Inter-basin water transfer and water security: A landscape sustainability science perspective.

Inter-basin water transfer (IBWT) projects have been implemented worldwide as a strategy to enhance water security. However, there have been increasing concerns about the unsustainability of such projects due to their environmental and socioeconomic impacts. This study aims to provide a state-of-the-science overview of sustainability assessments of IBWT, with the objectives of identifying key knowledge gaps and suggesting future research directions. Through a systematic review of 232 publications on this subject, we synthesized environmental, socio-cultural, and economic gains and losses of IBWT for both the donor (or source) and recipient basins. Our results show that most of the IBWT sustainability-related studies were from Asia and North America, with China contributing the largest share. These studies predominantly focused on a single dimension of sustainability-environmental, economic, or social. The findings suggest that IBWT projects influence the sustainability of both the donor and recipient basins in diverse and context-dependent ways. We identify three major knowledge gaps: limited understanding of the underlying environmental and social processes, insufficient multiscale and holistic perspectives, and the lack of robust, integrated sustainability assessment methods. To help fill the gaps, we propose a framework for assessing the sustainability of IBWT projects from a landscape sustainability science perspective. This new framework considers both the donor and recipient basins as an integrative regional social-ecological system, with a dynamic relationship between landscape patterns and ecosystem services mediated by water transfer.