This is very interesting analysis from Roger Pielke Jr. explaining clearly the dam managers decision challenges:
Long-time readers may remember discussions here earlier this year about the management of the Wivenhoe Dam near Brisbane, Australia and the role of such management in the flooding of Brisbane. One of the issues in that flooding was the role of reservoir management in the magnitude of the flood, which I described as follows:
Wivenhoe Dam near Brisbane, Australia is at the center of controversy in its role in the recent flood. The dam, as is commonly the case, is expected to serve two seemingly contradictory functions. On the one hand it is a buffer against drought, meaning that it is desirable to keep it more full in the eventuality of low precipitation. On the other hand, the dam is a buffer against floods, meaning that it is desirable to keep it more empty in the eventuality of heavy precipitation. Since keeping the reservoir full and empty are not simultaneously possible, it then is necessary to balance these objectives. Since future precipitation is uncertain, the dam’s management is thus a matter of decision making under uncertainty (where risks are known) and ignorance (where they are not).
A reader (thanks DB!) passes on a lengthy article from the Great Plains Examiner out of Bismark-Mandan, North Dakota on the management of upper basin reservoirs on the Missouri River. The article describes a decision context and outcome remarkably similar to what we saw in Australia earlier this year.