Assistant Research Professor Florida State University
This study explored changes in magnitude and seasonality of reservoir inflows for 58 dams in the West and Southwest U.S. from 1993-2022. We also examined climatic variables near dams to identify potential drivers. Monotonic and non-monotonic trend and changepoint analyses were applied. Our findings indicated a general downward trend in inflows, with significant annual decreases for California dams and seasonal decreases for Upper Colorado dams. Of the 58 dams, 21 had significant downward annual median inflow trends, along with strong downward high inflow trends in spring and median trends in fall. We found that inflow trends correlated more strongly with temperature than precipitation, especially in California's snow dominated region. Seasonality shifts occurred for low and high inflows - low inflows increased in spring and decreased in fall, while high inflows increased in summer and decreased in winter. These findings have significant implications for reservoir managers. Results can help identify plausible inflow changes over time and recognize the need to implement plans ensuring ongoing functionality.
