1964～2012年晋西黄土丘陵区圪洞流域径流变化分析

Temporal Changes of Annual Runoff in Gedong Basin of Loess Hilly Region in Western Shanxi Province during 1964-2012

为研究晋西黄土丘陵区圪洞流域的径流变化及其影响因素,基于圪洞流域1964～2012年的土地利用资料、降雨和径流等实测数据,运用变差系数、滑动平均法、累积距平法表征流域径流变化趋势,拟合建立年径流系数与土地利用变化的多元线性关系,定量评价不同土地利用类型对径流的影响。结果表明,圪洞流域年径流深变差系数在2001～2012年间最大,说明径流在该年段变化差异较大,这与流域开始大面积植树造林有关。流域年降水量下降趋势不明显,而年径流深呈明显下降趋势。1964～1979、1980～2000、2001～2012年三个阶段降水和径流的线性相关系数R2分别为0.887 6、0.799 7、0.698 5,呈明显的下降关系,这表明流域人类活动对径流影响逐渐加强。年径流系数与土地利用变化的多元线性关系表明林地可有效减少产流,流域径流主要来自草地与耕地和其他两个地类,草地产流率是耕地和其他部分的5倍。

In order to study the temporal changes in annual runoff and its influencing factors in Gedong Basin of Loess Hilly Region in Western Shanxi Province, based on the land use, the measured data of precipitation and runoff during 1964-2012, the variation trend of the basin runoff was characterized by the variation coefficient, moving average method, and accumulated anomaly method. The influence of different land use types on the runoff was quantitatively evaluated by the multivariate linear relationship between the proposed annual runoff coefficient and the land use change. The results show that the variation coefficient of annual runoff depth in Gedong basin was the largest during 2001-2012, which indica- ted that the variation of runoff in this period was quite different, and it was related to the large area afforestation started in the basin. The downward trend of annual precipitation was not obvious, but the annual runoff depth showed a clear downward trend. By analyzing the linear relationship between precipitation and runoff from 1964 to 1979, from 1980 to 2000 and from 2001 to 2012, the linear correlation coefficient R2 was reduced from 0. 887 6 to 0. 799 7 and finally to 0. 698 5, indicating that the human activities in the basin affected the runoff gradually strengthened. The multiple linear relationship between annual runoff coefficient and land use change showed that the forest land can effectively reduce run- off. Runoff mainly came from grassland and cultivated land and other types. Grassland yield rate was five times that of cultivated land and others.