Temperature field and dynamic types of shallow groundwater in the northwest inland basin: A case study of the Jiuquan East Basin

Abstract

Temperature is an inherent property of groundwater.Groundwater temperature field and dynamic characteristics are objective manifestations of groundwater flow system.Based on multi-point, long series and high precision groundwater temperature monitoring data, the characteristics of shallow groundwater temperature distribution and dynamic type of water temperature in Jiuquan East Basin are studied, in order to reveal the relationship between the characteristics of shallow groundwater temperature field and groundwater flow system under the influence of human activities such as groundwater exploitation in northwest inland basin.The results show that the shallow groundwater temperature ranges from 9.33℃ to 20.77℃, and the average water temperature is 13.54℃.From the recharge area to the discharge area, the shallow groundwater temperature increases gradually along the direction of groundwater runoff, and the average groundwater temperature in January is higher than that in July.The comparison of different groundwater flow systems with similar circulation depth shows that the shallow groundwater temperature is negatively correlated with groundwater dynamic conditions.The average groundwater temperature of the water flow system with large surface water recharge and strong hydrodynamic conditions is lower, and that of the water flow system with small recharge and weak hydrodynamic conditions is higher.The temperature dynamics of shallow groundwater are affected by human activities such as natural groundwater circulation and groundwater exploitation.From groundwater recharge area to oasis area in the middle reaches and drainage area in the lower reaches, the temperature dynamic of shallow groundwater can be divided into four basic types, which are river recharge type, water temperature stability type, groundwater exploitation related type and sinusoidal fluctuation type respectively.

Keywords

• heihe river basin
• jiuquan east basin
• groundwater flow system
• groundwater
• temperature field
• dynamic classification