黄土高原变绿对黄河中游延河流域径流演变的影响估算

近年来,黄土高原变绿对黄河中游,特别是黄土高原的径流演变扰动显著且影响强烈,估算其影响对保障区域水安全与黄河流域高质量发展意义重大。基于1959～2016年黄河中游延河干流延安水文站控制流域(以下简称“延河流域”)径流量及同期面降水量,识别了径流演变的变异年份,分析了径流与降水和土地利用/覆被变化间的响应关系,定量估算了黄土高原变绿对延河流域径流非一致性变化的影响。结果表明:延河流域在1970、1996年发生了径流变异,总体呈现衰减趋势; 若以1970年之前径流过程为参照基准,则可得统计期内降水变化导致径流减少2.8×10⁸ m³,贡献率为18.1%; 1971～1995年,延河流域径流主要受以水利工程建设为主导的人类活动影响,驱动径流减少4.75×10⁸ m³,贡献率为30.6%,之后径流变化由新增人类活动和植被恢复为主导的黄土高原变绿联合驱动,贡献率分别为3.7%和47.6%。综上所述,黄土高原变绿正在成为驱动延河流域径流减少的主要因素,潜在威胁着黄土高原未来的水资源安全与社会发展。

Influence of Greening Loess Plateau on Streamflow Change in Yanhe River Basin of the Middle Yellow River,China

Recently, greening Loess plateau has a significant and strong influence on the runoff evolution in the middle Yellow river, especially in Loess plateau, so the estimation of its influence is of great significance for ensuring regional water security and high-quality development of Yellow river basin. The runoff and surface precipitation in the basin controlled by Yan'an hydrological station in the main stream of Yanhe river, the middle Yellow river from 1959 to 2016 were collected to investigate the influence of greening Loess plateau on runoff change in the basin. Therein, the testing methods for change point were used to identify the change year of runoff in Yanhe river basin, and the double mass curve was used to determine the linear regression relationship between precipitation and runoff. Then, the quantitative attribution of runoff variation at different stages was implemented. The results show that runoff change in Yanhe river basin occurs in 1970 and 1996 with the overall trend of attenuation; taking the runoff before 1970 as a reference, it can be found that runoff change mainly results from water conservancy engineering construction among human activities from 1971 to 1995, and the influence drives 30.6% of total runoff reduction; after 1996, the attribution of runoff change becomes the combination of extra human activities and the vegetation restoration by greening Loess plateau, which contribute 3.7% and 47.6% of total runoff reduction, respectively; precipitation-driven runoff reduction is 2.8×10⁸ m³, contributing 18.1% of total runoff reduction. Therefore, it can be concluded that greening Loess plateau has become the main factor leading to runoff reduction in Yanhe river basin in recent years, and should be paid more attention because it may threaten the water resource security and social development in Loess plateau.