流域尺度下季节性休耕生态补偿标准的空间优化研究——以海河流域为例

Spatial Optimization of Seasonal Fallow Ecological Compensation Standards at the Basin Scale:A Case Study of the Haihe River Basin

季节性休耕是地下水超采综合治理的重要措施,探究区域差异化的休耕生态补偿标准对于制定和完善休耕生态补偿机制、确保政策的可持续性具有重要意义。本文以作为中国粮食主产区和地下水超采最为严重的海河流域为例,基于生态补偿理论框架,构建海河流域三级子流域尺度下的生态经济模型,并运用模型测算不同政策情景下各子流域空间优化的休耕生态补偿标准,模拟作物种植结构的变化和地下水压采效果。结果表明:海河流域区域差异化的休耕补偿标准取值范围为218~689元/亩。制定基于各子流域空间优化的休耕生态补偿标准可以激励农民压减冬小麦种植面积、调整作物种植结构,在保证农户的生产收益不受损失的前提下,实现更大的地下水压采目标。实施区域差异化的休耕生态补偿标准,在维持现行政策效果的前提下,可以减少10%的公共财政支出;在扩大政策覆盖范围的情况下,可使流域平均新增地下水压采量67立方米/亩;在财政资金有限的情况下,能够确保政策实施的有效性和可持续性。

Seasonal fallow is an important mean for the comprehensive management of groundwater.It is of great significance to explore the regionally differentiated fallow ecological compensation standards for formulating and improving the ecological compensation mechanism,thus ensuring the long-term sustainability of the policy.This paper takes the Haihe River Basin as an example,which is both the main grain production area and the most severe groundwater overdraft region in China.Based on the theoretical framework of ecological compensation,we construct an ecological-economic model at the spatial scale of 15 sub-basins in the Haihe River Basin.We then use the model to optimize the fallow ecological compensation standards in each sub-basin under different policy scenarios and to simulate the changes in cropping structure and the effects on groundwater extraction.The results are as follows.(1)The value range of regionally differentiated fallow ecological compensation standards in the Haihe River Basin is 218-689 yuan/mu.(2)The implementation of fallow ecological compensation standards based on spatial optimization of each sub-basin can incentivize farmers to reduce the planting areas of winter wheat,adjust cropping structure,and achieve greater groundwater conservation goals without compromising the cultivation income.(3)The implementation of regionally differentiated fallow ecological compensation standards can reduce public financial expenditure by 10%while maintaining the effects of the current policy;in the case of expanding the policy coverage,it can increase the average additional groundwater conservation by 67m3/mu in the basin.Therefore,under the condition of limited financial budget,the regionally differentiated fallow ecological compensation standards can ensure the effectiveness and sustainability of policy implementation.