Hydrological elements for ecosystem conservation: a comprehensive water
management for a binational wetland in the arid northwest of Mexico.
Abstract
The water agreements between Mexico and the United States have been
crucial to restore and preserve the wetlands of the Colorado River
Delta. Nowadays, the increase of water demand and climate change in the
northwest of Mexico could threaten the conservation of the Cienega de
Santa Clara, a coastal wetland composed of 4,709 ha of marsh area in the
limits of the Sonoran Desert. This ecosystem was recognized
internationally by the international Ramsar convention for playing vital
ecological roles, including the habitat service for endemic, endangered
and migratory species. Since the inflow reductions by the trial run of
the Yuma Desalting Plant during 2010-2011, and earlier events, the
hydrology of the wetland has not been completely understanding due to
accessibility. Therefore this study was conducted to obtaining the
hydrological elements to conserve the wetland, analyzing three
scenarios: 1] normal inflow conditions of the Wellton-Mohawk canal;
2] inflow reductions, and; 3] an increase of temperature in
consequence of global warming. Water and mass balances were conducted
every month during one year; in-situ measurements of inflows were
carried out on Wellton-Mohawk, Riíto Drain, groundwater, and
precipitation; also were including evapotranspiration outputs estimated
using local weather registers and Penman-Monteith formulations. The
implications of the increase in temperature considered include the
Intergovernmental Panel on Climate Change projections for the one
hundred years. Finally, the results showed superficial water
disconnections between the hydrological system of the wetland and the
Gulf of California. This behavior was observed in the three scenarios,
mainly in the summer months. A continuous disconnection reduced the
wetland area and the water storage. Therefore, the hydrological
functionality of the wetland depends on the water supply thru
Wellton-Mohawk canal, which was determinate that at least a continuous
discharge of 5.10 m3 s-1 during
summer months is needed to maintain its functionality.