Average Annual Release Rate For Uncontrolled Reservoir

When the average annual release rate (IRESCO = 0) is chosen as the method to calculate reservoir outflow, the reservoir releases water whenever the reservoir volume exceeds the principal spillway volume, $V_{pr}$. If the reservoir volume is greater than the principal spillway volume but less than the emergency spillway volume, the amount of reservoir outflow is calculated:

$V_{flowout}=V-V_{pr}$​ if $V-V_{pr}<q_{rel}*86400$ 8:1.1.9

$V_{flowout}=q_{rel}*86400$ if $V-V_{pr}>q_{rel}*86400$ 8:1.1.10

If the reservoir volume exceeds the emergency spillway volume, the amount of outflow is calculated:

$V_{flowout}=(V-V_{em})+(V_{em}-V_{pr})$

if $V_{em}-V_{pr}<q_{rel}*86400$ 8:1.1.11

$V_{flowout}=(V-V_{em})+q_{rel}*86400$​

if $V_{em}-V_{pr}>q_{rel}*86400$ 8:1.1.12

where $V_{flowout}$ is the volume of water flowing out of the water body during the day (m$^3$ H$_2$O), $V$ is the volume of water stored in the reservoir (m$^3$ H$_2$O), $V_{pr}$ is the volume of water held in the reservoir when filled to the principal spillway (m$^3$ H$_2$O), $V_{em}$ is the volume of water held in the reservoir when filled to the emergency spillway (m$^3$ H$_2$O), and $q_{rel}$ is the average daily principal spillway release rate (m$^3$/s).