جستجوی مقالات مرتبط با کلیدواژه « شبکه زهکشی » در نشریات گروه « کشاورزی »

Urban runoff management models are considered as a useful tool in planning, design and development. One of the most usable models in this field is the SWMM. One of the main problems in studying urban drainage network with these models is the correct choice of parameters. To overcome this problem, the sensitivity analysis method could be used, which shows the relationships between variables included in the model with each other and the priority of their impacts on the model output. The purpose of this study is to determine the sensitivity of affective variables that influence urban flood peak using the SWMM model in Azimiyeh region of Karaj. In order to that, the estimated initial value of the percentage of impervious area, slope, width, curve number, N-Manning for impervious area, depth of depression storage on impervious area, percent of impervious area with no depression storage reduction were decreased and increased to a constant value in the range of acceptable changes and their effect on peak discharge was investigated as a dependent variable. Based on the results, the amount of impervious areas and the percent of impervious area with no depression storage had highest and lowest effect on peak discharge, respectively. 30% increase in the amount of impervious areas, as the most effective parameter, caused peak discharge to be increase 5.09 percent.

The purpose of the current research is to evaluate the performance of the drainage network and flood control nodes in the base period (1980-2020) and under the influence of climate change for 25 and 50-year return periods in the central part of Tehran's sixth district. The results of calibration and validation of the model showed a good fit between the observational data and the simulation. So that the value of coefficient (NS) in the calibration stage for the first to third event is 0.77, 0.72 and 0.64 respectively and this coefficient was obtained in the validation stage for two events, 0.72 and 0.70, respectively. the drainage network was evaluated for the return period of 25 and 50 years for the base period and under the influence of climate change. The results showed that with the increase of the return period in the base period and in the future, there is overflow and flooding in some flood channels and nodes of the drainage network, so that the number of flood nodes in the base period (1980-2020) and under the influence of climate change scenario RCP2.6 and RCP8.5(2021-2050) for the 25-year return period is 10, 13 and 15 respectively. The number of flood nodes in the base period (1980-2020) and under the influence of climate change scenario RCP2.6 and RCP8.5(2051-2100) for the 50-year return period are 12, 17 and 19, respectively. Increasing the dimensions of channels and implementing methods (LID) is an operational solution to solve the problem of elevation.

The behavior of many complex natural phenomena, such as rivers, can be analyzed by fractal tree geometry. Zarrineh Rud sub-basin in Kurdistan province is one of the most watery basins of Urmia basin, which hydrological condition has a great impact on runoff management and downstream flows. Therefore, it is necessary to study the characteristics of this basin using fractal geometry. In the present study, the fractal behavior of Zarrineh rud basin in Kurdistan province has been investigated using GIS layers of stream, DEM map, and application of Strahler, Hack, Horton and fractal tree geometry by Richardson method. According to Hack's law, the slope of the basin trend line is high and this indicates a relatively high erosion in the Zarrineh Rud basin. According to Horton's law, the form factor decreases between stream order 1 and 2 and is almost the same for stream order 3 and higher. In addition, the fractal structure indicates that there is a fractal behavior in the range of stream order 2 and higher. Finally, based on the Richardson method, the fractal dimension of the basin was calculated in the range of 1.695- 1.837, which includes a significant part of the basin space. In addition, the results indicated that the fractal dimension obtained for the stream order 4 by the Horton method was 1.67, which is consistent with the results obtained by the Richardson method. Finally, it can be mentioned that, considering the special topography, climate, and hydrologic conditions of Zarrineh rud sub-basin, it is possible to help the country's planners and decision-makers to better manage this basin by identifying the hydrological behavior of the river.

River behavior is affected by two categories of natural, and human factors. Natural factors such as floods, soil erosion, mass movement and human factors such as facility construction, land-use change, and sand removal from the bed, play a key role in the behavior and intensification of river changes. The serious and irreparable dangers that may be posed by river movements and changes indicate the need to study its morphology in the study phase before any action is taken. The network of streams continuously changes its location based on time, environmental factors and human interventions. It is very important to study the stream changes to provide the should be omitted management solutions for the should be omitted soil conservation. One of the new methods in this regard is to use the should be omitted fractal geometry. The purpose of this study was to calculate the fractal dimensions of the stream and to investigate its relationship with the morphometric characteristics of the basin

To do this, a should be added topographic map of the should be added basin in Firouzkouh, Tehran province was prepared. The map of the streams was prepared and the morphometric characteristics of the basin were determined by using the ARC GIS 10.3 software. Then, three fractal dimensions of the should be added drainage network (stream branch), drainage density, and basin area were calculated. Finally, the morphometric characteristics of the basin associated with the fractal dimensions were investigated by entering the data obtained from the calculations in the SPSS 18 and Curve Expert software 

The results showed that the minimum and maximum fractal dimensions of the bifurcation ratio were 0.25 and 2.99, of should be omitted the drainage density was 0.19 and 2.34, and of should be omitted the area was 0.76 and 2.60. The fractal dimension of the should be added, the should be added dimension of drainage density, and the should be added fractal dimension of the should be added total area of the basin were 1.84, 0.71, and 1.46, respectively. The fractal dimension of the should be added ratio and the sub-basin area were inversely related with the determination coefficient of 0.90, and the fractal dimension of drainage density and the area and the fractal dimension of an should be added area with the sub-basin area was directly related with the determination coefficients of 0.88, and 0.87, respectively. The more elongated the basin and the lower the form, roundness, and elongation factors, the smaller the bifurcation dimension. the fractal dimension of the area is directly related to the compactness factor, elongation factor, form factor, bifurcation ratio, equivalent rectangle width, and equivalent rectangular length, and is inversely related to other variables. Based on the results, the more elongated the basin and the smaller the form, and elongation factors, the lower the area dimension. The fractal dimension of drainage density is directly associated with the circularity factor, compactness factor, elongation factor, form factor, area ratio, bifurcation ratio, equivalent rectangle width and equivalent rectangular length, and is inversely associated with other variables. Therefore, as the basin becomes more circular, the fractal dimension of the drainage density is increased. Therefore, the fractal dimension of drainage density is increased then as the basin becomes more rounded

According to the coefficient of explanation of the obtained models for the relationship between fractal dimensions, and morphometric properties, the studied fractal dimensions can be easily calculated and analyzed using morphometric properties. Due to the importance of stream characteristics in the management of watersheds in terms of flood, erosion, and soil conservation, the fractal models can be used to make quick and accurate decisions for the should be omitted management. Finally, considering that the use of fractal geometry is a new method in studying the characteristics of waterway networks, it is suggested that basins be analyzed fractally in different regions with different morphometric conditions.

Many natural phenomena have many variables that make it difficult to find relationships between them using common mathematical methods. This problem, along with the impossibility of measuring all elements of nature, has led to a major evolution in the way of understanding and explaining phenomena. In this way, one can use the fractal geometry with the theory that many natural phenomena are order in the chaos. Each element of nature is represented as a fractal geometry number. In fact, fractal geometry is a quantitative tool for studying the geomorphology of drainage networks and modeling many complex natural phenomena. Since geological variables have a profound effect on the nature and activity of the drainage networks. In this study, the role of lithology and geological formations is studied to quantify the drainage networks and used fractal dimension to indicate sensitivity to erosion of the formations of this area.

The present study consists of four main sections. The first section is the collection of maps and data. In this section, geological maps of 1:100000 areas were provided and selected from the geological formations of Yazd- Ardakan basin, three geological formations of Kahar, Granit and Taft. Sensitivity to erosion of these formations was studied in this area using PSIAC, Feyznia and Selby methods. In second section, fractal dimension is estimated in 30 plots of 1 × 1 km2, three geological formations of Kahar, Granite and Taft. In each geological formation, fractal dimension was calculated by box counting method using Fractalyse software and the number of plots required in each formation was determined using Graphical method. In the third section of this study, morphometric indices were calculated including drainage density, number of ranks, average length of rank and rank frequency. In the final section, uncertainty analysis of fractal dimension efficiency was studied in classification and separation of geological formations. In most studies in the field of fractal dimension, the uncertainty of this method is not considered. As a result, their findings do not have enough accuracy to generalize to natural phenomena. Therefore, in this study, uncertainty of fractal dimension efficiency was investigated in 30 plots of 1 × 1 km2 that were excluded from other study sections for testing this method.

The mean fractal dimension of 1.149 represents Taft formation, the mean fractal dimension of 1.161, is Granite formation and the amount of 1.207 is Kahar formation. The highest fractal dimension was calculated in Kahar formation (1.279) and the lowest in Taft formation (1.046). In addition, the correlation coefficient is 99%. The results also indicated a significant and meaningful relationship between fractal dimensions of drainage networks and morphometric properties. In this paper, a positive relationship is observed between morphometric parameters and fractal dimension, so that the greatest correlation coefficient is found between the fractal dimension and the drainage density (0.99). The results of uncertainty analysis of fractal dimension showed which fractal dimension in the geological formation of Kahar with 90% has a steady trend and in two geological formations of Taft and Granite, this amount is about 70%. Therefore, fractal dimension in the drainage network identification of the Kahar formation is more powerful than two other granite and Taft formations.

The drainage networks are the most prominent landscapes on earth that are the basis of many hydrological and geomorphological models. Due to the geomorphological characteristics of the region, the drainage network shows its own fractal properties that are saved as code in it. In fact, drainage networks are fractal phenomena with fractal behavior. In this study, the fractal dimension and morphometric properties of the drainage network were used to analyze the sensitivity to erosion of the geological formations of this area. PSIAC and Feyznia methods did not perform well in separating the sensitivity to erosion of Taft and granite formation, and they are unable to distinguish between these two formations. So, using the Selby method, six effective factors were investigated on the resistance and sensitivity of formations to erosion (Schmidt Rebound Hardness, weathering, distance between joints, direction of the joints relative to the slope, the width and connection of the joints) in Taft and Granite formations. The study of these factors leads to field visits and spends a lot of time and cost. As the results of the resistance to erosion of formations were shown by Selby method, Granite formation has less resistance to Taft formation. Due to the climatic conditions in this area, Granit formation is susceptible to weathering. Extreme weathering acts as arenization process. In fact, fractal dimension in three geological formations of the study area is well showed the difference in resistance to erosion of both Taft and Granite formations. The results of this study showed that fractal dimension allows for a quick and accurate analysis of the erosion characteristics and sensitivity to erosion of the formations of this area.

The type of rivers are dry or seasonal in arid or semiarid zone and current flowing through them is short or if there is no flow. One of the best methods to divert the flow in the river basin system is implementation with subsurface drainage network in the river bed A laboratory model for study the effects of hydraulic and geometric characteristics of the intake flow rate diversion was designed ¡ Which the possibility measuring the inflow and outflow of diversion was considered.in this study were evaluated the effect of bed slope intake and diameter size of particle on diversion flow in two condition¡ water level constant and without control input discharge . The results showed that the slope of the porous medium tangible impact on current of deviation is in a state of constant water level. But the steep increase in input mode increases the deviation is negligible in Dubai. The 20% increase in diameter drains¡ in case the input of 9% and 20% in fixed alignment surface water drainage flow improves.The SPSS were using to obtain an equations that by them can estimate the diversion flow base of head flow hydraulic conductivity in porous media.

The sub surface flows resulting by rainfall are one of the main sources of supplying water. In these conditions, swap of agricultural lands in different seasons is one of the main problems of farmers which are caused by an increase in the level of subsurface water or impropriety of the soil texture. In such conditions, the sodium and salty soil cause a decrease in the efficiency of crops harvest. In addition, water collected from rainfall is one of water resource in urban and non-urban areas, therefore determining the drainage coefficient for estimating drainage water of it is very important. Therefore, in this study, different methods of determining the drainage coefficient in sodium and salty soil have been investigated. The obtained results have shown that the maximum of drainage coefficient in steady method is 2.4 mm/day. However, this coefficient changes throughout the day according to the irrigation calendar method from the minimum 0.37 to the maximum 2.49 mm/day. The results have indicated that the amount of the obtained drainage coefficient by steady method is always more than the amount obtained by unsteady method. But the amount of this coefficient is the equal in the beginning of summer using both methods. Therefore, using steady method causes an increase in the estimated subsurface flow amount so it is suggested to use the unsteady method to estimate the drainage coefficient.

Water collection systems and disposal of superficial rain runoff are of the important components of urban planning and development, and any negligence in the system design could be problematic for human societies. In the superficial water collection networks design, design errors increase with the increment and extension the network. To reduce the error, the network design should be accurate. Computer models have greatly contributed to the accurate design and played a very useful role in achieving economical plan.
A study was done to determine the optimum dimensions of Gorgan city drainage network using hydrologic-hydraulic model SWMM. In this study, to calibrate the model, four rainfall events in dates 22/11/1390, 30/11/1390, 12/01/1390, 12/02/1390, were used and the speed of the corresponding runoffs in the chosen sub basin were recorded. In this study, Nash-Sutcliff, square root of error and bias error were used as model performance indices in the estimating peak discharge and flow volume.
The model calibration results showed that the simulated peak discharge and flow volume are in good correspondence with the observed values (BIAS%=11.44, RMSE 0.006 and NS=0.70) and the calibration results were used for the optimum values of parameters. To evaluate and test model validation, two rainfall events in dates 2/02/1391, 16/02/1391, were used. The evaluation results were confirmed the efficiency and accuracy of the model, so that the model performance indices were acceptable in both cases (BIAS%=8.01, RMSE 0.00043 and NS=0.69). After evaluating model performance, design rainfall with return period was calculated and model with design return period was performed in respect to the optimal parameters and dimensions of the drainage network. Peak discharge passing through the channels was identified based on design rainfall intensities. The adequacy of existing network to carry runoff with design return period was assessed with regard to model results based on presence or absence of added load and flood conditions at the nodes and channels. According to the model results, 40.11, 58.30 and 48.12 percent of drainage network channels possess critical and flood conditions in 2, 5 and 10 return periods respectively. Finally, the optimal dimensions of flood channels were determined by the model through trial and error test according to the type of optimal dimensions for each design return period.
The results of the study indicate that the model has the accuracy required for urban runoff simulation and it can be used for urban runoff management plans and designing superficial water collection and disposal networks.

In arid and semi-arid regions، collection of surface and subsurface waters in small seasonal rivers is very crucial، particularly in dry seasons. The cost of construction and maintenance of classical water intakes makes them inappropriate for these rivers. In this study a rather new method to divert surface and subsurface water is experimentally evaluated. In this kind of intakes، a couple of trenches are excavated and the drain pipes are installed in them and then filled with very porous materials. Indeed the system acts as a river drainage network. This method not only reduces the construction and maintenance costs but also minimize the disturbance of river topology and morphology. Therefore this intake is also suitable for rivers with high sedimentary loads. In a few small rivers in Khorasan Razavi province، Islamic republic of Iran، such systems have been installed but their design and applicability have not been evaluated. In this research، experimental model of the intake to collect flow was built for flow diversion and flow rate deviation examined. Results showed a direct relationship between flow diversion with water level and with increasing distance between the drainages، the drainage flow increases. Drainage flow in the porous medium is initially decreased and then increased and drainage flow is the lowest in the middle drainage. In the review drainage arrange، the drainage of two deep with shorter porous medium is more suitable. Finally، regression mathematical model for the structural design of the intake subsurface with porous medium and drainage system were presented.