Journal of Changjiang River Scientific Research Institute ›› 2025, Vol. 42 ›› Issue (1): 35-43.DOI: 10.11988/ckyyb.20230942

• Water Resources • Previous Articles     Next Articles

Impact of Lancang River Cascade Hydropower Stations on Mekong River During Dry Seasons in the Context of Changing Environment

ZHANG Pan-quan(), GUAN Zhen, LI Hong-gang, YANG Qing   

  1. Cascade Control Center of Huaneng Lancang River Hydropower Co., Ltd., Kunming 650214, China
  • Received:2023-08-29 Revised:2023-10-14 Published:2025-01-01 Online:2025-01-01

Abstract:

The runoff of the Mekong River is undergoing transformation under the influence of environmental changes. Enhancing the scientific understanding of Mekong River drought and the role of cascade reservoir operations on the Lancang River contributes to the effective management of cross-border water resources and the development of the Lancang-Mekong Cooperation. Based on the discharge data from Jinghong Hydropower Station and runoff measurements from hydrological stations along the Mekong River, as well as the Standardized Precipitation Evapotranspiration Index (SPEI), temperature, and precipitation data, this study examines the impact of cascade hydropower stations on the Lancang River during the dry season. Results reveal that over the past 40 years, the meteorological drought frequency in the Mekong River was 25.6%, with higher frequency in flood season reaching 35.7%, and 21.4% in dry season. SPEI during flood season exhibited a decreasing trend of 0.14 per decade. Persistent warming and interannual precipitation variability since 2000 have resulted in sustained meteorological droughts in the Mekong River. Following the operational adjustments of cascade hydropower stations since 2010, the average discharge from Jinghong Hydropower Station during dry season has increased by 92.9% compared to the multi-year average. The discharge from Jinghong accounts for significant proportions of the runoff at key hydrological stations along the Mekong River, specifically 83.5% at Chiang Saen, 68.1% at Vientiane, 37.3% at Pakse, and 35.0% at Kratie. Notably, the proportion of water replenishment to Kratie can reach approximately 45% during the lowest runoff period from March to April. Particularly during drought conditions in the Lancang-Mekong Basin, these replenishments effectively alleviate water demand downstream. The operations of the Lancang River cascade hydropower stations significantly enhance water replenishment in the Mekong River during dry season, highlighting their substantial regulatory role and positive impact on downstream regions.

Key words: drought, dry season, reservoir operation, influence analysis, Lancang-Mekong River

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