黑河上游多年基流变化及其原因分析

Annual base flow change and its causes in the upper reaches of Heihe River

利用递归数字滤波法分割黑河上游主要水文站点的基流量,用移动平均、曼-肯德尔(Mann-Kendall)突变检验,小波分析方法分析研究区多年基流变化特点,并对基流影响因子进行分析。结果显示:黑河上游祁连、扎马什克、莺落峡三站多年平均基流指数均大于0.4;祁连与莺落峡多年基流量呈上升趋势,二者都在1979年发生增加到显著增加的突变。扎马什克基流波动较大,总体呈下降趋势;三站基流分别存在11年、6年、15年的明显变化周期。基流量变化主要受降水的影响。人类活动对基流的影响主要表现在造成黑河上游森林面积减少,使其补给调节基流的能力下降,从而使基流量减少且更易受气候变化的影响。黑河上游基流变化特征符合西北地区对全球气候变化的响应的一致性,同时也有其受到祁连山冰雪融水补给、山区特殊地形等影响,从而体现对全球气候变化响应的差异性。

Base flow is one of the most important river hydrological characteristics in dry season. In recent years, with the global water issues becoming more prominent, base flow has become research focus in eco-hydrology. For the stability and hysteresis, base flow is significant to maintain river＇s ecological functions, determines river＇s ecological water requirement, and provides food and service for the locals in arid and semi-arid regions. The study area, upper reaches of Heihe River Basin, is located in the Qilian Mountains, northern part of Tibetan Plateau, China, with elevations of 2300-4000 m. The watershed area is 1. 0009 × 10^4 km^2. The recursive digital filter technique was used to separate annual base flow of three main hydrological stations in the upper reaches of Heihe River. The methods of moving average, Mann-Kendall abrupt test and wavelet variance were employed to explain the characteristics of the annual change of base flow. Precipitation and temperature data of six adjacent meteorological observational stations and human activities were used to analyze the influencing factor of base flow. The results indicated that the Base flow Index （BFI） was greater than 0.4 in Qilian, Zhamashike and Yingluoxia stations. The notable increase of base flow was observed in 1979, when there was an abrupt point at Qilian and Yingluoxia stations. The base flow fluctuated at Zhamashike station. The periods of base flow were 11, 6 and 15 years respectively at Qilian, Zhamashike and Yingluoxia stations. The change of base flow was mainly affected by precipitation. The influence of human activities on base flow was another factor. The forest areas were decreased by human activities, which made the capacity of recharging and adjusting base flow in decline. In turn, the base flow went down and was greatly influenced by climatic change. The base flow change showed the consistency with the response of Northwest China to the global climate change and also reflects the differences in response to global climate change.