Ali Abdollahzadeh; Majid Ownegh; Amir Sadoddin; Raoof Mostafazadeh
Abstract
Identification the source areas of surface runoff and flood prone zones and their impact on residential expansion are important. The aim of the present study is to consider the impact of potential runoff coefficient and flood inundation for different recurrence intervals in analyzing residential expansion ...
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Identification the source areas of surface runoff and flood prone zones and their impact on residential expansion are important. The aim of the present study is to consider the impact of potential runoff coefficient and flood inundation for different recurrence intervals in analyzing residential expansion for the current land use pattern as well as suitable land use allocation based on the systemic land use planning of Iran in the Ziarat watershed in Golestan Province. The pre-processed Landsat TM image 2010 was used to determine the land use map of the study area and then a suitability analysis is then carried out to establish the potential residential development area in the framework of Iranian systemic land use planning model. The raster layers of slope, soil type, and land use were prepared and the potential runoff coefficient values were determined using the attributes. Floodplain zonation maps were delineated by integrating HEC-RAS and ArcGIS in different return periods. The results indicate that the residential area covers 3.4% of the study area and 9% of the study area was assigned as 1 and 2 suitability classes, according to land use planning model. On the basis of the potential runoff coefficient map, the average runoff coefficient was 0.51%. Based on the combined flood zone maps and runoff coefficient, the flood prone areas will increase for 25, 50, 100, and 200 year floods for both current and determined residential land uses. The areas of flood-secure regions in current residential land use were 318.47, 317.46, 316.44, and 316.44 ha for different design floods respectively. Increasing the return period from 20-50 to 100-200 years lead to an increase of flood zone extent (3.5 ha).
Seyed Hamidreza Sadeghi; Raoof Mostafazadeh; Amir Sadoddin
Abstract
Assessment of suspended sedimentgraph (SG) and rating loops are important tools for analyzing the behavior of watersheds and successful implementation of watershed management measures in reducing sediment. However, the development and analysis of SGs and rating loops and influencing factors need more ...
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Assessment of suspended sedimentgraph (SG) and rating loops are important tools for analyzing the behavior of watersheds and successful implementation of watershed management measures in reducing sediment. However, the development and analysis of SGs and rating loops and influencing factors need more attention in watershed-scale. Therefore, the present study aimed to conduct the analysis of 13 observed and simulated sedimentgraphs (SGs) during October 2011 and November 2012, in Galaz-Chai Watershed with an area of 103km2 located in West-Azarbaijan Province, Iran. Towards this attempt, the SG of observed events was derived using instantaneous unit sediment graph (IUSG) concept, and the effects of different land uses were investigated. Also, the variation and patterns of the simulated sedimentgraphs (SGs) and rating loops were plotted and interpreted with the respective land use types. Based on the results, an early peak occurred in SGs with respect to the observed hydrograph peak rates and consequently had clock-wise pattern. Increase in falling limb of hydrograph could be attributed to the participation of sediment production from agricultural land in watershed upstream. The model predicted SGs with good accuracy according to the Nash-Sutcliffe criterion (70%). Analysis of results indicated that the type and distribution pattern of different land uses had significant effect on the shape of SGs and sediment rating loops.
Raouf Mostafazadeh; Amir Sadoddin; Abdolreza Bahremand; Vahedbordi Sheikh; Habib Nazarnejad
Volume 2, Issue 2 , July 2010, , Pages 83-93
Abstract
Assessment of flood control projects in the same conditions is essential in order to improve decision making that assist us in watershed management purposes. Focus of this study is on assessing hydrological effects of the Jafar-Abad watershed management project. The study area (109 km2) located in north ...
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Assessment of flood control projects in the same conditions is essential in order to improve decision making that assist us in watershed management purposes. Focus of this study is on assessing hydrological effects of the Jafar-Abad watershed management project. The study area (109 km2) located in north of Iran in the Golestan province. Paired t-tests were performed for Indicators of Hydrologic Alteration (IHA) in Taghi-Abad gauging station, located in the outlet of the catchment, before and after construction of 58 check dams. HEC-HMS model was calibrated using 12 storm events and validated for study area. Calibrated HEC-HMS model was applied to rainfall-runoff modeling in sub-catchments and Level-pool method used for reservoir elements. Design flood hydrographs for 2-100 year return periods were simulated for both before and after check dams construction periods. The results of statistical analysis indicate that existing flood control measures had no significant impact on the hydrologic characteristics measured by IHA in 95% confidence level. The results indicated that constructed structures do not have important effect on IHAs and the amount of these effects was less than 1.5 percent in all cases. Also, by increasing in return period, the effects of structures on peak discharge and flood volume were reduced.
