The Study About Allocation Of Soil And Water Conservation Measures And Quantitative Health Evaluation Of Eco-economy System In Anjiagou Small Watershed

The small watershed of Anjiagou in Dingxi City has the typical characteristics of the semi-arid ecological environment in Loess Plateau, which has been managed for more than 50 years. In this paper, taking it as the study object, based on the detailed analysis of the status and characteristics of the small watershed, the author analyzed soil and water conservation measures taken in this watershed to find the best combination of various measures, which will give a scientific basis to the optimal allocation of water and soil conservation measures in the Loess Plateau area in the future. And in addition, 19 factors were selected as evaluating factors from the three aspects of resource-environmental support, economic support and social state effect to build the evaluation index system and to quantitatively evaluate the health status of eco-economy system in the small watershed of the region. The mean square difference method was used to ensure the index weigh, and a watershed system integrated evaluation model was set up using multi-objective linear weight function method, by which the health level of this watershed system was identified during different stages. The main results were obtained as follows:(1) In gully slope of <25°, the level terrace has better efficiency in conserving water and soil, and there the grain output was higher than that slope; with the uplift of the slope, the grain output has the downward trend. And therefore, the middle and lower parts of the slope were the suitable sites for planting crops, and especially the lower one was better.(2) In gully slope of > 25°, the upper and middle parts of shady slope and sunny slope were not suitable for broad-leaved trees as well as the lower part of sunny slope, relatively suitable for shrubbery resisting wind and tolerating drought such as Hippophae rhamnoides and Caragana microphylla. Broad-leaved trees only should be planted in the lower part of shady slope and gully channel.(3) Relatively speaking, every place was appropriate for planting Medicago sativa.(4) The health index of the watershed has an increasing trend annually ever since been managed, which was 0.151 in 1960s and up to 0.507 in 2005. The watershed experienced the fragile stage and the relatively stable stage, and now developed in the direction of good health stage.(5) The development of health about eco-economy system in the small watershed is very uneven. By 2005, the health index in resource-environmental support and the one in social state effect has all been in the stage of good health; and only the health index in economic support was still at the stage of the relative stability of health. This showed that the backward of economic development affected very much the health about eco-economy system in the small watershed.(6) Ecological environment in the small watershed was gradually improved, and in the situation of a virtuous circle. Quantized value of most indexes about eco-economy has been in the increasing trend, and only one of population density and the proportion of agricultural labors in the decreasing trend. And therefore, the growth of population and agricultural labors had a serious impact on the health about eco-economy system in the small watershed.