wet state (SOL_BD) and average water usable by the plant (SOL_AWC) are among the most important factors controlling the flow rate in the study basin, respectively. Based on the results simulated by the PSO algorithm, it was found that the SWAT model has an acceptable accuracy for estimating the monthly runoff in the study area. So, in the recalibration phase, the r-factor and p-factor indices were 1.23 and 0.88, respectively, and the explanatory and Nash-Sutcliffe coefficients were 0.77 and 0.75, respectively. In the validation stage, the r-factor and p-factor indexes were 1.31 and 0.84, respectively and the explanatory and Nash-Sutcliffe coefficients were 0.72 and 0.73, respectively. In this study, the best combination resulting from the application of Taguchi method for the parameters of the number of simulations, the number of repetitions, the speed calculation weight and the appropriate parameters in the PSO algorithm were determined as 40, 100, 0.2 and 0.15 respectively (A4B4C4D3).
Conclusion
The results show that the SWAT model has an acceptable accuracy for estimating the monthly runoff in the Jawanmardi Watershed, and the PSO method is an effective algorithm in calibrating and determining the uncertainty of the model in this basin, and the use of the Taguchi test design method is a suitable way to determine the best combination of PSO algorithm parameters is for researchers who use this method to optimize the SWAT model.
Sima Rahimi Bondarabadi; Saeed Jahanbakhsh; Behrooz Sari Saraf
Abstract
Any change in the concentration of greenhouse gases will upset the balance between the components of the climate system. But, the change in the concentration of these gases and how they will affect in the future is unknown. To study the effects of climate change on different systems in the future, climate ...
Read More
Any change in the concentration of greenhouse gases will upset the balance between the components of the climate system. But, the change in the concentration of these gases and how they will affect in the future is unknown. To study the effects of climate change on different systems in the future, climate variables must first be simulated under changes in greenhouse gases (climate scenarios). There are several ways to do this, the most reliable of which is the use of climatic models. AOGCMs can simulate climate parameters globally in large scale, while these may not be suitable for small scales. One of the most important downscaling methods is dynamic methods that are based on increasing the resolution and analysis of planetary climate models. Here, in this research, climate change status in Karkheh River Basin where a major basin for water and agricultural yields is studied. For this purpose, the PRECIS model was used. PRECIS is an exponential dynamics downscaling model used to estimate the temperature and precipitation rates for the period of 2070 to 2100 under A2 and B2 scenarios. According to the results of climate change assessment under scenario A2, precipitation would increase up to 11% and up to five degree centigrade would rise in average maximum and minimum temperature while concerning B2 scenario, an increase in precipitation up to 7% and a rise in temperature rise up to three degree centigrade are estimated. However, under both the scenarios, despite, the fall’s precipitation is higher than the winter’s precipitation.
Mahmoudreza Tabatabaei; Amin Salehpour Jam; Jamal Mosaffaie
Abstract
The proper estimation of the amount of suspended sediment in rivers has an important role in erosion and sediment studies, hydrology and management of watersheds. The simulation of suspended sediment in hydrological systems that has a lot of complexity and at the same time our understanding of the components ...
Read More
The proper estimation of the amount of suspended sediment in rivers has an important role in erosion and sediment studies, hydrology and management of watersheds. The simulation of suspended sediment in hydrological systems that has a lot of complexity and at the same time our understanding of the components and processes within them is always uncertain led to the use of many intelligent models, including artificial neural networks (ANNs). However, the use of these smart models also faces challenges. Determining the proper structure of the network requires optimization of the parameters used (such as the optimal number of neurons and layers, weight and bias, and the type of activation functions), which their proper calibration, using test and error, leads to a lot of time spent in low efficiency. In this study, a multilayer perceptron (MLP) was used to simulate the daily sediment load of the Nirchai River at the site of the Nair hydrometric station in Ardebil province. In order to train the models, in addition to the error back propagation (BP) algorithm, Particle Swarm Optimization (PSO) algorithm was used to optimize the weight and bias of ANNs. The fuzzy clustering method was also used to increase the power of generalization of the models. The results showed that training of ANN models with PSO algorithm with decreasing estimation error (decreasing the PBIAS of estimation and root mean square error up to 0.3% and 10.4 tons per day respectively) is more effective than ANN models that use only error BP techniques. Due to insufficient recorded sediment data in most hydrometric stations of the country on the one hand and the need to train ANNs with sufficient data on the other hand, the use of evolutionary algorithms (e.g. PSO algorithm) can be a good solution for improving the efficiency of intelligent models.
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 ...
Read More
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.
Ali Mohammad Ghaeminia; Mohammadali Hakimzadeh Ardakani
Abstract
With regards to the wind erosion phenomenon importance, it is vital to quick identification of areas that are sensitive to dust removal and wind erosion processes. In this research, a lightweight and efficient device is designed, fabricated and evaluated in order to create conditions for applying constant ...
Read More
With regards to the wind erosion phenomenon importance, it is vital to quick identification of areas that are sensitive to dust removal and wind erosion processes. In this research, a lightweight and efficient device is designed, fabricated and evaluated in order to create conditions for applying constant wind stress on soil particle surfaces and measuring erosive particles. The production of wind power by a blower and measuring the amount of loose and unstable particles that were harvested in the reservoir with the highest efficiency were the principles of designing the device. The prototype of the device was designed using components and parts, and the device was evaluated in the field. The device is usable by a user in the field without the need for a power generator and the weight of the particles collected in the tank indicates the relative erodibility of the test site to the wind. Using the air filter bag (tank), it was possible to achieve a minimum loss of fine particulate matter and has been reduced the measure of less than the actual amount of land erosion. The result of the comparison of the sensitivity of soil sensitivity to erosion by the device in desert lands of northern Yazd-Ardakan Plain with the height of winding of the soil with the installation of the index showed that this device has good capability (R2= 0.57) in the rapid detection of areas susceptible to wind and without measuring physical and chemical properties of the soil, there is an early identification of wind erosion-sensitive land. This device does not actually simulate the natural processes of wind erosion created by the particle saltation, but using it, a new index can be obtained for assessing soil erodibility and subsequently identified the location of dust emissions.
Mehdi Ahmadi; Bagher Ghermezcheshmeh
Abstract
In the last decades, greenhouse gases in atmosphere have increased as a result of natural and human activities and thus, earth temperature has increased. Rising global temperature, in turn, leads to significant changes in related fields, especially water resources and agriculture. So, investigating and ...
Read More
In the last decades, greenhouse gases in atmosphere have increased as a result of natural and human activities and thus, earth temperature has increased. Rising global temperature, in turn, leads to significant changes in related fields, especially water resources and agriculture. So, investigating and modeling climate changes can be considered as a very important factor in water resources management planning. Different studies have been done in the field of climate change issues in the world, but, at the moment, AOGCM model is the most reliable tool to generate climate scenarios. It is necessary to downscale AOGCM data using different techniques in station scale and compare linear and nonlinear downscaling models. In liner method SDSM and in nonlinear method ANN programming were used in MATLAB. For investigating the amount of error, mean biomass monthly and annual and for extreme data, variance and for analyzing uncertainty Man-Witney test were used in 95 percent level. Results showed the amount of mean monthly errors are 0.75, 12, 11 and 7 mm in Ghaemshahr, Babolsar, Ghoran Talar and Bandpey in SDSM model and 3, 2, 26 and 4 mm in ANN model and the amount of mean annual errors are 9, 146, 141 and 87 mm in SDSM model and 45, 32, 321 and 48 mm in ANN model (increased or decreased), respectively. Examining the performance of variance showed that ANN model was somewhat better than SDSM model. Also, results of uncertainty for 12 months in Ghaemshar, Babolsar, Quran Talar and Bandpey stations showed 8, 3, 6 and 4 in SDSM model and 4, 2, 2 and 3 in ANN model, respectively. In general, this study showed that in studies on climate change effects on runoff, uncertainty, and when limited data are available, SDSM model should be used and when the aim is investigating the flood and its minimum and maximum estimation, it is better to use ANN model.
mehdy teimory; Asadollah Khoorani; Masoud Bakhtiarikia
Abstract
Runoff estimation is a fundamental activity in water resource management, and plays an important role in the best usage of a hydrologic system. Runoff estimation is usually based on different hydrological models. Calculation of intensity and duration of precipitation is not efficient in the most regions ...
Read More
Runoff estimation is a fundamental activity in water resource management, and plays an important role in the best usage of a hydrologic system. Runoff estimation is usually based on different hydrological models. Calculation of intensity and duration of precipitation is not efficient in the most regions of the globe for determining general properties of precipitation because these calculations are based on pointed data of ground observation, whereas precipitation is a spatial phenomenon. The aim of this paper is simulating monthly runoff of Kalam Basin based on satellite data of precipitation using SWAT model. In order to running SWAT, precipitation data of TRMM and GPCP, temperature, relative humidity, wind speed and solar radiation is used for the period of 1998 to 2012 for study area. Also, soil and land use maps and DEM are converted to the model format for study area. Period 2001 to 2009 is used for calibration and 2010 to 2012 for validation of the model. Nash Sutcliffe Efficiency Index and Weighting Coefficient was 0.41, 0.44, 0.32 and 0.37 for TRMM and GPCP respectively for calibration and 0.52, 0.71, 0.10 and 0.19 for validation. The results indicated that SWAT achieved a reasonable fit after calibration by using TRMM and not reasonable using GPCP data the model.
nasim arman; Ali Shahbazi; mohammad faraji; somaieh dehdari
Abstract
Water harvesting and surface runoff control systems are the important components of urban planning and development and ignoring these issues is likely to raise crisis. In order to decrease the urban flood damages, the urban runoff is needed to be evaluated correctly. Today some of models are developed ...
Read More
Water harvesting and surface runoff control systems are the important components of urban planning and development and ignoring these issues is likely to raise crisis. In order to decrease the urban flood damages, the urban runoff is needed to be evaluated correctly. Today some of models are developed for urban runoff simulation. One of the most important models in evaluating and management of urban runoff is SWMM. The aim of this study is to evaluate SWMM efficiency on urban runoff simulation in Izeh urban basin. To define design rain, concentration time was computed while considering the duration of the cloudburst as equal to this time. Also three performance indexes of Nash-Sutklif, errors sum of squares and Bias were used in order to model calibration and validation. Moreover, areas of high susceptibility were determined for two, five, 10, 20 and 50 years of return periods. Later, it was found that the principle reason of inundation is the lack of sufficient capacity of water ways. In some points, even with sufficient capacity, inundation occurs, confirmed by model. In these cases the causes stem from the improper design and construction of bridges which has lessen the size of water ways and caused junk clogging. Three rainfall events were recorded on March 13, 2017, March 28, 2017 and April 6, 2017 which were considered in order to calibrate and evaluate the model performance. Along with that, the discharge, depth and velocity of water at the outlet were considered as well. The results of the SWMM application gave indication of a good matchup between discharge, depth and the velocity of runoff for observed and estimated data. In this case, this model could be utilized to well predict the inundation hazard, design and the estimation of the cost and volume of drainage systems, management of watershed and prioritization of region to address flooding issues.
Ayyub Moradi; Ali Najafinejad; Majid Ownegh; Choghi Bairam Komaki
Abstract
Simulation of runoff and sediment in watersheds require different modelling approaches, each provided for certain condition. Semi-distributed hydrological model (SWAT model) is one of the most widely used modelling approaches in this context. Among the most important spatial information needed by SWAT ...
Read More
Simulation of runoff and sediment in watersheds require different modelling approaches, each provided for certain condition. Semi-distributed hydrological model (SWAT model) is one of the most widely used modelling approaches in this context. Among the most important spatial information needed by SWAT model, is the map of digital elevation model (DEM) which plays an important role in the model results for the exploration of hydrographic properties of watersheds, estimation of the spatial distribution of runoff and sediment load and its accuracy. The aim of this study was to evaluate the effect of different digital elevation models on runoff and suspended sediment in Galikesh watershed, Golestan Province. For this purpose, three types of DEM with the spatial resolutions of 30, 90 and 1000 meters were selected and for a period of 27 years, SWAT model was implemented. SWAT-CUP software and SUFI2 method were used for the model calibration and validation. Nash-Sutcliffe (NS) criterion for discharge and in calibration phase (1990-2007) for the resolutions of 30, 90 and 1,000 meters, was obtained respectively, 0.63, 0.63 and 0.62 and for suspended was obtained respectively 0.69, 0.68 and 0.67 which is considered satisfactory, given the presumed numerical ranges acquired from the previous studies. The amounts of watershed’s annual runoff for the resolutions of 30, 90 and 1000 meters, were respectively, 11.23, 11.30 and 11.39. The results that the use of different of digital elevation models would result in essentially similar results in runoff and sediment estimations, although changes in suspended sediment was slightly overestimated. This is attributable to the inverse modelling logic and lack of considering the parameters which arise directly from the DEM map. , due to data limitations in the Swat model calibration, the digital elevation model used to simulate the runoff did not have much impact on runoff and sediment estimations.
Behnoush Farrokhzadeh; Sepideh Choobeh; Hamid Nouri; Massoud Goodarzi
Abstract
In addition to climate change, the land use changes as an ancillary factor affects flooding. Thus evaluation of impacts of climate change and land use change (together) on flood situation in the coming decades will open a new way to deal with this phenomenon. In this research, to study the effects of ...
Read More
In addition to climate change, the land use changes as an ancillary factor affects flooding. Thus evaluation of impacts of climate change and land use change (together) on flood situation in the coming decades will open a new way to deal with this phenomenon. In this research, to study the effects of climate change on 2020s in Balighloo Chai Watershed, HadCM3 under A2 and B1 senarios was downscaled with LARS-WG. Results showed an increase between 8.78 to 12.86 percent in average of annual rainfall in 2020s. Average annual temperture increases 0.66 °C in 2020s. After examining past hanges in land use, two scenarios were developed to predict the impact of land use changes on the runoff in the coming decades: the first scenario assumes a constant in current land use and the second scenario assumes continuation of changes rate during past decades in the future. Results showed a decrease between nine percent in rangelands and five percent increase in agricultural lands area respectively in 2020s. In order to simulate the hydrologic system in the coming decades, HEC-HMS model was calibrated and validated using data of past period, and was used with new curve number, impersive area and hytograph estimated for the future decades. Then the coming decades predicted hydrographs were compared to the past ones. Results showed an increase in peak flow and flood volume in April while they will decrease in March, May and June. If land use change occures with climate change, this increase will be intensified.
Abolghasem Bagheri; Alireza Nikooie; Farhad Khodadad Kashi; Mohsen Shokatfadaei
Abstract
Although government’s supportive payments to agricultural activities is fulfilled for the purpose of increasing of social benefits, but it will cause some economic and environmental externalities. So that today the development of agricultural activities lead to decline in groundwater level in most ...
Read More
Although government’s supportive payments to agricultural activities is fulfilled for the purpose of increasing of social benefits, but it will cause some economic and environmental externalities. So that today the development of agricultural activities lead to decline in groundwater level in most of these aquifers. This topic has increased the interest of related governmental sectors in developing and application of water conserving policies in aquifers. The objective of this study was to analyze and evaluate the outcomes of energy subsidies decline as specified water conservation policy alternatives on groundwater consumption and cropping patterns on the aquifer of Mahyar plain in Isfahan province, using non-linear optimization model. A Positive Mathematical Programming (PMP) model was developed and calibrated to land and water usage data for a base period of 2004-2005. The PMP approach produces a constrained non-linear optimization model that mimics the land and water allocation decision facing producers each year. The choice variables in the model are the acreages planted to each of the major crops and the water use by crop. The result showed that water application per acre decreased significantly under the high price scenarios, during the early years of the simulated period. This suggests that high energy prices have a significant effect on the rate of increment of the Mahyar aquifer stability.
Ahmad Sharafati
Abstract
Rainfall runoff models are used mostly in simulation of flood events. Also, calibration of rainfall runoff model parameters is an important and challenging issue in flood simulation. Due to random characteristic of these parameters, the deterministic optimization is not a suitable approach for calibration ...
Read More
Rainfall runoff models are used mostly in simulation of flood events. Also, calibration of rainfall runoff model parameters is an important and challenging issue in flood simulation. Due to random characteristic of these parameters, the deterministic optimization is not a suitable approach for calibration of rainfall runoff model. So, in this study, the SUFI (Sequential Uncertainty Fitting) algorithm is used as a stochastic approach and the optimized range of parameters were extracted. The obtain results shown, in calibration step, the correlation coefficient between observed hydrographs (three events) and the best generated hydrographs were more than 0.9 and also, the average difference between observed hydrographs and the best generated hydrographs were less than 5 percent. Furthermore, in validation step, the correlation coefficient between observed hydrograph and the best generated hydrograph was 0.99 and also, the average difference between observed hydrograph and the best generated hydrograph was 11 percent. So, the SUFI algorithm is a suitable approach in stochastic calibration of HEC-1 model.
Arash Zare Garizi; Ali Talebi; Monireh Faramarzi
Abstract
In this study, SWAT model was used for simulating soil erosion and sediment transport in Gharesou Watershed, Golestan Province and for identifying and prioritizing critical areas of soil erosion. After model calibration, validation and uncertainty analysis using semi-automatic SUFI-2 method, the outputs ...
Read More
In this study, SWAT model was used for simulating soil erosion and sediment transport in Gharesou Watershed, Golestan Province and for identifying and prioritizing critical areas of soil erosion. After model calibration, validation and uncertainty analysis using semi-automatic SUFI-2 method, the outputs of the calibrated model were used for assessing spatial pattern of soil erosion and sediment. For this purpose, four indices including: load per unit area index, concentration index, load index and total index were defined and analyzed based on the model outputs. The results indicated that, despite lack and uncertainty of available data, SWAT model performance in simulating soil erosion and sediment transport in Gharesou watershed is quite acceptable. During calibration, the simulated monthly sediment loads matched the observed values with a Nash-Sutcliffe coefficient of 0.24 and PBIAS of -17%. The values for validation period were 0.2 and -12.1% respectively, indicating the model’s weakness in simulating sediment dynamics and its capability in predicting average sediment load. Assessing spatial pattern of erosion and sediment indices showed that, in general, critical sub-watersheds based on load per unit area index are located in upstream areas of watershed while sensitive sub-watersheds in terms of sediment concentration are situated in the middle part of the watershed, and sensitive sub-watersheds with respect to sediment load are in downstream. Suitable conservation practices were recommended for each zone based on their ecohydrological conditions. The outputs of this study can help experts and managers in planning of management practices for the watershed.
Ahmad Nohegar; Arash Malekian; Majid Hosseini; Arashk Holisaz; Edris Taghvaye Salimi
Abstract
Two factors of cost and time are related directly to the accurate estimate of runoff in the watersheds. More detailed information on the status of rainfall runoff also facilitate decisions on future programs for watershed managers, a step towards the preservation of natural resources for sustainable ...
Read More
Two factors of cost and time are related directly to the accurate estimate of runoff in the watersheds. More detailed information on the status of rainfall runoff also facilitate decisions on future programs for watershed managers, a step towards the preservation of natural resources for sustainable development. In this study, in order to achieve optimal amount of runoff in the Shafaroud watershed, first significant rainfall data of four stations during 1998 to 2011 were collected and combined with other maps of the study area, such as DEM, land use and soil as input data in the form of SWAT model was software. After running the model, the SUFI-2 and GLUE algorithms in SWAT-CUP program used to evaluate the data uncertainty and the most accurate simulation. The first three years (1998-2000) of rainfall data for warm-up and the next 7 years (2001-2007) for the calibration and final 4 years (2008-2011) were used for the validation. Finally, with multiple simulations, the uncertainty of the parameters assessed with P-factor, R-factor, and NS coefficients. The results indicated in runoff simulation, the SUFI2 algorithm ( =0.85, NS=0.74) is more accurate than GLUE algorithm ( =0.82, NS=0.71).
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 ...
Read More
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.
Seyed Aliasghar Hashemi; Sargis Ghazariyan
Abstract
In this research, two small sub-basins were selected in Darjazin Watershed of Semnan to evaluate the effect of ruck check dams on peak and volume of flood in small watersheds. Two watersheds were chosen as study area in a part of southern Alborz Mountain with arid and semi-arid climate. These watersheds ...
Read More
In this research, two small sub-basins were selected in Darjazin Watershed of Semnan to evaluate the effect of ruck check dams on peak and volume of flood in small watersheds. Two watersheds were chosen as study area in a part of southern Alborz Mountain with arid and semi-arid climate. These watersheds are located in upland of Mahdishahr city and many check dams are constructed for flood control in past few years. All check dams were examined during field operation and their sedimentation were assessed. Results showed that all check dam reservoirs were filled by sediment. In this research, the peak and volume of floods were assessed in three scenarios of 1) watersheds with no check dams 2) watersheds with empty of sediment check dam reservoirs and 3) watersheds with full of sediment check dam reservoirs. HEC-HMS model was used for rainfall-runoff simulation. . Mean comparison test by paired method for all three scenarios showed that flood peak and volume have significant difference at α=1% level. But, flood peak and volume in scenario 2 are computed less than that of scenario 1 and in scenario 3 are computed more than that of scenario 2. On the other hand, flood peak and volume in the scenario 3 slightly decreased by 4.8 and 5.7 percent respectively compared to scenario 1 where is not significant based on the objectives of project.
Bagher Ghermezcheshmeh; Aliakbar Rasuli; Majid Rezaei Banafsheh; Alireza Massah Bovani; Alimohammad Khorshiddust
Abstract
Increasing Green House Gases (GHG) may change the climate in different areas. Investigation of parameters are difficult due to induced changes in climate parameters, such as precipitation and temperature. For predicting global climate change, different climate scenarios are defined, using AOGCM models. ...
Read More
Increasing Green House Gases (GHG) may change the climate in different areas. Investigation of parameters are difficult due to induced changes in climate parameters, such as precipitation and temperature. For predicting global climate change, different climate scenarios are defined, using AOGCM models. AOGCMs are able to simulate global atmospheric circulation patterns. However, the spatial resolutions of such models are coarse; for example HadCM3 has spatial resolutions of 3.75 and 2.5 in longitude and latitude, respectively. Therefore, to study climate change in a given area, the outputs of the used AOGCMs must be downscaled properly. For this reason, statistical and dynamical methods have been developed. Statistical methods establish a relationship between AOGCM outputs and climate parameters such as precipitation and temperature. For example, many statistical methods use multiple regressions to predict future climate parameters. However, the accuracy of downscaling procedure varies depending on the geographical position of the studied station in relative to the nearby AOGCM grids. In this research, the accuracy of SDSM was tested in different synoptic stations of northwest Iran. This area has a complex topography and climate due to intrusion of different rain bearing weather systems to the region. First of all, daily climate data (precipitation, maximum and minimum temperature) were collected and their time series created. HadCM3 data for the girds over the studied area was obtained and SDSM model was applied for each climate parameters of all synoptic stations in the region. Then, the difference between the SDSM outputs and observed parameters were evaluated for all the stations and the performance of the downscaled outputs were evaluated by comparing the mean and variance of the model outputs and those of the NCEP/NCAR for the present climate. The morpho-climatic parameters were derived for each station and their relations with the magnitude of the model error were evaluated. Results showed that the error in precipitation has significant relation with the distance to the grid center, whereas the error in maximum temperature is related to the difference between the elevation of a given station and the mean elevation of the HadCM3 grids. For example, in Urmia station, the error is the highest of 104 mm while in Saqez the error is the lowest of 9.4 mm. Also, the maximum temperature accuracy in stations with elevation near to mean elevation of the grid is higher. Pars Abad station with 32 m elevation and with high elevation difference with the grid mean elevation, showed 1.14 ºC of error and Tabriz station with less elevation difference to grid mean elevation, showed 0.0.08 ºC of error.
Majid Mahmoodabadi; Elham Sirjani
Abstract
Soil erosion is a dynamic process with high variability in sediment size distribution. Dynamic recognition of sediment size distribution is as a base for modeling of soil erodibility and movement of nutrients, pollutants and fine particles in consequence of erosion. This study focused on sediment transport ...
Read More
Soil erosion is a dynamic process with high variability in sediment size distribution. Dynamic recognition of sediment size distribution is as a base for modeling of soil erodibility and movement of nutrients, pollutants and fine particles in consequence of erosion. This study focused on sediment transport mechanisms due to sheet erosion on two different soils (cropland and sandy) using flume experiment. The experiment was performed applying different flume slopes (1.5 and 2 %) and flow rates (75, 100, 125, 150, 175 and 200 ml/s). The result showed that hydraulic condition as well as soil type, played an important role in selective transport of sediment particles so that, in the sediment size distribution of cropland soil two peaks were observed. For the first (fine particles with size of 0.042 mm), the dominant transport mechanism was attributed to suspension- saltation, while for the second peak (large particles with diameter of 1.5 mm), bed load was known as the main transport mechanism. Moreover, increasing stream power, the selectivity of fine particles declined therefore, both fine and large particles were transported by the flow. For sandy soil, only one peak for the range of 0.109 to 0.175 mm was observed. In this soil, saltation was the main mechanism in transporting sediment. Increasing flow rate, the frequency of particles smaller than 0.015 diminished, whereas particles larger than 0.218 mm increased. For both soils at higher stream powers, the relative importance of transport as suspension and bed load decreased and increased, respectively. The findings of this research reveal that sediment size distribution and also transport mechanisms depend on hydraulic condition such as slope and flow rate.
Seyed Ahmad Hosseini; Nasrolah Javaheri; Mehdi Habibi
Abstract
This study investigated the status of sediment transport and deposition in Khar-rud River, Qazvin province, Iran. The aim was to determine the possibility of construction of sand and gravel mining workshops in the margin of Khar-rud Flood-plain. Here with calculating sediment transport rate and specifying ...
Read More
This study investigated the status of sediment transport and deposition in Khar-rud River, Qazvin province, Iran. The aim was to determine the possibility of construction of sand and gravel mining workshops in the margin of Khar-rud Flood-plain. Here with calculating sediment transport rate and specifying the distribution of sediment deposits in various parts of the river, an applied program for sand harvesting from the river bed, is developed. In this project, after preparing the basic information, such as information about river geometrical shape, roughness coefficients of different sections, information related to size gradation of suspended sediments and bed material, river hydrology data and boundary conditions of downstream hydraulic system, using HEC-RAS model, sediment loads and its distribution along the river was simulated. Simulation was done based on classified data from daily flow discharges during a 37-year period. After calibrating the HEC-RAS model and selecting Yang sediment transport equation as the closest relationship to the sedimentary data measured by regional Hydrometric stations, the average volume of sediment yield from the river was estimated 1.75 million tons per year. Finally, considering the changes in the river bed elevation for each cross-section, the amount of sediment passing during simulated 37-year was calculated. Using the results of the model and sedimentation changes along the study reaches, the volume of sediment transport in each river cross section, the river width and its private region and considering the maximum permissible depth of bed-material removal equal to 1 m, the most suitable mining length and period in the different reaches of river was determined, discussed and showed in ARC-GIS environment. Based on simulation results, the average depth of sand which can be taken safely from the river-bed was estimated to be 40cm and the most suitable period of time for sand mining along the river was recommended from January to May. It was determined that HEC_RAS hydraulic model, covers about %63 of initial engineering judgments for the amount and location of sand mining.
Ataollah Kademorasoul; Mostafa Chorom
Volume 1, Issue 1 , May 2009, , Pages 1-8
Abstract
Water resources management is one of the most important environment challenges in watersheds. Loosing of soil caused by water erosion is one of dominant geographic processes over the most lands of the world. Nowadays, the feasibility of using mathematics models and advancement software technology has ...
Read More
Water resources management is one of the most important environment challenges in watersheds. Loosing of soil caused by water erosion is one of dominant geographic processes over the most lands of the world. Nowadays, the feasibility of using mathematics models and advancement software technology has made available the quick recognition of erosion and sedimentation processes. In this study, the model of WEPP (version 2006) was provided for simulation and forecast of erosion and sedimentation in the study watershed. The WEEP model is a deterministic model with distributed parameters. In this research, watershed of Imamzadeh Abdollah of Baghmalek which lies in north-east of Khuzestan province is studied. Creation of a climate file is made available as an input file using the model of CLIGN and software of BPCDG as well as preparation of soil, basin management file using Excel and EPIC models. All the parcels of basin were defined for the model and executed using the aerial photos, drainage map, hypsometric map and software of Arc View (version, 3.3). Outputs of the model in the erosion section indicated average soil erosion which was some 22.54 tonha-1. Also, the sediment load was about 3468.2 tons, which indicated a difference of 9 percent in comparison with measured rates. Meanwhile, outputs of the model have well provided the feasibility of distinguishing sensitive hillsides to erosion. Based on outputs and ruling management on the hillsides, the protective recommendations like the proper ways for planting and gabion covering, building traces or groins in course of taking the best management practices were accomplished.
