Any changes the planet experiences in the future could have a profound effect on these regions because there is a close relationship between these ecosystems' health and the weather and water cycle. Intensive hydrologic data have been collected over the past 30 years from part of this basin, ARS' Walnut Gulch Experimental Watershed. This year, the program will concentrate on understanding the San Pedro riparian system on the U.S. side of the border. Scientists will establish baseline data by measuring surface water, groundwater, and transpiration. They'll compare their measurements to readings collected from satellites and aircraft during five overflights through October 1997.
Scientists expect to monitor how humans change the area.
We can already see some evidence from satellite images. The U.S.-Mexico border is clearly visible because of different livestock grazing practices in the two countries. Then a basin-scale hydrological model will integrate these and other variables. Scientists hope the effort will improve how computer models predict the impact of environmental changes on the hydrology and ecology of this and other large basins.