近期冰川表面径流系数变化的影响因素——以天山乌鲁木齐河源1号冰川为例

Factors Affecting the Variation of Glacier Surface Runoff-Coefficient——A Case Study of Vrumqi No. 1 Glacier

采用水量平衡法计算得到天山乌鲁木齐河源1号冰川1982—2014年物质平衡值,与实测物质平衡值对比分析发现:(1)水量平衡法适用于冰川区多年物质平衡的计算,其中1号冰川1982—2014年计算值与实测值误差在1%以内,与之对应的山岩区和冰面径流系数分别为0.7和0.85。(2)1982—2005年的物质平衡值与实测物质平衡值高度相关,且误差较小,在这一阶段径流系数能较好地反映冰川区的产流情况;而2005—2014年计算得到的物质平衡值与实测物质平衡值之间有较大差距,且变化趋势差异明显,说明这一阶段径流系数受一些因素影响存在较大的波动。选取误差较大的2005—2008年和误差较小的1996—1999年进行逐月分析,发现在夏平衡中,计算结果普遍要高于实测物质平衡值。分析认为水热条件的改变以及相应的冰川产流系数的变化是导致这一差异的主要原因。分析结果表明在长时间尺度上利用水量平衡计算冰川物质平衡值准确度较高。

The mass balance of Urumqi Glacier No. 1（ Glacier No. 1） was calculated by water balance method and direct measurement method respectively. Water balance method is a kind of calculating method,which studies about the relationship between storage,supply and consumption of water resource in a certain area in a certain period of time（ Time for this research is a mass balance year）. Mass balance calculated by this method and acquired by filed observation was compared and analyzed. Therefore we got their correlation and expected to apply it to other high latitude and altitude areas.Mass balance and glacial runoff data of Urumqi Glacier No. 1 used in this research were acquired from Annual Report of Tianshan Glacier Station,and that started observing in 1959. The data used by this study is collected from1982-2014. The data of runoff was measured by the hydrology station of Urumqi Glacier No. 1 Glacier,which is located in the lower reaches of the glacier about 300 m,and catchment area is about 3. 34 km2. The data of precipitation and runoff was provided by Daxigou Meteorological Station located in the altitude of 3 539 m,which is distant from the terminus of Urumqi No. 1 Glacier about 3 km.Through the comparison of these two kinds of methods,we found that：（1） It is better to use water balance method to calculate the mass balance in long time series. The result of water balance method was 1% different from the result of direct measurement during 1982-2014,and the corresponding glacier runoff coefficients were 0. 7 and0. 85,respectively.（2）The results of water balance method during 1982-2005 had a high correlation with the direct measurements,and the error was relatively small. Besides that,the glacier runoff coefficient reflected the glacier runoff well. However,there were obvious differences between the two kinds of methods during 2005-2012 which showed that the glacier runoff coefficients changed a lot. According to analyzing the two periods of 2005 to 2008 with large error and 1996 to 1999 with small error,we found that the results of water balance method were generally higher than that of the direct measurement in summer. The analysis showed that the changes of water conditions and the corresponding in the glacier runoff coefficient were the main reasons for these differences.The data of precipitation and runoff in the study area was combined with the measured mass balance data,and their potentially internal relationship was found,which could be used to acquire the meteorological data easily and to deduce the mass balance data which is difficult to be acquired. This conclusion is helpful to extending the study area from a single glacier or basin to a large regional scale. Limited to the shortage of data,for the example,this study only discussesd the single glacier,Urumqi Glacier No. 1. Overall,this study shows that using the potential of water balance method can compute the data of glacier mass balance more accurate on long time scale.