Escenarios de manejo del agua para la cuenca del Rio Grande/Bravo

The actual water planning and management policies of the Rio Grande/Bravo basin no longer respond to the sustainable needs of water users, environment and international commitments of this transboundary basin between Mexico and the United States. As a result of this situation, a group of universities, research centers and NGO's from both countries, such as The University of Texas at Austin and the Mexican Institute of Water Technology (IMTA), made a consortium around a project known as "A physical assessment of the opportunities for improved management of the water resources of the bi-national Rio Grande/Bravo basin" (the Physical Assessment Project). The objective of this project is to examine the hydro-physical opportunities for expanding the beneficial uses of the fixed water supply in the Rio Grande/Bravo basin. The present project is part of this joint effort from the IMTA, The University of Texas at Austin and the Autonomous University of Zacatecas to evaluate the impact of alternative water management policies, called "Scenarios", for the water users of both nations. A basin simulation model for the Rio Grande/Bravo was built in the WEAP software (Water Evaluation And Planning System) developed by the Stockholm Environment Institute. The simulation model includes dams, aquifers, tributary rivers; concessions/water rights; the account of the storage and allocation of treaty obligations; policies, operations and water allocation for both countries. For the evaluation of the Scenarios a reference scenario was developed called the "Baseline Run", that was compared and calibrated with the historical data in the basin. Through a comparison of each scenario's results with the Baseline Run, the advantages or disadvantages were estimated from the implementation of each scenario for water users in both nations and for the treaty obligations. In this report, 12 scenarios are analyzed and evaluated, which include the permanent and temporal buy back of concessions/water rights, ground banking through the In Lieu method; and modernization and improvement of agriculture infrastructure specified in Minute 309 of the IBWC/CILA. In some scenarios the joint result of two or more scenarios working together is evaluated. Moreover, in a particular scenario the extraordinary delivery of water from the San Juan River to the treaty obligations was evaluated, only under deficit conditions of water delivery for treaty obligations. The first part of this report provides the background and the objective of the project. Also, in this section the Physical Assessment Project is described, the participant institutions, as well as the work and contributions made by each member of this consortium. The second part describes the methodology used, which establishes the Baseline Run, defines the parameters of comparison, shows the results for the Baseline Run and specifies the hydrological conditions used in this research. The parameters of comparison used include the mean supply and shortage for different water users; as well as performance criteria indices such as reliability, resilience and vulnerability for certain water large users; mean, minimum and maximum storage for reservoirs and aquifers; mean, minimum and maximum delivery of water for the 6 Mexican tributary rivers established in the 1944 Treaty, by year and by 5 year cycle; among other parameters. The third section shows the development, analysis, and considerations assumed and results for each scenario, as well as their comparison with the Baseline Run. Finally, in the last section the conclusion for each scenario and for the complete research project are presented.