Developing interactive land use scenarios on the Loess Plateau in China, presenting risk analyses and economic impacts

This study aimed to present a risk analysis of the effects of different land use scenarios on reducing soil and water losses, using a physically based hydrological and soil erosion model. We quantified the effect of various land use scenarios on the expected rate of discharge and sediment loss during a single rain event in a small agricultural watershed on the Loess Plateau in China, using the geometric mean and stochastic distributions of measured field saturated conductivity (K-s) values. Land use scenarios were based upon physical, economic and agricultural interests, and effects on farmers' incomes were evaluated using empirically derived equations. A physically based hydrological and soil erosion model was used to quantify the effects of land use on discharge and soil loss. Using geometric mean values of K-s as the model input resulted in higher values for runoff coefficients and total soil loss compared with the use of stochastic K-s values. The use of stochastic K-s-distributions resulted in a range of model outcomes reflecting the effect of spatial heterogeneity on simulated discharge and soil loss. The conservation-driven scenario was most effective in reducing water and sediment losses by runoff and erosion, followed by the soil-driven scenario and the agriculture-driven land use scenario. Only the agriculture-driven scenario resulted in a small increase in household income, while a serious loss of income is predicted for the other scenarios. The use of variability of parameters and a Monte Carlo analyses allows statistical analyses and comparison of computed results for alternative land use scenarios, and leads to a more balanced judgement. (C) 2004 Elsevier B.V. All rights reserved.