Rule curve reservoirs
Rule curve reservoirs are divided into five zones as illustrated in Figure 9.3,
Figure 9.3 Operating zones in a Rule curve reservoir
This zone serves as storage buffer to diminish the impacts of high floods. Under normal circumstances the water level in the reservoir is kept at Flood control level to maintain optimal protection and reserve water for supply. If the water level is within the Flood control zone, water is released at a rate up to maximum downstream release. The release can be limited by spillway conditions.
If a Spillway bottom level time series is specified (see the Spillways, Section 9.6) the lower level of Flood control zone is defined by the Spillway bottom level, no matter whether this is above or below the Flood control level.
This zone is between the Flood control level (lower level of the flood control zone) and the first Reduction level for a given water user. In the Normal operating zone all demands are fulfilled. The extend of this zone can vary for individual water users.
If the water level is in this zone, a demand is only partially fulfilled. A variable number of reduction level curves and corresponding reduction factors can be specified for each connected water user as described in Section 9.3 ‘Users’. The lower limit of the Reduced operating zone is the Minimum operation level. If this level is not specified then the lower limit is the Dead zone level (Top of Dead Storage).
If the water level reaches this zone, only downstream release (minimum release requirement for environmental flows is maintained). No water for usage is being released. The Conservation zone only exists if a minimum operation level has been specified.
If the water level reaches the Inactive (Dead storage) zone, water can only be lost due to evaporation or bottom infiltration.
