A PRELIMINARY EXPERIMENTAL STUDY ON NON-LINEAR RELATIONSHIP BETWEEN SEDIMENT YIELDAND DRAINAGE NETWORK DEVELOPMENT

In this paper an experimental study on network development in a drainage system is conducted. The results shows that at first the network density increases, then reaches the maximum and finally reduces to a minimum while the erosion modulus decreases in the process. The bifurcation, defined by Smith, has a maximum value of 3.62. It reduces with increasing density and reaches to the minimum value for fully developed network. The fractal value D is defined by -1nK1/lnK2, in which K1 and K2 are constants in the Horton's laws about stream number and average channel length, respectively. The value of D is 0.55 in the begining stage of network development then increases to the maximum value of 0.78, and finally reduces to a stable value of about 0.69. The phenomenon can be explained with the fact that the network development is a nonlinear process. The relationship between D and bifurcation and sediment yield in the model exhibit nonlinear characteristics, although the erosion modulus is monotonously decreasing with time.