Balancing Water Needs in the Face of Climate Variability: Progress by the U.S. Army Corps of Engineers

摘要

In large river basins such as the Columbia River and Sacramento-San Joaquin basins, reservoir operations for flood control and water supply often play a central role in determining both the seasonality and annual amount of hydropower production. Additionally, where system-wide flood control storage is distributed between a number of reservoirs in different parts of the basin, rebalancing flood control and refill objectives in response to hydrologic changes poses a significant systems engineering problem. Global climate variability is expected to produce systematic changes in winter climate and mountain snowpack in the Western United States, resulting in higher flows in winter, earlier spring peak flows, and lower flows in spring and summer. The magnitude of these hydrologic changes is largely dependent on mid-winter temperature regimes, elevation, latitude, and proximity to the ocean. In the context of managed flood control, the associated seasonal streamflow timing shifts are likely to disrupt the balance between flood control objectives and reservoir refill for water supply, hydropower production, and instream flow augmentation. To adapt to these hydrologic changes, evacuation of reservoirs for flood control may need to move earlier in the year as warming progresses to prevent floods, and refill may also need to begin earlier.