Purpose - The watershed areas of the Tijuana and Upper San Pedro Rivers span the international border between the United Stated and Mexico. Both watersheds have been studied extensively and
are undergoing explosive population growth. Water resource issues are critical factors influencing economical and environmental sustainability in these ecologically-fragile, semiarid ecosystems. From
an ecological perspective, these watersheds are meaningful landscape units for study and management because of the shared functional relationships that exist within their boundary areas.

Very different social, political, and economical influences occur on the two sides of this international border. One result for these transboundary watersheds is that a significant gap exits between the watershed as an ecological unit, and the watershed as a planning and administrative unit. The natural processes within the watershed areas are not restricted by borderline boundaries, but affect all of the other systems within it regardless of the nationality of their location. Difficulties of researching and managing the resources in an area divided by multiple nationalities arise due to the social political, and economical differences between those nationalities. Research methods and political policies on one side of a border may not be the same as those on the other side of that same border, thus making research and management of a shared resource difficult.

Objective - The objective of the Transborder Watershed Research Program is to initiate for the Tijuana River and Upper San Pedro River basins an integrative program of research that explores the gap between the transborder watershed as an ecological unit, and the transborder watershed as a planning and administrative unit. Geographic models will be used to answer the central research questions put forward in this project.

---