Valorization of Irrigation Water in A Basin with Large Hydropower Production through Coupled Hydrological and Electric System Modelling

The problem of allocation of limited water resources for multiple and diverse activities with growing demand calls for the need to develop appropriate tools for water valorization. This work develops a methodology to estimate the economic value of water in a basin with large hydropower production and a growing demand for rice irrigation, based on a coupled hydrological and electric system modelling approach. Inflow deficits to the hydroelectric system induced by the irrigation reservoirs within the basin are simulated under different irrigation scenarios. The simulated inflow deficits are integrated to an existing model of the interconnected electric system to evaluate the associated increase in generation costs under different energy scenarios. The impact of inflow deficits in turbinated and spilled flow and generation costs are comprehensively explored. Both annual mean and interannual variability of overcosts increase with increasing irrigation demand. However, if normalized by yearly varying rice planted area, the distribution of additional costs does not change substantially. Moreover, the distribution of normalized overcosts per unit irrigated area is also invariant to energy scenarios, although the relative impact in total costs decreases as the proportion of hydroelectric generation diminishes.