Showing 1573 results for on
H. R. Ghazvinian, H. Karami, Y. Dadrasajirlou,
Volume 28, Issue 2 (8-2024)
Abstract
One method used to estimate the evaporation rate involves employing various types of evaporation pans, including the standard Colorado Sunken and Class A evaporation pans. This study aimed to investigate and compare the evaporation rates from two pans, Class A and Colorado Sunken, in Semnan City. The Colorado Sunken evaporation pan was utilized as the test pan, and the test was conducted in an open space near the Faculty of Civil Engineering at Semnan University, located in Semnan City. Evaporation measurements were recorded daily for 123 days, from June 1, 2017, to September 31, 2017. The evaporation amount from the Class A pan was obtained from the synoptic station of Semnan city, situated 2.39 km away from the test site, and was subsequently analyzed. Meteorological data, including maximum and minimum temperature, maximum and minimum relative humidity, wind speed, sunshine hours, and air pressure, were also collected from the Semnan synoptic station and compared with the experimental evaporation data. The results indicated no significant difference in the daily evaporation amount between the Class A pan and the Colorado Sunken pan during the tested periods. The best statistical distribution, based on Kolmogorov–Smirnov test, for the Class A evaporation pan and the buried Colorado pan, were selected as Error with (k-s=0.05019) and Gamma with (k-s=0.05552). The coefficient of determination between the two pans was estimated to be approximately 93%. Further analysis revealed that the rate of evaporation is most closely associated with the maximum daily temperature. Pearson's correlation coefficient for the maximum temperature with the Class A evaporation pan and the Colorado Sunken pan was found to be 0.623 and 0.647, respectively.
Y. Choopan, H. Arianpour,
Volume 28, Issue 2 (8-2024)
Abstract
Reducing the effects of the misuse of urban wastewater is to use it in agriculture along with the subsurface irrigation system, which effects on the soil also require extensive investigations. Therefore, the present research was performed in a randomized complete block design with two factors of the type of irrigation source (well water W1 and treated urban wastewater W2) and the type of irrigation system (surface S1 and subsurface drip S2) in three replications (R) for a soil depth of 0-40 centimeter during two crop seasons. The results showed that the potassium, sodium, salinity, and sodium absorption ratio were significant at the 1% probability level in the comparison of system type and irrigation source type, whereas the values of pH, calcium, and magnesium were not significant in the comparison of system type and irrigation source type. The lowest value of calcium, magnesium, sodium cations, chlorine, phosphate, and sulfate anions was obtained in the W1S1 treatment. Also, the highest parameters of salinity, calcium, magnesium, phosphate, potassium, and chlorine were observed for the W2S2 treatment. It can be concluded that irrigation with urban wastewater has improved the chemical properties of the soil, and the type of irrigation system has had minor changes.
S. Esmailian, M. Pajouhesh, N. Gharahi, Kh. Abdollahi, Gh. Shams,
Volume 28, Issue 2 (8-2024)
Abstract
Studying the process of soil erosion and evaluating its effective factors is one of the most important prerequisites for proper management of soil and water resources. This study was conducted to investigate the production of surface and pipe runoff and sediment using artificial rainfall on silt loam soil in the laboratory. So, the soil was collected from the study area and transported to the laboratory. Laboratory experiments were performed on a soil bed in a rectangular flume with three pipes, at slopes of 2%, 6%, 10%, 14%, and 18% under simulated rain (30 mm/h) for one hour. Related graphs were drawn in Excel to analyze the results, and Spearman's correlation test was used in SPSS software to check the correlation between runoff and sediment values in each slope. The results showed that with the increase in slope, the sum of surface and pipe runoff and sediment increased over time. For example, in a slope of 2%, the runoff and sediment in the initial moments of the experiment increased from 0 to 1.3 liters and 26.2 g m-2 at the end of the experiment. Also, the correlation coefficient between runoff and sediment in the slopes was 0.98, 0.62, 0.4, 0.93, and 0.15, respectively, which was significant in some, but in others, it was not significant because of soil loss.
V. Rezaei, S. S. Eslamian, J. Abedi Koupai, A. R. Gohari,
Volume 28, Issue 2 (8-2024)
Abstract
The relationship between intensity-duration-frequency of rainfall is a significant tool for estimating flood discharge. According to the sparsely available rain gauge stations and the development of technology, it is possible to use satellite rainfall data with different temporal and spatial resolutions. PERSIANN rainfall data with a time resolution of 1 and 6 hours were used in this research. Also, the spatial resolution of these data is 0.04 x 0.04 degrees. Rainfall data from synoptic stations around the Kan basin were also used. Three common continuous probability distributions of Gamble, Pearson type 3, and Log Pearson type 3 with return periods of 2, 5, 10, 25, 50, and 100 years were investigated to calculate and check the IDF curve. In general, the precipitation intensity obtained from Gumble's method was more than Pearson Type 3's method. Log Pearson type 3 distribution did not provide acceptable results in this research. The two interpolation methods of inverse distance weighting and empirical Bayesian kriging were used to generalize the frequency intensity curves to the entire Kan basin. The results showed little difference between these two methods, except for Pearson type 3 probability distribution.
H. Ebrahimi Golbosi, E. Fazel Najafabadi, M. Shayannejad,
Volume 28, Issue 2 (8-2024)
Abstract
Surface irrigation is one of the most common irrigation methods. Due to the low efficiency of surface irrigation, water loss is significant in this system. It is necessary to know the characteristics and coefficients of water infiltration rate in the soil for accurate and adequate planning of surface irrigation. One of the equations used in this field is Phillip's infiltration equation. In this study, the infiltration coefficients of Phillip's equation and Manning's roughness coefficient in border irrigation are determined based on the comparison of the actual advance curve with the advance curve calculated with the dynamic wave model, and the results were compared with the double cylinder method and the two-point method of Ebrahimian et al. (5). The actual infiltration volume was obtained from the difference between the inlet and outlet volumes. The error of the mentioned method in calculating the infiltration volume was 5.53%. Meanwhile, the errors in the double cylinder and two-point Ebrahimian (5) method were 59.62% and 19.08%, respectively. In heavy soils, the longer the length of the border increases, the method is more accurate in estimating Philip's coefficients, while in light soils, the advancing time, which in addition to length is a function of permeability, input discharge, and the slope of the bottom of the bed is increased, the accuracy of the method in estimating Philip's penetration coefficients is increased.
A.r Vaezi, Kh. Sahandi, F. Haghshenas,
Volume 28, Issue 3 (10-2024)
Abstract
Water erosion can be affected by land use change and soil degradation by agricultural activities. This study was conducted to investigate the effects of land use change in poor pastures on soil physical degradation and water erosion in semi-arid regions. Experiments were performed in 42 soil samples taken from seven areas covering the two land uses: poor pasture and rainfed agriculture, which have different soil textures (clay loam, silty clay loam, sandy clay loam, silt loam, loam, sandy loam, and sandy loam). The physical characteristics of soils were measured in the samples of both types of land use and its changes were expressed as physical degradation of the soil. The soil's susceptibility to water erosion was measured under simulated rainfall with 50 mm h-1 intensity for 60 min. The results showed that the land use change in pastures leads to the physical deterioration of soils; so bulk density, porosity, macropore, field capacity, saturated point, aggregate size, and aggregate stability were degraded with a rate of 28, 22, 41, 11, 5, 62, and 63 percentages. The structural characteristics of soil (aggregate size and stability) had the highest physical deterioration due to the land use change in the pastures. The change in land use change greatly increased the sensitivity of soils to water erosion. A significant relationship was found between the susceptibility of water erosion and the soil's physical degradation. The soils with coarser and more stable aggregates have higher physical degradation by the land use change and in consequence show more susceptibility to water erosion.
M.j. Aghasi, S.a.r. Mousavi, M. Tarkesh, S. Soltani,
Volume 28, Issue 3 (10-2024)
Abstract
Astragalus is the vegetation of many mountains of Iran's plateau and plays a major role in providing ecosystem services due to its pillow shape and deep rooting system, they facilitate the control and penetration of precipitation into the soil. The correlation of Astragalus ecosystems with arid and semi-arid climates has made them vulnerable to climate change. In this study, a runoff yield map based on the Budyco curve under current and future conditions of climate change (2050) was prepared using climate and temperature data from the Chelsea site (CanESM2 GCM) in TerrSet software and by using maps of sub-watersheds, annual precipitation, annual potential evapotranspiration, soil depth, plant accessible water and the current and future "Land Cover - Land Use" map, with a combination of field methods and species distribution models at the local scale of the Shur River watershed of Dehaghan (Central Zagros). Finally, the excess runoff damage produced due to climate change was estimated using the replacement cost method. The results indicated an increase in the annual runoff volume of the watershed from 70 million cubic meters to 105 million cubic meters under climate change conditions for the RCP26 scenario in 2050. Taking into account the cost of 10 million Rials for controlling 530 cubic meters of runoff through various watershed management projects, preventing the damages of excess runoff produced requires a credit amounting to 660 billion Rials based on the present value. This study proved the ability of TerrSet software to predict and produce an ecosystem service map of runoff yield under climate changes or land use changes and with the purpose of valuation on a local scale. Also, the above valuation can be the basis for planning and providing credit for the study and implementation of watershed management projects to deal with the threats of climate change.
B. Attaeian, F. Teymorie Niakan, B. Fattahi, V. Zandieh,
Volume 28, Issue 3 (10-2024)
Abstract
The objective of this study was to investigate the effect of wildfire in the rangelands of the Gonbad region of Hamedan on soil organic carbon storage in two control and fire areas after three years of fire, and the feasibility of using remote sensing in indirect estimation of soil carbon. Therefore, 20 soil surface (0-10cm depth) samples were collected from the burned area and 20 samples from the control area (40 samples in total) by the systematically random method after three years of fire time. Changes in organic carbon, total nitrogen, acidity, and salinity of surface soil were tested by independent t-test between control and fire areas. Then, to investigate the linear relationship between the storage of soil organic carbon with other parameters, the Pearson correlation was used in SPSS v. 26. The results of the independent t-test showed that there was no significant difference in EC, acidity, and soil organic carbon of the control and fire areas, but the amount of total soil nitrogen showed significantly different. The results showed a significant positive correlation was observed between soil organic carbon and total nitrogen at the level of one-hundredth of 0.830 (p< 0.01) in the fire area, and the BI index showed a significant negative correlation of 0.727 (p< 0.05). In the control area, a significant positive relationship was observed between organic carbon and total nitrogen at the rate of 0.627 (p <0.05). The results of processing Landsat 8 images (OLI-TIRS sensor) in the fire area showed that there was a statistically significant relationship between soil organic carbon and light and wetness index obtained from tasseled cap (-0.726 and 0.674, respectively) and PC1 component obtained from principal component analysis and -0.724 (p <.05). These results indicate that it is possible to use tasseled cap images to predict soil organic carbon in fire areas.
M. Amiri, E. Fazel Najafabadi, M. Shayannejad,
Volume 28, Issue 3 (10-2024)
Abstract
One of the important issues in river engineering is flood trends. In general, two types of methods are used to determine the flood trends in rivers. The first group of hydraulic methods, such as the dynamic wave method, is based on solving continuity and momentum equations or Saint-Venant equations. The second category is hydrological methods like the non-linear Muskingum method. In this research, both methods have been used to determine the trends of flood hydrographs in the Plasjan River, one of the main tributaries of the Zayandehrud River. The coefficients of the non-linear Muskingum method were obtained by optimizing and solving the related equation with the fourth-order Runge-Katai numerical method using MATLAB software and the dynamic wave method using the two-dimensional HEC-RAS software. In this study, four flood events were used. In the non-linear Muskingum method, the first event was used for model calibration and the other three events were used for validation. The error rate in this method for the second, third, and fourth events was 84.23, 6.6, and 7.96 percent, respectively, and the error rate in the dynamic wave method for these four events was 17.58, 87.3, 5.4, and 6.21 percent, respectively. Therefore, the dynamic wave method is more accurate in estimating the output hydrograph. However, the non-linear Muskingum method has acceptable accuracy and is recommended in terms of cost, required information, simplicity, and speed of calculation in situations where sufficient information is not available.
M.a. Abdullahi, J. Abedi Koupai, M.m Matinzadeh,
Volume 28, Issue 3 (10-2024)
Abstract
Today, the problems related to floods and inundation have increased, particularly in urban areas due to climate change, global warming, and the change in precipitation from snow to rain. Therefore, there has also been an increasing focus on rainfall-runoff simulation models to manage, reduce, and solve these problems. This research utilized SewerGEMS software to explore different scenarios to evaluate the model's performance based on the number of sub-basins (2 and 8) and return periods (2 and 5 years). Additionally, four methods of calculating concentration time (SCSlag, Kirpich, Bransby Williams, and Carter) were compared to simulate flood hydrographs in Shahrekord city. The results indicated that increasing the return period from 2 to 5 years leads to an increase in peak discharge in all scenarios. Furthermore, based on the calculated continuity error, the Kirpich method is preferred to estimate the concentration-time in scenarios with more sub-basins and smaller areas. For the 2-year return period, a continuity error of 4% was calculated for the scenario with 2 sub-basins, while for the 5-year return period, the continuity error was 19%. On the other hand, the SCSlag method is preferred to estimate the concentration-time in scenarios with fewer sub-basins and larger areas. For the scenario with 8 sub-basins, a continuity error of 16% was calculated for the 2-year return period, and 11% for the 5-year return period.
M. Heidarpour, Kimia Akhavan, N. Pourabdollah,
Volume 28, Issue 3 (10-2024)
Abstract
One of the ways to improve the characteristics of the hydraulic jump in the stilling basin is to use natural and artificial roughness. Recently, due to the advantages of immersed plates compared to other non-continuous artificial roughness, such as the smaller number of these and the vanes' ability to design their geometry and arrangement, it has been approached more. In this article, the effect of submerged vanes with three contact angles of 45°, 75°, and 90° has been investigated on the improvement of the characteristics of a hydraulic jump and its effect on parameters such as the depth ratio, relative length, energy loss rate, and bed shear force coefficient has been evaluated. The results of this research showed that the average effect of submerged vanes on reducing the depth ratio, jump length, and roller length compared to the classical mode is 9.4%, 24.6%, and 28.4%, respectively and the average relative energy loss is 5.5% compared to the classical state and maximum relative energy loss at the angle of 90 degrees of submerged vanes is 6.5%. Considering these results and other conditions such as ease of construction and use, stabilization, and reduction of economic costs among the available choices of sunken vanes, the angle of incidence of 75° is a suitable option for the optimal design of the stilling basin.
M. Tajsaeid, M. Gheysari, E. Fazel Najafabadi, R. Jafari, E. Seyfipurnaghneh,
Volume 28, Issue 3 (10-2024)
Abstract
and water management in the field. Therefore, its measurement has special importance. The surface soil has a great diversity in soil moisture and different methods were used to measure this property. Due to the problems of contact methods of soil moisture measurement, remote sensing has gained attention because of the possibility of analyzing and monitoring soil moisture on a large and global scale. In this research, satellite data and moisture measured in selected fields located in Hormoaz Abad Plain have been analyzed and compared. Sentinel-2 satellite data have been analyzed using the Google Earth Engine system. The results of this research showed that the use of triple indices in the OPTRAM model to estimate moisture is not very accurate, but the use of the EVI plant index has provided better results than the other two indices.
Sh. Kiyani, T. Rajaee, M. Karamdokht Behbahani,
Volume 28, Issue 3 (10-2024)
Abstract
In this research, the hydraulic parameters of flow have been investigated on SMBF flumes in two simple and multiple modes. In this research, Flow3D software was used for the numerical simulation of SMBF flow. The simulations have been performed in three flow rates (5, 15, and 30 liters per second) and three opening rates (0.075, 0.1, and 0.15 meters). The results showed that when multiple SMBF flumes are used instead of simple SMBF flumes, the maximum velocity increased by 12% on average at a flow rate of 5 L/s, 19% at a flow rate of 15 L/s, and 10% at a flow rate of 30 L/s. The energy consumption of multiple SMBF flumes has been reduced on average by 21% at a flow rate of 5 L/s, by 66% at a flow rate of 15 L/s, and by 122% at a flow rate of 30 L/s compared to simple SMBF flumes. Finally, the observations showed that during the productivity of multiple SMBF flumes compared to simple SMBF flumes, the size of eddies has decreased and the number of eddies and the area of flow turbulence have increased.
