海南岛干旱地区昌化江径流变化及影响因素

Changes in runoff in Changhua River in the arid area of Hainan Island and their influencing factors

识别降水量和径流量变化过程及其影响因素对流域生态安全有重要意义。以海南岛干旱区昌化江流域主要控制水文站宝桥站58年(1956-2013年)水文资料为基础,采用肯德尔秩次相关等统计方法和GIS技术研究流域内降水径流的变化特点及变化原因。结果表明:(1)降水和径流序列均呈缓慢上升趋势,但2003年后径流序列有明显下降。(2)应用有序聚类分析径流系数跳跃成分,结果显示1989年和2003年前后发生了较大改变。(3)将1956-1988年作为无人类活动影响的基准期,建立降水-径流关系,分析人类活动对径流变化过程的影响,表明人类活动的间接影响使昌化江径流量减小,流域植被覆盖率减少使蒸发作用加大,导致径流量降低。(4)2003-2013年人类的活动影响使得昌化江径流量大幅减少,其中直接影响减少量63.5 mm,间接影响减少量为53.7 mm,总减少量为117.1 mm,人类活动综合影响对径流量下降的贡献率为13.9%。禁止砍伐热带雨林,减少种植经济作物对维护流域生态安全尤为关键。

Identifying the processes of change in precipitation and runoff and their influencing factors is important to the ecological security of basins.Based on 58 years(from 1956 to 2013)of hydrological data of Baoqiao Station,a main control hydrological station in Changhua River Basin in the arid area of Hainan Island,the characteristics and causes of change in precipitation and runoff in the basin were studied by statistical methods such as Kendall rank correlation and GIS technology.Results showed that(1)Both precipitation and runoff series showed a slow upward trend,but the runoff series decreased obviously after 2003.(2)The jump components of runoff coefficient were analyzed by ordered cluster analysis,and the results showed that great changes had taken place around 1989 and 2003.(3)The period from 1956 to 1988 was taken as the baseline period with no influence of human activities.The relationship between precipitation and runoff was established to analyze the influence of human activities on the changing processes of runoff.The results showed that the indirect influence of human activities reduced the runoff of Changhua River,and the decrease in vegetation cover in the basin increased evaporation,leading to the decrease in runoff.(4)From 2003 to 2013,the impacts of human activities greatly reduced the runoff of Changhua River.Among them,the reduction caused by the direct effect was 63.5 mm,which was caused by the indirect effect was 53.7 mm,and the total reduction was 117.1 mm.The percent contribution of the combined effect of human activities to the reduction in runoff was 13.9%.Banning of deforestation of tropical rain forests and reduction in the cultivation of cash crops are particularly critical to safeguarding the ecological security of the basin.