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Effect of hillslope topography on soil erosion and sediment yield using USLE model

100%

Sabzevari T. , Talebi A.

Acta Geophysica

2019

tom Vol. 67, no. 6

1587--1597

Catchment hillslopes in nature have a complex geometry. Complex hillslopes have different plans (convergent, parallel and divergent) and different curvature (straight, concave and convex). In this study, the erosion rates of the nine complex hillslopes were investigated using the universal soil loss (USLE) method. The topography factor (LS function) in the USLE was developed as a function of plan shape and profile curvature. The hillslopes studied were divided into sets of complex pixels and the erosion over the pixels was calculated. Total erosion was regarded as the sum of erosion of all pixels. Furthermore, to calculate the sediment delivery ratio of each pixel, a new travel time equation for complex hillslopes was employed. Results showed that the mean erosion of convex hillslopes was 1.43 times that of concave and 1.19 times that of straight slopes. The effect of curvature shape on erosion was much greater than plan shape effect. The highest erosion belonged to convex divergent slopes, and the least erosion was related to concave divergent slopes. The laboratory results intended for validation of the numerical model also show that in hillslopes with fixed plan, the erosion rate in the convex hillslopes exceeds that of concave and straight hillslopes. Also, in the hillslopes with fixed curvature profile, the erosion rate in the convergent hillslopes is more than in the divergent and parallel ones.

Synthesis and characterization of tin oxide nanoparticles via the Co-precipitation method

80%

Tazikeh S. , Akbari A. , Talebi A. , Talebi E.

Materials Science Poland

2014

tom Vol. 32, No. 1

98--101

The present study illustrates the characteristics and co-precipitation method for synthesis of tin oxide nanoparticles. The tin oxide nanoparticles were produced using tin chloride, Triton X-100 and ammonia precipitators. Structure, size and surface morphology of the tin oxide was studied by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results show sphere shaped tin oxide nanoparticles without chlorine contamination. The crystallite size determined by the Scherrer formula is about 23 nm. Lattice parameters calculated by Nelson-Riley equation show high quality of crystallization.