پديد آورندگان :
سلطاني گردفرامرزي، سميه دانشگاه اردكان - دانشكده كشاورزي و منابع طبيعي , عسگري ورزيده، سميه دانشگاه اردكان , تازه، مهدي دانشگاه اردكان - دانشكده كشاورزي و منابع طبيعي
كليدواژه :
مورفولوژي رودخانه , مئاندر , زاويه مركزي , طول رودخانه , شعاع
چكيده فارسي :
اكثر سازه هاي آبي مانند سدها، پل ها و ايستگاه هاي پمپاژ در كنار رودخانه ها ساخته شده و تحت تاثير تغييرات موفولوژيكي رودخانه قرار مي گيرند. استفاده از تصاوير ماهواره اي و سيستم اطلاعات جغرافيايي مي تواند در افزايش دقت بررسي اين تغييرات موثر باشد. در اين پژوهش، مورفولوژي قسمتي از رودخانه گاماسياب در استان همدان به طول 50 كيلومتر در شهرستان نهاوند بررسي‌شده است. بدين منظور تصاوير سنجده TM و ETM ماهواره ي لندست در سه دوره زماني 2000.1990 و 2013 مسير رودخانه، در محيط نرم‌افزار ARCGIS رقومي شد. سپس در محيط نرم‌افزار AUTO CAD، برخي پارامترهاي هندسي رودخانه مانند زاويه مركزي، شعاع دايره مماس بر قوس‌ها، طول رودخانه و تعداد قوس ها براي بررسي تغييرات با روش برازش دايره‌هاي مماس بر قوس رودخانه اندازه گيري گرديد. سپس با نرم‌افزار SPSS تجزيه و تحليل آماري بر روي مقادير پارامترهاي هندسي صورت گرفت. بررسي مقادير پارامترهاي هندسي به‌دست‌آمده گوياي آن است كه با افزايش تعداد مئاندر از 15 عدد در سال 1990 به 40 عدد در سال 2013 تغييرات مورفولوژي قابل‌توجهي در اين بازه از مسير رودخانه ديده شده و طول رودخانه از حدود 51 كيلومتر به حدود 60 كيلومتر افزايش يافته است. همچنين با توجه به روند افزايشي شعاع پيچان‌رودها از سال 1990 نسبت به سال 2013 ( از 203/7 به 593/1 متر) و افزايش زاويه مركزي از سال 1990 تا سال 2013 از حدود 58 درجه به 62/5 درجه، شكل رودخانه به صورت خمدار توسعه يافته تبديل شده است.
چكيده لاتين :
River morphology is the science of knowing the river system in terms of general shape, dimensions and characteristics of hydraulic geometry, the direction and longitudinal profile of the bed, as well as the mechanism of its changes. Morphological study is needed to understand the current conditions and the potential for future river changes in the future, and perhaps it is only that it is possible to predict the natural behavior of the river in relation to natural changes or actions arising from the implementation of various river engineering projects. Most of the water structures such as dams, bridges and pumping stations are located in the margins of rivers that can be affected by changes in river morphology. Application of remote sensing images and Geographical Information Systems (GIS) can be effective to achieve a more accurate analysis. Today, land use change, vegetation cover and morphological changes of rivers in River Engineering Sciences are of great importance using remote sensing and GIS techniques. Yamani and Sharafi (2012) showed that morphological changes and erosion of the Herrud River from the upstream downstream has decreased. Also, the geological and lithological structures of the bed and river bank are the most important factors in the stability of the bed. Yousefi et al. (2013). In order to investigate the changes of some Meander parameters in the Karun River using Landsat satellite images, morphological parameters of 20 Meanders were determined in an interval of 128 km length of Karun River after the preparation of a land use map for each period. Rashidi et al. (2016) studied geomorphologic changes of the Karoon River bed and its causes from 1334 to 1391. The results indicate significant changes in river morphology including latitudes, meanders, and sedimentary islands due to the decrease in the discharge, the construction of multiple bridges along the path, geological factors and vegetation. The study of past research shows that the study of river morphology in other countries has also been of great importance. Clerici et al. (2015) examined the morphological changes of the Taro River in Italy over the last two centuries and showed that human beings have made the most of the changes for agricultural and industrial purposes, the construction of multiple bridges and casualization. According to the research, the main issue of this research is to investigate the changes in the Gamasiab River, which in recent years has threatened the communication paths, landscapes and, in summary, human structures along the river banks. Therefore, the objective is to study the variation of the morphology of the Gamasiab river from the point of view of the central radius and angle, and the number of archs during the 1990-2013 period, and the extent of the development of the piers.
