洞庭湖流域径流量对气候变化和人类活动的响应研究

The research of runoff responses to climate change and human activities in the Dongting Lake catchment

为了定量化研究气候变化和人类活动对洞庭湖流域径流量变化的影响,采用累积距平分析和Mann-Kendall趋势检验对流域内4个水文站和16个气象站1985—2010年的水文及气象数据进行统计分析,并利用径流量变化定量分析方法,计算了气候变化和人类活动对径流的改变量及其贡献率。研究结果表明:降水量的下降和潜在蒸散发量的上升导致整个洞庭湖流域及湘江、资水、沅江、澧水4个子流域突变后相对于突变前径流量分别减少了28、15、130、112 mm和102 mm;洞庭湖流域径流量的减少主要受气候变化的影响,其贡献率为64%,人类活动虽然能增加径流,但是两者的叠加影响整体上仍使径流量减少。因此,洞庭湖流域的水文干旱是自然环境演化的结果,与全球气候变化的大格局息息相关。

Climate change and human activities are the two main factors that affect the hydrological processes and water resources in a catchment. The objective of the study is to distinguish the contribution of climate change and human activities on the variation of runoff in the Dongting Lake catchment. The daily hydro-climatic data from 1985—2010 were analyzed with the accumulated anomaly analysis method and the non-parametric Mann-Kendall test. The contribution of climate change and human activities on the change of runoff were calculated by the quantitative method. The whole period was divided into two sub-periods according to the breakpoint（period 1：before the breakpoint; period 2：after the breakpoint）. Compared to period 1, the runoff at the whole Dongting Lake catchment decreased by 28 mm with the four sub-catchments of Xiangjiang, Zishui, Yuanjiang and Lishui decreased by 15 mm, 130 mm, 112 mm and 102 mm respectively during period 2. The decrease of annual precipitation and the increase of annual potential evapotranspiration may account for the runoff change. Results showed that climate change was the main contributor for the decrease of runoff, accounting for 64% of the runoff change.The overall impacts of human activities and climate change may result in a decrease of catchment runoff despite of the potential increase of runoff caused by human activities. The study implies that the hydrological drought in the Dongting Lake catchment was mainly influenced by the natural factor such as climate change.