Mohammadhossein Rezaei Moghadam; Nooshin Pirouzi Nejad
Volume 18, Issue 47 , April 2014, , Pages 109-132
Abstract
River channel change, such as bank erosion and accretion are natural processes in alluvial rivers. This paper aims to investigate migration and channel change plan form and effect on bank erosion and accretion done in Gamasiab River in Kermanshah Province. This study used aerial photography taken ...
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River channel change, such as bank erosion and accretion are natural processes in alluvial rivers. This paper aims to investigate migration and channel change plan form and effect on bank erosion and accretion done in Gamasiab River in Kermanshah Province. This study used aerial photography taken in 1955, 1969, 2003 and IRS satellite imagery of 2010 with a resolution of 5/8 m, aerial photographs were orthophoto in ARCMAP software based on 1/25000 topographic map. Shoreline was digitized and river was divided into 12 reaches. By comparing river in the sequence period investigated the positions have a change. Using the ARCMAP software to create polygons that represented the difference between two positions we calculated erosion and accretion separately for each side of the river. The area of bank accretion along the river had been 285.5 ha and from 1955 to 1969 this area had been 402.6 ha from 1969 to 2003 and the area of bank accretion was 112.9 ha from 2003 to 2010. Bank erosion had been 347 ha from 1955 to 1969, and this was been 414.17 ha from 1969 to 2003 and the area of bank erosion had been 138.2 ha from 2003 to 2010. Results show that the amount of bank erosion is more due to bank accretion in the Gamasiab River. Change and migration in river is the cause of the erosion. Some places in river show about 400 m of movement.
Amjad Maleki; Homayoon Hasadi; Nooshin Pirouzi Najad
Volume 17, Issue 46 , February 2014, , Pages 223-239
Abstract
This study was done to identify effective factors on flooding in Razavar basin in the north of Kermanshah province by using SCS model. For flood estimating, primarily Razavar watershed was divided to sub-watersheds with stream orders of 5, 6, and 7 then effective factors such as area, slope, CN, lag ...
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This study was done to identify effective factors on flooding in Razavar basin in the north of Kermanshah province by using SCS model. For flood estimating, primarily Razavar watershed was divided to sub-watersheds with stream orders of 5, 6, and 7 then effective factors such as area, slope, CN, lag time, time of concentration, density of rainfall, land use, slope, geology, and vegetation were studied and the peak flood discharge was estimated by SMADA software. Peak flow estimation by SCS method showed maximum of 100 years return period peak discharge of Razavar watershed with 8 stream order was 691.85 m3/s and the minimum of 100 years return period was related to sub-watershed number of 10 with 5 stream order about 28.9 m3/s. For determining the most effective factor in the flood basin and to predict the amount of discharge and present a suitable discharge model as a dependent and others as independent variables we introduced these values and analyzed them by SPSS software. Simple regression, multiple and logarithmic, forward and step by step models were applied for the basin. It should be noted that the models presented with a confidence level of 0.01 percent were acceptable. The results show that the area, lag time, and CN are the most effective factors in flooding.
