No abstract

Urban wastewater treatment and reuse are crucial for achieving water sustainability. Yet, pathways of realizing water-climate synergies in the planning of wastewater infrastructure remain unclear. In this paper, we examine the nexus of urban water stress and climate impact resulting from the expansion of wastewater infrastructures across over 300 cities in China. We demonstrate how the effect of alleviating urban water stress from wastewater treatment and reclaimed water reuse has been highly uneven across cities, costing the country a 183% increase in life-cycle greenhouse gas emissions during 2006-2015. Decoupling the climate impact of wastewater infrastructure from significant water stress is plausible by 2030, potentially leading to up to 35% reduction of greenhouse gas emissions. However, given the growing demand for water reuse and investment in the diffusion of low-carbon technologies at each life-cycle stage of wastewater systems, this decoupling would be a challenging endeavor.

Differentiating spatial-temporal hydropower risk triggered by climate change is crucial to climate adaptation and hydropower programming. In this research, we use a fixed-effect model on 5,082 plants in China to estimate how the revenue of hydropower plants responded to climate change over 16 years, and project the revenue change and fit the damage function driven by 42 climate realizations. Results show that the revenue change of the hydropower sector demonstrates substantial regional variation and would reduce by 9.34% ± 1.21% (mean ± s.d.) yr-1 on average under RCP 8.5 by 2090s as compared to 2013, about 4 times larger than that under RCP4.5. Carbon leakage caused by thermal power substitution reaches 467.56 ± 202.63 (112.49 ± 227.45) Mt CO2e under RCP8.5 (RCP4.5). Different climatic conditions manifest locally, and different climate resilience makes the response function regionally heterogeneous. Southwest China is identified as the priority region for adaptation through integrated evaluation of historical climate sensitivity, future climate variability, and regional hydropower importance, informing more adaptation and investment needs of further hydropower development in the area.