SCERP Transborder Watershed Research Program Proposal Abstract

SCERP Transborder Watershed Research Program

Return to Research/1998 SALSA Research Activities

The Southwest Center for Environmental Research and Policy (SCERP) is a university consortium dedicated to applied environmental research of the U.S.-Mexican border region. SCERP was created by the U.S. Congress in October 1990 legislation that stated the consortium was to "initiate a comprehensive analysis of possible solutions to the acute air, water quality, and hazardous waste problems that plague the United States-Mexico border region." SCERP carries out its mission through a cooperative agreement with the U.S. Environmental Protection Agency.

As part of their mission, SCERP has recently initiated the "Transborder Watershed Research Program" (TWRP), a multi-year study of the Tijuana River in California/Baja California Norte and the San Pedro River in Arizona/Sonora. The program is headed by Dr. Ward Brady (Arizona State University) and Dr. Richard Wright (San Diego State University) and is being conducted in collaboration with the SALSA research effort in the Upper San Pedro Basin.

THE TRANSBORDER WATERSHED RESEARCH PROGRAM

ABSTRACT

(1 May 1998)

The Tijuana and San Pedro watersheds span the international border between the United States and Mexico. Both watersheds have been studied extensively, both watersheds are undergoing explosive population growth, and water resource issues are critical factors influencing sustainability in these ecologically-fragile, semiarid ecosystems. From an ecological perspective, these watersheds form meaningful landscape units for study and management because of the shared functional relationships that exist within their boundaries. However, very different social, political, and economic influences occur on the two sides of this international border. One result for these transboundary watersheds is that a significant gap exists between the watershed as an ecological unit and the watershed as a planning and administrative unit. The overall objective of the Transboundary Watershed Research Program is to initiate for the Tijuana and San Pedro basins an integrative program of research which explores this gap and identifies barriers to--and opportunities for--bridging this gap. While two watersheds are being studied, one goal of our study is to integrate these studies in a cooperative analysis through the use of common models.

Integrative approaches to watershed research combine ecological, economic, political, and social factors in the study of watershed processes. Land uses are influenced by these factors and, in turn, impact ecosystem dynamics through events that can be identified and monitored. The principal objective of our research is to investigate the dynamic interrelationships between human and natural factors as reflected by land use patterns in the Tijuana and San Pedro watersheds. Our central research question therefore is: What economic, social, political, and ecological processes interact to generate land use patterns in the Tijuana and San Pedro watersheds, and how do these patterns and processes influence environmental conditions in the two basins?

Our research approach will focus on characterizing the distribution and intensity of land use in each watershed and developing models which describe the interrelationships between land use patterns and ecological and human factors. Patterns of land use will be documented using maps, planning documents, aerial photographs, and satellite imagery to generate a GIS-based record of recent land use change.

Numerous studies are being conducted on both watersheds. Consequently, a sizable amount of data currently exists (collected by government agencies, private organizations, and university researchers). However, these data vary greatly in thematic content, geographical coverage, and scale and resolution. In the Tijuana Watershed our research and data needs will focus on the land use-ecological relationships (especially among land use, urban runoff, non-point source pollution, and the estuarine ecosystem). To insure a comparative analysis of the two watersheds, we intend to take a similar approach in the Upper San Pedro. Numerous studies are currently being conducted in the Upper San Pedro that emphasize ecological and landscape processes. We have been in contact with these researchers and intend to build upon and complement their studies and work cooperatively to avoid duplication. Specifically, we intend to look at land use as the ecological process which characterizes human influences and resource demands on the landscape. For both watersheds, our goal is to integrate existing information into a larger land use model which will investigate the interdependencies and feedback among ecological, economic, social, and political factors influencing land use. In particular, our models will explicitly consider the impact of the border on watershed properties and dynamics.

Several types of modeling activities will be undertaken. For the San Pedro Watershed, we will develop a hierarchically structured, patch dynamic, watershed model. This watershed model will be spatially explicit and will use grid-based, remotely sensed data as well as integrated ecological and socio-economic data. Of particular interest will be socio-economic and institutional factors influencing patch development and patch influences on water resources and the riparian ecosystem components of the watershed. For the Tijuana Watershed, we will develop a similar GIS-linked model, that, when coupled to an empirically-based runoff model, will serve to both manage the spatial and temporal datasets and predict pollutant loading to the estuarine ecosystem. For both watersheds, land use characteristics which will be described for each patch type will include 1) social and economic factors, 2) surface and subsurface water flow, 3) point-source and non-source pollution, 4) biodiversity, and 5) other activities such as fuel combustion that give rise to air pollution which in turn impacts water quality.

As part of our efforts to characterize environmental conditions in these two semi-arid, transborder watersheds we will also evaluate applications of existing approaches including EPA's Index of Watershed Indicators, the PLAnning for Community Energy Economic and Environmental Sustainability (PLACE3S) model, and EPA's BASINS software package. Indices for the Index of Watershed Indicators have not been computed for the Mexico portions of the watersheds, thus providing an incomplete characterization of the total area of each basin. This deficiency will be overcome by our cross-border program perspective.

The overall goal of the transborder watershed program is to provide information for decision makers that will aid in policy formation and adaptive management aimed at sustainable ecological and human health in the two basins. Our research will assist in meeting the need for 1) reasonably sophisticated and accurate integrated transborder watershed models which can be used to support watershed management and restoration decisions and for 2) education and public outreach to help local citizens and other stakeholders recognize the importance of a watershed-wide perspective. One tool for communicating results of our research will be a web site which will portray the physical, social, economic, and political characteristics of the watersheds as well as the results of the modeling efforts. This easily accessible medium should be an invaluable aid in helping stakeholders visualize and understand spatial patterns and relationships over the watersheds. For the Tijuana watershed, another major product of the program will be press-ready negatives for a folio-size multi-color atlas that will contain the same information in hard copy form. (In the second year of the project, development of an atlas for the San Pedro watershed will also begin in collaboration with the SALSA project). In addition, our research will:

1) increase understanding of relationships between anthropogenic factors and physical/biological processes;

2) improve knowledge of baseline conditions in the watershed;

3) increase collaboration among scientists from SCERP institutions;

4) improve cooperation between researchers, community groups and government agencies having interests in the watersheds;

5) increase understanding of the influence of cross-border asymmetries on watershed processes through cooperative analysis of the San Pedro and Tijuana Watersheds;

6) identify stressors and high risk areas;

7) identify data gaps; and

8) develop improved methodologies for addressing environmental problems in transborder watersheds, taking into account new methodologies and guidelines recommended by NAS/NRC and EPA.