基于生态水文理念的流域水资源规划研究 ——以子牙河为例

传统水资源规划一般仅关注水文循环中的"蓝水"资源,忽视了占水文循环60%以上的"绿水"资源。基于生态水文理念来研究流域水资源规划方法,可实现区域可持续发展。本文以子牙河流域为例,从流域降雨着手,剖析大气降水、蓝水和绿水转化过程,构建基于生态水文理念下的流域水资源规划模型。通过调整种植结构、节水灌溉制度、产业结构、居民生活用水、养殖业用水等方案,以及南水北调中线配套工程措施,利用构建的流域水资源规划模型,对各项规划措施进行模拟。结果表明:75%保证率和50%保证率下,自然植被耗水量分别为76.3亿m3和88.2亿m3,农业生产耗水量分别为126.8亿m3和142.1亿m3。城市生活、工业生产、第三产业和农村生活耗水量均分别为7.9亿m3、2.6亿m3、3.1亿m3和3.3亿m3。相对于调整之前,75%保证率下,子牙河流域耗水量减少11.9亿m3,50%保证率下减少13.2亿m3。其中,占总耗水量最大的农业生产部门对耗水削减的贡献量最大,达到了7.6亿m3(75%保证率)和8.8亿m3(50%保证率),占总削减量的60%以上,表明种植结构和节水灌溉制度的调整对减少子牙河流域耗水量起到了重要作用。本文研究成果可为流域水资源高效可持续利用提供必要的技术支撑。

Water resources planning driven by eco-hydrology theorem: A case study of Ziya River basin

Traditional water resources planning usually focuses on “blue water” in the hydrologic cycle, ignoring “green water” which accounts for over 60% of the hydrologic cycle. The method of water resources planning at watershed scale based on the concept of eco-hydrology involves a comprehensive analysis of a combined system composed of water resources, social economy and ecological environment through water consumption management to attain sustainable regional development. This paper, from the precipitation of watershed, analyzed the conversion of precipitation from “blue water” to “green water” and constructed a watershed-scale water resources planning model based on the concept of eco-hydrology that contained water resources system module, social economy system module and ecological environment system module. The computation of “green water”, which is the core module of the water resources planning model, adopted the Penman-Monteith model based on the Leaf Area Index (LAI) of MODIS remote sensing and optimized parameters based on the spatial differences of vegetation in the watershed. The “green water” computation was achieved through the transformation of water from the traditional evapotranspiration model at a single-point scale to a multiple-point scale of the watershed evapotranspiration model. Also the processes spatial and temporal variations of two key parameters, including soil evapotranspiration coefficient and vegetation stomatal conductance, were established. Finally, the model was used to simulate water resources planning in a watershed, which involving the actual water consumption by vegetation ecology, residential use, industrial production, food production and different trees/grass. By using Ziya River basin as a case study and 2008 as the reference year, the paper calibrated and verified the parameters of the model and the relative error between the monthly simulated and measured evaporation of different vegetation types (7%), which proved that the model had an acceptable simulation accuracy. By matching planting structure, water-saving irrigation regime, industrial structure, residential water use and aquaculture water use with engineering measures of the middle line of the South-to-North Water Transfer Project, the constructed water resources planning model was used to quantify different planning measures. The results showed that under 50%–75% rate of assurance, water use by natural vegetation was 8.82–7.63 billion m3, that by agriculture was 14.21–12.68 billion m3 and those by urban life, industrial production, tertiary industry and rural life were respectively 0.79, 0.26, 0.31 and 0.33 billion m3. Water consumption in Ziya River basin dropped by 1.19 billion m3 under 75% assurance rate and by 1.32 billion m3 under 50% assurance rate after the implementation of the planning measures. Agricultural production (as the largest water consumer) contributed the most to the water consumption cut, which reached 0.76 billion m3 under 75% assurance rate and 0.88 billion m3 under 50% assurance rate after using the planning measures. This was at least 60% of the total water consumption cut, indicating that the adjustment of planting structure and irrigation pattern was critical in cutting down water consumption in Ziya River basin. The results of the study provided necessary technical support for the efficient and sustainable utilization of water resources in watershed.