以怀来县为例 ,在分析该县水土资源及土地利用现状的基础上 ,发现水土资源利用存在的问题是 :水资源难以满足土地利用的需求 ,土地利用结构与布局不合理 ;利用灰色线性规划模型 ,进行水土资源的优化配置 ,得出了不同节水条件、不同生态经济目标下 ,9种典型的土地资源优化配置方案 ,为首都圈防沙治沙和水土资源的充分合理利用提供决策依据

The irrational use of land and water resources in regions around Beijing is the main cause of the environmental deterioration and the sandstorms. Huailai County is one of the six typical sand regions, which is taken as a case in the present study. Based on digital land use map of 2000 and contour map of Resources and Environment Data Center of IGSNRR, CAS, the land and water resources and their utilization status in Huailai were studied and the problems of land and water use was found: the water resource was insufficient to meet the needs for existing land use; both land use structure and land use distribution was irrational.In order to solve these problems,the Grey Linear Programme model was used to allocate the land and water resources optimally. The optimum land allocation modes were obtained under different water-saving levels and agriculturalwater supplies; theoretical base was provided about rational use of the regionalland and water.Four conclusions are drawn:1) In the optimum land allocation modes, tendenciesof each land use type under different water-saving levels are the same on the whole.2) Under three typical water use conditions (normal water use, moderate water-saving and high water-saving ), there is one land use allocation mode that the source of sand is generally controlled, one mode that the source of sand is totally controlled and one mode that the source of sand is totally controlled and the structure of crops is rational, although different amount of agricultural water supply is needed. 3)The characteristic of normal water use condition shows the investment in water-saving facilities is very little, but it needs large amount of water-supply; that of moderate water-saving condition needs certain investment to improve the efficiency of water use and the amount of water supply is lower than the first case; and that of high water-saving condition needs the lowest amount of water supply but considerable investment to improve the efficiency of water use. So the modes under moderate water-saving condition is feasible.4)Under moderate water-saving condition, there are three typical modes of optimum land allocation. When theagricultural water supply is 5.85 billion m 3,land types that are apt to form sandstormsconvert to lands moderately covered by grass, the source of sand is generally controlled and the benefit of land is 1.51 billion yuan. When the amount of agricultural water supply is 6.05 billion m 3,lands that apt to form sandstorms convert to lands highly covered by grass, the source of sand is totally controlled, and the benefit of land is 1.62 billion yuan. When the amount of agricultural water supply is increased to 6.385 billion m 3,not only the source of sand is controlled but also the structure of croplandsis rational, and the benefit of land is 1.72 billion yuan.