A non-linear technique based on fractal method for describing gully-head changes associated with land-use in an arid environment in China

Only few studies have focused on quantifying and/or modeling changes in gully-head shape. The present paper proposed a non-linear technique based on fractal method for describing gully-head changes quantitatively, and carried out a case study in the Yuanmou Basin in the Longchuan River Valley, Yunnan Province, southwest China. Seventy-seven gullies under 5 different land-uses were investigated in 1998 and again in 2002. For the study period, the gully-head retreat rate in different land-uses showed a decreasing order BL (bare land) > FL (farmland for only crops) > OC (mixture of orchards and crops) > FG (combination of forest and grass) > FSG (combination of forest, shrubs and grass). Correspondingly, the three proposed fractal characteristics (the fractal curvature Pτ, ΔPτ = change in the fractal curvature Pτ, ΔD = change in the fractal dimension D) of the gully-heads followed the same order BL > FL > OC > FG > FSG, also. These findings suggested that the three parameters (Pτ, ΔPτ, ΔD) proposed can sensitively reflect the gully-head changes associated with land-use, and may be used as feasible parameters for understanding and predicting gully development under land-use change and global change.