عنوان مقاله [English]
The network of streams is a blueprint for landing. In general, streams in nature have a tree pattern. Rivers are one of the most important geomorphic landscapes in which the connection between the system of forces and forms of landform is clearly understandable, because these factors are exclusively involved in the determination of the flow morphology. The dried bed of Urmia Lake is in the low slope with a gentle slope in which drainage networks are flowing. These rivers are formed on a short scale and have always been agents or factors that have changed the way and formed them. Reduce the water level of the urmia lake in recent years has caused the land portions of the dried bed and geomorphic processes that extend into the substrate. These Micro Drainage Network, despite the fact that they have a permanent and natural access to the final discharge of the stream into the Lake Urmia; from a longitudinal and transversal point of view, they are constantly changing and evolving and have a special dynamism; however, what is important is the way and the main factors of these developments. And the formation of streams that are not the same in all areas of the study and do not have a uniformity and this is the main objective of the research.
Lake Urmia is located at four coordinates of 44 degrees &59 minutes to 45 degrees & 56 minutes east and 37 degrees & 4 minutes to 38 degrees & 16 minutes north latitude between the two provinces of East Azarbaijan and western. This study examined the drainage network emerged in the dried lake bed, the model order_matrix analysis is used. In this method, the network of channels of the basins is classified according to the Strahler model and then the network of drainage network is divided into three parts: right, center and left. The basin dividing line is the line of the drainage network that have the largest category. Continuing this stream, the main line between the two right and left sides of the basin divides the basin into two. Eventually The distribution of traces of streams is counted and written in the framework of a square array whose rows and columns are equal to the largest category of river basins. The infrastructure for data collection in this study is satellite imagery of 2015 available in the Google Earth software environment. For this purpose, the network vector data streams derived from satellite imagery, in MapViewer software using strahler methods stream classification and metadata graph lines and drainage network category 1 to 6 in Grapher software and Curvexpert were drawn. After acquire and storing the images, they are georeferencing with high-precision in the context of the Global Mapper software, and aligned all the existing streams on the captured images and taken in Shpefile format.
Results and discussion:
According to the results of metadata category and number of drainage network categories 1 to 6 exponential correlation has been established and according to the most correlation coefficient and determine the category and number of drainage in the right half morphological evolution drainage is steeper than the left half. The correlation between the class and the average length of streams both halves of the inverse square. The coefficient of determination between the two halves of the category and the average length is approximately equal drainage and is about 0/98. The mean length of drainage in the mid-additive process accelerated its decline, so that accelerated the process of increasing and decreasing the average length of drainage in the left half of the right half is more severe.
The results of the research show that although the correlation between the number and class of drainage in the study area is high, however, due to the higher correlation coefficient and the determination of the number and number of drainage in the right half of the morphological evolution of the shorter drainage than the left half. The trend of mean changes in the length of the right and left dividers of the channel network of the research area is different with the trend of changes in the category, number and length of its drainage. In such a way that in each right and left, the average length of the canals increases from 1 to 4 and then from grade 4 to grade 6 this mean decreases with a steep slope.