Assessment of climate change Impacts on reservoir operation and performance: A case study of Pong Reservoir, India

Changes in monsoon patterns, amount of precipitation, rising air temperature, and melting of Himalayan snow and glacier cover are affecting the river flows, operation, and performance of major water storage infrastructures such as reservoirs. Several studies using GCM's have already registered worsening reservoir performance and higher capacity (storage) requirements as a result of climate change around the world, including India. In this paper, we have selected the Pong reservoir in the Beas river of Indus basin in India to assess the effect of climate change on river runoff and reservoir performance in meeting it's irrigation demand. The reservoir has a catchment area of 12,561 km^2, which has inflow contribution from both monsoon rainfall and snow and glacier melt runoff. The pong reservoir primarily meets the irrigation demand (7913 Mm³/yr, 1.6 Mha command area), generates hydropower (plant capacity: 396 MW), and caters the domestic water requirements in the Basin. In addition to meeting these demands, the reservoir also has to ensure flood control and maintain adequate environmental flow to sustain ecosystems in the downstream.

The GCM projections of future rainfall and temperature between 2021-2100 for different RCP's which was forced into HYSIM rainfall-runoff model to estimate the future runoff in Beas river. Based on the 4 scenarios, we assessed the ability of the reservoir in reducing the impact of climate change through optimizing the operation by comparing the performance of the reservoir (resilience, vulnerability, sustainability and reliability) under different scenarios and computed the Climate Effect. Based on the preliminary results, we found that the seasonal changes under future climatic scenarios will pose a major challenge to the operation of Pong reservoir despite the increase in runoff in the catchment area due to accelerated runoff induced by rising temperature. The results also revealed undesirable reservoir storage capacities depending the future climatic scenario.