Assessing urban water-energy nexus characteristics in China and the US

The Water-Energy Nexus (WEN) provides a comprehensive concept for the cooperative management of resources. Although the WEN system in cities is intricately connected to socioeconomic activities, relationship between WEN and economic systems remains understudied. This study introduces a tri-dimensional Nexus Pressure Index (NPI) to assess the pressure on WEN system. Gross Domestic Product (GDP) per capita and city tiers in the urban agglomeration were used to assess the relationship between the characteristics of WEN and economic system. We conducted a case study of 296 cities in China and 1330 counties in the United States from 2012 to 2019. During the 9 year study period, on average, pressure on WEN system have relieved by 22% in China and 27% in the United States, measured by NPI. Cities with most ideal characteristics (low pressure in all dimensions) rank merely in the middle of all eight classes, with GDP per capita 74% and 85% of the highest-GDP-per-capita class in China and the US respectively. Well-performing WEN system does not yield best economic outcomes. High water pressure correlates with better economic performance in the US, while high-energy-pressure cities had GDP per capita about 50% and 70% of the class with highest GDP per capita in China and the US, respectively, suggesting stronger economic constraints from energy stress. Urban agglomeration analysis revealed a negative relationship between WEN and economic performance. NPI in emerging cities is 0.6-1 lower than NPI in regionally-central cities in China, while 0.2-0.5 lower in the US. These results underscore the contradiction between preferred WEN characteristics and higher economic performance, and underpin the resource curse hypothesis at city-level in the two considered giants. A sustainable approach to harmonize WEN and economic system is in urgent need.