جستجوی مقالات مرتبط با کلیدواژه "sufi2" در نشریات گروه "آبخیزداری، بیابان، محیط زیست، مرتع"

This study aims to simulate runoff and runoff quality of Zarrineh river basin by SWAT model. Calibration and verification were done respectively with monthly runoff statistics in SWAT CUP by SUFI2 method for 1992-2013, for 12 sub basin, 226 HRU and monthly nitrate data for 2006-2009. The highest runoff sensitivity and runoff quality with minimum Pvalue and maximum absolute value Ttest belong to soil cure number and nitrogen hydrolysis. The maximum number in calibration and verification belonged to Zarrineh dam station by R2=NS=0.81 and minimum number belonged to Janagha station by R2=NS=0.47. The value of these two coefficients in calibration of nitrate in all basin were 0.58 and 0.44 and their coefficient in verification were 0.51 and 0.42 respectively. Statistical results showed that a good performance in the SWAT model simulation of monthly flow and nitrate in the basin of Zarrineh river. Then the simulation was conducted by best management practices model. In this study protective measures watershed simulated stone lines, contour lines and mulching considered as a management solution. The best solution was contour lines by 17.89% reduced nitrate amount input to Urmia Lake see also 11.17% discharge the ground water.

SWAT is a continuous-time model that operates on a daily time step at the basin scale. The objective of such a model is to predict the long-term impacts of management and the timing of agricultural practices within a year (i.e., crop rotations, planting and harvest dates, irrigation, fertilizer, and pesticide application rates and timing) on large basins. It could, at the basin scale, be used to simulate the water and nutrients cycle of landscapes whose dominant land use is agriculture. It could also help assess the environmental efficiency of best management practices and alternative management policies. The SWAT model uses a two-level disaggregation scheme: a preliminary sub-basin identification is carried out based on topographic criteria followed by further discretization, using land use and soil type considerations. Areas with the same soil type and land use form a Hydrologic Response Unit (HRU), a basic computational unit assumed to be homogeneous in hydrologic response to land cover changes.The development of the digital computer has added a new dimension to hydrology. Previously, finding solutions for different problems took hours with a pen and pencil method, but now it takes seconds with modern computers. Moreover, much more complex methods of analysis are now feasible because of the speed of the solution-finding provided by the computer. The impact of the computer has been particularly great in the area of rainfall-runoff modeling. As flood routing and unit hydrograph analysis are mathematical modeling’s, surface-water hydrology is, historically, concerned with modeling. Due to the climate type and the spatial and temporal inconsistency of rainfall in Iran, large floods cause many damages in different parts of the country annually, as the Mediterranean climate and different weather conditions throughout a year provide the ground for the majority of short-term atmospheric rainfall.

Karkheh Basin is one of the main watersheds of Iran which has a Mediterranean climate whose level increases during the spring due to simultaneous rains and snowmelt. As one of the most important hydrological processes of the watershed for better understanding the hydrological issues of flood control structures for long-term planning, applying best management practices and making better use of their potentials, Runoff simulation plays an important role in water resources studies. Thus, to calibrate the model, select sensitive parameters were used in the sensitivity analysis step. Having imported the sensitive parameters into SWAT-CUP software, they were repeated 500 times with the SUFI2 algorithm, and finally, the optimal value for each parameter was determined.

At Hamidiyeh station, the Nash Sutcliffe coefficient was -0.19 and -0.04 in both calibration and validation periods, respectively, and was 0.76 and 0.77 in Chamangir Station, respectively. The coefficients of determination for the Hamidiyeh station in the calibration and validation periods were 0.02 and 0.22, respectively, and for the Chamangir station, they were 0.88 and 0.75, respectively.This study investigated simulated runoff, using the SWAT model based on the meteorological data regarding the Karkheh watershed. A comparison of simulated runoff results with observational runoff at the hydrometric stations was performed automatically by the SWAT_CUP software package SUFI2 algorithm. Correlation between observed and simulated data was calculated based on the Nash Sutcliffe coefficient and the determination coefficient at different stations of the basin. Nash coefficient - Sutcliffe and coefficient of determination at all hydrometric stations except for the five stations which differed in their calibration and validation periods, were found to be close to their optimum values.

The coefficient - Sutcliffe of the other 6 stations was more than 0.5, indicating that the model was capable of simulating runoff. In the mirage stations of Sarab Seyed Ali, Pulchehr, and Noorabad, the SWAT model failed to simulate runoff well, which could be due to the location of these stations in the elevated areas of the basin and its branches that were snowy. The lack of proper distribution of meteorological stations in these areas makes the model unable to simulate well the snow runoff. In Hamidiyeh and Pai-Paul stations, the SWAT model was could not establish a reliable relationship between the observed and simulated runoff due to the impact of the construction of the Shahid Abbaspour Dam on the river flow hydraulics.

The aims of this project was to assess the capability of SWAT model and SWAT-CUP software in hydrological simulation and to evaluate the uncertainty of SWAT model in estimating runoff in arid and semi-arid watersheds. Model calibration and uncertainty analysis were performed using the Sequential Uncertainty Fitting (SUFI2) algorithm. In the stage of calibration and validation of water flow, performance of SWAT model was evaluated using R2, bR2 and NS coefficients between observed and simulated records. Based on the results, R2, bR2 and NS were estimated to be respectively 0.75, 0.59 and 0.67 in the calibration stage, and 0.46, 0.24 and 0.42 in the validation stage. The results showed that the performance of the model is weak during calibration. Also output of the model is acceptable but performance is not significantly high in general. The most important reasons behind the poor accuracy are lack of data on water diversion for agriculture, irrigation use, and cropping pattern within the watershed.

The biggest restriction of natural resources in Iran is dry and semi-dry climate and deficit of water resources. Non-normative use of natural resources causes imbalance between water components and demand. The main objective of this study is to test the performance and usability of the simulation model to estimate water balance and groundwater flow in 223.9 km2 of Golgol catchment in Ilam Province using Soil and Water Assessment Tools (SWAT) model and SUFI2 Program. The input data model include topographic, land use and soil maps and also climatologically data, including daily precipitation, temperature, relative humidity and stream flow. In order to determine the important parameters of the model, the parameter sensitivity analysis using "One At a Time " (OAT) was performed and the effect of various parameters such as stream flow, lateral flow and ground water flow on water balance evapotranspiration was examined. In order to calibrate the model SUFI2 algorithm was used.Simulation model for 13 years from 1997 to 2009, was the first of eight years (2004, 1997) for model calibration and the next five years (2009-2004) were selected for validation of model results. Statistical indices P-factor, d-factor, Nash Sutcliffe (NS) and the coefficient of determination (R2) on a monthly basis for the evaluation model was chosen.The Nash-Sutcliff coefficient for calibration and validation period is 0.65 and 0.49 respectively. The results show satisfactory performance of the SWAT model to simulate the water balance components in the Golgol catchment. The obtained values of R2 in both calibration and validation are 0.66 and 0.51 respectively which is indicating the relative desirability of the model. The results of simulation show that the average annual rainfall of 503 mm, the maximum amount is belong to evapotranspiration that equal 366 mm (72%) of the total precipitation in the catchment. The total groundwater and lateral flow is equal 77 mm (15.3 %), the surface runoff is 47.8 mm (9.5 %) and annual losses equivalent to 3% of total precipitation. The share of 15.3 percent of the total sub surface flow and groundwater from total precipitation is valuable for planners to implement management plans in study area.

Runoff and sediment measurement is difficult in mountain watershed because of many different problems such as time and financial limitations. So using simulation model is necessary in this regard. Accuracy and precision evaluation of models for different watershed of Iran is necessary. The aim of this study was the evaluation of SWAT model efficiency in simulation of runoff and sediment yield in Chelchay watershed in Golestan province, Iran and also calibration and validation of SWAT. SUFI2 algorithm was used for calibration and validation. Nash-Sutcliff for calibration period (2001-2005) and validation period (2006-2009) for average daily discharge was 0.5 and 0.4 respectively and for sediment concentration was 0.71 and 0.92 that is good according to past research results. Because SWAT is complex and integrated model and can be used as a management tool in watershed management so it is suggested that it would be used for evaluation of management activities effects in Chelchay watershed.