Showing 5 results for Mehri
M. Heidarour, S. F. Mousavi, A. R. Roushani Zarmehri,
Volume 10, Issue 3 (fall 2006)
Abstract
Because of slight variation of the static head due to discharge fluctuations, the labyrinth weirs are considered to be economical structures for flood control and water level regulation in irrigation networks, as compared to other devices. Labyrinth weirs are composed of folded sections observed as trapezoidal and triangular in plan view. In this study, rectangular and U-shaped labyrinth weirs were investigated. Experiments were conducted on 15 labyrinth weir models. The models included eight rectangular labyrinth models and six U-shaped labyrinth models with different heights and lengths, and one linear model. All the experiments were performed in a horizontal rectangular flume, 7 m long, 0.32 m wide and 0.35 m high. The results indicated that for all the models, discharge coefficient increased sharply with an increase in Ht/P and attained a maximum value. This coefficient then decreased smoothly with a further increase in Ht/P. Increasing height of weirs increased the discharge coefficient for both rectangular and U-shaped weirs. The results also showed that increasing the length parallel to the flow direction decreased and increasing the length perpendicular to the flow direction increased the discharge coefficient. Generally, the discharge coefficient for rectangular weir was less than that of the U-shaped weir. The obtained results compared with those of Tullis et al. (1995) showed that discharge coefficient for U-shaped weir is more and for rectangular weir is less than that of the trapezoidal weir for angle of the side legs of 8 and 12 degrees.
Majid Hejazi Mehrizi, Hossein Shariatmadari, Majid ََafyuni,
Volume 17, Issue 64 (summer 2013)
Abstract
Application of sewage sludge has been considered as an organic fertilizer in arid and semi-arid regions of Iran. This study was conducted to investigate cumulative and residual effects of sewage sludge on soil inorganic fractions and their relation to phosphorus (P) availability. Two levels of application (50 and 100 Mg ha-1) and three consecutive times of sewage sludge application (1, 3 and 5 years) with a control treatment were studied in a randomized complete block split plot design with three replications. Composite soil samples were collected from 0-30 depth at the end of 5th year of application. Increasing the rate and application year of sewage sludge enhanced dicalcium phosphate (Ca2-P), octacalcium phosphate (Ca8-P), apatite (Ca10-P), aluminum phosphate (Al-P), iron phosphate (Fe-P) and available P but decreased occluded P (OC-P). Residual effect of sewage sludge application resulted in increased inorganic fractions in blocks treated for 1 year compared to control. Positive correlations were observed between inorganic P fractions and Olsen P, wheat yield and P uptake (except OC-P). We concluded that inorganic P fractions and P availability increased in sewage sludge amended soil.
F. Mehri Yari, H. Pirkharrati, Kh. Farhadi, N. Soltanalinezhad, F. Naghshafkan,
Volume 24, Issue 1 (Spring 2020)
Abstract
Soil pollution by heavy metals is a serious environmental problem that threatens the human health. The present study was carried out to investigate and detect the contamination of heavy metals of arsenic, copper, lead, zinc and iron due to human and natural activities in the sediment of lake bed and the surface soils of the eastern part of Urmia Province, West Azarbaijan Province. A total of 20 soil samples and surface deposition from the depths of 0 to 30 cm were collected randomly from the studied areas. After preparing the samples, extraction was carried out to determine the concentration of the heavy metals in the soil by using hydrochloric acid and nitric acid, and the total concentration of metals was measured using ICP-OES. The results of the calculation of the contamination factor showed that copper, iron, zinc and lead in the class of low and medium pollution and arsenic in 65.5% of the samples were very high in the class. The high concentrations of copper, lead and zinc contamination in the margin of the city and the contamination of arsenic in the lake bed were observed. The analysis of the contamination factor maps and contamination index with land use and geological map showed that copper, lead and zinc were mostly affected by human activities and arsenic influenced by the maternal materials in the region.
S. Mehri Babadi, M. Afyuni, Sh. Ayoubi,
Volume 24, Issue 1 (Spring 2020)
Abstract
For sustainable soil management, the effects of slope position and land use change on soil and water resources are essential. In this research, three land uses including degraded pasture, drought and apple gardens were selected to determine the effect of slope position and land use on some physical and chemical properties of soil in the Koohrang area of Chaharmahal and Bakhtiari province. Each of the applications was divided according to the position of the slope, and from three applications and organic matter (OM), saturated hydraulic conductivity (Ks), water repellency (RI), dispersible clay (DC) and weighted average aggregate diameter (MWD) were studied as the physical and chemical properties of soil. The results showed that Ks had the greatest coefficient of variation. Also, the results of the mean comparison revealed that all of the measured physical and chemical properties had a significant difference in different slope applications and positions at 5% level. In general, the garden and the base position of the slope had better qualitative conditions than other land uses and slope positions. Rangeland degradation and change in the use of pasture from dryland cultivation led to a decrease in soil quality, which could reduce soil utilization and exhaust some of the land from the production cycle. The results of the correlation between chemical and physical properties of soil showed that in general soil organic matter had the highest correlation with other parameters.
M. Mehri, M. Hashemy, S. Javadi, M. Movahedinia,
Volume 27, Issue 3 (Fall 2023)
Abstract
Rapid urbanization is responsible for impervious area increases and more runoff generation in urbanized catchments. Higher runoff volume in urbanized catchments leads to higher flood risk. One of the methods of runoff management is low impact development (LID). Bio-retention cell (BRC) is one of the infiltration-based LID practices that allows restoring the pre-development hydrologic cycle. However, the overall hydrologic performance of BRCs can vary depending on different urban environments. In this study, the hydrologic performance of BRC in terms of runoff and flood reduction was investigated in a highly urbanized area in the east of Tehran, Iran. The SWMM model was used to evaluate the performance of BRC. The results showed that BRC for rainfall with a return period of 2 to 50 years reduced the total runoff volume by 76.2% to 70.2% and the peak discharge by 65.9% to 36.4%, respectively. Also, for rainfall with a return period of 2 to 50 years, BRC resulted in 15.2% to 27.5% infiltration of rainfall in the study area, respectively. This study demonstrates that BRC can help restore the natural hydrologic cycle of urbanized catchments by reducing runoff and increasing infiltration.
