along, particularly in comparison with other nearby watersheds such as the Nu. Four dams
have been completed—including Xiaowan, a massive concrete arch dam that, at nearly 300
meters high, is currently the world's tallest dam structure—and one is nearing completion.
Taken together, these projects represent the development of about one-quarter of the basin's
total hydropower potential. Tens of thousands of villagers have been resettled by the dam
projects to date, and thousands more will be resettled in the years to come.
Displacement and resettlement, particularly by force, coercion, or government order, are
the most controversial and politically sensitive social consequences of hydropower develop-
replete with methodological and political challenges, but crucial to formulating policy that
accounts for the full range of costs and benefits associated with dams. Villagers resettled for
dam projects in the Lancang basin, some more than twenty years ago and some much more
recently, have faced the loss of farmland; a shift in income-generating activities away from
agriculture and toward self-employment and wage labor; a disruption in the social networks
of trust and reciprocity with other villagers that provide economic and social support; and a
fundamental alteration in the cultural ties between people and place.
ECOLOGICAL AND CULTURAL DIVERSITY ON THE LANCANG
The Mekong is a transboundary river whose main stem and extensive network of tributaries
support the livelihoods of tens of millions of people in China, Myanmar, Laos, Thailand,
Cambodia, and Vietnam. Many sections of the river were mapped extensively beginning
in the mid-nineteenth century, but other sections—in particular the upper Lancang in Yun-
nan—remained a mystery that inspired exploration on a global scale. A small group of
French Jesuits stationed in Vietnam undertook an overland trek along the Mekong between
1866 and 1873, which would become known as the Mekong River Expedition (Osborne