NM Tech Researchers Study Panama's Rio Chagres Watershed

by George Zamora

SOCORRO, N.M., July 8, 2002 -- A hydrologist and a geologist at New Mexico Tech have joined an international team of researchers in an ongoing investigation of Panama's Rio Chagres Watershed, with the goal of providing a better understanding of the hydrology, geology, and chemistry makeup of the watershed.

Jan Hendrickx, professor of hydrology at New Mexico Tech, and Bruce Harrison, associate professor of geology at the research university, have teamed up with researchers from four countries to determine the hydrologic properties of soils typically found along the dense tropical forest that abuts the length of the Panama Canal.

The Rio Chagres and its tributaries have long played an important role in Panama's history, up to the watershed's current international significance as the major supplier of the millions of gallons a day needed to operate the Panama Canal's lake and lock system and provide hydro-electric power to open and close the locks. In addition, the watershed serves as the primary source of drinking water for Panama City and nearby communities.

"The area which surrounds the Panama Canal really is the ideal test site for studying these types of watersheds,"
Hendrickx says. "From the Atlantic to the Pacific, there's a strong gradient of precipitation--which goes from very low to
very high as you travel east to west--all within a span of less than 100 miles."

The primary water source of the Chagres Watershed is a range of steep, dome-shaped mountains that are covered with an emerald canopy of dense, tropical cloud forest.

It is in this lush setting that Hendrickx, Harrison and fellow researchers set up field camps earlier this year to study the flora, fauna, and geology of this important watershed in Central America.

The New Mexico Tech geoscientists worked with a research group whose focus was characterizing soils and hydrology in the area, using geomorphology and cosmogenic dating techniques.

"We were there taking samples during what was essentially the dry season in Panama, so there wasn't much runoff occurring," Hendrickx says. "Most of the rain that did fall during that time was taken up by the vegetation."

Yet, Hendrickx and Harrison noticed that streams and rivulets were discharging throughout the forest, usually from various holes found at the base of the steep slopes.

Hendrickx says that preliminary analyses show that the soils being tested from these areas are of very high clay content, and
subsequently exhibit very high water-retention capacity.

"Because of these soil characteristics, the watershed basically acts like a big sponge," Harrison relates.

"We were further able to identify several areas in our field study where water was flowing out of the soil, in some places directly from these holes we found along the slopes," he adds.

During the last half of the last century, more than two- thirds of the tropical forest that adjoins the Canal Zone were cut down, mostly through slash-and-burn methods employed by subsistence farmers moving into the areas.

"There was a lot of pressure at one time to clear up parts of the Canal's forests for agriculture," Harrison says. "Families typically would stay for two or three years to farm the land, but would then move on because the soil is so infertile.

"People in Panama are now questioning what impact these deforestation methods that were being used will now have on their current water supply," Harrison relates.

"If you take all the jungle out, then you're definitely going to have a significant impact, particularly with respect to sediment yield and water yield in these types of watersheds," he asserts.

In an effort to reverse the deterioration of the tropical forests surrounding the Panama Canal, many of these endangered environments in Panama are now under the federal protection of its national park and nature reserve systems -- a conservation management plan that seems to have markedly slowed the decimation of the Canal's vital watersheds.

However, the Canal Watershed Monitoring Project, which is funded by the U.S. Agency for International Development and
administered by the Smithsonian Tropical Research Institute, recently determined that water degradation--caused by the combined effects of erosion, sedimentation, and eutrophication (the natural process by which lakes age)--may soon become the largest threat to the future of the Panama Canal.

Since the upper Chagres Watershed has largely been free of human activity and colonization, the scientific information derived from the international, multidisciplinary study being conducted by the New Mexico Tech researchers and their collaborators may soon provide valuable data to ensure the sustained viability of the much larger Panama Canal Watershed, as well as other watersheds around the world that are faced with similar problems.

"The type of rainfall gradient that we encountered in the tropical cloud forests, just 40 miles or so outside of Panama City, are similar to those found in places like Hawaii, New Zealand, and northern Australia," Harrison points out.

In addition to the New Mexico Tech geoscientists participating in the Chagres Watershed study, other researchers
involved are from Colorado State University, University of Vermont, the U.S. Geological Survey, the Smithsonian Tropical
Research Institute, Universidad Tecnologica de Panama, and Goettingen University in Germany, as well as from three U.S. Army research organizations, including the Army Research Office and the Yuma and Aberdeen proving grounds.