It's a small world. Water issues don't adhere to national boundaries. Researchers from water resources management study water from the smallest field scale (i.e., pores in soil) to the largest (observing water movement using satellites). The whole spectrum of science, from the highly technical study of global circulation models, to the study of international water legislation is conducted on a truly global scale.
It's a small world that we all share, but there is still a big world out there to discover!