1957—2015年叶尔羌河流域气候变化特征及其径流响应

Response of Runoff Volume to Climate Change in the Yarkant River Basin during the Period of 1957-2015

根据流域内气象、水文站点的长期观测数据,利用线性趋势、相关系数、累积距平、Mann-kendall(M-K)突变检验等方法分析不同区域的干、湿季气候变化特征,并假定不同的气候情景组合,分析径流对气候变化的响应程度。结果表明:(1)1957-2015年4个单元气温和降水量呈增加趋势;除上游外,相对湿度、平均风速和大风日数呈减小趋势,流域径流量呈增加趋势。(2)气温在1996年发生突变;降水量未出现明显突变点;相对湿度在2005年左右发生突变;除下游外,平均风速在1983年发生突变;径流量于1993年发生突变,突变后径流量增加了9.08×10^8m^3。(3)相关性分析显示,流域径流量与湿季平均气温、平均最低(最高)气温呈极显著正相关,与湿季平均风速、大风日数和相对湿度呈负相关,除上游径流与干季降水量呈正相关外,其他区域与降水量呈负相关。(4)敏感性分析表明,当降水量不变,气温升高1℃,径流量增加9.06%;当气温不变,降水量增加10%,径流量减小1.67%,这主要与径流组成有关。流域77.4%的径流量来自雪冰融水补给,当降水量增加时,气温降低,减少了冰川积雪的融化,因而流域径流与气温呈正相关,与降水量呈负相关,且对气温变化更敏感。

The characteristics of the dry and wet climate changes in different regions were analyzed using the linear trend,correlation analysis,cumulative anomaly and the Mann-kendall(M-K)mutation test based on the longterm observation data from the meteorological and hydrological stations in the Yarkant River Basin.Moreover,the different climate scenario combinations were assumed to analyze the response degree of runoff volume to climate change.The results showed that:(1)Both the temperature and precipitation in the 4 units were in an increase trend;in addition to the upper reaches,the relative humidity,average wind speed and wind days in the drainage basin were in a decrease trend,but the runoff volume was in an increase trend;(2)The mutations of temperature and relative humidity occurred in 1996 and 2005 respectively,but there was no obvious mutation of precipitation;the mutation of mean wind speed in the drainage basin occurred in 1983 except in the lower reaches,and the runoff volume was sharply increased by 9.08×10^8 m^3 in 1993;(3)The correlation analysis showed that the runoff volume was positively correlated with the mean air temperature and the minimum(maximum)air temperature in wet season,and negatively correlated with the average wind speed,gale days and the relative humidity in wet season.In addition to the runoff volume was positively correlated with the dry season precipitation in the upper reaches,it was negatively correlated with precipitation in other areas;(4)Sensitivity analysis showed that,when precipitation was constant and the temperature increased by 1℃,the runoff volume was increased by 9.06%;when the temperature did not change and the precipitation increased by 10%,the runoff volume was decreased by 1.67%,which was mainly related to the runoff composition.The 77.4%runoff was recharged by ice-snow melt water.With the increase of precipitation,the temperature was decreased,and the melting of glacier and snow was reduced.At this time,the increase of precipitation could not make up for the recharge decrease of ice-snow melt water,so the runoff volume was positively correlated with temperature but negatively correlated with precipitation,and it was more sensitive to temperature change.