Possible Scenarios of Global-Warming Impacts on Evaporation in Mexico

Abstract

We constructed five possible scenarios to define the impacts of global climate change on evaporation and soil-water moisture-content deficiency in the Balsas River, Bravo River, Grijalva River, Lerma River, Panuco River, and Papaloapan River basins in Mexico. They are based on forecasts of the Hadley Centre that predicts for Mexico an increase in air temperature between 3 °C and 5 °C by the end of the twenty-first century. These basins are the most important watersheds in Mexico. We used increases in air temperature 1–5 °C above the current conditions to construct five possible scenarios for two surfaces: water and short grass. Then, we analyzed the impact of each of these five possible scenarios in the potential evaporation and soil-water moisture-content deficiency for both surfaces. The results showed that, with the increases in air temperature, just mentioned, they produced an increase in potential evaporation in open water surfaces of 2.5–12.1% for 1 °C and 5 °C of increase in air temperature, respectively. The evaporation on short-grass surfaces will increase 2.6–12.7% for 1 °C and 5 °C of increase in air temperature, respectively. Soil-water moisture-content deficiency in short-grass surfaces will increase 3.3–16.0% for 1 °C and 5 °C of increase in air temperature, respectively, all of these compared with current values. In the most adverse scenario, reductions in food production in the Bravo River basin will be in the order of 28%, composed of the 16% of additional water demanded by crops plus 12.1% of additional evaporation on surface-water reservoirs located in the watershed.