Hydrologic Changes, Dam Construction, and the Shift in Dietary Protein in the Lower Mekong River Basin

Abstract This study links the changing hydrology in the Lower Mekong River Basin (LMRB) caused by accelerated dam construction to a dietary shift from fish to land-animal meat (meat hereafter) as a primary source of protein. A shift toward a westernized diet in the LMRB countries (i.e., Cambodia, Lao PDR, Thailand, and Vietnam) has been observed in the recent past. However, neither the hydrological changes from dam construction as a cause for the dietary shift nor the effects of increasing shift from fish to meat on virtual water have been adequately studied. Here, we derive a univariate relationship between fish catch and flooded areas by using a hydrodynamic model and yearly fish catch data. We find a strong correlation between catch per capita and yearly flood occurrence in the LMRB. Results suggest that fish catch in the Tonle Sap Lake region may reduce by ~8% under a scenario of altered flood occurrence caused by potential reduction in peak flow in the main stem Mekong by 50%. The same reduction in peak flow could, however, lead to an increase in catch within a larger LMRB sub-region but such increase would be marginal. Next, based on the historical production and consumption of meat, we find an increase in meat production and consumption per capita over time. Further, analysis of land use change suggests a 2% cropland expansion mainly due to an increase in meat production. Finally, from the virtual water trade (VWT) network we find that the total VWT of the LMRB tripled from 1988 to 2016 due to a significant rise in trade partners.