小流域水土保持生态经济系统内外部效益评价

Assessment of lnternal and External Benefit of Wate and Soil Conservation Eco-economic System in the Small Watershed

小流域生态经济系统在实施一定的水土保持措施以后，所产生的效益可划分成两个部分。其中一部分效益作用于流域界线以内，受益人为流域的内部使用者，我们称之为内部效益；而另一部分效益作用于流域界线以外，受益人为流域资源的外部使用者，我们称之为外部效益。本文分别采用综合环境生产力指数法和效益系数法研制开发小流域内外部效益评价模型，从而对流域治理过程中两种效益的变化进行评价。

The eco-economic benefit can be divided into two parts in the stnall watershed in which some measures of water and soil conservation have been done. The one part of the benefit occures within the watershed, people benefit from the watershed by using the internal resources of eco-economic system, so it is called internal benefit. The other part affects outside the watershed, people benefit from the watershed by using the external resources of eco-economic system,so it is called external benefit.In this paper, the way of multiple index of environment productivity and the way of benefit coefficient are used to set up the assessing models of internal and external benefit in the watershed.