窟野河流域河川基流量变化趋势及其驱动因素

河川基流量的变化是区域气候变化与人类活动的综合反映,其对维持生态系统健康具有重要的意义.以黄土高原水蚀风蚀交错区典型流域窟野河流域为研究对象,利用1959-2005年实测水文、气象资料,基于Chapman-Maxwell数字滤波法的基流量计算,分析窟野河流域河川基流量的变化趋势与演变特征,从气候变化和人类活动两方面探讨了河川基流量变化的驱动因素.结果表明:(1)近50年来,流域内7个时段(全年；春季、夏季、秋季、冬季；汛期、非汛期)的基流量均表现为极显著减少趋势,全年基流量的减少量为0.628 mm/a,并在1980和1996年发生两次明显的突变；(2)与基准期(1959-1979年)相比,水土保持效应期(1980-1995年)的全年日基流量在5％,50％和95％的频率上相对减少率分别为30％,38％和54％,煤炭开发期(1996-2005年)的全年日基流量在5％,50％和95％的频率上相对减少率分别为57％,68％和100％；(3)流域河川基流量减少是气候变化和人类活动共同作用的结果,降水量的变化一定程度影响基流量,但主要驱动因素是流域内大面积连片开采煤炭资源和过量开发利用地下水.

Change trends and driving factors of base flow in Kuye River Catchment

The variation of base flow is a comprehensive reflection of the change of regional climate and human activities, and it is an important element to maintain sustainable development of the ecosystem. In this study, the Kuye River catchment, a tributary of the Yellow River, with a drainage area of 8706 km² on the Loess Plateau, was chosen to investigate the change trends and evolution characteristics of base flow. Based on Chapman-Maxwell base flow separation technique, the total runoff from Wenjiachuan hydrological station, which is the maximum control station in the Kuye River catchment, was separated into surface runoff and base flow. The nonparametric Mann-Kendall test and the Pettitt test were used to identify the trends and change points in the base flow during 1959 to 2005. The results indicated that: (1) In the past 50 years, a significant negative trend was detected in the annual base flow in all 7 time periods. For total year period, the average change rate is 0.628mm/a. The change points significantly occurred in 1980 and 1996. (2) Analysis of flow duration curves showed that, compared to the contrast period from 1959 to 1979, the relative changes of annual base flow for 5%, 50% and 95% exceeding time were lowered by 30%, 38% and 54%, respectively, in the treat period from 1980 to 1995, and the relative changes of annual base flow for 5%, 50% and 95% exceeding time were lowered by 57%, 68% and 100%, respectively in the coal mining period from 1996 to 2005. (3) The significant negative trend in base flow is a comprehensive effect of the change of regional climate and human activities, and the main factor is that excessive exploitation of a large area of coal resources and utilization of groundwater.