Trends in normalized difference vegetation index time series in differently regulated cascade reservoirs in Wujiang catchment, China

•NDVI mutation point in sub-catchment matched with the dam construction year.•Future degradation degree in the sub-catchments is greater than that in the past.•Different reservoir regulation type showed different vegetation degradation trends.•Reservoirs with shorter retention time suffered heavier vegetation degradations.•The impact scope of damming on vegetation would be expanded over time.