基于树轮宽度的伊塞克湖入湖径流量重建与分析

中亚区域气候与水文变化特征及其对全球气候变化的响应重要而复杂,伊塞克湖流域周边山区分布的天山云杉原始森林为揭示区域过去几百年气候水文变化事实和规律提供了良好的载体。本文利用伊塞克湖周边山区4个点的树木年轮宽度、入湖年径流量以及CRU格点气象资料,基于对树轮宽度指数对区域水文和气候要素响应关系分析,利用区域树轮宽度差值年表重建了伊塞克湖355 a来的入湖径流量变化历史,二者线性转换方程的方差解释量为30.2%。重建径流量的丰枯阶段变化与天山北坡的玛纳斯河、乌鲁木齐河相对应。但与天山南坡的阿克苏河流域的径流量的低频变化特征不一致,在1850年前的变化趋势相反。空间相关分析发现伊塞克湖流域重建径流量变化能较好地代表中亚天山北坡以及哈萨克斯坦东南部和新疆北部平原区降水变化。此外,还发现了伊塞克湖径流量与北大西洋长周期年代际震荡(AMO)在年代际尺度的同步变化。

Comparison of drought-sensitive tree-ring records from the Tien Shan of Kyrgyzstan and Xinjiang (China) during the last six centuries

In this study, tree-ring width data of Schrenk spruce (Picea schrenkiana) from the upper timberline of the Tien Shan (Kyrgyzstan) were analyzed to investigate the effect of climate change. Growtheclimate response analyses revealed that the tree rings of spruce at the upper timberline of the Tien Shan also can provide hydrometeorological (precipitation and streamflow) signals. Tree-ring records from both Kyrgyzstan and Xinjiang exhibited similar tree-growth variability at both annual and decadal time scales during the common period 1457e2009. In Xinjiang and Kyrgyzstan, tree growth was reduced during the Little Ice Age (LIA); however, the timing and magnitude of LIA differ between the two regions. During 1470e1660, the two chronologies diverged, and this phenomenon is considered to be caused by a different response to the harsh climate of the LIA. In this study, the tree-ring width series from the upper tree line of the Tien Shan is negatively associated with temperature. As opposed to previous studies, the tree-ring width series from the upper timberline of the Tien Shan appears to respond well to hydrometeorological factors. Therefore, we highlight the need for more detailed ecophysiological response studies for spruce trees at the upper timberline of the Tien Shan, in particular, with regard to the role of water availability and temperature during the growth season.

August–September Runoff Variation in the Kara Darya River Determined from Juniper(Juniperus turkestanica) Tree Rings in the Pamirs-Alai Mountains, Kyrgyzstan, Back to 1411 CE

A 606 year runoff reconstruction of the Kara Darya River was developed, based on the tree-ring width chronology of Turkestan juniper(Juniperus turkestanica) from the Pamir-Alai Mountains of Kyrgyzstan. Preliminary comparison between the snow cover variation and these climate/runoff reconstructions found that Central Asian snow cover may have strong associations with large-scale ocean-atmosphere-land circulations. The runoff reconstruction demonstrated that instrumental runoff was not representative of runoff over the past 606 years. The drought of the 1960 s-1990 s resulted in low runoff levels during the past 50 years;however, this probably does not represent a worst-case scenario for the Kara Darya because the runoff reconstruction showed additional extremely low runoff prior to the 20 th century. The reconstruction will provide a long-term perspective on runoff variation in the Kara Darya River basin, aid sustainable water resource management and be useful in guiding expectations of future variations and water resource planning.

Mass balance of saline lakes considering inflow loads of rivers and groundwater: the case of Lake Issyk-Kul, Central Asia

This study aimed to elucidate the influence of inflow water on the salinity concentration process of a saline lake and the mass balance of Lake Issyk-Kul,a tectonic saltwater lake in Kyrgyzstan.Based on the survey results and meteorological data from 2012 to 2015,we analyzed the dissolved chemical composition loads due to water inflow.Then,we discussed the relationship between the increase in salinity and water inflow into the lake.Through the water quality analysis data,we used the tank model to estimate the river inflow and analyze the loads by the L-Q curve.The groundwater loads were then estimated from the average annual increase in salinity of the lake over a period of 30 a.The results suggest that Lake Issyk-Kul was temporarily freshened between about AD 1500 and 1800 when an outflowing river existed,and thereafter,it became a closed lake in AD 1800 and continued to remain a saline lake until present.The chemical components that cause salinization are supplied from the rivers and groundwater in the catchment area,and when they flow into the lake,Ca^(2+),HCO_(3)−and Mg^(2+)precipitate as CaCO_(3) and MgCO_(3).These compounds were confirmed to have been left on the lakeshore as evaporite.The model analysis showed that 1.67 mg/L of Ca^(2+)and Mg^(2+)supplied from rivers and groundwater are precipitated as evaporite and in other forms per year.On the other hand,salinity continues to remain in the lake water at a rate of 27.5 mg/L per year.These are the main causes of increased salinity in Lake Issyk-Kul.Since Na^(+)and Cl^(-)are considered to be derived from geothermal water,they will continue to flow in regardless of the effects of human activities.Therefore,as long as these components are accumulated in Lake Issyk-Kul as a closed lake,the salinity will continue to increase in the future.

吉尔吉斯斯坦楚河过去407年径流量重建

紧邻丝绸之路经济带核心区的中亚地区跨境河流众多,水资源分配极不均衡。揭示中亚跨境河流径流变化规律,对水资源调配管理,缓解区域水资源紧张局面有深远影响,对促进东西方经济文化交流和"一带一路"建设具有重大的战略意义。文章选取中亚重要跨境河流——楚河为研究对象,利用吉尔吉斯斯坦天山山区雪岭云杉(Picea schrenkiana)树轮宽度资料重建楚河自公元1610年以来4~9月径流量,重建方程方差解释量为44%。重建径流量序列表明,径流量最大值和最小值分别出现在1795年和1917年。18世纪湿润期在持续时间、数量级和强度上最为显著,在1734年、 1785年、 1794年和1795年出现径流量极大值;在1700~1703年、 1726~1730年、 1734~1737年、 1746~1753年、 1755~1757年、 1763~1767年、 1769~1770年和1789~1795年偏湿。20世纪干旱期在持续时间、数量级和强度上最为严重,1917年、 1984年和1995年出现径流量极小值;1911~1920年、 1926~1928年、 1943~1946年、 1977~1982年、 1984~1987年和1995~1998年偏干。多窗谱分析结果显示楚河径流量存在2 a、 2.3~2.4 a、 3 a、 5 a、 30 a和46~68 a准周期变化。楚河径流量重建序列与乌鲁木齐河、开垦河和玛纳斯河径流量重建序列的丰枯变化有一定程度的一致性,表明天山北坡地区可能存在大范围的公共水文信号。正相位AMO(负相位NAO)时期,西风环流输送增强,楚河径流量偏多;负相位AMO(正相位NAO)时期,西风环流输送减弱,楚河径流量偏少。