The proposed developed genetic algorithm (GA) model was applied to search the optimal daily rule curve of the Mosul regulating reservoir. It is located 8 km downstream Mosul main
along Tigris river, (Figure 1). The regulating reservoir is constructed to verify the main purpose which is the regulation of the outflow released from the upstream main Mosul dam
according to the downstream water requirements along Tigris river in such away that a minimum discharge of 330 m3/sec can be maintained over as long as possible, in-addition to satisfy
enough water head for the operation of pump storage lake scheme constructed beside the regulating reservoir. The regulating reservoir began in the operation since 1986 to verify its
function. The storage volume-surface area stage curves of the reservoir is shown in Figure (2). For the flow record data, two periods of daily inflow, outflow and water level at the reservoir (1986-1990) and (1994-2007) were used. The case study reservoir may be classified as short term
reservoir in which the storage fluctuation occurs daily according to its construction function.