Each set of data contains multiple-year observations of soil and runoff loss under widely varied rainstorms, which are typical to semi-arid climates. With an increase of slope angles, runoff per unit area slightly increased on

SSP, but it decreased after reaching a maximum at 15° on LSP, which may be related to the complicated effect of several factors (e.g. crusting, rill development, rainfall conditions) on soil infiltrability. Soil loss per unit area increased with slope angles on both SSP and LSP. There were 36.4% less runoff but only 3.6% less soil loss per unit area produced on LSP than on SSP, which selleck chemicals was likely ascribed to more runoff infiltration and greater flow velocity on long slope as a comparison of short slope. Event recurrence interval is a better rainfall index than event rainfall amount in correlating rainfall to soil loss and runoff. The correlation between soil loss and recurrence interval can be best fitted with a linear equation on SSP and a polynomial equation on LSP. Storms with recurrence intervals greater than 2 years contributed to about two thirds of the total runoff and soil loss. Z-VAD-FMK The slope equations in USLE/RUSLE overestimated the S factor in this region.

On the steep cropland, a fraction of annual precipitation was often responsible for majority of annual total erosion in this semi-arid region. In general, the soil conservation practices were more effective in reducing soil loss than in reducing runoff on steep cultivated croplands. The five conservation practices (earth banks,

woodland, alfalfa, terrace and grassland) generated 123.8%, 118.9%, 111.0%, 30.3% and 15.2% of the mean annual runoff on cropland, and correspondingly yielded 48.9%, 25.1%, 10.6%, 6.9%, and 6.4% of mean soil loss on cropland. The effectiveness of soil erosion control in storms greater than 2 years in recurrence intervals decreased in the order of terraces > grasses > woodland > alfalfa > earth bank, while the effectiveness in reducing runoff caused by storms greater than 10 years in recurrence intervals decreased in the order of grasses > terraces > woodland > earth banks > alfalfa. We gratefully acknowledge Liothyronine Sodium that the following people at Shanxi Institute of Soil and Water Conservation have been involved in field monitoring and data compiling in the different periods: Wang, X.P., Liu, S.P., Zeng, B.Q., Jia, Z.J., Fu,J.S., Zhang, Z.G. This project was funded by the Graduate School at University of Minnesota (Grant No. 22166). The manuscript also benefits from the comments and suggestions of Dr. Batelaan and two anonymous reviewers. “
“Perth, located on the west coast of Western Australia (Fig. 1), is Australia’s fourth most populous (∼2 million people) city and experiences a Mediterranean-type climate, dominated by wet winters and relatively dry summers.