What major factor contributes to reservoir turnover?

Reservoir turnover is primarily influenced by temperature changes in the water, which affect water density and stratification. Warm water is less dense than cold water, causing it to remain on the surface, while colder water, being denser, tends to sink. This temperature gradient creates distinct layers or strata within a reservoir, typically resulting in warmer water on top and cooler water below.

When temperature changes occur, especially in seasonal cycles, the upper strata may cool down, becoming denser and leading to a phenomenon known as turnover. This process involves the mixing of the upper and lower layers of water, which redistributes oxygen and nutrients throughout the entire water column. It is essential for maintaining a healthy aquatic ecosystem.

In contrast, factors like rainfall impact water volume but do not directly lead to the turnover process. Aquatic vegetation can influence habitat and water chemistry but does not play a direct role in the density-driven mixing that characterizes turnover. Thus, focusing on the changes in temperature and their effects on water density clarifies why this factor is pivotal to understanding reservoir turnover.