Are hydropower and irrigation development complements or substitutes? The example of the Nam Ngum River in the Mekong Basin

Abstract

Hydropower and irrigation developments to address rising demand for food and energy are modifying the water balance of the Mekong Basin. Infrastructure investment decisions are also frequently made from a sub-catchment perspective. This paper compares river flows with irrigation development stages in the Nam Ngum sub-basin where the potential for irrigation and hydropower expansion is largely untapped. It shows that full hydropower development in this basin allows irrigation water use to triple, even as it reduces competition with environmental flow requirements. The implications for the wider Mekong are, however, unclear, particularly given uncertainty over parallel transformations elsewhere in the basin.

Keywords:

• water resources development
• water balance
• optimization/simulation model
• Mekong

Acknowledgements

The authors thank the Lao Ministry of Natural Resources and Environment (MONRE), the Lao Ministry of Agriculture and Forestry (MAF), the Department of Irrigation of MAF, the National Agricultural and Forestry Research Institute of MAF, the NN1 Hydropower Plant Company, and the Nam Ngum River Basin Committee for the provision of pumping and irrigation data, rainfall data and for the fruitful discussions. The authors are grateful to the Department of Meteorology and Hydrology of MONRE, and to Khonetavanh Douangchanh for the provision of hydro-meteorological records. They thank Chanthaviphone Inthavong and Kaona Boupha for the provision of information about the Napheuy multipurpose hydropower project. They are also grateful to Bounthanh Bounvilay, Robyn Johnston, Peter McCornick and Andrew Noble who took part to the initial stages of the project implementation.