Number 40, Spring 2003

Up-close Delta studies bring its issues alive

Nine teams of researchers studying the Colorado River Delta area, report making great strides in building up a much-needed body of knowledge.

The impetus for their investigations came from a 2000 conference on the Colorado River Delta & Upper Gulf of California that UC MEXUS and the Udall Center for Studies of Public Policy of The University of Arizona co-sponsored.

Colorado River Delta
Satellite photo of the Colorado River Delta.

Participants discovered a severe lack of binational data on the ecologically sensitive area spanning the U.S.-Mexico border. This left decision-makers and stakeholders to determine the future of the region with few facts at their disposal.

As a result, UC MEXUS, CONACYT and CICESE joined forces to offer a binational grants program specific to the Colorado River Delta’s Upper Gulf of California. In 2001 nine teams of UC and Mexican researchers received support for projects ranging from ecology to hydrology.

The research teams met for a workshop at UC Santa Barbara in January to report on their preliminary studies and findings.

Studies of the water supply, vegetation and wildlife, both on land and in the sea, have provided basic data on which to project the effects of changes in those environments.

In addition to advances in science, researchers reported increased interactions and enhanced relationships between UC and Mexican institutions. New areas of binational investigation have grown out of the current ones, often involving new researchers, many of whom had not known one another prior to these studies.

Water usage is a core issue in planning for the region. The research team of Jesús Ruiz, Universidad Autónoma de Baja California, and Richard Snyder and Khalid Bali, UC Davis, focused on farmers and agriculture workers in the area. They worked with UC Davis Cooperative Extension and the State of Baja California to install equipment, create manuals and schedule classes to improve agricultural irrigation efficiency and reduce demand for precious Colorado River water.

The reduction of water flow that resulted from the damming of the Colorado River has affected the sea as well as the land. Sediment deposits have shifted radically since then. Luis G. Alvarez, CICESE, with Tommy Dickey and Grace Chang, UC Santa Barbara, documented new areas of erosion and buildup, noting the economic implications for fish farming ponds and harbors.

Using a remote sensing device, Alejandro Hinojosa Corona, CICESE, and Leal A. K. Mertes, UC Santa Barbara, graphically illustrated the effect of reduced or increased Colorado River flow.

Luis Calderón-Aguilera, CICESE, and Enric Sala, Scripps Institution of Oceanography, UC San Diego, confirmed damage to habitat, and depletion in the numbers of endangered species and the fish supply. They created data and methodology for on-going research to simulate the effects of fishing and changes in fresh-water flow as a basis for resource management and water policy.

Several collaborators focused on specific areas vital to the ecology of the Delta. Two engineers and an ecologist (John Dracup and Kate Huckelbridge, UC Berkeley, and Silvia Ibarra-Obando, CICESE) joined forces to study the Cienega de Santa Clara wetland. Their model aims to demonstrate how changes in the quantity and quality of inflow would affect the wetland's hydrology, water quality vegetation and wildlife.

Also working in the wetlands, Drew Talley, UC Davis, and Eric Mellink, CICESE, are looking at the primary food sources supporting the most common bird species nesting there. Identifying food sources allows researchers to project changes that would result from alterations to the habitat.

Miguel Lavin, CICESE, and Libe Washburn, UC Santa Barbara, described the mode and manner of larvae movement from spawning areas in the Upper Gulf of California and the nursery ground on the Colorado River Delta.

Jay Barlow and Armando Jaramillo, UC San Diego, and Horacio de la Cueva, CICESE, began tracking the movement and surviving numbers of the severely endangered vaquita. Their data will help identify critical areas and seasons for vaquita recovery.

Sharks, in contrast, remain relatively plentiful but under studied. The data that Milton Love, UC Santa Barbara, and Oscar Sosa-Nishizaki, CICESE, are developing on the numbers, varieties, sizes and genders of those that inhabit the Gulf of California will help correct that inequity.