Complex nonlinear dynamic systems are ubiquitous in the landscapes and phenomena studied by earth sciences in general and by geomorphology in particular. Many natural landscape features have an aspect such as fractals...Complex nonlinear dynamic systems are ubiquitous in the landscapes and phenomena studied by earth sciences in general and by geomorphology in particular. Many natural landscape features have an aspect such as fractals. In the many geomorphologic phenomena such as river networks and coast lines this is visible. In recent years fractal geometry offers as an option for modeling river geometry and physical processes of rivers. The fractal dimension is a statistical quantity that indicates how a fractal scales with the shrink, the space occupied. This theory has the mathematical basis but also applied in geomorphology and also shown great success. Physical behavior of many natural processes as well as using fractal geometry is predictable relations. Behavior of complex natural phenomena as rivers has always been of interest to researchers. In this study using data basic maps, drainage networks map and Digital Elevation Model of the ground was prepared. Then applying the rules Horton-Strahler river network, fractal dimensions were calculated to examine the relationship between fractal dimension and some rivers geomorphic features were investigated. Results showed fractal dimension of watersheds have meaningful relations with factors such as shape form, area, bifurcation ratio and length ratio in the watersheds.展开更多
Gully erosion is one of the most important forms of land degradation in many regions of the world.Understanding the process of gully erosion therefore is important for better management of the wa-tersheds prone to gul...Gully erosion is one of the most important forms of land degradation in many regions of the world.Understanding the process of gully erosion therefore is important for better management of the wa-tersheds prone to gully erosion.However,many different aspects of gully erosion,like hydrological behavior,are still not fully understood.The present study investigates the spatial distribution of soil moisture content(SMC),as one of the hydrological factors,at different depths and points across the cross section in the vicinity of the headcut of three gullies located in the Kalat County,Khorasan Razavi Province,Iran.SMCs were measured at depths of 10,20,30,50,70 and 100 cm at each seven points across the study cross sections one to three days after occurrence of three rain events.Two sampling points were symmetrically located at a distance of 50 cm outside the gully banks,two at the vertex of the sidewalls,two in the middle of the sidewalls and one at the center of gully cross section.SMCs were measured using a weighted method.Results of the study revealed a broad range of changes in SMCs at various depths and points.The minimum and maximum SMCs were found to be about 2%and 38%,respectively,for the study period and gullies under consideration.The coefficient of variation(CV)had drastic changes for various gullies and storm events from 2 to 107%.Results further indicated that SMC moved from the sidewalls towards the floor of the cross section.Accordingly,the maximum SMC for storm events was associated with the point located in the center of gullies,which indicated the role of gully system in draining soil moisture.The findings of this study will help watershed managers un-derstand the important role of gully facies in changing water content of the soil that affects other eco-hydrological processes.展开更多
文摘Complex nonlinear dynamic systems are ubiquitous in the landscapes and phenomena studied by earth sciences in general and by geomorphology in particular. Many natural landscape features have an aspect such as fractals. In the many geomorphologic phenomena such as river networks and coast lines this is visible. In recent years fractal geometry offers as an option for modeling river geometry and physical processes of rivers. The fractal dimension is a statistical quantity that indicates how a fractal scales with the shrink, the space occupied. This theory has the mathematical basis but also applied in geomorphology and also shown great success. Physical behavior of many natural processes as well as using fractal geometry is predictable relations. Behavior of complex natural phenomena as rivers has always been of interest to researchers. In this study using data basic maps, drainage networks map and Digital Elevation Model of the ground was prepared. Then applying the rules Horton-Strahler river network, fractal dimensions were calculated to examine the relationship between fractal dimension and some rivers geomorphic features were investigated. Results showed fractal dimension of watersheds have meaningful relations with factors such as shape form, area, bifurcation ratio and length ratio in the watersheds.
基金The present manuscript has been partially supported by the Agrohydrology Research Group of Tarbiat Modares University(grant IG-39713),Iran,concerning the corresponding author
文摘Gully erosion is one of the most important forms of land degradation in many regions of the world.Understanding the process of gully erosion therefore is important for better management of the wa-tersheds prone to gully erosion.However,many different aspects of gully erosion,like hydrological behavior,are still not fully understood.The present study investigates the spatial distribution of soil moisture content(SMC),as one of the hydrological factors,at different depths and points across the cross section in the vicinity of the headcut of three gullies located in the Kalat County,Khorasan Razavi Province,Iran.SMCs were measured at depths of 10,20,30,50,70 and 100 cm at each seven points across the study cross sections one to three days after occurrence of three rain events.Two sampling points were symmetrically located at a distance of 50 cm outside the gully banks,two at the vertex of the sidewalls,two in the middle of the sidewalls and one at the center of gully cross section.SMCs were measured using a weighted method.Results of the study revealed a broad range of changes in SMCs at various depths and points.The minimum and maximum SMCs were found to be about 2%and 38%,respectively,for the study period and gullies under consideration.The coefficient of variation(CV)had drastic changes for various gullies and storm events from 2 to 107%.Results further indicated that SMC moved from the sidewalls towards the floor of the cross section.Accordingly,the maximum SMC for storm events was associated with the point located in the center of gullies,which indicated the role of gully system in draining soil moisture.The findings of this study will help watershed managers un-derstand the important role of gully facies in changing water content of the soil that affects other eco-hydrological processes.
