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      • Open Access Article

        1 - Simulation of Stream Flow Hydrographs Using Flexible Distributed Hydrological Model (WetSpa) in Khorram Abad Basin
        ehsan fatapour Ali Afrous babak aminnejad Ali Saremi amir khosrojerdi
        Background and Purpose: The use of hydrological models in watersheds has always been of interest to water resources researchers. Hydrological simulation models are valuable tools for investigating challenging issues related to watershed management, such as the effect of More
        Background and Purpose: The use of hydrological models in watersheds has always been of interest to water resources researchers. Hydrological simulation models are valuable tools for investigating challenging issues related to watershed management, such as the effect of climate change on water resources and the effect of urbanization on floods and droughts. Spatial distribution hydrological model WetSpa is used to simulate river flow at basin scale. The model uses the observed topography, land use, soil map, and daily meteorological time series (rainfall, evaporation and temperature) to predict hydrographs and distributional-spatial hydrological parameters of the basin. In this article, the object-oriented, modular and process-oriented model of WetSpa, which is prepared based on the flexible modeling approach, is applied to simulate the daily hydrograph in Khorramabad basin.Method: The inputs of the model include digital elevation maps, soil type, land use, and time series of precipitation, temperature, and potential evaporation and transpiration, which are from the statistics of 6 meteorological stations in a ten-year period (water year 84-85 until 93-94) is used. After preparing the inputs of the model, at first the maps of the distribution parameters are automatically generated in the map format by the GIS pre-processing component of the model. After that, the model is calibrated using a 5-year statistical period (water year 84-85 to 89-88) of precipitation, temperature, and potential evaporation and transpiration data. The model uses Thiessen polygons to apply precipitation, temperature, and evaporation data. For this purpose, the daily discharges of Jam Anjir hydrometric station located at the outlet of the studied watershed are used. Model calibration is done manually by determining the values of 11 global (general) parameters of the model, so that the best match between simulation and observational hydrograph is obtained. And finally, the validation of the model is carried out based on a 5-year statistical period (water year 89-88 to 94-93) and the values of the global parameters obtained in the calibration stage.Findings: The maps of distributed parameters are produced, which after preparing the inputs of Mashdand's production model showed that the average potential runoff coefficient of the area is 63% and the concentration time of the area is 17 hours. In the following, according to the 11 global parameters, which symbol and range of changes are specified in table (3), the model global (general) parameters values  are obtained in the calibration stage. Comparing the simulated hydrograph by the model and the observed hydrograph in the calibration stage shows that the best match between the observed and simulated data is established with a correlation coefficient of 0.39. Validation of the model is also based on a 5-year statistical period (water year 89-88 to 94-93) and the values of global parameters. The output files of the model illustrate that 26.15% of the precipitation becomes runoff during the calibration period. During the validation period, the share of total runoff from precipitation is 26.42%. Moreover, the simulation results of the model demonstrate the ratio of evaporation to precipitation in the calibration and validation periods is 57.18 and 69.20%, respectively. Additionally, the results of the evaluation of the model based on the Kling-Gupta index (KGE) present the value of 0.68 for the calibration period and 0.74 for the validation period.Results: In this article, the effectiveness of WetSpa model is investigated in order to simulate the daily flow of Khorram Abad River at Cham Anjir hydrometric station. According to the results obtained from this research, it can be said that the Wetspa spatial distribution model has the ability to simulate the hydrological behavior of the basin with acceptable accuracy. The graphical comparison of the calculated and observed hydrographs for the calibration and evaluation period also shows a relatively good match between the two hydrographs. Examining the results of calculating of the water balance components by the model demonstrates that the outflow in the calibration and validation period accounted for 26.15 and 26.42% of the total precipitation respectively, seems logical considering the major land use of mountains and pastures in the irrigation basin. Manuscript profile
      • Open Access Article

        2 - Modeling the Effects of Land Use Change on Surface Runoff in the Watershed of Khorramabad Using RS and GIS Integration Model and L- THIA
        hadis rashidi Ali Haghizadeh Hossein zeinivand Naser Tahmasebipour
        Background and Objective: land use change, mainly socio-economic benefits to follow. However, these changes have negative effects on the natural environment. Due to the high volume of runoff from a lack of permeability in the city and Non-use of certain areas or any str More
        Background and Objective: land use change, mainly socio-economic benefits to follow. However, these changes have negative effects on the natural environment. Due to the high volume of runoff from a lack of permeability in the city and Non-use of certain areas or any structure in addition to the problem of flooding in low-lying areas for water infiltration in several studies to develop models with simulation approach to land use changes have taken place. In this study, L-THIA model for estimating runoff from land use changes in the area of Khorramabad is used. The Model of L-THIA, a model to assess long-term effects land use change on water resources using simple and availability data Such as long-term climate data, land use map and soil map applicable.  Methods: This study was conducted in a period of 10 years and in the period of 2004-2014. Landsat images from the site the US Geological Survey has been downloaded and various corrections have been made. Land use maps were prepared and used using Landsat 7 satellite images of ETM sensors and Landsat 8 images of OLI sensors related to 2004 and 2014, respectively. Precipitation data are provided by the Regional Water Authority. After sorting, they are prepared for future analysis. By combining land use map and soil texture map in GIS software, the soil hydrological group is produced. Finally, the prepared maps are given to the L-THIA model and the effect of land use change on surface runoff is investigated.Findings: The results of modeling using L-THIA, increased annual runoff in ten years shows that this increased volume of runoff and the need for control over land use change in the region. User modifications to increase mainly in residential areas and loss of woodland and grassland.Discussion and Conclusion: As the results of this study show, the L-THIA model has a good ability to express the effect of land use change on the volume and depth of runoff. Also, using the results of the study, it is possible to prepare control programs for land use changes to prevent runoff in the area.  Manuscript profile
      • Open Access Article

        3 - Hydrological Simulation of Taleqan Watershed Using SWAT
        Mahsa Aghakhani Touraj Nasrabadi Alireza Vafaei Nejad
        Background and Objective: Hydrological modeling of watersheds plays a significant role in study, development and management of water resources. Based on importance of Taleqan Watershed as a main supplier of Alborz and Tehran Provinces water resources, in this study, sur More
        Background and Objective: Hydrological modeling of watersheds plays a significant role in study, development and management of water resources. Based on importance of Taleqan Watershed as a main supplier of Alborz and Tehran Provinces water resources, in this study, surface water hydrological simulations in this basin are investigated. Method: Hydrological simulations were performed by applying physical semi-distributed SWAT (Soil and Water Assessment Tool) model. Moreover, model calibration and sensitivity analysis were done using SUFI-2 algorithm. Model performance is evaluated by means of statistical indicators such as Nash-Sutcliffe (NS) and coefficient of determination (R2). Findings: Sensitivity analysis showed that the parameters of the curve number (CN), soil evaporation compensation, and soil available water capacity are the most important factors to control the flow in the basin. At Gelinak station (watershed outlet), NS and R2 coefficients values after calibration are 0.84 and 0.87, respectively. These values in validation interval were obtained as 0.79 and 0.84. Discussion and Conclusion: The results show good performance of the watershed simulations. Moreover, it was shown that the model has good capability for monthly surface runoff prediction of the Taleqan basin. Due to reducing field operations costs of required components measurements and especially due to reducing the time required to analyze issues, applying this model is efficient for improving water resource management and environmental protection.   Manuscript profile