Itanagar: Arunachal Pradesh chief minister Pema Khandu on Wednesday sought to dispel public misconceptions over the hydrological impact of upstream Chinese mega-projects, saying installed power generation capacity in megawatts (MW) does not correlate directly to water storage volume.Khandu said India’s proposed 11,000-MW Siang Upper Multipurpose Project (SUMP) holds larger live storage capacity than China’s massive 60,000-MW Medog dam on Yarlung Tsangpo River, making it an effective downstream buffer.Addressing concerns over how an 11,000-MW Indian project could moderate water releases from a facility nearly six times its installed power capacity upstream, Khandu took to the microblogging platform X to clarify the distinction between energy generation and reservoir retention.“The key is to understand water storage, not just power capacity. The Chinese Medog project is reported to have around 5.5 Billion Cubic Metres (BCM) of estimated storage, while SUMP has around 9.2 BCM of live storage. So why does China have 60,000 MW while SUMP has 11,000 MW? Because MW and water storage are different things,” Khandu said.Elaborating on the physics governing hydroelectric power generation, CM said energy generation depends heavily on the hydraulic head, the elevation drop through which water falls. The steep elevation decline at Yarlung Tsangpo’s Great Bend in Tibet enables China to generate immense power without proportionately massive water retention volumes. Consequently, higher wattage capacity does not automatically equate to a larger volume of impounded water.To illustrate the point using local examples, Khandu highlighted the variance in power-to-storage ratios across Arunachal Pradesh’s own hydroelectric ventures in Dibang Valley.Citing examples from Arunachal Pradesh, Khandu compared the proposed 3,097-MW Etalin Hydroelectric Project in Dibang Valley, which has a minimal storage capacity of 7.5 million cubic metres (MCM), with 2,880-MW Dibang Multipurpose Project, designed with around 4 BCM of reservoir storage.CM’s statement came amid a public debate and protests in Upper Siang over pre-feasibility survey activities for SUMP.
