国土空间规划中水源涵养功能生态保护红线备选区的识别

水源涵养功能重要性是生态保护红线划分工作中重要的评价指标之一。通过对以往生态系统水源涵养功能区划分的指标及其区域导向的系统梳理,在进一步明晰国土空间规划中水源涵养功能生态保护红线区域指向的基础上,按照国土空间规划关于“三区三线”自下而上试划的要求,探讨了水源涵养重要性生态保护红线划分及其评价的改进方法。选取中国典型喀斯特区域六盘水市作为研究案例区,分别用环保部2015版与2017版《生态保护红线划定技术指南》中的模型法、NPP法以及本研究提出的改进方法,对六盘水市水源涵养功能生态保护红线进行了试划。对比三种方法的划定结果可以看出,改进方法因评价数据精度的提高减少了《生态保护红线划定技术指南》方法的区域损失,提高了区域判别的精准性,可望为国土空间规划中生态保护红线的划定提供科学依据。

Identification of the candidate areas of ecological protection red lines based on water conservation function in territory spatial planning

The importance of the water conservation functional region is one of the key classification indexes to define the ecological protection “red line”, i.e. the ecological protection area with the highest priority. After reviewing the classification indexes previously used for identifying the water conservation functional region and investigating their potential influences on applied areas, we propose a new method of the Red Line determination, taking the water conservation ability into account and discuss an improvement in the evaluation of the red line determination method, fulfilling the requirement of the national spatial planning, i.e. the “Three Zones and Three Lines” bottom-up determination (Three Zones represent ecological space, agricultural space, and urban space; Three Lines represent ecological conservation redline, permanent capital farmland, and urban development boundary). The study area in this paper is Liupanshui, Guizhou, a typical karst landform region in China. After combing through the previously used indexes as well as the target areas for classifying the water conservation function, we compare results of the Red Line determined by three methods, which are the modeling method, the quantifying index method (NPP) (both methods were proposed in the “Guidelines for the Delimitation of the Ecological Protection Red Line” and published by the MEP of China respectively in 2015 and 2017) and an improved method we newly propose in this study. Our method introduces two factors. One is the “vegetation cover index”, used in recognizing non-ecological land and in increasing the weight of the positive effects of the water conservation function on the forest land. The other is the “elevation index”, for including qualified mountain top areas as alternatives of the red line. In Liupanshui, 34.25% of the cultivated land areas is selected as the candidates for the red line, using our newly proposed method. The percentage of the cultivated land is less than the ones obtained by the modeling method (46.62%) and NPP (38.54%). Further, our method identifies more candidates of forest land areas by the amount of 44.2%, while the modeling method reaches 25.31% only and NPP reaches 43.74%. In conclusion, using the vegetation cover index and the elevation index to classify the water conservation functional regions, the red line determined by our method has a better match with the real ecological condition of Liupanshui, compared to the results from the modeling method and NPP. Therefore, we advocate these two indexes to be included as additional indicators in the “Guidelines for the Delimitation of the Ecological Protection Red Line”, in order to increase the precision of the redline determination.