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Showing 23 results for Development
Determination of the Suitable Location of Soil Moisture Sampling in Drip-Tape Irrigation Management in A Maize Field
Z. Amiri, M. Gheysari, M. R. Mosaddeghi, M. S. Tabatabaei, M. Moradiannezhad,
Volume 23, Issue 2 (9-2019)
Abstract
Location of soil moisture sampling in irrigation management is of special importance due to the spatial variability of soil hydraulic characteristics and the development of root system. The objective of this study was determination of the suitable location for soil moisture sampling in drip-tape irrigation management, which is representative of the average moisture in the soil profile (θavg) as well. For this purpose, soil moisture distribution (θij) at the tassel stage of maize and one irrigation interval (68-73 day after plant) were measured at the end of season. The results showed more than 70% length of the root of plant was located in 30 cm of the soil depth. By accepting ±10% error in relation to the averaged soil moisture, some region of soil profile was determined which was in the acceptable error range and also near the averaged soil moisture (0.9θavg<θRec<1.1θavg). By overlapping θRec in one irrigation interval, the appropriate location for soil moisture sampling was the horizontal distance from drip-tape line to 20 cm and the depth of 10-20 cm from the soil surface. To determine the appropriate place for soil moisture sampling, the development of root system and the maximum concentrated root length density in the soil profile extracting the maximal soil moisture should be taken in to account, parallel with the averaged soil moisture.

Study of the Effect of Crossover Structures and Roughness Coefficient on Depth and Flood Plain of the Urban Watercourses (Case Study: Zarkesh Watercourse, Mashhad)
S.a.r Esmaili, A. Mosaedi,
Volume 26, Issue 1 (5-2022)
Abstract
In recent decades, population growth, urban sprawl, urban environmental changes, and related issues are one of the significant issues in proper planning to manage the urban environment. One of the issues in urban development is the occurrence of floods and flooding due to heavy rains. In this research, flood modeling was studied in Mashhad Zarkash watercourses. The amount of rainfall for the return period of 10, 25, 50, 100, and 200 years were extracted by CumFreq software using the maximum 24-hour rainfall statistics of three rain gauge stations closer to the Zarkesh, Jagharq, Sar-e-Asyab, and Torqabeh watercourses basins during the statistical years 1364 to 1390. The peak discharge was calculated using the US Soil Protection Organization (SCS) rainfall-runoff method. Zarkesh watercourse is located on the outskirts of Mashhad. River and flood flow modeling was performed using Arc GIS, HEC-GEORAS, and HEC-RAS software in two conditions including structure (bridge) and no structure. Due to urban marginalization, urban development and land use change have greatly expanded in this region. The results of flood simulation showed that flood levels with a return period of 50 years increased by 50000 m2 equal to 22% in the presence of a structure compared to the state without a structure. The results of this research show that the construction of bridges on the river, the roughness coefficient by land use change, and the number of curves due to land permeability changes are effective in the flood zone.

Bio-Retention Cells Performance in Restoring the Hydrologic Cycle of Highly Urbanized Catchments
M. Mehri, M. Hashemy, S. Javadi, M. Movahedinia,
Volume 27, Issue 3 (12-2023)
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.

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