Simonit and Perrings found that only 37 percent of the currently forested area positively impacts dry-season water flows, offering up roughly 37.2 million cubic meters of seasonal flow (equivalent to US $16.37 million in revenue to the Panama Canal Authority).
In parts of the watershed not currently under forest, they found that reforestation of areas with high precipitation rates, flat terrain, and soil types with high potential infiltration would enhance dry-season flows. However, they note that these conditions exist in less than 5 percent of watershed not currently under forest.
"Water supply is, however, only one amongst many ecosystem services affected by reforestation of the watershed," said Perrings, a professor in the School of Life Sciences in ASU's College of Liberal Arts and Sciences. "And the balance between services depends on the type of reforestation undertaken." Accordingly, the duo investigated two reforestation scenarios: natural forest regeneration and teak plantation.
"We found that if all existing grasslands were allowed to regenerate as natural forest, there would be a reduction in dry-season flows across the watershed of 8.4 percent, compared to 11.1 percent if reforestation took the form of teak plantations." In both cases, these conditions potentially pose a problem for the Panama Canal Authority. Even with water-saving advances in the new locks, the canal is expected to need 14 percent more water when the expansion takes full effect, and other options for securing dry-season flows are not cost-free. However, the Panama Canal Authority is not the only beneficiary of the watershed, and water is not the only ecosystem service supplied. "Both natural forest and teak plantations offer benefits in the form of carbon sequestration and timber products, a
|Contact: Margaret Coulombe|
Arizona State University