Showing 46 results for S. A.
S. A. Kazemeini, H. Ghadiri, N. Karimian, A. A. Kamgar Haghighi, M. Kheradnam,
Volume 12, Issue 45 (fall 2008)
Abstract
In order to evaluate the interaction effects of nitrogen and organic matter on growth and yield of dryland wheat, an experiment was conducted at the research station of the College of Agriculture, Shiraz University at Bajgah in 2005 and 2006. The experimental design was split plot in which three levels of nitrogen (0, 40, and 80 kg N ha -1) were main factors and additive organic matters including liquorice root residue at 15 and 30 Mg ha -1, municipal waste compost at 10 and 20 Mg ha -1, and wheat residues at 750 and 1500 kg ha -1 (all rates equivalent to 50 and 100%) were sub factors. A check treatment (no additive materials) was also included in the experiment. Results indicated that with increasing nitrogen level from zero to 40 and 40 to 80 kg ha-1, wheat yield increased significantly. Among yield components, number of seeds per spike increased significantly with zero to 40 and 40 to 80 kg nitrogen ha-1, but number of spikes m-2 increased significantly only when nitrogen level was increased from zero to 80 kg ha-1. Compared to check (no additive materials), maximum wheat grain yield (32%) was obtained from 100% compost application. Results of nitrogen and organic matters interaction effects indicated that 100% compost application and increasing nitrogen level from 40 to 80 kg ha -1 had no significant effect on dryland wheat yield. This showed the positive impact of compost application on the reduction of nitrogen fertilizer. Thus, it appears that 50% of the required nitrogen fertilizer could be replaced by compost. Applying organic matter increased soil water in both years, however, among organic matters, compost had a more pronounced effect on increasing soil water.
M. Bahreini Touhan, E. Dordipour, S. A. Movahedi Naeini,
Volume 14, Issue 53 (fall 2010)
Abstract
Kinetical study on non-exchangeable potassium (NEK) release is necessary for management, optimum use of soil resources, availability and supplying power of potassium. Information about NEK release rate in Golestan soils is limited. The aim of this study was to investigate the NEK release of saturated soil sample by calcium using acid citric and CaCl2 extractants from 2 to 1844 h duration in 12 dominant soil series in Golestan province. Different soils indicated various responses to continuous extraction. The rate of K released in different soils was lower in CaCl2 than that of Citric acid. Potassium release was faster in earlier periods of the extraction in all soils followed by a lower release rate. Due to high coefficient of determination and low value of the standard error of the estimate, the NEK release kinetic by citric acid and CaCl2 were well described by Elovich and Parabolic diffusion equations and Power, First order and Elovich equations, respectively. Therefore, NEK release rate was controlled by K diffusion from weathered surface of soil minerals.
J. Abedi- Koupai , S. S. Eslamian1, S. A. Gohari , S.a Gohari , R. Khodadadi ,
Volume 14, Issue 54 (winter 2011)
Abstract
Channel lining is essential to increase resistance against scour, reducing water losses and as a result increase water conveyance efficiency. Since the canal lining has significant costs, selection of type of lining must be made with great care and with considering engineering properties. One of the conventional lining for water conveyance cannel is concrete lining. Because of advantages of concrete lining including durability (about 40 years) and low maintenance costs, this type of lining is the best option in many regions, however the construction expenses is high. So far many researches have been published about the types and the durability of concretes containing synthetic pozzolans. Due to high production of wheat in our country, nano particles of wheat ash sheath (NPWAS) were used. In this study the mechanical properties of concrete (compressive strength, tensile strength and durability) incorporating nano-particles of wheat ash sheath were investigated. The results showed that the compressive and tensile strength of samples incorporating 20 percent of NPWAS has not statistically significant difference (P<0.05) with the values of tensile and compressive strength of control samples. Therefore, the optimum replacement percentage of NPWAS was 20 percent by weight of cement. Moreover, results of durability of concrete samples showed that concrete containing 20 percent NPWAS were more durable than control samples in the magnesium sulfate solution. NPWAS with having 90.56 percent of silicon dioxide, high pozzolanic activity and ability to perform substantial chemical reaction with calcium hydroxide would decrease porosity and increase resistance of concrete.
F. Salehi, M. J. Bahrani, S. A. Kazemaini, H. Pakniyat, N. A. Karimian,
Volume 15, Issue 55 (spring 2011)
Abstract
Crop residues are beneficial substances that can bring about important changes in soil biological, chemical and physical properties and can also increase or stabilize crops yield. A field experiment was carried out at Research Station of College of Agriculture, Shiraz University, Shiraz, Iran, to determine the effects of wheat (Triticum aestivum L.) residue rates in combination with N levels on some soil properties in common bean (Phaseolus vulgaris L.) cultivation for two years (2008-2009). The experiment was conducted as split split-plot arranged in a completely randomized blocks design with three replications. Treatments were two red bean cultivars as main plots, N levels (0, 34.5, 69, and 103.5 kg ha-1) as sub-plots and residue rates (0, 25, 50 and 75%) as sub sub-plots. The results showed that application of crop residues significantly increased soil organic carbon, N, K, and P contents. Heavy crop residue (75%) application had no effects on these soil properties. Thus, retaining 50% crop residue was optimum for proper soil quality. Increased N application increased soil N, decreased P and K contents, and had no effects on organic carbon.
S. Dodangeh, J. Abedi Koupai, S. A. Gohari,
Volume 16, Issue 59 (spring 2012)
Abstract
Due to the important role of climatic parameters such as radiation, temperature, precipitation and evaporation rate in water resources management, this study employed time series modeling to forecast climatic parameters. After normality test of the parameters, nonparametric Mann-Kendall test was used in order to do trend analysis of data at P-value<0.05. Relative humidity and evaporation (with significant trend, -0.348 and -0.42 cm, respectively), as well as air temperature, wind speed, and sunshine were selected for time series modeling. Considering the Autocorrelation function (ACF) and Partial Autocorrelation function (PACF) and trend of data, appropriate models were fitted. The significance of the parameters of the selected models was examined by SE and t statistics, and both stationarity and invertibility conditions of Autoregressive (AR) and Moving average (MA) were also tested. Then, model calibration was carried out using Kolmogorov-Smirnov, Anderson- Darling and Rayan-Joiner. The selected ARIMA models are ARIMA(0,0,11)*(0,0,1), ARIMA(2,0,4)*(1,1,0), ARIMA(4,0,0)*(0,1,1), ARIMA (1,0,1)*(0,1,1), ARIMA (1,0,0)*(0,1,1) for relative humidity, evaporation, air temperature, wind speed and sunshine, respectively. The fitted models were then used to forecast the parameters. Finally, trend analysis of forecasted data was done in order to investigate the climate change. This study emphasizes efficiency of time series modeling in water resources studies in order to forecast climatic parameters.
S. A. Ghasemi , Sh. Danesh,
Volume 16, Issue 61 (fall 2012)
Abstract
In this research, the quality of the effluent from the City of Mashhad wastewater treatment plants was evaluated based on Ayers and Westcot irrigation water quality guideline, and the potential impacts of these effluents on soil and plants were assessed. For this purpose, the effluent from each of the three existing wastewater treatment plants was sampled on a regular basis, for a period of one year, and their parameters of importance in regard to the agricultural use such as pH, electrical conductivity (EC), concentrations of Sodium, Calcium, Magnesium, Chloride, Boron, Nitrate (NO3-N), bicarbonate and heavy metals were measured. Based on the obtained results, the agricultural use of the effluents from the wastewater treatment plants has severe restriction in regard to the bicarbonate concentrations (8-12.1 meq/L). Also, in view points of parameters such as EC (1250-1874 µS/cm), Sodium (5.8-8.7 as SAR), Chloride (3.2-6.5 meq/L) and adj RNa (7.8-11.7), the effluents were categorized in the class of waters with low to moderate restrictions. However, the measured values of pH (7.3-8), Boron (0.2-0.8 mg/L), Nitrate Nitrogen (0.5-4.2 mg/L) and heavy metals did not indicate any restrictions for agricultural use. From the results of this research, it can be concluded that the use of effluent as irrigation water requires careful planning, monitoring and management strategies.
M. Liaghat, F. Khormali, S. A. Movahedynaeini, E. Dordipour,
Volume 16, Issue 61 (fall 2012)
Abstract
Studies on the soils of western Golestan province show that regardless of increased rain and presence of clay minerals with high cation exchange capacity, potassium extractable with ammonium acetate is low. In order to find the reason for this low amount of available K, clay minerals and micromorphology of the soil porosity were studied. Twenty disturbed and undisturbed samples from each horizon were taken for physicochemical properties, mineralogy and micromorphological studies. Four selected profiles included Gypsic Aquisalids, Typic Endoaquepts, Typic Calcixerolls and Typic Hapludalfs. The results showed that in addition to the clay content and type of clay minerals in soils that can affect soil available K (Kava.), it seems soil porosity can also affect Kava. mainly through their effects on extension of roots, water and nutrients transmission. Favorable content of clay and dominance of smectites in Mollisols and also higher porosity and dominance of channel porosities caused the presence of higher Kava, in these soils. presence of HIS. poor soil drainage, reduction of Fe3+ in smectite crystal lattice in Inceptisols, and also less amount of porosities caused the presence of higher potassium fixation and reduction of Kava. in these soils.
S. Jafari, Z. Iranshahi , Gh. Fathi, S. A. Syadat,
Volume 16, Issue 61 (fall 2012)
Abstract
Cadmium is a toxic element in plant nutrition and is considered as a contaminant of food and feed. A greenhouse experiment was carried out to examine the effects of combined application of cadmium and zinc on responses of wheat on a clay loam soil texture. This experiment was designed in a factorial experiment with randomized complete block design (RCBD) and four replicates per treatment. Three levels of cadmium (Cd 0, Cd 50 and Cd 100 mg kg-1) and three levels of zinc (Zn 0, Zn 50 and Zn 100 mg kg-1) were added to the pot in factorial(9 treatments), and then Chamran seed variety of wheat (triticum aestivum L.) was planted in each pot. The statistical analyses showed that Cd application significantly (P0.01) decreased grain, straw, and total yield, but Zn application increased these parameters significantly (P0.01). Application of Cd separately decreased the grain yield by 61.5 while application of Zn separately increased the grain yield by 36.9. Cd application increased the Cd concentration and uptake by grain and straw as well as total uptake but by increasing Zn application, Cd uptake was decreased by wheat. Cd concentration was higher in straw than that grain, but Zn showed a different trend. Decreasing Zn applications decreased total uptake of Cd from 42.9 in Zn0 to 7.8 mg kg-1 in Zn100 treatment. Although this soil was very calcareous, this characteristic did not control Cd absorbtion.
S. A. Mohseni Movahed, M. Akbari, P. Salehi Moghadam,
Volume 17, Issue 66 (winter 2014)
Abstract
As pressurized irrigation is not possible for all circumstances, the use of modern techniques in surface irrigation is essential. In this paper, BISEDOM, a new mathematical model for evaluation, design and optimization of border irrigation is introduced. The effects of weighting coefficients of indicators are investigated based on the potential to improve and the most appropriate weighting scheme in optimization process is presented. In this model, volume balance equations for hydrodynamic simulation and SA method for optimization steps are used. Due to the nature of the SA, its parameters are determined by the method of sensitivity analysis. In this model, evaluation of different combinations of decision variables (inlet flow, length, width and slope of the strip) and consequently the performance of irrigation efficiencies reagent strip in an objective function is possible. Finally, the results indicate that the proposed method for weighted indicators has significant effects on improving performance of border irrigation. Model validation results in three parts of design, evaluation and optimization in comparison with SIRMOD and asymptote method showed that the results are very close to each other. The results also indicate that the proposed model has a good efficiency in comparison with other existing models especially for optimization purposes.
S. A. A. Hashemi,
Volume 17, Issue 66 (winter 2014)
Abstract
Check dams are considered as main measures for flood and sediment control in watersheds, and their uses have been rapidly increased from 1990 onward in Iran. This research is done in Darjazin watershed in north of semnan city. The check dams have been constructed from 15 years ago in two sub basins of the watershed for flood control in Mahdishar. More than 650 check dams were evaluated for effects on flood. The collected data in the field was fed to ArcGIS software. The effects of these structures on flood reduction were evaluated by HEC-GeoHMS extension and HEC-HMS model. Because of homogeneity of watershed management projects in the basin due to building more check-dams in different watercourses, any flood discharge is related to check dams. Evaluating the effects of check dams on flood by t-test showed significant differences between flood discharge before and after construction of check dams at 5 percent level. So, check dams have been able to reduce flood discharge by 16.7 percent on average.
H. Kashi, H. Ghorbani, S. Emamgholizadeh, S. A. A. Hashemi,
Volume 18, Issue 67 (Spring 2014)
Abstract
Change in land use and tillage practices has great influence on soil physical and chemical properties. The present study has focused on the effects of converting undisturbed soil to agricultural lands. Chemical and physical soil properties, infiltration, cation exchange capacity (CEC), electrical conductivity, pH, bulk density, porosity, sodium, potassium, total Ca + Mg, organic matter percentage, sodium adsorption ratio (SAR) and lime percentage were measured using standard frequently used methods. Fifty soil samples from agriculture land and other 50 soil samples from undisturbed land were collected from 0 – 30 cm depth and different statistical analysis were performed. Agriculture land is Cultivated for more than 20 years. The results showed that change in land use from undisturbed to disturbed soil did not significantly changed soil organic matter content. Also, soil electrical conductivity showed a huge increase whereas pH showed non-significant changes due to land use change. Unlike pH, SAR, organic matter percentage and lime percentage, some other soil parameters showed significant decrease in quality through land use change. Correlation coefficients of the effective factors were calculated to explain the main reason for lowering soil quality. The results showed that sodium in EC bulk density in porosity and CEC sodium and Ca+Mg in SAR EC in soil infiltration and Ca+Mg in organic matter showed the most correlation.
M. Hosseini, S. A. Movahedi-Neeni, M. Zeraat Pishe,
Volume 18, Issue 68 (summer 2014)
Abstract
Effects of five various tillage systems on soil porosity, volumetric water content, diurnal and nocturnal soil temperatures, plant water uptake and dry matter yield was investigated using a completely randomized design with five treatments and four replications in Gorgan University of Agricultural Sciences and Natural Resources research farm located in Seyed-Miran during 2009-2010 growing season. Tillage systems were: moldboard plough followed by one discing (20-25 cm) rototiller (12-17 cm) double disc (8-10 cm) Chisel plow (25-30 cm) No-tillage. Results show that during all stages of wheat growth, the highest and the lowest soil porosities at 0-8 cm depth were obtained by moldboard plough and No-tillage treatments respectively. For all stages except before tillering and harvest, the highest soil porosity obtained by moldboard treatment at 8-16 cm depth. Increasing tillage intensity increased those porosity that keep water in potentials greater than -5 and those in potentials less than -15 bar. No-tillage and moldboard induced the highest and the lowest soil temperatures respectively before earring stage. Tillage intensification, increased soil porosity and root density. More roots reduced soil water content in response to increased water uptake by wheat, resulting greater dry matter accumulation.
S. A. Banimahd, D. Khalili, A. A. Kamgar-Haghighi, Sh. Zand-Parsa,
Volume 18, Issue 70 (winter 2015)
Abstract
In the present research, the performances of six empirical models, i.e., simple threshold exceedance, fixed proportion exceedance, quadratic function of storage, power function of storage, cubic function of storage, and exponential function of storage were investigated for estimation of groundwater potential recharge in a semi-arid region. First, the FAO Dual Crop procedure was used to calibrate evaporation from bare soil during the occurrence of potential recharge period. Then, the empirical models were calibrated utilizing soil moisture and potential recharge data. For validation of empirical models, soil moisture and potential recharge were simultaneously estimated for an independent event. Results indicated that 5 of the six models (except for the simple threshold exceedance model) were able to estimate potential recharge with a reasonable accuracy, showing the maximum computed value of NRMSE (Normalized Root Mean Square Errors) of 24.4 percent. According to validation results, exponential, cubic, and power function models provided better estimation of potential recharge in comparison with the linear models. Also, all of the applied empirical models were able to simulate soil moisture during the recharge period with an acceptable accuracy. Finally, the exponential model with minimum NRMSE value for soil water simulation and also acceptable performance of potential recharge estimation was recommended for estimation of potential recharge in the study area.
S. Shakeri, S. A. Abtahi, N. A. Karimian, M. Baghernejad, H. Owliaie,
Volume 19, Issue 73 (fall 2015)
Abstract
The aim of this study was to assess the kinetics of nonexcheangable potassium release in surface and subsurface soil horizons, using organic and inorganic extractions, in Kohgilouye-va-Boyerahmad Province. Kinetics of K+ release was studied by successive extractions of K from 64 selective surface and subsurface soil samples, using 0.01 M CaCl2 and 0.01 M oxalic acid, for 1948 h, with two replicates. Nonexchangeable K+ release was fitted by Elovich, Pseudo-first order, Power function and Parabolic equations. Result showed that the average nonexchangeable K+ released (extracted by 1M HNO3) was 356 mg/kg, while those extracted by CaCl2 and oxalic acid after 1948 h were only 58% and 52% of the total amount of nonexchangeable K+ of the soils, respectively. In all soil samples, nonexchangeable K+ released by oxalic acid was less than that released by CaCl2, due to the high buffering capacity resulting from high carbonates in the soils. Potassium release rate in Elovich and Parabolic equations were significantly correlated with non-exchangeable potassium and some physical and chemical characteristics. Based on high Coefficients of determination (r2) and low Standard errors (SE), Elovich, Power function, First order and Parabolic equations were selected as the best equations for prediction of K+ release from the soils.
D. Rajabi, H. Karami, Kh. Hosseini, S. F. Mousavi , S. A. Hashemi,
Volume 19, Issue 73 (fall 2015)
Abstract
Non-linear Muskingum model is an efficient method for flood routing. However, the efficiency of this method is influenced by three applied parameters. Therefore, efficiency assessment of Imperialist Competition Algorithm (ICA) to evaluate optimum parameters of non-linear Muskingum model was addressed in this study. In addition to ICA, Genetic Algorithm (GA) and Particle Swarm Optimization (PSO) were also used to find an available criterion to verify ICA. In this regard, ICA was applied for Wilson flood routing then, routing of two flood events of DoAab Samsami River was investigated. In case of Wilson flood, the target function was considered as the sum of squared deviation (SSQ) of observed and calculated dischargem. Routing two other floods, in addition to SSQ, another target function was also considered as the sum of absolute deviations of observed and calculated discharge. For the first floodwater based on SSQ, GA indicated the best performance however, ICA was in the first place, based on SAD. For the second floodwater, based on both target functions, ICA indicated a better operation. According to the obtained results, it can be said that ICA could be recommended as an appropriate method to evaluate the parameters of Muskingum non-linear model.
H. Daliran Firouz, F. Mokhtari, S. Soltani , S. A. Mousavi,
Volume 19, Issue 74 (Winter 2016)
Abstract
Floods are considered as most destructive among all natural hazards which impose lots of damages on human societies. Hence, it is important to estimate such damages and losses and to determine flood impact areas for management plans. HEC-FIA software as a new model (Sep. 2012) was used in Ghohrood and Ghamsar watershed basins to estimate flood-driven losses and impacts. In this model, HEC-RAS and HEC-Geo RAS are used to produce inundation map in different return periods of flood as HEC-DSS file and by using the data collected in relation to regional agricultural land, building and human, human and financial losses are directly estimated. According to the results of this model, agriculture, building and human losses respectively in Ghohrood watershed are about 354 million rials with 24 buildings affected, and in Ghamsar watershed this is about 12879 million rials with 36 buildings damaged. The advantages of this model over the previous models are estimating the direct economic and human losses for what has occurred and for possible floods in the future. The results can help with watershed management, flood insurance and risk management.
Mohseni Movahed S. A.,
Volume 20, Issue 76 (Summer 2016)
Abstract
In the ICSSDOM simulation-optimization model, simulated annealing algorithm is combined with a hydrodynamic simulation model named ICSS. In this model the ability of weighting of indicators is also considered. In this study, using this model the performance of the S-L-R5 canal in the DEZ irrigation network was evaluated in a period of 10 days. With presenting a proposed method for weighting the indicators and its various options, using parametric sensitivity analysis, optimal adjustment of intake and check structures was obtained. It was found if the coefficient of each index is selected as a direct ratio of the ideal improvement potential of the indicator, the percentage of the improvement is more than the other investigated options. In addition, due to the interaction of the indicators in the multi-objective functions, the consistency of the weighting method with the nature of the optimization problem in this study has been shown. Statistically, the adequacy of the 10-day period of study was confirmed. The model validation with mathematical asymptote method shows 6% error which indicates the model is valid. For example, on the first day, based on the option three (The optimal option), the optimal gate opening for 5 intakes and one check control was between 3.9 to 14.7 Cm. In this condition optimal delivery was between 46 to 178 liters per second.
S. A. M. Mirmohammady Maibody, S. Dybaie, H. Shariatmadari, N. Baghestani,
Volume 21, Issue 2 (Summer 2017)
Abstract
The adaptability of Haloxylon appilium to adverse environmental conditions and especially its capability for an appropriate establishment in saline and desert soils has introduced this plant as a suitable means for biological methods to stabilize sand dunes, control erosion and prevent desertification in arid regions. In order to evaluate the ecophysiological characteristics of Haloxylon appilium some characteristics of soils under the long term establishment, survival and development of this plant and ion composition of this plant growing in Yazd province in thirty two growing trees of similar ages and traits within 8 locations of Chah Afzal and Ashkezar were investigated and their height (H), crown diameter (CD) and the above ground biomass index (Yi) were measured. Also, after cutting the trees from their collars, soil profiles were dug underneath the tree locations and soil samples were taken at depths of 0-30, 30-60, 60-90 and 90-120cm from four sides of each profile. The samples were then analyzed for Electrical Conductivity (EC), pH and Cl, Na, Ca, Mg, K concentrations in 1:5 soil to water extracts. The results showed statistically significant differences in soil parameters between the two regions, except for pH and Mg concentrations. The ion concentration of the plants in the two regions showed statistically significant differences for only Cl in shoots and Ca in roots. Based on the plant growth indices the Chah Afzal and Eshkezar regions were respectively evaluated as suitable and unsuitable for Haloxylon appilium growth. In spite of a higher salinity, the higher Ca and K concentration and lower Na/K ratio of Chah Afzal soils may explain the better plant performance in this region against Eshkezar, however, comprehensive researches on application of Ca and K fertilizer are needed to confirm this hypothesis
S. Shakeri, S. A. Abtahi,
Volume 22, Issue 4 (Winter 2019)
Abstract
This research was carried out to assess the origin and clay minerals characteristics and their relationship with potassium forms in the calcareous soil of this region, with the humid climate conditions. Based on aerial photos and topographic maps, physiographic units were separated and soil sampling was done in each diagnostic horizon. The results showed that smectite was the main and dominant clay mineral in the study area. In well-drained pedons, the convincing process for smectite abundance seemed to be mainly the transformation of palygorskite and mica. According to the results, the exchangeable potassium in the surface horizon was higher than that of the subsurface horizons. The main reason for the higher level of exchangeable K in the soil surface, was more smectite and organic carbon. The results revealed that unlike exchangeable and non-exchangeable K, because of the suitable conditions like temperature and humidity in surface horizons, the relative mean of structural K in the surface soils was less than that in the subsurface. Also, since an increase in calcium carbonate resulted in a decrease in amount of clay and the amount of relative clay minerals (dilution effect), the amounts of exchangeable, non- exchangeable and structural K were decreased.
S. A. Banishoaib, A. Bordbar, A. A. Kamanbedast, A. Masjedi, M. Heidarnejad,
Volume 23, Issue 4 (winter 2020)
Abstract
A ‘spillway’ is a structure used to provide the controlled release of flood water from upstream into downstream area of a dam. As an important component of every dam, a spillway should be constructed strongly, reliably and efficiently to be used at any moment. Labyrinth and stepped spillways are presented as appropriate modifications to those spillways hardly capable of managing the maximum potential discharge. Owing to their nonlinear crests for a given width, labyrinth and stepped spillways have a larger discharge rate than linear- crest spillways at an identical height. Compared to other energy dissipaters, the combination of stepped and labyrinth spillways is known as a very strong energy dissipater. In the following part, the combination of these two structures and their dimensional change for increasing the water- energy dissipation are addressed. To conduct this study, an experimental flume with a 90- degree bend in the Islamic Azad University of Ahwaz was used. In total, 90 experiments were conducted on three different labyrinth- shape stepped spillway models with two different lengths, three different widths, and five different discharges. Analysis of the results showed a greater energy loss reduction in triangular rather than rectangular or trapezoidal labyrinth- shape stepped spillways. In addition, energy loss was greater in labyrinth spillways with two cycles than those with one cycle. Energy loss was increased by raising the Froude number from 0.05 to 0.1; in contrast, energy loss was decreased with increasing the Froude number from 0.1 to 1.0, which was due to the submergence of steps, a decrease in the roughness of steps and an increase in the intensity of aeration.
