Impacts of recent drought and warm years on water resources and electricity supply worldwide

1 Recent droughts and heatwaves showed the vulnerability of the electricity sector to surface water 2 constraints with reduced potentials for thermoelectric power and hydropower generation in different 3 regions. Here we use a global hydrological-electricity modelling framework to quantify the impacts of 4 recent drought and warm years on hydropower and thermoelectric power usable capacity worldwide. 5 Our coupled modelling framework consists of a hydrological model, stream temperature model, 6 hydropower and thermoelectric power models, and was applied with data of a large selection of 7 hydropower and thermoelectric power plants worldwide. Our results show that hydropower utilisation 8 rates were on average reduced by 5.2% and thermoelectric power by 3.8% during the drought years 9 compared to the long-term average for 1981-2010. Statistically significant (p<0.01) impacts on both 10 hydropower and thermoelectric power usable capacity were found during major drought years, e.g. 11 2003 in Europe (-6.6% in hydropower and -4.7% in thermoelectric power) and 2007 in Eastern North 12 America (-6.1% in hydropower and -9.0% in thermoelectric power). Our hydrological-electricity 13 modelling framework has potential for studying the linkages between water and electricity supply under 14 climate variability and change, contributing to the quantification of the “water-energy nexus”. 15