Oilfield drilling sites are the potential dispersive pollution source of groundwater, especially to shallow groundwater. The pollution risk assessment in these areas is an important reference for effective groundwater management and protection. The vulnerability assessment alone is not sufficient for groundwater contamination risk assessment. In this study, we developed a comprehensive groundwater pollution risk assessment method for oilfield drilling sites that combine groundwater vulnerability, pollution source hazard, and groundwater value function to produce a more comprehensive result. Consider the oilfield drilling area in Yitong County of Jilin Province, China, as an example. Thematic maps of the three aspects (groundwater vulnerability, pollution source hazard, and groundwater value function) were generated in ArcGIS environment to assess the contamination risk of groundwater in quaternary pore unconfined aquifer. The results show that 9.92% of the study area is characterized as being at high risk. These areas are mainly distributed around the center position of the oil drilling site, floodplains, and the reservoir. The moderate risk area accounts for 21.04% of the total area. It is distributed in the first-level terrace, mainly because of the high function value of groundwater. The remaining 69.04% of the study area is characterized as none and mild risk, mainly distributed in the valleys and terraces. This integrated groundwater contamination risk assessment method is suited for comparative assessment of multiple-point sources of contamination at a regional scale. Finally, the groundwater contamination risk grade distributed in this area provides a reference for effective protection and sustainable supply of groundwater in the oilfield drilling area.

Sustainable groundwater utilization is important for social and economic development. There is a need for groundwater sustainability assessment in small-scale areas lacking detailed mining data. Here, exploiting water level data series, we propose an indicator of groundwater sustainability based on the response to mining (MGSI) for better evaluation; it integrates groundwater data and spatio-temporal variability at a local scale. A decomposition coefficient was applied to decompose the pressure exerted by groundwater mining on the groundwater system for each monitoring well. It correlated with the groundwater response state. In Da’an City, Jilin Province, China, the appraised results revealed that the aquifer type exhibiting the greatest risk to groundwater sustainability changed from phreatic to confined during 2008–2017. The spatio-temporal distribution of different sustainability levels between and within the aquifers indicated that adjustment of the groundwater mining layout should be the focus of groundwater management in Da’an City. Additionally, the Mann–Kendall trend test and Sen’s slope trend analysis effectively explained the sustainable evolution of groundwater in Da’an City and confirmed the reliability of the MGSI method. The proposed method highlights the effects of groundwater mining on sustainability and helps us better understand the interaction between anthropogenic activities and groundwater resources.

The water cycle in urban areas is called the natural-social dualistic water cycle, and it is driven not only by natural forces, but also by human activities. As the drivers of the social water cycle, human perspire continuously, and this is often overlooked as a contributing factor to the water cycle. This paper proposes a method for quantifying the water evaporation induced by human perspiration and respiration in megacities. A calculation based on the sweating prediction model was applied to the city of Beijing to evaluate the evaporation from the human body. The results show that the greatest volume of evaporation produced by human occurs in summer, and the least in spring. The total evaporation produced by human was converted to the evaporation on unit area of the city and reached 5075.2 m³/km² in the six core districts of Beijing. According to the calculation, the total volume was considerable and reached 14.0 million m³ in 2020, which was equivalent to the annual evapotranspiration from an area of 104.9 km² of Acer truncatum forest (15 cm diameter at breast height, afforestation density 800 plants/hm²), and even twice the annual total water use in Tartu, Estonia. The results of the study provide a reference for dualistic water cycle research and water cycle flux calculation in urban areas.