气候变化和人类活动影响下澧水流域径流及其不同组分的变化简

目前径流变化相关研究较少涉及径流的不同组分。利用湖南省澧水流域4个水文站点长序列观测资料，不仅分析了2007-2011年相对于1985年以前径流总量及其历时曲线的变化，也分析了地表径流和基流及其历时曲线的变化。与1985年以前比，流域年降雨量保持不变，最显著的变化为森林覆盖率的增加和大量水库的修建。这些人类活动没有造成年径流总量、年基流量和年地表径流量的显著变化，但在日时间尺度上对径流过程产生了重要影响。地表径流和地下径流对人类活动存在差异性响应，2007年以后地表径流在洪峰期流量变小而其他时段变大，而地下径流汇水受人类活动影响较小，基流流量除枯水期外与1985年以前基本一致。本文所揭示的规律可能在中国南方具有一定的代表性。

Recent change of runoff and its components of baseflow and surface runoff in response to climate change and human activities for the Lishui watershed of southern China

Temporal change of baseflow and surface runoff, two components of river runoff,receives little attention though the runoff variation has long been an important concern worldwide. This study made a comparison of hydrological regimes in the Lishui river watershed, a mountain watershed in southern China between two periods of 1950s-1985 and2007-2011. We examine not only the temporal change of runoff and its FDC(flow duration curve), but also the temporal change of its two components and their FDCs. The data used mainly involves the long-term observations at four gauging stations, 13 rainfall stations and two meteorological stations. Annual precipitation remains almost unchanged between the two periods compared with the former period. The latter period, however, was characterized by a high forest cover(about 70% in 2009) and numerous reservoirs. The substantial change in land surfaces induced by human activities makes no statistically significant difference both in annual runoff volume and its two components, which varies by about 10% between two periods. Human activities, however, play an important role at the daily time scale. Our examinations on FDCs show a differential response of the surface runoff and the baseflow to human activities. Responding to the reservoir operations and the high vegetating cover after2007, the daily surface-runoff discharge decreases in the high-flow period and increases in other periods. The daily baseflow discharge remains insensitive to human activities, with FDCs after 2007 coinciding with those before 1985 except in the low-flow period. Out result may be typical of the humid southern China and is thus indicative of other rivers in southern China.