基流分割法在黄河流域地下水研究中的应用

Baseflow Separation for Groundwater Study in the Yellow River Basin,China

为研究黄河流域地下水可再生能力变化规律和制定黄河流域水资源管理方案,应用基流指数法（BFI）和直线平割法的原理与方法,计算了黄河流域干流13个水文断面与20条主要支流31个水文断面的基流量,并分析了基流量的形成机理、地下水对黄河水的贡献、基流变化过程、流域地下水资源的构成及地下水资源总量。研究结果表明：花园口断面的基流量占多年平均径流量的44%,流域内河水与地下水存在极其密切的转化关系,地下水对黄河水的贡献很大。黄河的径流量与基流量主要来自兰州以上的源区,兰州断面的年径流量与基流量分别占花园口断面径流量的59%和60%;而兰州以下到花园口之间的上、中游地区,地下水对黄河水的贡献很小。1990年前后,黄河干流与支流河段的基流量发生了很大变化。除玛多以上的源头段基流量衰减率较大外（衰减率为0.38）,兰州以上的干流河段基流量衰减率较小（0.08～0.20）,而兰州以下的黄河干流基流量衰减率都很大（0.22～0.31）。基流量的剧烈衰减是天然和人类活动（如地下水开采）共同作用下地下水资源量减少的结果。从流域水循环的观点考虑,黄河流域的区域地下水资源由参与黄河水循环的地下水资源、未参与黄河水循环的地下水资源和流域地下水的开采等3大部分构成。1990年6月—2000年6月近10年黄河流域地下水天然资源量平均值为353.9亿m3/a,比多年地下水资源量平均值减少了15%。

The principle and methods of base flow index （BFI） and line separation have been em ployed to calculate the baseflow in 13 hydrologic sections on the main stream and 31 hydrologic sectiorts on 20 major tributaries of the Yellow River basin. Based on the baseflow separation results, a comprehensive analysis was made on the forming mechanism of baseflow,the contribution of groundwater to the Yellow River,baseflow changes, the composition and the total amount of groundwater resources in the basin,which has provided a sound and reliable foundation to evaluate the groundwater renewal capability and set up a rational water resources management strategy in the Yellow River basin, The research result shows that the baseflow of the Huayuankou section accounts for 44% runoff for many years average. The extremely close relationship existed between groundwater and the Yellow River and the groundwa ter had great contribution to the river. The runoff and baseflow of the Yellow River are mainly from the source area above Lanzhou. The annual runoff and baseflow of the Lanzhou section account for 59% and 60% of the Huayuankou runoff section. However, the groundwater contribution to the Yellow River water was very small in the vast area of upper and middle reaches of the Yellow River between I.anzhou and Huayuankou. Around 1990s, the baseflow in the main stream and tributaries of the Yellow River had been changed greatly. The main stream above Lanzhou had a sharp baseflow reduction （decrease rate of 0.08 - 0. 20） except the source above Maduo （decrease rate of 0. 38）. However, in the major hydrological sections downstream the Yellow River in Lanzhou, baseflow had large reduction rate （0.22 -0.31）. The dramatic reduction of baseflow mainly results from the reduction of groundwater resources quantity affected by the nature and human activities such as groundwater exploitation. From the viewpoint of hydrologic cycle on the basin scale,the regional groundwater resource of the Yellow River basin was constituted of three following parts： groundwater resource that participates in the Yellow River water cycle, groundwater not involved in the Yellow River water cycle and the groundwater exploitation in the basin. The natural groundwater quantity from June 1990 to June 2000 is estimated to be 35.39 billion m^3/a, which is 15% less than that of groundwater resource of many years average.