Use of the STELLA model for evaluating prospective urban water-use scenarios in Baja, California, Mexico

In the State of Baja California, Mexico, the main source of water is the Colorado River from the United States. An International Water Treaty signed by Mexico and the United States in 1944 regulates surface waters from three international rivers: Tijuana, Bravo/Grande and Colorado. In this document, the United States guaranteed to deliver to Mexico an annual average volume of 1850 million cubic meters (Mmc). In 1944, this water volume was considered enough to irrigate 100 thousand hectares and to supply urban water needs of 47,000 Mexicali people (Aguirre B. C.1974). Today, with severe increases of demand for urban water, farmers ask for its water. The objective of this study is to determine possible scenarios of future water consumption in the international border of Mexico/United States, to modify main conflict elements, as well as to find alternative solutions to cover the actual water demand. Data was analyzed by using the STELLA model, which included: total surface water, wells system, and water availability from the All American Canal. An equation of hydrological balance was used. The results illustrate that if we do not use water correctly; water availability in the region will be not only be an obstacle for the social and economical development, but also, a potential factor of conflict among users on both sides of the border.