Rio Sonora is situated in Sonora state in northwest
Mexico. The main branch of the river is approximately 300 km long
and the river's watershed covers a total area of 29,000 km2.
The average precipitation in the watershed is 412 mm/year, with a
maximum of 552 mm/year in the northern, mountainous region and a minimum
of 268 mm/year in the terminus of the watershed, where the state's
largest city, Hermosillo, is located. Flows in the river near Hermosillo
range from near zero in the late spring/early summer, to 16 m3/s on
the "wet" months.
The Rio Sonora watershed, along with the entire state
of Sonora, has experienced drought conditions for a decade. One of
the consequences of the drought is than the only surface water reservoir
for the city of Hermosillo has been empty for four years.
The tour covered the length of the Rio Sonora, from
its terminus in the city of Hermosillo to its source near Cananea,
where the largest copper mine in Mexico is located. The course studied
how flows in the river are managed and what the sources of the water
quality problems are in the basin. Students learned about the difficulties
of managing a watershed under intensive pressures from growing municipal
populations and expanding industry.They visited the Coste de Hermosillo
region, which is a coastal basin that has experienced intensive groundwater
pumping for irrigation, resulting in severe saltwater intrusion problems