Journal of Watershed Management Research

Mendeley  

Zotero  

Erfani Pour Ghasemi V, Dastorani M T, Hajibigloo M, rahimi-aghcheshmeh F. (2021). Investigating and Prioritizing of the Factors Affecting on Morphological Changes in a part of the Kashfarood Channel. jwmr. 12(24), 249-261. doi:10.52547/jwmr.12.24.249
URL: http://jwmr.sanru.ac.ir/article-1-1049-en.html

Extended Abstract
Introduction and Objective: River systems are subject to serious changes over the time. These changes vary from region to region depending on the conditions of the river. Forecasting the process of river changes and presenting engineering plans depends on understanding the current behavior and morphology of the river and evaluating changes in the past. The purpose of this study was to investigate the effective factors (hydraulic, soil properties, vegetation, and river pattern) on instability and bank erosion of Kashafrood River in Khorasan-Razavi province of Iran.
Material and Methods: In order to better evaluation of the effects of different factors, the river path was divided into 14 reaches and geometrical parameters needed to show the changes in river morphology were measured and calculated. The HEC-RAS hydraulic model through the HEC-Geo RAS annex was used to investigate the flow hydraulic properties of the Kashafrood River. Next, the analysis of the model output results was performed for flow discharges with different return periods for 14 cross-sections along the river. Soil samples were also taken from the riverbank, and transferred to the laboratory for granolometery and other studies. Other factors such as the type and density of vegetation, geometrical properties, erosion rate and the impact of human factors on river changes were also studied during the field visits.
Results: The results of river morphological analysis showed that the meandering coefficient (MC) for most of the reaches studied in this study is less than 1.99. Therefore, based on the Wollmann-Leopold and Schumm methods some reaches are classified as straight and some others as light meandering reaches. Hydraulic properties of the flow such as flow velocity, Froude number, and hydraulic depth of flow, shear stress and flow power have been varied from one reach to another, but in the present study they had no considerable effect on bank erosion. The results also showed that soil salinity was more affective to bank erosion among the studied soil properties, and the other soil parameters had no significant effect on river bank erosion. Vegetation status of the river bed and banks has played an important role in the stability of the banks. The river pattern was also found affective to bank erosion, as the erosion rate at the concave parts of the river was higher.
Conclusion: Among the various factors studied in the field of hydraulic, morphological, soil and vegetation characteristics of the Kashafrood bed and banks in the present study, soil salinity, vegetation cover density and meandering status of the reaches have been effective in bank erosion.