Final answer:
The total change in reservoir height during these two periods is 198 feet.
Step-by-step explanation:
The total change in reservoir height during these two periods can be calculated by finding the difference between the drop in the first year and the rise in the next year.
Therefore, the expression that shows the total change in reservoir height is: 512 - 314 feet.
Calculating this expression, the total change in reservoir height is 198 feet.