Model-Based Assessment of Water, Food, and Energy Trade-Offs in a Cascade of Multipurpose Reservoirs: Case Study of the Sesan Tributary of the Mekong River

Abstract

The Mekong River Basin in Southeast Asia is undergoing rapid development in the exploitation of its water resources. Although hydropower is the most dominant driver for water development, the possibilities for multipurpose reservoirs have been increasingly discussed but not well studied. The authors assess the potential benefits and negative impacts of a multipurpose reservoir cascade facilitating hydropower and irrigation in the Sesan River, a transboundary tributary of the Mekong. A model-based assessment approach was developed where the hydropower operations of a cascade of reservoirs were simulated together with the irrigation water withdrawals. The assessment revealed that the reservoirs created considerable irrigation potential (28,348 ha), and the resulting losses for hydropower generation were relatively small (−1.6%). The river flow impacts were significant, but they originated mainly from the hydropower operations. The inclusion of irrigation led to an increased competition of water resources during the dry season. In addition, the assessed hydropower and irrigation development affected negatively protected areas, agriculturally valuable land, and forest cover. Gaps and shortcomings in the model-based assessments of water resources development were further recognized, including this one, concluding that particularly the connection to ecological and social domains remains often weak and needs, therefore, to be strengthened.

Effect of Proposed Large Dams on Water Flows and Hydropower Production in the Sekong, Sesan and Srepok Rivers of the Mekong Basin

“…Their complementary (or conflicting) effects with hydropower, however, are important for water resources management and should be the subject of further research. Thus far, water withdrawals for agricultural production have not been found to be conflicting significantly with hydropower in this basin (Räsänen et al ., ). Preliminary modelling on climate change and hydropower operations suggests that hydropower operations have the greatest impact on seasonal flow patterns and that energy production will not be substantially affected by impacts of climate change on basin hydrology (Piman et al ., ).…”

“…Future irrigation water demands, land use change and climate change have been studied in this basin before (Ty et al ., ; Piman et al ., ; Räsänen et al ., ); thus, these factors were not considered in this study. Their complementary (or conflicting) effects with hydropower, however, are important for water resources management and should be the subject of further research.…”

Hydropower versus irrigation—an analysis of global patterns

“…The authors proposed that downstream countries could provide alternative energy sources to Kyrgyzstan in exchange for releasing irrigation water during the irrigation season, essentially reverting to the Soviet era flow release regime. On the other hand, Räsänen et al (2015) found that multipurpose cascade reservoirs on a transboundary tributary of the Mekong created considerable irrigation potential at the expense of a relatively small hydroelectricity generation loss. Another study in the Nam Ngum, a sub-basin of the Mekong, similarly showed that full hydropower development allowed irrigation water use to triple and also improved environmental flow requirements during low-flow periods (Lacombe et al 2014).…”

Water-Energy-Food Nexus in a Transboundary River Basin: The Case of Tonle Sap Lake, Mekong River Basin

“…When discussing the nexus, it is useful to recognise that it has different dimensions: we discuss what we consider to be the two key dimensions of the nexus. The first dimension promotes the nexus as an approach for research and analysis by, for example, quantifying the linkages between the nexus sectors [1,6,[21][22][23]. The second dimension presents the nexus more as a policy-making tool that is seen to facilitate cross-sectoral collaboration and integrated planning and policy-making [3, 4,9,24].…”