The previous Drought Plan only contemplated three indices that reflected scarcity in the basin: the basin system state index; the state index of the transfer system; and the global state index. In all three cases, the indices were calculated by normalizing between 0 and 1 of an indicator that, in different proportions, weighted the stocks at day 1 of each month in each system and the accumulated year-on-year contributions. The indicator for the global index was calculated using a weighted sum of both indicators, and the global index was calculated using the same formula as the indices for the two subsystems.
Among the main novelties of the new PES, regarding the characterization of drought situations are: