Preprints
https://doi.org/10.5194/hess-2021-360
https://doi.org/10.5194/hess-2021-360

  05 Aug 2021

05 Aug 2021

Review status: this preprint is currently under review for the journal HESS.

Satellite observations reveal thirteen years of reservoir filling strategies, operating rules, and hydrological alterations in the Upper Mekong River Basin

Dung Trung Vu1, Thanh Duc Dang1,2, Stefano Galelli1, and Faisal Hossain3 Dung Trung Vu et al.
  • 1Pillar of Engineering Systems and Design, Singapore University of Technology and Design, Singapore
  • 2Department of Civil and Environmental Engineering, University of South Florida, Tampa, FL, USA
  • 3Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA

Abstract. The current situation in the Lancang–Mekong River Basin is emblematic of the issues faced by many transboundary basins around the world: riparian countries prioritize national water-energy policies and provide limited information on how major infrastructures are operated. In turn, such infrastructures and their management become a source of controversy. Here, we turn our attention to the Upper Mekong River, or Lancang, where a system of eleven mainstream dams controls about 55 % of the annual flow to Northern Thailand and Laos. Yet, assessing their actual impact is a challenging task because of the chronic lack of data on reservoir storage and dam release decisions. To overcome this challenge, we focus on the ten largest reservoirs and leverage satellite observations to infer 13-year time series of monthly storage variations. Specifically, we use area-storage curves (derived from a Digital Elevation Model) and time series of water surface area, which we estimate from Landsat images through a novel algorithm that removes the effects of clouds and other disturbances. We also use satellite radar altimetry data (Jason) to validate the results obtained from satellite imagery. Our results describe the evolution of the hydropower system and highlight the pivotal role played by Xiaowan and Nuozhadu reservoirs, which make up to ~85 % of the total system's storage in the Lancang River Basin. We show that these two reservoirs were filled in only two years, and that their operations did not change in response to the drought that occurred in the region in 2019–2020. Deciphering these operating strategies could help enrich existing monitoring tools and hydrological models, thereby supporting riparian countries in the design of more cooperative water-energy policies.

Dung Trung Vu et al.

Status: open (until 25 Oct 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Dung Trung Vu et al.

Data sets

Storage time series of each dam in the Lancang Basin Dung Trung Vu https://github.com/dtvu2205/210520

Model code and software

Code used to generate the storage time series of each dam Dung Trung Vu https://github.com/dtvu2205/210520

Dung Trung Vu et al.

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Short summary
The lack of data on how big dams are operated in the Upper Mekong, or Lancang, largely contributes to the ongoing controversy between China and the other Mekong’s countries. Here, we rely on satellite observations to reconstruct monthly storage time series for the ten largest reservoirs in the Lancang. Our analysis shows how quickly reservoirs were filled in, what decisions were made during recent droughts, and how these decisions impacted downstream discharge.