博尔塔拉河源流区径流对气候变化的响应及预测

Response and prediction of runoff to climate change in the headwaters of the Bortala River

冰川径流是西北干旱区径流的主要组成部分,研究未来气候变化对冰川径流的影响对西北干旱区径流至关重要。以博尔塔拉河上游源流区为研究区,构建嵌入冰川模块的SWAT模型,模拟温泉水文站1972-2018年月径流过程,并在此基础上研究了气候变化情景下(RCP4.5和RCP8.5)未来(2020-2050年)气候变化对冰川径流的影响。结果表明:SWAT模型能够很好地模拟源流区径流变化过程,在整个模拟期间,径流数据的纳什系数(NSE)为0.82,偏差百分比(PBIAS)为-3.22%,均方根误差与实测值标准差的比值(RSR)为0.42,决定性系数(R^(2))为0.84,模型性能评定为优。根据CMIP5气候模式2种情景的模拟结果,2种情景模拟未来总径流都呈现出增加趋势,分别将以0.31×10^(8) m^(3)·(10a)-1和0.40×10^(8) m^(3)·(10a)-1的速度继续增加,冰川径流占比较历史时期的27.61%分别提升了4.84%和9.38%。冰川径流增加是径流量增加的主要原因。通过相关性分析发现,随着气温的升高,冰川消融时间提前,冰川消融加速,冰川积累时间减少,导致冰川面积进一步的缩减。研究结果可为博河地区水文资料历史变化、未来演变趋势和预防气候变化带来的潜在风险提供依据。

Glacial runoff is a major component of runoff in the northwest arid zone of China.Understanding the impact of climate change on glacial runoff is crucial,but few studies have been conducted in this field of study in the Bortala River Basin,Xinjiang,China.In this paper,we present the glacier module that was added to the SWAT model and used to simulate monthly runoff in the headwater area of the upper Bortala River Basin.We successfully simulated monthly runoff at the Wenquan hydrological station during the period 1972-2018.Further,we investigated the impact of future climate change scenarios(RCP4.5 and RCP8.5 scenarios for 2020-2050,based on CMIP5 climate data)on glacier runoff.The model was able to accurately simulate changes in the source area’s runoff process.The results showed that:For the whole simulation period,the Nash-Sutcliffe efficiency was 0.82,the percent bias was−3.22%,the ratio of root mean square error to standard deviation of measured value was 0.42,and the coefficient of determination was 0.84,thus allowing the model to be rated as“excellent”.Increasing runoff trends were identified in the simulations of both future climate scenarios,with total runoff increases of 0.31×10^(8) m^(3)·(10a)^(−1) and 0.40×10^(8) m^(3)·(10a)^(−1) and increases in the percentage of glacial runoff of 4.84%and 9.38%,respectively,when compared with the historical period,in which the glacial runoff percentage was 27.61%.These increases in glacial runoff percentage are the main causes of the increases in runoff volume.Correlation analysis revealed that as the temperature increases,glacier ablation advances and accelerates,and glacier accumulation time decreases,leading to further future shrinking of glacier area.The study provides a basis for making changes to historical hydrological information,exploring future evolutionary trends,and mitigating potential climate change risks in the region.