Document Type : Research
Authors
1
Graduated in Watershed Management Engineering, Faculty of Natural Resources, Yazd University, Yazd, Iran.
2
Assisstant Prof., Faculty of Mathematic, Yazd University, Yazd, Iran.
3
Sari Agricultural Sciences and Natural Resources University
4
PhD in Water Sciences and Engineering, Urmia University.
10.22092/wmrj.2023.362706.1546
Abstract
The fractal dimension serves as a metric for assessing the level of intricacy within a set of data. Fractal geometry is a numerical instrument for simplifying the complex phenomena of nature, which is important in measuring the behavior and power of the morphological features of the watershed by creating fractal patterns. Consequently, the of this study to investigate the relationship and interaction amid the morphological parameters of the watershed area and the fractal dimension in the generation of runoff and sediment yield.
The data were obtained from hydrometric and synoptic stations of watersheds with national statistics. Based on the basic maps, the characteristics of the watershed were prepared. The studied fractal parameters were calculated using the box counting method in Fractalyse 2.4 software. Using the factor analysis technique, 85 parameters related to the watershed were identified. In order to perform further analyzes in watersheds to calculate the annual runoff and sediment with different return periods, five different scenarios (based on climate, based on physical characteristics, climate and physical at the same time, fractal dimension) were considered for hydrological homogeneity of watersheds. Correlation was also performed to estimate the discharge and sediment with different return periods with different parameters.
Results and Discussion
The results of the factor analysis technique showed that among the 85 parameters related to the watershed, 18 are the effective parameters of the area, the slope area is 8-12 and 12-20%, the area of the east slope in 9 directions, the length of the 100-m level lines in the watershed, the total length of the stream , the concentration time base Kirpich method, height difference, fractal of 200-m level lines, deviation from the moisture standard, temperature difference, average slope, net slope of the main stream, average temperature, average moisture, average precipitation, elongation coefficient and fractal of the basin environment. Meanwhile, the parameter of the fractal dimension of the 200-m horizontal lines and the fractal dimension of the watershed has been able to explain significant amounts of the overall changes in discharge and sediment, which explains well the role of fractal parameters in the relationship between discharge and sediment.
According to the results, in large watersheds, almost all effective factors in the estimation of discharge and sedimentation are summarized in the area and fractal of the environment of the basin, and these two parameters justify the most changes in discharge and sedimentation. It can be concluded that to control the erosion and runoff of basins, the best thing to do is to divide large basins into smaller basins and carry out watershed works in these small sub-basins. the findings of this research can provide considerable help to various stakeholders who are involved in the development and management of watersheds.
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