Global warming effects on the water balance in Mexico

In Mexico, agriculture exceeds all other sectors in water use. Irrigation i s the main component of the demand within agriculture. The smallest climati c and meteorological change will affect this water requirement. Small incre ases in temperature would increase the evapotranspiration and the demand fo r irrigation water. For this reason, studies to prevent the potential effec ts of climatic change on agriculture, are important. The results obtained in this study, using the modified radiation model, ser ved to create isolinear potential evapotranspiration maps for Mexico. The a rea most vulnerable to climatic change, as shown by these maps, is the nort hern region of the country, where the increase in water requirements for th e crops will rise in greater proportion than in other regions. This increas e could reach an annual average of 8% for the critical temperature rises an alyzed (+3 degrees C), as proposed by the Inter-governmental Panel on Clima tic Change. Although the study results are indicative, they may be useful i n planning, designing and operating irrigation districts and hydraulic work s in the future.