Ariyan Matboo; Vahedberdi Sheikh; Ali Mohammadian Behbahani; Arash Zare Garizi
Abstract
Introduction
The hills surrounding the international wetlands of Almagol and Ajigol in the Golestan Province are exposed to severe erosion and every year a large amount of sediments from these hillslopes discharge into these wetlands. Whilst a large extent of these surrounding hills, covered with Biological ...
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Introduction
The hills surrounding the international wetlands of Almagol and Ajigol in the Golestan Province are exposed to severe erosion and every year a large amount of sediments from these hillslopes discharge into these wetlands. Whilst a large extent of these surrounding hills, covered with Biological Soil Crusts (BSC), has been destroyed due to lack of awareness of their values, sensitivity and ecological functions. Improving soil properties, preventing direct contact of raindrops with the soil surface, all indicate the important role of BSC in hydrological processes and soil loss control.
Materials and methods
In this study, the role of BSC in the hydrological processes of dry areas was investigated using a rain simulator. After a field survey and evaluation of the area, different treatments including biological crust with a dominant lichen cover, biological crust with a dominant moss cover, an area covered with vascular plants, an area without cover and areas covered with a combination of moss and lichen were selected to perform rain simulation and compare their effects on the hydrological processes of the selected region. Rain simulation was done in 2×1 meter plots for 30 minutes and intensity of 82 mm per hour. The start time of runoff and the volume of produced runoff at the outlet of the plot were measured and recorded. Also, at five-minute intervals from the beginning of the simulation process, 500 ml runoff samples were collected and transferred to the laboratory for testing in order to estimate the sediment concentration and mass. In addition, the depth of the wetting front caused by the infiltration of rain was measured at the beginning, middle and end sections of the plots.
Results and discussion
The results of rainfall-runoff simulations at a 2×1 m2 plot scale with a rainfall intensity of 82 mm.h-1 and a duration of 30 minutes plots, showed that the average mass of sediments from plots with the dominant cover of moss (104 g), lichen (91 g), lichen-moss combination (176 g) and bush (99 g) was significantly higher than bare soil (1133 grams). Therefore, in case of destruction of the existing BSC and the formation of bare lands, the sedimentation rate will increase by more than 5 times. A significant decrease in water infiltration into BSC causes a significant increase of 30-40% in runoff generation compared to the treatment covered with bushes and a significant increase of 8-18% compared to the bare soil treatment.
Conclusions
by reducing soil loss and sediment concentration, BSC cause the production and transfer of high-quality runoff to the wetlands and as a result maintain the ecological function and health of the region’s wetlands. The results of this research show the positive influence of BSC on the hydrological and ecological performance of arid areas in the north of Gorgan Plain and protection of Ramsar-listed wetlands in the region.
Hamed Harriri; seyed abbas hosseini; Amir Khosrojerdi
Abstract
Introduction
Predicting changes due to climate change and its possible consequences on hydrological processes of the watershed helps to solve the challenges facing managers and water resources planners in the coming period. The effects of this phenomenon and gabion check dams simultaneously on the sedimentation ...
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Introduction
Predicting changes due to climate change and its possible consequences on hydrological processes of the watershed helps to solve the challenges facing managers and water resources planners in the coming period. The effects of this phenomenon and gabion check dams simultaneously on the sedimentation of Dehbar Basin have not been studied so far, so the aim of this study is to investigate this with the perspective of the next 30 years, using SWAT and LARS-WG models and the ability of these two models to simulate climate change and remove gabion check dams.
Materials and methods
In this research, the performance of gabion dams as a reservoir in the Dehbar Basin, 10 km west of Mashhad and south of the city of Torghabeh, which has a cold semi-arid climate, is compared to the amount of sediment output from the basin for the next 30 years with the LARS-WG statistical model and SWAT hydrological simulation model has been evaluated. There are five gabion dams in this area. To predict the meteorological variables of the upcoming period at the level of Dehbar Watershed, after recalibrating the LARS-WG model, the HadGEM2 model and three scenarios of RCP8.5, RCP4.5 and RCP2.6 were used for the microscaling of meteorological data in the period of 2050- 2020. Kolmogorov Smirnov (K-S), t and F statistical tests were used to check the performance of the simulation results in this model. To prepare and implement the SWAT model, the map and digital model information of elevation, soil, land use, hydrological and meteorological data were used. The tank was used to introduce gabion dams to the model. In order to analyze the sensitivity, calibration and validation of the SWAT model, SUFI-2 semi-automatic algorithm was used.
Results and discussion
The average values of the simulated precipitation are in good conformity with the observed values and the biggest difference is related to the months of February and April. Regarding the standard deviation values of monthly rainfall, the biggest difference belongs to the months of February and March. The average simulated minimum temperature is also in very good agreement with the observed values. Also, for the maximum temperature, a trend similar to the minimum temperature is seen. Also, the p-value obtained from the t-test for the aforementioned variables, there is no significant difference between the average temperature and precipitation data produced and the observed data, and the LARS-WG model has been able to calculate the average temperature and precipitation very well. To simulate monthly precipitation in all scenarios (RCP8.5, RCP4.5 and RCP2.6) in the horizon of 2050 in the first seven months of the year is lower than the monthly precipitation in the base period, but an increase in precipitation is observed for the second five months of the year. Also, in the horizon of 2050, the temperature will increase on average compared to the base period. To draw the curve of the sediment gauge, the method of batch average with modified FAO coefficient was used. The amount of observed sediment was calculated as 2.14 tha-1yr-1. For the calibration and validation of the SWAT model, at first, using CUP_SWAT software, the parameters that had a greater effect on the discharge and sediment output from the basin were identified. In order to analyze the sensitivity, calibration and validation of SWAT model, SUFI-2 semi-automated algorithm was used. After that, the effects of climate change on the amount of runoff and sediment in the basin were investigated using the validated SWAT model. The results show a decrease in rainfall, an increase in temperature and a decrease in runoff in the horizon of 2050. The precipitation changes for RCP4.5 and RCP2.6 scenarios are +9.3% and +3.1%, respectively, and -4.6% for RCP8.5 scenario. On average, gabion dams reduce 57.09% of sediment exit from the basin.
Conclusion
In this research, the effects of climate change on the sediment output from Dehbar Basin in the period from 2020 to 2050 and the effect of gabion dams in the existing conditions (presence of dams) and in the conditions of removal of these dams were investigated. In all scenarios, the minimum and maximum temperature increased in the 2020-2050 period compared to the base period. One of the negative effects of temperature increase is change in the amount and time-spatial pattern of precipitation. The results indicate that the SWAT model is capable of simulating hydrological processes and sedimentation in relatively small to medium watersheds with complex conditions such as Dehbar Basin, even with limited observational data, with acceptable accuracy. The increase in the amount of sediment at the outlet point of the watershed, despite the decrease in rainfall and runoff, indicates short-term rainfall with high intensity, which increases the occurrence of flooding conditions. From the changes in the amount of erosion and sedimentation in the horizon of 2050 and with different scenarios, it can be concluded that the climate change will affect the erosion of the basin in the future and the simulation model can be effective in predicting the erodibility. Therefore, the results obtained from the SWAT model provide the possibility of recommending its use in the region.
Mehdi Vafakhah; Mostafa Zabihi Silabi; Sedigheh Modarresi Tabatabaei; Hossein Sarvi Sadrabad; Arezoo Shafiei Bafti; Negin Ghaderi Dehkordi; Mohammadreza Riahi; Seid Saeid Ghiasi
Abstract
Extended abstractIntroductionInvestigating the climatic condition over watersheds has a decisive role in water resource management planning. Meanwhile, changes in temperature and precipitation have a great effect on the discharge of rivers, soil erosion, and fluctuations in the level of ground water, ...
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Extended abstractIntroductionInvestigating the climatic condition over watersheds has a decisive role in water resource management planning. Meanwhile, changes in temperature and precipitation have a great effect on the discharge of rivers, soil erosion, and fluctuations in the level of ground water, and the occurrence of floods. It is very necessary to carry out research related to climate change in order to prepare as much as possible to deal with the harmful costs caused by this change. The review of the studies conducted in Iran also shows that the scale of the study is in most cases at the local level and the study of the mean annual discharge trend and its magnitude has not been studied especially over Iran country. Therefore, the current research was planned with the aim of determining the mean annual discharge trend and magnitude over Iran. Materials and methodsIn the present study, the trend of mean annual discharge in Iran was determined by considering the effect of dams using Mann-Kendall and Sen’s slope methods. First, the statistics of all the hydrometric stations located in the Iran six major drainage watersheds were obtained from Iran Water Resources Management Company. Finally, 139 hydrometric stations with a statistical period of 17 to 65 years were selected in this study. The statistics of these stations were compared with the data available in nearby stations and suspicious values were also controlled. The homogeneity of the data and reconstructing the missing data was carried out using the run test and linear regression through the station with the highest correlation coefficient for each station with incomplete station, respectively. In the next step, non-parametric Mann-Kendall and Sen’s slope estimator tests were carried out within XLSTAT software in order to evaluate the trend and its magnitude analyses. After determining the trend of the study hydrometric stations, the spatial distribution map of the mean annual discharge trend in Iran six major drainage watersheds were prepared within Arc/GIS 10.2 software. Results and discussionThe results showed that 14 hydrometric stations were affected by the dam. However, in the hydrometric stations without dam, 84, six and 35 hydrometric stations have a decreasing trend (60%), an increasing trend (5%), and no trend at the 95% confidence level, respectively. Examining the trend of the time series of mean annual discharge in each of Iran six major drainage watersheds also showed that 80% of the study stations in the Persian Gulf and Oman Sea watershed have a decreasing trend, while no trend were detected in 20%, 10% and 9% of the total study stations in the Caspian Sea, the Central Plateau, and the Persian Gulf and Oman Sea watersheds, respectively as well as all the stations of the eastern watershed (Hammon). In the meantime, all study hydrometric stations in Urmia Lake and Sarakhs watersheds and 68% of the study hydrometric stations in the Caspian Sea watershed have a decreasing trend. ConclusionThe results obtained from this research showed that the decreasing trend was detected in most of the hydrometric stations (84 hydrometric stations). Therefore, the decreasing trend of hydrometric stations in Iran can be related to the decrease in rainfall, increase in temperature and the emergence of excruciating droughts caused by climate changes and also human interference, including the excessive increase in the construction of dams and the change of unprincipled land use. However, one of the limitations of the current research is not taking into account climate changes and land use changes and determining the contribution of each of the mentioned factors in the decreasing and increasing trend of the mentioned stations. The results of the present research can be very useful and important for water planners and politicians in order to manage water resources.
Jalal Heidari; Alireza Vaezi; Mohammad amir Delavar
Abstract
The variety of factors affecting soil properties leads to temporal changes in the soil erosion process. This research was conducted to assess short-term changes in runoff and soil loss in rainfed wheat furrows under fallow conditions. To this end, three rainfed lands with 15% slope gradient were selected ...
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The variety of factors affecting soil properties leads to temporal changes in the soil erosion process. This research was conducted to assess short-term changes in runoff and soil loss in rainfed wheat furrows under fallow conditions. To this end, three rainfed lands with 15% slope gradient were selected in south west of Kermanshah Province. In each land, furrows with five m in length and 30 cm in width were created using sowing set. Runoff and soil loss were measured using simulated flows with a discharge of 0.5, 1, 1.5 and 2 L.min-1 at intervals of five minutes to 60 minutes 60 minutes in three replications. Results showed that the lowest soil loss was recorded in flow discharge of 0.5 L.min-1 (2.66 g.m-2) and the highest of soil loss was produced in flow discharge of 2 5 L.min-1 (85.33 g.m-2). Also, the lowest runoff was recorded in flow discharge of 0.5 L.min-1 (0.47 L) and the highest of soil loss was produced in flow discharge of 2 5 L.min-1 (7.65 L). The effect of time on runoff and sediment variables was significant in all flow discharge (p<0.01). Runoff production was low at the beginning of the experiment and increased over time. The pattern of temporal changes in soil loss was different from runoff production, amount of soil loss at the beginning of the experiment was higher values than the final test times, which associated with to supply of erodible soil particles in the rills in the beginning of the experiment. With starting the experiment to 25 minutes, the rate of soil loss changes drastically and then until the end of the experiment, it followed a uniform reduction pattern and in the final stages, it is almost constant. The results showed that rill erosion is strongly influenced by flow intensity and its value changes over time and these changes are independent of flow production and depended on the transmittance of soil particles transferable in the rill.
Sakineh Damadi; Abdolhamid Dehvari; Mohammad reza Dahmardeh ghaleno; Mahboobeh Ebrahimiyan
Abstract
Every year, floods destroy the economic and social structure of communities and cause a lot of financial and human losses. One of the effective factors in the occurrence of floods is the development of urbanization around rivers. Due to climate change, in recent decades, Sistan and Baluchestan Province ...
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Every year, floods destroy the economic and social structure of communities and cause a lot of financial and human losses. One of the effective factors in the occurrence of floods is the development of urbanization around rivers. Due to climate change, in recent decades, Sistan and Baluchestan Province with hot and dry climate, is prone to floods. The aim of the present study is to zoning the flood of Sarbaz Watershed using HEC-RAS hydraulic model. To conduct the research, the SCS model of the area was first determined according to satellite images, land use map and runoff curve number. Then, the flood discharge of the basin with 10, 25, 50 and 100 years return periods was simulated using the HEC-HMS hydrological model. The simulation results resulted in the occurrence of peak flood discharges of 3363.8, 4563.7, 54462 and 6359.3 m3s-1 for return periods of 10, 25, 50 and 100 years in the study basin, respectively. In order to evaluate the efficiency of the model in calibration and validation stage, Nash-Sutcliffe evaluation indices and the mean square error were used, the results of which indicate the optimal performance of the model. Then, the flood zoning map of Sarbaz Watershed in Rusk City was prepared in desired return period with the help of HEC-RAS hydraulic model. The results showed that with the return periods of 10, 25, 50 and 100 years, 366.86, 397.12, 449.95 and 580.78 hectares of flood zone of Sarbaz Watershed in Rask City area will increase, respectively.
maryam zare; Ommolbanin bazrafshan; Mojtaba Pakparvar; gholamreza Ghahari
Abstract
Limitations of physical and experimental methods for estimating the evapotranspiration have been rationalized the employment of remote sensing technology to solve the energy balance equation in recent years. In this study, in order to investigate the evapotranspiration factor in the application of the ...
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Limitations of physical and experimental methods for estimating the evapotranspiration have been rationalized the employment of remote sensing technology to solve the energy balance equation in recent years. In this study, in order to investigate the evapotranspiration factor in the application of the HEC-HMS model and to optimize the flood estimation, using Landsat 8 Satellite Images (nine images) and the meteorological data related to the Kelestan Station and the SEBS Evapotranspiration Model for the period 2015-2017, ET values were calculated in the region of Kelestan Located in the Northwest of Shiraz, and the results were compared to the FAO Penman-Monteith equation to verify the accuracy of this model in the region of Kolding with water body. Evaporation in HEC-HMS including the direct evaporation of water, evaporation from soil surface, and transpiration of plants was estimated as an average elevation. In this study, we attempted to replace the actual evapotranspiration in the HEC-HMS model, The amount of runoff from the precipitation is calculated more accurately. The results showed that after scrutinizing the ET input, the simulated flood correlation with the measured flood was increased with R2 from 92 to 99%, and RMSE from 0.14 to 0.01, respectively. The results also indicated that the use of Landsat 8 Satellite Images and SEBS model is a suitable tool for estimating actual evapotranspiration in mountainous and field areas in hydrological studies. This research is for the performance of SEBS in determining the spatial and temporal distribution of evapotranspiration in a mountainous and hydrological area. Because the calculation of ET in hydrological models can improve the results and increase the accuracy of these models.
Ramin Salmasi; Mohsen Farahbakhsh; Hossein Asadi
Abstract
High soil phosphorus (P) can increase the amount of runoff P and cause pollution of P in water bodies. In this paper, to select the best method between laboratory extracting and rainfall simulator method for determining environmental threshold level of P concentration was compared. For this purpose, ...
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High soil phosphorus (P) can increase the amount of runoff P and cause pollution of P in water bodies. In this paper, to select the best method between laboratory extracting and rainfall simulator method for determining environmental threshold level of P concentration was compared. For this purpose, surface soil was sampledfrom 30 points of Talkherood Watershed inEastern Azerbayjan with widely available P contents. After determining some of general properties, four soil P tests comprising Olsen, Mehlich-3, Iron oxide, and Soltanpour were used. Water soluble P in lab was measured and runoff soluble P of soils was determined with using rainfall simulator by applying 75 mm h-1 rainfallfor 30 minutes. Relationship between P concentrations determined by four methods with a) water soluble soil P, as P loss index, and b) runoff soluble P, showed that environmental soil P concentration can be estimated by both lab extracts and rainfall simulation methods for lime soils of this region. As the lab extracts method are easier and less time-consuming, this method is recommended for threshold concentration estimation. Since in iron oxide method, slope difference between the two split-lines was greater than other methods and high correlation coefficients were obtained for all of the methods, as a result iron oxide method is better than others for threshold concentration estimation of available P concentration. Since changing point for dissolved reactive P was seen in 0.36 mg l-1 concentration, as a result this concentration is lower than environmental P concentration for eutrophication phenomenon.
Negin Ghaderi; Karim Soleimani; Ataollah Kavian; Mostafa Rashidpoor
Abstract
Urban watersheds due to their development, have more complex hydrological behavior than natural watersheds, and understanding their hydrological response will help to design appropriate flood control facilities. In this study, SWMM model was used to investigate the potential of urban runoff production ...
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Urban watersheds due to their development, have more complex hydrological behavior than natural watersheds, and understanding their hydrological response will help to design appropriate flood control facilities. In this study, SWMM model was used to investigate the potential of urban runoff production in a part of Babolsar urban area. The purpose of this study was to analyze the water availability of rainwater collected during different return periods for urban use. For this purpose, the SWMM model defined 65.65 ha of study area in the form of six hydrological units (from 5.94 to 16.82 ha), six output nodes and four channels were defined, and the height of runoff from 24-hour rainfall was obtained with different return periods. According to these results, the 24-hour rainfall with a 25-year return period is 70.37 mm, of which 33.73 mm for infiltration and 35.60 mm for runoff. Results showed that about 52.1% of rainfall of Babolsar City plan could have the ability to become runoff. The highest runoff coefficient is in the hydrological unit S3, which has a value of 0.637 at the 100 year return period. However, the lowest runoff coefficient is in hydrological unit S1 which has a value of 0.352 at 2-year return period. The results also showed that the runoff coefficient is directly related to the return period and the larger rainfall has a higher runoff coefficient. Through the collection systems, in addition to reducing the flood hazards of Babolsar City, a water supplement that offsets part of household consumption in the non-urban sector, also water resources management can be done.
asrin hosseini; mohammad reza golabi; safar marofi; nasim khalediyan; mohammad solatani
Abstract
Simulation of the rainfall-runoff process is the most important step in water engineering and water resource management studies. Exploitation of surface water and underground water resources, river management and flood warning requires prediction of river and runoff discharges of the watershed. In this ...
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Simulation of the rainfall-runoff process is the most important step in water engineering and water resource management studies. Exploitation of surface water and underground water resources, river management and flood warning requires prediction of river and runoff discharges of the watershed. In this study, Extended Kalman Filter-based Neural Network (EKFNN) method was used for rainfall-runoff modelling. Then, the results were compared with the Gene Expression Planning method, which showed good performance in rainfall-runoff modelling in most recent studies. The data used in this study is related to daily runoff and rainfall of the rain gauge and hydrometric stations of Malayer plain which includes Peyhan, Marvil and Namyleh stations, during the period of 2001 to 2013. The results indicated that the EKFNN model was superior to GEP model in daily river flow modelling in Malayer plain. In addition, the speed of implementation of the Gene Expression Planning model was greater and was able to present results in a short time. Finally, EKFNN model was selected as the superior model for Malayer plain.
Mozhdeh Mohamadi; Jafar Mamizadeh; Eghbal Ehsanzadeh
Abstract
Surface water collection networks are responsible for collecting, transporting and directing runoff to the nearest acceptable outlet. In this research, simulation and evaluation of Ilam City runoff system with the ASSA mathematical model developed by the Autodesk Inc. was carried out. In the present ...
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Surface water collection networks are responsible for collecting, transporting and directing runoff to the nearest acceptable outlet. In this research, simulation and evaluation of Ilam City runoff system with the ASSA mathematical model developed by the Autodesk Inc. was carried out. In the present research, the entire study area, which includes in-city and outsides, was divided into 46 sub-basins. The physical properties of each sub-basin were determined using the ArcGIS software and field investigation. Within the Ilam City there are four main channels that lead the runoff of sub-basins out of the city. The runoff from sub-basins was calculated using three methods of rational, modified rational and SWMM. The results of the study showed that the collecting system only had a flood transfer ability during the two year return period and during the return periods greater than five years the major part of the main channels in the city were waterlogged and damaged.
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 ...
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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.
Parviz Abdinejad; Mohammad Roghani
Abstract
The present research was carried out at a research station in Qarehchryan, located in north-west of Zanjan City, Iran. Rainwater catchment systems had dimensions of 5×8 m, with five treatments of control (withness)(A), without vegetation and gravel with gravelly filter (B),without gravelly filter ...
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The present research was carried out at a research station in Qarehchryan, located in north-west of Zanjan City, Iran. Rainwater catchment systems had dimensions of 5×8 m, with five treatments of control (withness)(A), without vegetation and gravel with gravelly filter (B),without gravelly filter (C), impervious a part of the system with gravelly filter (D) and without gravelly filter (E) in a randomized complete block design with three replications. There were nine daily rainfall events from April until late August 2013, with two times irrigation with an interval of 60 days, 45 liter for every seedling and 33 times of measurement of moisture at depths of 20 and 50 cm. Results showed that spring rainfall had not been able to produce runoff in the control treatments and had no effect on soil moisture. Soil moisture influence has been increased by daily rainfall in both B and C treatments compared to control treatments.. Soil moisture influence from daily precipitation has been increased up to 30 percent in D and E treatments due to insulating surface of existing systems and impervious surface of rainwater catchments. Timeline of the average moisture at the depths of 20 and 50 cm is almost similar in all treatments. This situation indicates that the distribution of moisture in depth of 20 to 50 cm is similar with no significant difference, but, the moisture at the depth of 20 cm is more than 50 cm.
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.
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 ...
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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.
Payam Ebrahimi; Jamileh Salimi Kochi; Mohsen Mohseni Saravi
Abstract
SWAT is a continuous, physically based and distributed hydrologic model which all several hydrological processes like discharge, sediment yield nitrogen are simulated for each one of it. The purpose of this study is to test the efficiency of the Soil and Water Assessment Test (SWAT) and its applicability ...
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SWAT is a continuous, physically based and distributed hydrologic model which all several hydrological processes like discharge, sediment yield nitrogen are simulated for each one of it. The purpose of this study is to test the efficiency of the Soil and Water Assessment Test (SWAT) and its applicability as a flow simulator, and using SWAT-Cup software and the SUFI2 algorithm as a means to calibrate and validate Neka Watershed in Mazandaran Province. Four indices were used to assess the goodness of calibration, viz., P-factor, R-factor, R2 and Nash-Sutcliffe (NS). Runoff data (1995-2004) of four hydrometery stations were used for calibration and (2005-2009) for validation of this watershed. The results of these values for flows at four stations for calibration process in Ablo, Pain zarandin, Karkhane siman and Sefid chah were 0.85, 0.78, 0.78, 0.89 for P-factor; 2.55, 2.03, 1.71, 2.43 for R-factor; 0.76, 0.62, 0.69, 0.71 for Nash-Sutcliffe and 0.71, 0.82, 0.76, 0.63 for R2. The results of validation were 0.87, 0.88, 0.72, 0.72 for P-factor; 3.61, 2.24, 3.56, 1.78 for R-factor; 0.74, 0.66, 0.58, 0.64 for Nash-Sutcliffe (NS) and 0.81, 0.68, 0.73, 0.61 for R2 respectively. In general, the results showed that SWAT could be a proper tool for simulating the flow rate values of the Neka Watershed.
Farzad Bayat Movahhed; Saeed Najafi; Mohammad Roghani
Abstract
Knowledge about optimizing use of rain water under different systems for overcoming water stresses, maximization of crop yield and how their effects is very important. So in this research effect of Rain Water Catchment (RWC) systems under five treatments viz. control (A), eliminated of vegetation and ...
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Knowledge about optimizing use of rain water under different systems for overcoming water stresses, maximization of crop yield and how their effects is very important. So in this research effect of Rain Water Catchment (RWC) systems under five treatments viz. control (A), eliminated of vegetation and pebble with a gravel filter (B), eliminated of vegetation and pebble without any gravel filter (C), insulated some portion by plastic with gravel filter (D) and insulated some portion by plastic without any gravel filter (E) on activity of photosynthetic parameters have been assessed. The research was conducted in a randomized complete block design with 3 replications for each treatment. RWCs were designed in 8, 5, and 0.5 meters for the length, width and depth respectively, as well as with 9 % downward slope. To facilitate runoff infiltration in root region; a gravel filter was created that was 10 cm diameter and 30 cm depth respectively, in all treatment. Four photosynthetic factor viz. Photosynthetic rate per unit leaf area, stomatal conductance, transpiration rate and substomatal CO2 adsorption were measured after 10 and 23 days after one rainfall event in 2011. Results showed there are significant differences between measured factors except substomatal CO2 adsorption under different treatments. Totally results of this research showed that two Rain Water Catchment systems including insulated some portion by plastic without any gravel filter (E) and eliminated of vegetation and pebble without any gravel filter (C) had maximum positive effect on activity of photosynthetic parameters in Apricot seedlings versus control treatment (A) exhibited minimum activity of photosynthetic parameters in Apricot seedlings. It can say the effect of treatments in runoff delivery to the Apricot seedlings is the cause of obtained aforementioned results.
Behrouz Mohseni; Hadi Razzaghian; Abdollah Darzi-Naftchali; Esmaeel Nikzad
Abstract
Runoff as one of the water balance components of a basin, is of great importance in watershed and water resources management. Suitable estimation of runoff is requires to determination of runoff coefficient. In this study, runoff coefficient was estimated for return periods of 25 and 50 years using rational, ...
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Runoff as one of the water balance components of a basin, is of great importance in watershed and water resources management. Suitable estimation of runoff is requires to determination of runoff coefficient. In this study, runoff coefficient was estimated for return periods of 25 and 50 years using rational, SCS and Cypress-Creek methods for basins up to 50 square kilometers. GIS software was used to overlay layers and basin analysis. Chow, s table was used to correspondence different methods. Due to the lack of compliance with Chow, s table and estimating lower runoff coefficients than reality in most of the study area, Rational Method did not provide suitable results. Cypress-Creek method was also effective in some basins due to it similarity with the SCS method. Average equivalent runoff coefficient of C25=0.37 and C50=0.41 demonstrated high accuracy of SCS method compared with two other methods. According to the soil conservation service method, minimum and maximum runoff coefficients of 25- year return period were related to Chalakrud 1 (0.06) and Safarood 4 (0.61) watersheds, respectively. Also, the minimum and maximum runoff coefficients of 50- year return were 0.1 (for Chalakrud 1) and 0.65 (for Safarood 4), respectively. According to the results of three methods, the lowest runoff coefficients were obtained for watersheds with the highest area and the lowest rainfall intensity.
Reza Sokouti; Hamidreza Peyrowan; Davood Nikkami; Mohammadhossein Mahdian
Abstract
Considering to high distribution of the marly lands in west Azarbaijan province and high sediment yield of such lands, in this research, the relation among the form and the rate of erosion on marls with their erodibility properties were studied. So marly regions of province with the special properties ...
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Considering to high distribution of the marly lands in west Azarbaijan province and high sediment yield of such lands, in this research, the relation among the form and the rate of erosion on marls with their erodibility properties were studied. So marly regions of province with the special properties were recognized and soils were sampled. Soil erodibility indices were determined and analyzed by statistical methods considering the form and the rate of erosion. Also portable rain simulator were used to study of the runoff and sediment yield potential of such soils. Finally the factors affected the soil erodibility were determined by variance analysis. Results showed erosion rate could be classified as moderate. Gully erosion had highest number in Gara-agaj and Gara-tape areas whereas rill erosion had high number in all area of marlly lands. Surface runoff volume ranged between 255 to 577 cm3 in Shabanlu and surface runoff coefficient 0.23 to 0.53 in Gara-tapeh. Maximum yielded turbidity was 180 gr/lit in Gara-Agaj area. Clay ratio was the effective factor to gully form and Surface runoff volume also was the factor to form surface and rill erosion.
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 ...
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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.
Davood Nikkami; Peyman Razmjoo; Farzad Bayat Movahed
Volume 2, Issue 2 , July 2010, , Pages 65-72
Abstract
The amount of water erosion is basically related to rainfall erosivity and its consequent runoff. In soil erosion and sediment yield models, intensity and energy of rainfall are mostly considered. In this research, some parameters such as the amount of rainfall, maximum intensity and energy in different ...
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The amount of water erosion is basically related to rainfall erosivity and its consequent runoff. In soil erosion and sediment yield models, intensity and energy of rainfall are mostly considered. In this research, some parameters such as the amount of rainfall, maximum intensity and energy in different basic times are correlated to the amount of runoff and sediment outflow from erosion plots to investigate rainfall erosivity index. For this purpose two years of precipitations of Sohrain-Gharacharian flood spreading research station were monitored by recording raingauge. During 2003-2004 period, two plough treatments of parallel and perpendicular to slope direction on three slope classes of 0-12, 12-20, and 20-40 percent with three replicates and randomized complete block design were studied under regional wheat planting and fallow conditions in 1.8x22 sq. meter erosion plots. The correlation between the amounts of runoff and sediment, as dependent variables, resulted from 12 rainfall events and the amounts of rainfall, maximum 1, 5, 15, 30, 60 and 120 minutes of rainfall intensity, rainfall energy and rainfall erosion index, as independent variables, computed by different methods were analyzed with the SPSS V11. Two variables of the amount of rainfall and the maximum rainfall intensity in different base times had the maximum correlation with the amount of runoff and sediment at the levels of 99 to 95 percent.
Ali Rezaei
Volume 2, Issue 1 , May 2010, , Pages 11-17
Abstract
Increasing runoff coefficient and flood intensity and extending dry land areas over the country basins are due to the destruction of vegetation cover. For monitoring the trend of temporal variation, maximum peak flows and maximum 24 hr rainfall data have been gathered from all climatologic and hydrometric ...
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Increasing runoff coefficient and flood intensity and extending dry land areas over the country basins are due to the destruction of vegetation cover. For monitoring the trend of temporal variation, maximum peak flows and maximum 24 hr rainfall data have been gathered from all climatologic and hydrometric stations of Ghizilozan basin. The acquisition data repaired and standardized within a period of 30 years. Then the data were divided into three categories with period of 10 years and finally six categories with period of 10 to 30 years were produced. The mean of variables for every period was calculated based on two years return period by fitting the distribution function of Pearson type III to selected data series. The mean of every category plotted with time period and fitted a line to them. The results showed that based on Kendall’s Tau method, there are significant and positive harmonizing between measured variations respect to time only in two climatology stations named Gitoo and Salamatabad and so two hydrometry stations named Sarcham and Dehgolan and in the others there aren’t any positive or negative harmonizing of data variations respect to time. But the slope of regression line of maximum 24 h of annual rainfall as an index of climate variations to the time, equal 0.031 and in contrast the slope of regression line of peak flow to time equal 0.059. Therefore, the slope of peak flow is 1.9 times of maximum 24 h of annual rainfall with time. This finding says that the vegetation cover because of dry land extending is destroyed and runoff coefficient and flood intensity is increased at studied basin.
Hossein Saadati; Shaban Ali Gholami; Foroud Sharifi
Volume 1, Issue 2 , July 2009, , Pages 87-98
Abstract
Lack of hydrometric data is the main issue for research and executive plans. In the present study in order to solve this issue, the capability of SWAT model has been studied in terms of daily discharge simulation in un-gauged watersheds. This model can simulate six hydrological and biological processes ...
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Lack of hydrometric data is the main issue for research and executive plans. In the present study in order to solve this issue, the capability of SWAT model has been studied in terms of daily discharge simulation in un-gauged watersheds. This model can simulate six hydrological and biological processes such as daily discharge, daily sediment, yearly and monthly water balance, water quality, agricultural products and estimation of vegetative cover for different animal grazing management systems. Simulation has been done for both gauged and un-gauged basins in Kasilian catchment for two time periods as calibration and validation of model. Calibration has been done using data derived from 4 years recording data (1987-1981) while validation has been done using 6 years data (1981-1986). Results show that, ABF, CN2 and REVAPC parameters are most sensitive and also Z and T-Laps parameters are low sensitive among other parameters. The model simulated runoff reasonable with r2=0.69, PBIAS=-2.5, and NS=0.72, whereas, the validation of model for the same data showed that r2=0.57, PBIAS=4.3, and NS=-0.54, which indicates that the performance this model is not quite valid for low stream flows because of sensitivity of hydrological parameters. The new version of SWAT model, modified during 2000 to 2005, has a capability in using GIS, thus it can be used in the same study area.
Seyed Masoud Soleimanpour; Majid Soufi; Hassan Ahmadi
Volume 1, Issue 1 , May 2009, , Pages 46-52
Abstract
Fars province has experienced gully erosion in six climate zones based on deMartonne classification method. After selecting one region from each climate zone, 15 active and representative gullies were investigated using morphometric characteristics and watershed area, slope gradient above gully heads, ...
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Fars province has experienced gully erosion in six climate zones based on deMartonne classification method. After selecting one region from each climate zone, 15 active and representative gullies were investigated using morphometric characteristics and watershed area, slope gradient above gully heads, linear advancement, form factor, particle size analysis, vegetation cover, gravel content and bare grounds were measured and sediment production was calculated. Effective factors on sediment production due to gully erosion were determined using Stepwise method provided in the SPSS software package. The results of this research revealed that four factors including slope gradient, maximum 24 hours rainfall, sand, and form factor had significant impact on sediment production with 99 percent of confidence. Slope gradient above the gully head was the most important factor on the sediment production. Slope gradient and form factor had positive relationship and maximum 24 hours rainfall and sand had negative relationship with gully development. The most important impact of slope gradient on the sediment production implies the velocity of surface runoff concentrated above gully heads. Alternative controls to decrease slope gradient would be effective on the reduction of gully development and sediment production.
