Inputs of terrestrial dissolved organic matter in dam reservoirs during precipitation: impact on water quality and management

With the significant increase in extreme rainfall of climate change and anticipated of dam reservoir, terrestrial dissolved organic matter (DOM) has received attention because of its role in regulating water quality and ecological functions. This study investigated the characteristics of soil and vegetation DOM under different heavy precipitation (HP) and associated flooding (AF) scenarios by UV–visible and fluorescence excitation–emission matrices coupled with parallel factor analysis (EEM-PARAFAC), as well as the resultant effects on water quality. The results showed that precipitation makes the substantial inputs of terrestrial DOM in dam reservoir. The changes in HP and AF were distinct between soil and vegetation DOM. Aromaticity and molecular weight of soil DOM were higher during AF compared to HP, while there was no significant difference in fluorescence components between the two events. Aromaticity and humification of vegetation DOM, as well as humic-like components, were higher during AF compared to HP. The terrestrial DOM inputs bring adverse effects on water quality for dam reservoir. Apart from incorporating the monitoring of terrestrial DOM, a multi-objective optimization adaptation strategy, as well as implementing ecological restoration at region scales, can mitigate the adverse effects. This study enhances the resilience of dam reservoirs against hazards risks during climate change.