In the Mekong River basin, Lao PDR, where slash and burn agriculture has long been
managed, relocation of villages from highlands to riparian and roadside areas proceeded for
economical development and restricting expansion of shifting cultivation (Thongmanivong et al.,
2006). In addition, governmental policy to restrict the slash and burn agriculture has been in
operation since the 1990s for the conservation of forests. As a consequence, the land use has
been reportedly changed, resulting in the shortened fallow periods and degraded fertility of
agricultural lands. However, no analysis clearly revealed possible hydrological consequences of
such a land use change. Thus, this study aims to analyze the impacts of land use changes on
streamflow to provide scientific information for national policy makers by looking into
meteorological and hydrological trends and rainfall-runoff relations for the tributary watersheds
of the Mekong River basin using measurement data obtained in the past two decades.