西北内陆张掖盆地地下水温度变化特征及主要影响因素识别

Groundwater temperature variation characteristics and main influence factors identification in Zhangye Basin of northwest China

西北内陆干旱区地下水温度变化与其补给水源区气象和水文条件密切相关。以西北内陆张掖盆地为研究区,应用灰色关联分析方法,在张掖盆地潜水和承压水温度动态变化特征研究基础上,通过诊断其与上游山区降水、气温(对冰川雪融水影响)、日照和出山地表径流量,以及当地气温、降水、日照和地下水埋深之间关联状况研究,识别张掖盆地不同埋藏条件下地下水(潜水与承压水)温度变化的主要影响因素,进而为确定地下水主要补给水来源提供科学依据。研究表明:1990-2009年期间研究区潜水和承压水温度分别下降了0.78℃和1.17℃,这与山区降雨量和出山径流量的明显增加和盆地日照时间减少密切相关,是主要影响因素。虽然山区气温升高加速冰川雪融化,但由于融水量有限,其对张掖盆地地下水温度的影响不明显。另外,受黑河调水和盆地地下水开采强度日趋增大影响,区内潜水和承压水温度变化趋势呈现相似特征迹象。

Groundwater temperatures regime is an important content in groundwater regimes.Changes in groundwater temperatures reflect not only the source and composition of groundwater recharge,but also the intensity of groundwater recharge,and to some extent reflecting the close degree between the change of groundwater resources and groundwater recharge areas' climate change.It can be used as an important scientific basis for groundwater resources evaluation.Groundwater temperatures are closely related with recharge area's meteorological and hydrological conditions in northwest arid region of China.In this paper,we take Zhangye basin as study area,on the basis of groundwater temperature dynamic variation characteristics research and identification of the relationship of the mountain areas and basin's precipitation,air temperature,duration of sunshine and mountainous runoff with groundwater temperature,we use grey correlation analysis method to identify the main influence factors of groundwater temperature of different buried conditions(shallow groundwater and confined groundwater).According to this we can provide a scientific basis for the recharge sources of the basin groundwater.The study shows that: The shallow groundwater and the confined groundwater decreased by 0.78 ℃ and 1.17 ℃ respectively in the study area from 1990 to 2009.The mountainous runoff has the maximum correlation with the groundwater temperature.Its grey correlation coefficients are up to 0.82(shallow groundwater temperature) and 0.81(confined groundwater temperature).The second one is basin's precipitation and their grey correlation coefficient with groundwater temperature is up to 0.73(both shallow groundwater and confined groundwater).The third one is mountainous precipitation and its grey correlation coefficient with groundwater temperature is up to 0.72(shallow groundwater) and 0.73(confined groundwater).The rising of air temperature in mountain area has no obvious effect on the basin groundwater temperature.In addition,the increasing of groundwater exploitation and Heihe water transfer lead the shallow groundwater and confined groundwater temperature nearly to the same trends in study area.Annual groundwater temperature changes slowly,and it difficult to be aware of this reason.But the groundwater temperature change can bring a lot of environmental geology problems,so the research of groundwater temperature change regime must be put much attention in the future.