Impact of Climate Change on Salinity and Drainage of Irrigated Lands in Mexico

About 10-40% of all irrigated lands in Mexico are affected by soil salinity at a high to moderate level, with 6 to 9% of irrigated lands having field drainage to control salinity. According to the existing climate change scenarios, a reduction of mean annual precipitation by 10 to 30% and a rise of mean annual air temperature by 2.3±1.0 °C are expected by the middle of the 21st century in the main irrigation regions in the center and northern parts of the country. These changes will reduce the availability of irrigation water by 30% compared to present levels. The objective of our study was to assess how the expected reduction in the availability of irrigation water could influence the salinity of irrigated lands and necessity for field drainage installation. Analysis of national data on the change of irrigated area affected by soil salinity during last years in Mexico and the experience of Aral Sea basin in the Central Asia with similar natural conditions and sufficiently detailed monitoring of the salinity of irrigated lands permitted to conclude that in case of less availability of irrigation water in Mexico the area affected by soil salinity will reach about 20 to 25% of irrigated lands, which means necessity not only to save irrigation water, but also further field drainage installation in large area.