Contribution of Internal Variability on Hydropower Production Under Changing Demand Scenario

Hydropower is the second-highest contributor to the energy consumed in India. Future potential hydropower relies upon water availability characterized by uncertainties in precipitation and temperature under changing climate. Whereas, the lack of certainty in hydropower production limits our understanding of the future contribution of hydropower, posing a threat to energy security. Several studies estimate model and scenario uncertainties have a significant contribution to potential hydropower estimation. Here, we analyze the role of Internal Climate Variability (ICV) in hydropower potential on Narmada, Tapi, and Mahi river basins, India. We estimate uncertainty due to ICV using fifty initial condition ensembles of the EC-EARTH3 model from CMIP6. The generated hydropower is the function of streamflow and reservoir storage. We estimate the streamflow projections for all ensembles using the Variable Infiltration Capacity (VIC) hydrological model for four time periods, historical (2001-2015), near term (2016-2045), mid-term (2046-2075), and end term (2076-2100). We compute storage and release from reservoirs to obtain the water head driving the power generation. We also predict the future energy demand using the SARIMA model with 95% confidence, indicating a 45% increase in its median by 2030. Our results show that uncertainty due to internal variability in streamflow gradually increases with time for all three basins. However, uncertainty in power generation gradually decreases with time.