Investigating the warming effect of urban expansion on lake surface water temperature in the Dianchi lake watershed

Dianchi lake (DCL) watershed, located in southwestern China, has undergone significant urbanization. Due to the accelerating urbanization in the watershed, the influence of urban expansion on lake surface water temperature (LSWT) has become increasingly significant. However, there is currently no quantitative study on the specific warming value of LSWT caused by urban expansion. This study primarily quantifies the increase in LSWT caused by urban expansion from two perspectives: the rise in near-surface air temperature (NSAT) resulting from urban expansion and the thermal runoff generated by urban expansion. We found that the DCL watershed experienced significant urban expansion between 2001 and 2018. In this context, the cumulative increase in LSWT caused by the newly added impervious surface (IS) through NSAT is about 0.25 °C. The cumulative warming of the newly added IS on the LSWT through thermal runoff is about 0.05–0.06 °C. Urban expansion mainly affects the LSWT by increasing the NSAT. [Display omitted] •Quantified the warming of LSWT due to urban expansion.•The differences in the effects of thermal runoff and NSAT on LSWT are discussed.•Measures to mitigate the impact of urban expansion on LSWT are proposed.