Showing 3 results for Shojaei
M. Vafakhah, G.h. Shojaei,
Volume 11, Issue 42 (winter 2008)
Abstract
Continuous measurement of river discharge is a hard and expensive task in hydrology. To overcome this problem, the stage readings at hydrometric gauges are permanently taken and the discharge of any time at which the actual discharge is unavailable will be estimated through a relationship between discharge and stage. To study the stage-discharge relations and the capability of long-term data in establishing a permanent stage-discharge relationship, and also to determine the best time to measure the discharge of rivers, a study was conducted at the hydrometric station of the Zayandehrud regulatory dam using data from 1990 to 2003. The data were analyzed using simple regression analysis, the percentage of relative error and factor analysis. The results indicated that the best model to show the stage-discharge relation at the studied station is a power function model. Moreover, the model used for every year can only be used for that year. The results also showed that the most suitable times for the measurement of discharge are July, December and March.
P. Shojaei, D. Farsadizadeh , A. Hoseinzadeh Dalir,
Volume 15, Issue 57 (fall 2011)
Abstract
Submerged vanes are low aspect ratio flow-training structures mounted vertically on the river bed at an angle to the prevailing flow. The aim of application of vane is to generate a secondary circulation in the main flow, designed to modify the near-bed flow pattern and thus redistribute flow and sediment transport within the channel cross section. Collar is a flat sheet with low thickness fixed vertically on the pier at stream bed level or near it. Installation of a collar leads to protect the river bed against the direct impact of downflow produced at the upstream face of the pier and therefore reduces the scour depth. This research is a laboratory study that examines the effectiveness of submerged vanes and combination of submerged vanes and collar as a pier scour protection device. Experiments were conducted in an 8 m long and 0.8 m wide flume and a cylindrical pier used was 6 cm in diameter. Clear-water scour tests with u*/u*c = 0.9 were performed with a collar 3 times wider than the pier diameter at the stream bed level and submerged vanes 1.5 times longer than the pier diameter at the stream bed level (H=0). Different arrays of vanes with different angles to main flow direction were employed. The highest reduction in the depth of scour hole with four vanes and a collar showed 61% reduction in scour depth.
P. Shojaei, M. Gheysari, H. Nouri, H. Esmaeili, S. Eslamian,
Volume 23, Issue 3 (Fall 2019)
Abstract
Creation and conservation of urban parks is challenging in arid environments where daily thermal extremes, water scarcity, air pollution and shortage of natural green spaces are more conspicuous. Water scarcity in the arid regions of Iran is major challenge for water managers. Accurate estimation of urban landscape evapotranspiration is therefore critically important for cities located in naturally dry environments, to appropriately manage irrigation practices. This study investigated two factor-based approaches, Water Use Classifications of Landscape Species (WUCOLS) and Landscape Irrigation Management Program (LIMP), to measure the water demand in a botanic garden. The irrigation water volume applied was compared with the gross water demand for the period from 2011 to 2013. On average, WUCOLS estimated an average annual irrigation need of 1164 mm which is 15% less than the applied value of 1366 mm while the LIMP estimate of 1239 mm was 9% less than the applied value. Comparison of estimated and applied irrigation showed that a water saving of 9% can be made by the LIMP method. The outcomes of this research stressed the need to modify the irrigation requirements based on effective rainfall throughout the year, rather relying on long-term average data.
