Quantifying spatiotemporal impacts of hydro-dams on land use/land cover changes in the Lower Mekong River Basin.

Many hydro-dams have been constructed in the Lower Mekong River Basin (LMRB) due to their high potential in hydro-power and economic development, but there are many knowledge gaps in understanding unintended, negative social and environmental consequences. One of the knowledge gaps is spatially explicit impact assessment of hydropower dams, especially when it comes down to policies for pay for ecosystem services. In reality, the spatial patterns of dam impacts are obvious, but little is known about the pattern and scope of the impact. Thus, this paper adopted an ellipse shape model in quantifying dam impacts and determined the spatial extents at different dam construction stages. The methods used were the proximity, trend, and cluster analysis on the time-series nighttime lights and enhanced vegetation index, which were then fitted to the ellipse model. The ellipse model was compared to the circular model using three criteria (compactness index, omission index, and ellipse index) to show the usefulness of the ellipse model. The spatial impacts of dams were measured by land use/land cover changes, at different spatial scales and different stage of dams. The results suggested that the ellipse model was able to capture the spatial and temporal effects of dams at different construction stages, when compared with satellite observations. This paper suggested an asymmetric pattern of dam impacts and there were spatial boundaries. These findings may help devising dam-related policies, especially when it relates to pay for ecosystem services. • The ellipse model was developed for spatially quantifying consequences of dams. • The ellipse model outperforms the circular model in depicting the dam impacts. • Different stages of dam cause distinct spatial extents and patterns of dam impacts. • Terrain and impoundment largely affect the dam impacts during dam construction. • Agricultural expansion primarily leads to the deforestation after dam operation. [ABSTRACT FROM AUTHOR]